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Sample records for amorphous-nanocrystalline silicon thin

  1. Electronic transport in mixed-phase hydrogenated amorphous/nanocrystalline silicon thin films

    Science.gov (United States)

    Wienkes, Lee Raymond

    Interest in mixed-phase silicon thin film materials, composed of an amorphous semiconductor matrix in which nanocrystalline inclusions are embedded, stems in part from potential technological applications, including photovoltaic and thin film transistor technologies. Conventional mixed-phase silicon films are produced in a single plasma reactor, where the conditions of the plasma must be precisely tuned, limiting the ability to adjust the film and nanoparticle parameters independently. The films presented in this thesis are deposited using a novel dual-plasma co-deposition approach in which the nanoparticles are produced separately in an upstream reactor and then injected into a secondary reactor where an amorphous silicon film is being grown. The degree of crystallinity and grain sizes of the films are evaluated using Raman spectroscopy and X-ray diffraction respectively. I describe detailed electronic measurements which reveal three distinct conduction mechanisms in n-type doped mixed-phase amorphous/nanocrystalline silicon thin films over a range of nanocrystallite concentrations and temperatures, covering the transition from fully amorphous to ~30% nanocrystalline. As the temperature is varied from 470 to 10 K, we observe activated conduction, multiphonon hopping (MPH) and Mott variable range hopping (VRH) as the nanocrystal content is increased. The transition from MPH to Mott-VRH hopping around 100K is ascribed to the freeze out of the phonon modes. A conduction model involving the parallel contributions of these three distinct conduction mechanisms is shown to describe both the conductivity and the reduced activation energy data to a high accuracy. Additional support is provided by measurements of thermal equilibration effects and noise spectroscopy, both done above room temperature (>300 K). This thesis provides a clear link between measurement and theory in these complex materials.

  2. Amorphous-nanocrystalline Al doped ZnO transparent conducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Diez-Betriu, X., E-mail: xdiezbetriu@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco 28049 Madrid (Spain); Jimenez-Rioboo, R.; Marcos, J. Sanchez-; Cespedes, E.; Espinosa, A.; Andres, A. de [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco 28049 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Al- doped ZnO films by RF- sputtering as amorphous TCO. Black-Right-Pointing-Pointer Structural characterization confirms amorphous-nanocrystalline nature of samples. Black-Right-Pointing-Pointer Optical gap dependence on substrate and grain size. Black-Right-Pointing-Pointer Resistivity correlates to the optical bandgap. - Abstract: Al-doped ZnO films have been deposited at room temperature by means of RF sputtering under different conditions and subjected to annealing treatments looking for amorphous Transparent Conducting Oxide (TCO) films in the search for their integration into the emerging area of the flexible electronics. Structural studies have been performed as well as optical and electrical characterization. Spectroscopic ellipsometry has been used for the determination of the optical gap for films grown on Si and the films thickness. The amorphous fraction of the films (up to 86%) depends on the substrate and RF power but not on the annealing temperature up to 600 Degree-Sign C for glass substrates. The resistivity is found to be independent of the amorphous degree and correlates to the optical bandgap which presents three regimes depending on the annealing temperature.

  3. Very high frequency plasma deposited amorphous/nanocrystalline silicon tandem solar cells on flexible substrates

    Science.gov (United States)

    Liu, Y.

    2010-02-01

    The work in this thesis is to develop high quality intrinsic layers (especially nc-Si:H) for micromorph silicon tandem solar cells/modules on plastic substrates following the substrate transfer method or knows as the Helianthos procedure. Two objectives are covered in this thesis: (1) preliminary work on trial and optimization of single junction and tandem cells on glass substrate, (2) silicon film depositions on Al foil, and afterwards the characterization and development of these cells/modules on a plastic substrate. The first objective includes the development of suitable ZnO:Al TCO for nc Si:H single junction solar cells, fabrication of the aimed micromorph tandem solar cells on glass, and finally the optimization of the nc-Si:H i-layer for the depositions afterwards on Al foil. Chapter 3 addresses the improvement of texture etching of ZnO:Al by studying the HCl etching effect on ZnO:Al films sputter-deposited in a set substrate heater temperature series. With the texture-etched ZnO:Al front TCO, a single junction nc-Si:H solar cell was deposited with an initial efficiency of 8.33%. Chapter 4 starts with studying the light soaking and annealing effects on micromorph tandem solar cell. In the end, a highly stabilized bottom cell current limited tandem cell was made. The tandem shows an initial efficiency of 10.2%, and degraded only 6.9% after 1600 h of light soaking. In Chapter 5, the nc-Si:H i-layers were studied in 3 pressure and inter-electrode distance series. The correlations between plasma physics and the consequent i-layers’ properties are investigated. We show that the Raman crystalline ratio and porosity of the nc-Si:H layer have an interesting relation with the p•d product. By varying p and d, device quality nc-Si:H layer can be deposited at a high rate of 0.6 nm/s. These results in fact are a very important step for the second objective. The second objective is covered by the entire Chapter 6. All silicon layers are deposited on special aluminum

  4. Highly flexible resistive switching memory based on amorphous-nanocrystalline hafnium oxide films.

    Science.gov (United States)

    Shang, Jie; Xue, Wuhong; Ji, Zhenghui; Liu, Gang; Niu, Xuhong; Yi, Xiaohui; Pan, Liang; Zhan, Qingfeng; Xu, Xiao-Hong; Li, Run-Wei

    2017-06-01

    Flexible and transparent resistive switching memories are highly desired for the construction of portable and even wearable electronics. Upon optimization of the microstructure wherein an amorphous-nanocrystalline hafnium oxide thin film is fabricated, an all-oxide based transparent RRAM device with stable resistive switching behavior that can withstand a mechanical tensile stress of up to 2.12% is obtained. It is demonstrated that the superior electrical, thermal and mechanical performance of the ITO/HfOx/ITO device can be ascribed to the formation of pseudo-straight metallic hafnium conductive filaments in the switching layer, and is only limited by the choice of electrode materials. When the ITO bottom electrode is replaced with platinum metal, the mechanical failure threshold of the device can be further extended.

  5. Investigation on Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The preparation, current status and trends are investigated for silicon thin film solar cells. The advantages and disadvantages of amorphous silicon thin film, polycrystalline silicon thin film and mono-crystalline silicon thin film solar cells are compared. The future development trends are pointed out. It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.

  6. Thin-film crystalline silicon solar cells

    CERN Document Server

    Brendel, Rolf

    2011-01-01

    This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

  7. Corrosion behavior of amorphous/nanocrystalline Al-Cr-Fe film deposited by double glow plasmas technique

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In order to improve the corrosion resistance of AZ31 magnesium alloy,the amorphous/nanocrystal Al-Cr-Fe film has been successfully prepared on AZ31 magnesium alloy by double glow plasma tech-nology.The amorphous/nanocrystalline consists of two different regions,i.e.,an amorphous layer on outmost surface and an underlying lamellar nanocrystalline layer with a grain size of less than 10 nm.The corrosion behavior of amorphous/nanocrystalline Al-Cr-Fe film in 3.5% NaCl solution is investi-gated using an electrochemical polarization measurement.Compared with the AZ31 magnesium alloy,the amorphous/nanocrystalline Al-Cr-Fe film exhibits more positive corrosion potentials and lower corrosion current densities than that of AZ31 magnesium alloy.XPS measurement reveals that the passive film formed on the Al-Cr-Fe film after the anodic polarization tests is strongly enriched in Cr2O3,Fe2O3 and Al2O3 at outer surface of the film and in the inner layer consists of Cr2O3,FeO and Al2O3.

  8. The effect of amorphous nanocrystalline inoculants on structures and properties of high speed steel

    Science.gov (United States)

    Zhao, Jianyong; Cui, Chunxiang; Zhang, Qiangxiong; Bai, Lina

    2017-06-01

    High speed steel (HSS) is widely used in the production of high-speed cutting tools and roll etc, and the modification method is an effective approach for improving the microstructure and properties of HSS. Fe-Al-Cr-Nb-C-N amorphous nanocrystalline inoculants were fabricated using the method of in situ reaction and rapid solidification. The phase compositions of Fe-Al-Cr-Nb-C-N inoculants were analyzed. And the effect of inoculants on structures and properties of AISI T1 HSS was studied. The results show that the inoculant is a mixture of amorphous and nanometer crystal, and Fe-Al(-Cr) intermetallic compounds are the matrix phases of inoculant, while particulate nitride, carbide and oxide are the important precipitation. After modification, the quenching and tempering microstructure of HSS has been refined significantly. The carbides contents increase and the sizes of carbides decrease in HSS. The hardness, red-hardness, wear resistance and impact toughness of T1 HSS were also improved obviously after modification.

  9. Investigation of Amorphous/Nanocrystalline Iron-Based Thermal Barrier Coatings

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Königstein, T.

    2017-02-01

    Because of their favorable thermophysical properties, good machinability and low material costs, iron-based coatings which exhibit a highly amorphous/nanocrystalline microstructure are currently in the focus of research. Considering the crystallization temperature of the material, iron-based coatings might be the next generation of thermal barrier coatings (TBCs) for low-temperature systems, reducing thermal losses. The objective of this research project is the development of highly amorphous, iron-based coatings. For this purpose, amorphous feedstock materials with different chromium contents have been developed and characterized regarding their microstructures, phase compositions, crystallization temperatures and amorphous content. The results show that the amorphous content is reduced with increasing particle size and chromium content. The coatings were deposited by air plasma spraying (APS) and high-velocity oxygen fuel spraying (HVOF). It is shown that all coatings exhibit amorphous structures. HVOF coatings show a smaller amount of amorphous content compared to the feedstock materials, indicating crystallization occurring in not fully melted particles or insufficient rapid cooling. The APS process can increase the amount of amorphous content compared to the feedstock material, as shown for x Cr = 15%. All coatings proof good thermal shock behavior. Lowest thermal diffusivity values were determined for APS coatings, which confirms the potential of iron-based TBCs.

  10. Investigation of Amorphous/Nanocrystalline Iron-Based Thermal Barrier Coatings

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Königstein, T.

    2017-01-01

    Because of their favorable thermophysical properties, good machinability and low material costs, iron-based coatings which exhibit a highly amorphous/nanocrystalline microstructure are currently in the focus of research. Considering the crystallization temperature of the material, iron-based coatings might be the next generation of thermal barrier coatings (TBCs) for low-temperature systems, reducing thermal losses. The objective of this research project is the development of highly amorphous, iron-based coatings. For this purpose, amorphous feedstock materials with different chromium contents have been developed and characterized regarding their microstructures, phase compositions, crystallization temperatures and amorphous content. The results show that the amorphous content is reduced with increasing particle size and chromium content. The coatings were deposited by air plasma spraying (APS) and high-velocity oxygen fuel spraying (HVOF). It is shown that all coatings exhibit amorphous structures. HVOF coatings show a smaller amount of amorphous content compared to the feedstock materials, indicating crystallization occurring in not fully melted particles or insufficient rapid cooling. The APS process can increase the amount of amorphous content compared to the feedstock material, as shown for x Cr = 15%. All coatings proof good thermal shock behavior. Lowest thermal diffusivity values were determined for APS coatings, which confirms the potential of iron-based TBCs.

  11. Studies of silicon carbide and silicon carbide nitride thin films

    Science.gov (United States)

    Alizadeh, Zhila

    Silicon carbide semiconductor technology is continuing to advance rapidly. The excellent physical and electronic properties of silicon carbide recently take itself to be the main focused power device material for high temperature, high power, and high frequency electronic devices because of its large band gap, high thermal conductivity, and high electron saturation drift velocity. SiC is more stable than Si because of its high melting point and mechanical strength. Also the understanding of the structure and properties of semiconducting thin film alloys is one of the fundamental steps toward their successful application in technologies requiring materials with tunable energy gaps, such as solar cells, flat panel displays, optical memories and anti-reflecting coatings. Silicon carbide and silicon nitrides are promising materials for novel semiconductor applications because of their band gaps. In addition, they are "hard" materials in the sense of having high elastic constants and large cohesive energies and are generally resistant to harsh environment, including radiation. In this research, thin films of silicon carbide and silicon carbide nitride were deposited in a r.f magnetron sputtering system using a SiC target. A detailed analysis of the surface chemistry of the deposited films was performed using x-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy whereas structure and morphology was studied atomic force microscopy (AFM), and nonoindentation.

  12. Amorphous silicon for thin-film transistors

    NARCIS (Netherlands)

    Schropp, Rudolf Emmanuel Isidore

    1987-01-01

    Hydrogenated amorphous silicon (a-Si:H) has considerable potential as a semiconducting material for large-area photoelectric and photovoltaic applications. Moreover, a-Si:H thin-film transistors (TFT’s) are very well suited as switching devices in addressable liquid crystal display panels and addres

  13. PREPARATION AND CHARACTERIZATION OF POLY-CRYSTALLINE SILICON THIN FILM

    Institute of Scientific and Technical Information of China (English)

    Y.F. Hu; H. Shen; Z.Y. Liu; L.S. Wen

    2003-01-01

    Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells.In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6. 05% without anti-reflection coating.

  14. Thin Silicon MEMS Contact-Stress Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kotovsky, J; Tooker, A; Horsley, D

    2010-03-22

    This thin, MEMS contact-stress (CS) sensor continuously and accurately measures time-varying, solid interface loads in embedded systems over tens of thousands of load cycles. Unlike all other interface load sensors, the CS sensor is extremely thin (< 150 {micro}m), provides accurate, high-speed measurements, and exhibits good stability over time with no loss of calibration with load cycling. The silicon CS sensor, 5 mm{sup 2} and 65 {micro}m thick, has piezoresistive traces doped within a load-sensitive diaphragm. The novel package utilizes several layers of flexible polyimide to mechanically and electrically isolate the sensor from the environment, transmit normal applied loads to the diaphragm, and maintain uniform thickness. The CS sensors have a highly linear output in the load range tested (0-2.4 MPa) with an average accuracy of {+-} 1.5%.

  15. Thin Silicon MEMS Contact-Stress Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Kotovsky, J; Tooker, A; Horsley, D A

    2009-12-07

    This work offers the first, thin, MEMS contact-stress (CS) sensor capable of accurate in situ measruement of time-varying, contact-stress between two solid interfaces (e.g. in vivo cartilage contact-stress and body armor dynamic loading). This CS sensor is a silicon-based device with a load sensitive diaphragm. The diaphragm is doped to create piezoresistors arranged in a full Wheatstone bridge. The sensor is similar in performance to established silicon pressure sensors, but it is reliably produced to a thickness of 65 {micro}m. Unlike commercial devices or other research efforts, this CS sensor, including packaging, is extremely thin (< 150 {micro}m fully packaged) so that it can be unobtrusively placed between contacting structures. It is built from elastic, well-characterized materials, providing accurate and high-speed (50+ kHz) measurements over a potential embedded lifetime of decades. This work explored sensor designs for an interface load range of 0-2 MPa; however, the CS sensor has a flexible design architecture to measure a wide variety of interface load ranges.

  16. Polycystalline silicon thin films for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Christian Claus

    2012-01-15

    For the thin polycrystalline Si films fabricated with the aluminium-induced-layer-exchange (ALILE) process a good structural quality up to a layer-thickness value of 10 nm was determined. For 5 nm thick layers however after the layer exchange no closes poly-silicon film was present. In this case the substrate was covered with spherically arranged semiconductor material. Furthermore amorphous contributions in the layer could be determined. The electrical characterization of the samples at room temperature proved a high hole concentration in the range 10{sup 18} cm{sup -3} up to 9.10{sup 19} cm{sup -3}, which is influenced by the process temperature and the layer thickness. Hereby higher hole concentrations at higher process temperatures and thinner films were observed. Furthermore above 150-200 K a thermically activated behaviour of the electrical conductivity was observed. At lower temperatures a deviation of the measured characteristic from the exponential Arrhenius behaviour was determined. For low temperatures (below 20 K) the conductivity follows the behaviour {sigma}{proportional_to}[-(T{sub 0}/T){sup 1/4}]. The hole mobility in the layers was lowered by a passivation step, which can be explained by defect states at the grain boundaries. The for these very thin layers present situation was simulated in the framework of the model of Seto, whereby both the defect states at the grain boundaries (with an area density Q{sub t}) and the defect states at the interfaces (with an area density Q{sub it}) were regarded. By this the values Q{sub t}{approx}(3-4).10{sup 12} cm{sup -2} and Q{sub it}{approx}(2-5).10{sup 12} cm{sup -2} could be determined for these thin ALILE layers on quartz substrates. Additionally th R-ALILE process was studied, which uses the reverse precursor-layer sequence substrate/amorphous silicon/oxide/aluminium. Hereby two steps in the crystallization process of the R-ALILE process were found. First a substrate/Al-Si mixture/poly-Si layer structure

  17. Amorphous molybdenum silicon superconducting thin films

    Directory of Open Access Journals (Sweden)

    D. Bosworth

    2015-08-01

    Full Text Available Amorphous superconductors have become attractive candidate materials for superconducting nanowire single-photon detectors due to their ease of growth, homogeneity and competitive superconducting properties. To date the majority of devices have been fabricated using WxSi1−x, though other amorphous superconductors such as molybdenum silicide (MoxSi1−x offer increased transition temperature. This study focuses on the properties of MoSi thin films grown by magnetron sputtering. We examine how the composition and growth conditions affect film properties. For 100 nm film thickness, we report that the superconducting transition temperature (Tc reaches a maximum of 7.6 K at a composition of Mo83Si17. The transition temperature and amorphous character can be improved by cooling of the substrate during growth which inhibits formation of a crystalline phase. X-ray diffraction and transmission electron microscopy studies confirm the absence of long range order. We observe that for a range of 6 common substrates (silicon, thermally oxidized silicon, R- and C-plane sapphire, x-plane lithium niobate and quartz, there is no variation in superconducting transition temperature, making MoSi an excellent candidate material for SNSPDs.

  18. Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Guy Beaucarne

    2007-01-01

    with plasma-enhanced chemical vapor deposition (PECVD. In spite of the fundamental limitation of this material due to its disorder and metastability, the technology is now gaining industrial momentum thanks to the entry of equipment manufacturers with experience with large-area PECVD. Microcrystalline Si (also called nanocrystalline Si is a material with crystallites in the nanometer range in an amorphous matrix, and which contains less defects than amorphous silicon. Its lower bandgap makes it particularly appropriate as active material for the bottom cell in tandem and triple junction devices. The combination of an amorphous silicon top cell and a microcrystalline bottom cell has yielded promising results, but much work is needed to implement it on large-area and to limit light-induced degradation. Finally thin-film polysilicon solar cells, with grain size in the micrometer range, has recently emerged as an alternative photovoltaic technology. The layers have a grain size ranging from 1 μm to several tens of microns, and are formed at a temperature ranging from 600 to more than 1000∘C. Solid Phase Crystallization has yielded the best results so far but there has recently been fast progress with seed layer approaches, particularly those using the aluminum-induced crystallization technique.

  19. Electroless plating of thin gold films directly onto silicon nitride thin films and into micropores.

    Science.gov (United States)

    Whelan, Julie C; Karawdeniya, Buddini Iroshika; Bandara, Y M Nuwan D Y; Velleco, Brian D; Masterson, Caitlin M; Dwyer, Jason R

    2014-07-23

    A method to directly electrolessly plate silicon-rich silicon nitride with thin gold films was developed and characterized. Films with thicknesses plating free-standing ultrathin silicon nitride membranes, and we successfully plated the interior walls of micropore arrays in 200 nm thick silicon nitride membranes. The method is thus amenable to coating planar, curved, and line-of-sight-obscured silicon nitride surfaces.

  20. Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/nanocrystalline coatings.

    Science.gov (United States)

    Qiao, Lei; Wu, Yuping; Hong, Sheng; Zhang, Jianfeng; Shi, Wei; Zheng, Yugui

    2017-11-01

    Fe-based amorphous/nanocrystalline coatings were prepared on the AISI 321 steel substrate by the high-velocity oxygen-fuel (HVOF) thermal spraying technology. The effect of selected parameters (oxygen flow, kerosene flow and spray distance) on the cavitation erosion resistance (denoted as Rc) of the coating were investigated by using the Taguchi method. Statistical tools such as design of experiments (DOE), signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to meet the expected objective. It was concluded that the kerosene flow had greater influence on the Rc of the coating and followed by the spray distance and the oxygen flow, respectively. The optimum spray parameters (OSP) were 963L/min for the oxygen flow, 28L/h for the kerosene flow, and 330mm for the spray distance. The Rc of the coating increased with the increase of hardness or the decrease of porosity, and the hardness had a greater influence on Rc than the porosity. The Fe-based coating deposited under the OSP exhibited the best cavitation erosion resistance in distilled water. The cracks initiated at the edge of the pores and the interfaces between the un-melted or half-melted particles, and finally leaded to the delamination of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Laser process for extended silicon thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hessmann, M.T., E-mail: hessmann@zae.uni-erlangen.de [Bavarian Center for Applied Energy Research, Am Weichselgarten 7, 91058 Erlangen (Germany); Kunz, T.; Burkert, I.; Gawehns, N. [Bavarian Center for Applied Energy Research, Am Weichselgarten 7, 91058 Erlangen (Germany); Schaefer, L.; Frick, T.; Schmidt, M. [Bayerisches Laserzentrum, Konrad-Zuse-Str 2-6, 91052 Erlangen (Germany); Meidel, B. [Schott Solar AG, Carl-Zeiss-Strasse 4, 63755 Alzenau (Germany); Auer, R. [Bavarian Center for Applied Energy Research, Am Weichselgarten 7, 91058 Erlangen (Germany); Brabec, C.J. [Bavarian Center for Applied Energy Research, Am Weichselgarten 7, 91058 Erlangen (Germany); Chair VI - Materials for Electronics and Energy Technology, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen (Germany)

    2011-10-31

    We present a large area thin film base substrate for the epitaxy of crystalline silicon. The concept of epitaxial growth of silicon on large area thin film substrates overcomes the area restrictions of an ingot based monocrystalline silicon process. Further it opens the possibility for a roll to roll process for crystalline silicon production. This concept suggests a technical pathway to overcome the limitations of silicon ingot production in terms of costs, throughput and completely prevents any sawing losses. The core idea behind these thin film substrates is a laser welding process of individual, thin silicon wafers. In this manuscript we investigate the properties of laser welded monocrystalline silicon foils (100) by micro-Raman mapping and spectroscopy. It is shown that the laser beam changes the crystalline structure of float zone grown silicon along the welding seam. This is illustrated by Raman mapping which visualizes compressive stress as well as tensile stress in a range of - 147.5 to 32.5 MPa along the welding area.

  2. Light management in thin-film silicon solar cells

    NARCIS (Netherlands)

    Isabella, O.

    2013-01-01

    Solar energy can fulfil mankind’s energy needs and secure a more balanced distribution of primary sources of energy. Wafer-based and thin-film silicon solar cells dominate todays’ photovoltaic market because silicon is a non-toxic and abundant material and high conversion efficiencies are achieved

  3. Light management in thin-film silicon solar cells

    NARCIS (Netherlands)

    Isabella, O.

    2013-01-01

    Solar energy can fulfil mankind’s energy needs and secure a more balanced distribution of primary sources of energy. Wafer-based and thin-film silicon solar cells dominate todays’ photovoltaic market because silicon is a non-toxic and abundant material and high conversion efficiencies are achieved

  4. Additives to silane for thin film silicon photovoltaic devices

    Science.gov (United States)

    Hurley, Patrick Timothy; Ridgeway, Robert Gordon; Hutchison, Katherine Anne; Langan, John Giles

    2013-09-17

    Chemical additives are used to increase the rate of deposition for the amorphous silicon film (.alpha.Si:H) and/or the microcrystalline silicon film (.mu.CSi:H). The electrical current is improved to generate solar grade films as photoconductive films used in the manufacturing of Thin Film based Photovoltaic (TFPV) devices.

  5. Material Properties of Laser-Welded Thin Silicon Foils

    Directory of Open Access Journals (Sweden)

    M. T. Hessmann

    2013-01-01

    Full Text Available An extended monocrystalline silicon base foil offers a great opportunity to combine low-cost production with high efficiency silicon solar cells on a large scale. By overcoming the area restriction of ingot-based monocrystalline silicon wafer production, costs could be decreased to thin film solar cell range. The extended monocrystalline silicon base foil consists of several individual thin silicon wafers which are welded together. A comparison of three different approaches to weld 50 μm thin silicon foils is investigated here: (1 laser spot welding with low constant feed speed, (2 laser line welding, and (3 keyhole welding. Cross-sections are prepared and analyzed by electron backscatter diffraction (EBSD to reveal changes in the crystal structure at the welding side after laser irradiation. The treatment leads to the appearance of new grains and boundaries. The induced internal stress, using the three different laser welding processes, was investigated by micro-Raman analysis. We conclude that the keyhole welding process is the most favorable to produce thin silicon foils.

  6. Advantages of thin silicon solar cells for use in space

    Science.gov (United States)

    Denman, O. S.

    1978-01-01

    A system definition study on the Solar Power Satellite System showed that a thin, 50 micrometers, silicon solar cell has significant advantages. The advantages include a significantly lower performance degradation in a radiation environment and high power-to-mass ratios. The advantages of such cells for an employment in space is further investigated. Basic questions concerning the operation of solar cells are considered along with aspects of radiation induced performance degradation. The question arose in this connection how thin a silicon solar cell had to be to achieve resistance to radiation degradation and still have good initial performance. It was found that single-crystal silicon solar cells could be as thin as 50 micrometers and still develop high conversion efficiencies. It is concluded that the use of 50 micrometer silicon solar cells in space-based photovoltaic power systems would be advantageous.

  7. Solar cell fabricated on welded thin flexible silicon

    Directory of Open Access Journals (Sweden)

    Hessmann Maik Thomas

    2015-01-01

    Full Text Available We present a thin-film crystalline silicon solar cell with an AM1.5 efficiency of 11.5% fabricated on welded 50 μm thin silicon foils. The aperture area of the cell is 1.00 cm2. The cell has an open-circuit voltage of 570 mV, a short-circuit current density of 29.9 mA cm-2 and a fill factor of 67.6%. These are the first results ever presented for solar cells on welded silicon foils. The foils were welded together in order to create the first thin flexible monocrystalline band substrate. A flexible band substrate offers the possibility to overcome the area restriction of ingot-based monocrystalline silicon wafers and the feasibility of a roll-to-roll manufacturing. In combination with an epitaxial and layer transfer process a decrease in production costs can be achieved.

  8. Analysis of the silicon market: Will thin films profit?

    Energy Technology Data Exchange (ETDEWEB)

    Sark, W.G.J.H.M. van; Brandsen, G.W. [Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Utrecht (Netherlands). Department of Science, Technology and Society; Fleuster, M. [Solland Solar Energy, Heerlen (Netherlands); Hekkert, M.P. [Copernicus Institute for Sustainable Development and Innovation, Utrecht University, Utrecht (Netherlands). Department of Innovation Studies

    2007-06-15

    The photovoltaic industry has been growing with astonishing rates over the past years. The supply of silicon to the wafer-based industry has recently become a problem. This paper presents a thorough analysis of the PV industry and quantifies the silicon shortage. It is expected that this leads to a decrease in production in 2006 rather than the usual increase. Due to a mismatch in expansion plans of silicon feedstock manufacturers and solar cell manufacturers, a large cell overcapacity will persist up to 2010. The thin-film PV market is expected to profit from the silicon shortage problem; its market share may substantially increase to about 25% in 2010. (author)

  9. Buried contact multijunction thin film silicon solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Green, M. [Univ. of New South Wales, Sydney (Australia)

    1995-08-01

    In early 1994, the Center for Photovoltaic Devices and Systems announced the filing of patent applications on an improved silicon thin film photovoltaic module approach. With material costs estimated to be about 20 times lower than those in present silicon solar cell modules along with other production advantages, this technology appears likely to make low cost, high performance solar modules available for the first time. This paper describes steps involved in making a module and module performance.

  10. Magnetocaloric effect in high Gd content Gd-Fe-Al based amorphous/nanocrystalline systems with enhanced Curie temperature and refrigeration capacity

    Directory of Open Access Journals (Sweden)

    Linlin Zhang

    2016-03-01

    Full Text Available The Gd-Fe-Al amorphous/nanocrystalline composites were successfully designed and obtained with both high Curie temperature (Tc and large magnetic entropy change (ΔSM. The Tc can be tuned from 172 to 280 K and refrigeration capacity (RC has a value between 690 and 867 J/kg under a field change of 0–5 T by changing the Gd contents and the formation of Gd nanocrystallites. And, ΔSM in Gd-Fe-Al amorphous/nanocrystalline composites reached a value of 7.2 J kg−1 K−1 under a field change of 0–5 T. The high RC in Gd-Fe-Al system were ascribed to the widening full width at half maximum (δFWHM up to 240 K of the magnetic entropy change (ΔSMmax peak because of the combination contribution of amorphous matrix and the precipitated Gd-riched nanocrystalline. Our research would shed light on how to design attractive candidates for magnetic refrigeration materials with high performance at near room temperature.

  11. Thin-film silicon for flexible metal-air batteries.

    Science.gov (United States)

    Garamoun, Ahmed; Schubert, Markus B; Werner, Jürgen H

    2014-12-01

    Due to its high energy density, theoretical studies propose silicon as a promising candidate material for metal-air batteries. Herein, for the first time, experimental results detail the use of n-type doped amorphous silicon and silicon carbide as fuel in Si-air batteries. Thin-film silicon is particularly interesting for flexible and rolled batteries with high specific energies. Our Si-air batteries exhibit a specific capacity of 269 Ah kg(-1) and an average cell voltage of 0.85 V at a discharge current density of 7.9 μA cm(-2) , corresponding to a specific energy of 229 Wh kg(-1) . Favorably in terms of safety, low concentrated alkaline solution serves as electrolyte. Discharging of the Si-air cells continues as long as there is silicon available for oxidation.

  12. Silicon Field Emission Arrays Coated with CNx Thin Films

    Institute of Scientific and Technical Information of China (English)

    Chen Min-gan; Chen Ming-an; Li Jin-chai; Li Jin-chai; Liu Chuan-sheng; Liu Chuan-sheng; Ma You-peng; Ma You-peng; Lu Xian-feng; Lu Xian-feng; Ye Ming-sheng; Ye Ming-sheng

    2003-01-01

    Arrays of silicon micro-tips were made by etching the p-type (1 0 0) silicon wafers which had SiO2 masks with alkaline solution. The density of the micro-tips is 2 ×104 cm-2. The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly.The CNx thin film, with the thickness of 1.27μm was deposited on the silicon micro-tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X-ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12.6 % and O: 17.9 %. The silicon arrays coated with CNx thin films had shown a good field emission characterization. The emission current intensity reached 3.2 mA/cm2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CNx thin films are likely to be good field emission cathode.The preparation and the characterization of the samples were discussed in detail.

  13. Silicon Field Emission Arrays Coated with CNx Thin Films

    Institute of Scientific and Technical Information of China (English)

    ChertMing-an; LiJin-chai; LiuChuan-sheng; MaYou-peng; LuXlan-feng; YeMing-sheng

    2003-01-01

    Arrays of silicon micro-tips were made by etching the p-type (1 0 0) silicon wafers which had SiO2 masks with alkaline solution. The density of the micro-tips is 2 ×104 cm-2. The Scanning Electron Microscope (SEM) photos showed that the tips in these arrays are uniform and orderly.The CNx thin film, with the thickness of 1.27μm was deposited on the silicon micro-tip arrays by using the middle frequency magnetron sputtering technology. The SEM photos showed that the films on the tips are smoothly without particles. Keeping the sharpness of the tips will benefit the properties of field emission. The X-ray photoelectron spectrum (XPS) showed that carbon, nitrogen and oxygen are the three major elements in the surfaces of the films. The percents of them are C: 69.5 %, N: 12. 6 % and O: 17.9 %. The silicon arrays coated with CNx thin films had shown a good field emission characterization. The emission current intensity reached 3. 2 mA/cm2 at 32.8 V/μm, so it can be put into use. The result showed that the silicon arrays coated with CNx thin films are likely to be good field emission cathode.The preparation and the characterization of the samples were discussed in detail.

  14. Transparent conducting oxide layers for thin film silicon solar cells

    NARCIS (Netherlands)

    Rath, J.K.|info:eu-repo/dai/nl/304830585; Liu, Y.|info:eu-repo/dai/nl/304831743; de Jong, M.M.|info:eu-repo/dai/nl/325844208; de Wild, J.|info:eu-repo/dai/nl/314641378; Schuttauf, J.A.|info:eu-repo/dai/nl/314118039; Brinza, M.|info:eu-repo/dai/nl/304823325; Schropp, R.E.I.|info:eu-repo/dai/nl/072502584

    2009-01-01

    Texture etching of ZnO:1%Al layers using diluted HCl solution provides excellent TCOs with crater type surface features for the front contact of superstrate type of thin film silicon solar cells. The texture etched ZnO:Al definitely gives superior performance than Asahi SnO2:F TCO in case of nanocry

  15. Transparent conductive oxides for thin-film silicon solar cells

    NARCIS (Netherlands)

    Löffler, J.

    2005-01-01

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses,

  16. Transparent conductive oxides for thin-film silicon solar cells

    NARCIS (Netherlands)

    Löffler, J.

    2005-01-01

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses,

  17. Compositional analysis of silicon oxide/silicon nitride thin films

    Directory of Open Access Journals (Sweden)

    Meziani Samir

    2016-06-01

    Full Text Available Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx films were grown on multicrystalline silicon (mc-Si substrate by plasma enhanced chemical vapour deposition (PECVD in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON structure. Secondary ion mass spectroscopy (SIMS, Rutherford backscattering spectroscopy (RBS, Auger electron spectroscopy (AES and energy dispersive X-ray analysis (EDX were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.

  18. Spectroscopic ellipsometry characterization of thin-film silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Jellison, G.E. Jr.; Modine, F.A. [Oak Ridge National Lab., TN (United States); Doshi, P.; Rohatgi, A. [Georiga Inst. of Technology, Atlanta, GA (United States)

    1997-05-01

    We have measured and analyzed the optical characteristics of a series of silicon nitride thin films prepared by plasma-enhanced chemical vapor deposition on silicon substrates for photovoltaic applications. Spectroscopic ellipsometry measurements were made by using a two-channel spectroscopic polarization modulator ellipsometer that measures N, S, and C data simultaneously. The data were fit to a model consisting of air / roughness / SiN / crystalline silicon. The roughness was modeled using the Bruggeman effective medium approximation, assuming 50% SiN, 50% voids. The optical functions of the SiN film were parameterized using a model by Jellison and Modine. All the {Chi}{sup 2} are near 1, demonstrating that this model works extremely well for all SiN films. The measured dielectric functions were used to make optimized SiN antireflection coatings for crystalline silicon solar cells.

  19. Thin buried oxide in oxygen-implanted silicon

    Energy Technology Data Exchange (ETDEWEB)

    Spaggiari, C.; Bertoni, S.; Cerofolini, G.F.; Fumagalli, P.; Meda, L. (Istituto Guido Donegani, Novara (Italy))

    1993-01-01

    SiO[sub 2] precipitation in oxygen-supersaturated silicon was studied. Oxygen was inserted by ion implantation into single-crystal silicon. Evidence is given for a special phenomenon of oxygen blocking due to hot clouds resulting from collisional cascades. In the region where blocking is active, precipitates are formed in as-implanted conditions. A model is formulated and specialized to predict the dependence on depth of precipitate density and size. The existence of a buried region of precipitates is useful for producing a thin buried oxide. The Low-Dose SIMOX (LODOX) structure obtained provides a solution for many problems that are typical of silicon substrates for complementary metal-oxide silicon (CMOS) applications. (Author).

  20. Infrared analysis of thin films amorphous, hydrogenated carbon on silicon

    CERN Document Server

    Jacob, W; Schwarz-Selinger, T

    2000-01-01

    The infrared analysis of thin films on a thick substrate is discussed using the example of plasma-deposited, amorphous, hydrogenated carbon layers (a-C:H) on silicon substrates. The framework for the optical analysis of thin films is presented. The main characteristic of thin film optics is the occurrence of interference effects due to the coherent superposition of light multiply reflected at the various internal and external interfaces of the optical system. These interference effects lead to a sinusoidal variation of the transmitted and reflected intensity. As a consequence, the Lambert-Beer law is not applicable for the determination of the absorption coefficient of thin films. Furthermore, observable changes of the transmission and reflection spectra occur in the vicinity of strong absorption bands due to the Kramers-Kronig relation. For a sound data evaluation these effects have to be included in the analysis. To be able to extract the full information contained in a measured optical thin film spectrum, ...

  1. Laser annealing of thin film polycrystalline silicon solar cell

    Directory of Open Access Journals (Sweden)

    Chowdhury A.

    2013-11-01

    Full Text Available Performances of thin film polycrystalline silicon solar cell grown on glass substrate, using solid phase crystallization of amorphous silicon can be limited by low dopant activation and high density of defects. Here, we investigate line shaped laser induced thermal annealing to passivate some of these defects in the sub-melt regime. Effect of laser power and scan speed on the open circuit voltage of the polysilicon solar cells is reported. The processing temperature was measured by thermal imaging camera. Enhancement of the open circuit voltage as high as 210% is achieved using this method. The results are discussed.

  2. Laterally inherently thin amorphous-crystalline silicon heterojunction photovoltaic cell

    Science.gov (United States)

    Chowdhury, Zahidur R.; Kherani, Nazir P.

    2014-12-01

    This article reports on an amorphous-crystalline silicon heterojunction photovoltaic cell concept wherein the heterojunction regions are laterally narrow and distributed amidst a backdrop of well-passivated crystalline silicon surface. The localized amorphous-crystalline silicon heterojunctions consisting of the laterally thin emitter and back-surface field regions are precisely aligned under the metal grid-lines and bus-bars while the remaining crystalline silicon surface is passivated using the recently proposed facile grown native oxide-plasma enhanced chemical vapour deposited silicon nitride passivation scheme. The proposed cell concept mitigates parasitic optical absorption losses by relegating amorphous silicon to beneath the shadowed metallized regions and by using optically transparent passivation layer. A photovoltaic conversion efficiency of 13.6% is obtained for an untextured proof-of-concept cell illuminated under AM 1.5 global spectrum; the specific cell performance parameters are VOC of 666 mV, JSC of 29.5 mA-cm-2, and fill-factor of 69.3%. Reduced parasitic absorption, predominantly in the shorter wavelength range, is confirmed with external quantum efficiency measurement.

  3. Activation Energy of Polycrystalline Silicon Thin Film Transistor

    Directory of Open Access Journals (Sweden)

    B.P. Tyagi

    2011-01-01

    Full Text Available The activation energy of a poly-Si thin film transistor is observed to be influenced by the grain size, trap state density and the inversion layer thickness. The present study aims to investigate these parameters theoretically so as to explore optimum conditions for the working of a polycrystalline silicon thin film transistor. Our computations have revealed that the activation energy decreases with the increase of gate bias for all values of grain size, trap states density and the inversion layer thickness. These findings are compared with the experimental results.

  4. Stability of thin films of microcrystalline silicon under light soaking

    Institute of Scientific and Technical Information of China (English)

    HAN Xiao-yan; Wang Yan; XUE Jun-ming; ZHAO Shu-wen; REN Hui-zhi; ZHAO Ying; LI Yang-xian; GENG Xin-hua

    2006-01-01

    Silicon thin films with different crystalline ratio(Xc) have been deposited by varying silane content(SC) of reactive gases in the RF-PECVD process.The effects of silane content on performance of the materials and the relationship between microstructure and opto-electronic properties were studied by means of Raman measurements,photoconductivity(σph),and dark conductivity(σd),followed by the measurements of light absorption coefficient(α),the product of quantum efficiency,mobility and lifetime (ημτ),before,during and after light soaking,respectively.The results indicate that the microcrystalline silicon near the transition region is suitable to prepare microcrystalline silicon of device grade,and that the amorphous region of the material is responsible to the light induced degradation.

  5. Low cost thin film poly-silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report presents the results of a project to design and develop a high density plasma based thin-film poly-silicon (TFPS) deposition system based on PQL proprietary advanced plasma technology to produce semiconductor quality TFPS for fabricating a TFPS solar cell. Details are given of the TFPS deposition system, the material development programme, solar cell structure, and cell efficiencies. The reproducibility of the deposition process and prospects for commercial exploitation are discussed.

  6. Doped nanocrystalline silicon oxide for use as (intermediate) reflecting layers in thin-film silicon solar cells

    NARCIS (Netherlands)

    Babal, P.

    2014-01-01

    In summary, this thesis shows the development and nanostructure analysis of doped silicon oxide layers. These layers are applied in thin-film silicon single and double junction solar cells. Concepts of intermediate reflectors (IR), consisting of silicon and/or zinc oxide, are applied in tandem cells

  7. Characterization of thin-film silicon materials and solar cells through numerical modeling

    NARCIS (Netherlands)

    Pieters, B.E.

    2008-01-01

    At present most commercially available solar cells are made of crystalline silicon (c-Si). The disadvantages of crystalline silicon solar cells are the high material cost and energy consumption during production. A cheaper alternative can be found in thin-film silicon solar cells. The thin-film sili

  8. Raman spectroscopy of thin-film silicon on woven polyester

    Energy Technology Data Exchange (ETDEWEB)

    Lind, Helena; Wilson, John [Department of Physics, School of Engineering and Physical Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS (United Kingdom); Mather, Robert [Power Textiles Limited, Upland House, Ettrick Road, Selkirk TD7 5AJ (United Kingdom)

    2011-12-15

    Thin-film silicon deposited by plasma-enhanced chemical vapour deposition (PECVD), encompasses both hydrogenated amorphous silicon (a-Si:H) and 'nanocrystalline silicon' (nc-Si), the latter being a two-phase mixture of discrete nanocrystallites in an amorphous matrix. It is distinguished from a-Si:H by a characteristic Raman spectrum. As the film structure moves from amorphous to more crystalline, the Raman TO phonon spectral region no longer consists of a broad amorphous peak at {proportional_to}480 cm{sup -1} but instead has an obvious narrower peak located at higher wavenumber. The accepted signature peak for nc-Si lies between these two and most probably arises from the hexagonal, wurtzite structure of the nanocrystals. Here we use Raman spectroscopy to show how the structure of thin-film silicon on woven polyester is influenced by the substrate as well as by the deposition conditions. We find that the rough surface of the textile substrate enables nc-Si formation, provided that the correct deposition conditions are employed and that the substrate temperature does not exceed 210 C. Although the gas mixture is the dominant parameter for determining the film structure, and input power also has a significant effect, we find that a specific combination of these interrelated parameters is essential to control the final structure. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Low temperature plasma deposition of silicon thin films: From amorphous to crystalline

    OpenAIRE

    Roca i Cabarrocas, Pere; Cariou, Romain; Labrune, Martin

    2012-01-01

    International audience; We report on the epitaxial growth of crystalline silicon films on (100) oriented crystalline silicon substrates by standard plasma enhanced chemical vapor deposition at 175 °C. Such unexpected epitaxial growth is discussed in the context of deposition processes of silicon thin films, based on silicon radicals and nanocrystals. Our results are supported by previous studies on plasma synthesis of silicon nanocrystals and point toward silicon nanocrystals being the most p...

  10. Microstructural and Electrical Properties of ZrO2 Thin Films Prepared on silicon on Insulator with Thin Top silicon

    Institute of Scientific and Technical Information of China (English)

    章宁琳; 宋志棠; 沈勤我; 林成鲁

    2003-01-01

    Amorphous zirconia thin films were deposited directly on silicon-on-insulator (SOI) substrates with thin top silicon by ultra-high vacuum electron beam evaporation. Spreading resistance profile and scanning transmission-electron microscopy (TEM) were used to detect the interface quality and microstructure, revealing that the interface between the zirconium oxide films and top silicon was abrupt and clear. The films kept to be amorphous up to the rapid thermal temperature of 700°C for 300s, but arriving at 700°C an unknown interfacial product appeared,which was probably ZrSixOy. High frequency capacitance-voltage (C- V) characteristics at 1 MHz performed on metal-oxide-SOI structure revealed that this interfacial product exhibited good electrical properties of zirconia thin films. When the annealing temperature increased from 600°C to 700°C, flat voltage VFB changed from -2.451 to -1.741 eV, showing the improvement in the quality of the films. The cumulative region capacitance decreased from 3.058 × 10-11F to 3.012 × 10-11F, indicating increasing equivalent oxide thickness, which is in agreement with the result of high-resolution cross-sectional TEM.

  11. Crystalline-silicon reliability lessons for thin-film modules

    Science.gov (United States)

    Ross, R. G., Jr.

    1985-01-01

    The reliability of crystalline silicon modules has been brought to a high level with lifetimes approaching 20 years, and excellent industry credibility and user satisfaction. The transition from crystalline modules to thin film modules is comparable to the transition from discrete transistors to integrated circuits. New cell materials and monolithic structures will require new device processing techniques, but the package function and design will evolve to a lesser extent. Although there will be new encapsulants optimized to take advantage of the mechanical flexibility and low temperature processing features of thin films, the reliability and life degradation stresses and mechanisms will remain mostly unchanged. Key reliability technologies in common between crystalline and thin film modules include hot spot heating, galvanic and electrochemical corrosion, hail impact stresses, glass breakage, mechanical fatigue, photothermal degradation of encapsulants, operating temperature, moisture sorption, circuit design strategies, product safety issues, and the process required to achieve a reliable product from a laboratory prototype.

  12. Raman and ellipsometric characterization of hydrogenated amorphous silicon thin films

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Hydrogenated amorphous silicon (a-Si:H) thin films were deposited by plasma-enhanced vapor deposition (PECVD) at different silane temperatures (Tg) before glow-discharge. The effect of Tg on the amorphous network and optoelectronic properties of the films has been investigated by Raman scattering spectra, ellipsometric transmittance spectra, and dark conductivity measurement, respectively. The results show that the increase in Tg leads to an improved ordering of amorphous network on the short and intermediate scales and an increase of both refractive index and absorption coefficient in a-Si:H thin films. It is indicated that the dark conductivity increases by two orders of magnitude when Tg is raised from room temperature (RT) to 433 K. The continuous ordering of amorphous network of a-Si:H thin films deposited at a higher Tg is the main cause for the increase of dark conductivity.

  13. Fabrication of PIN diode detectors on thinned silicon wafers

    CERN Document Server

    Ronchin, Sabina; Dalla Betta, Gian Franco; Gregori, Paolo; Guarnieri, Vittorio; Piemonte, Claudio; Zorzi, Nicola

    2004-01-01

    Thin substrates are one of the possible choices to provide radiation hard detectors for future high-energy physics experiments. Among the advantages of thin detectors are the low full depletion voltage, even after high particle fluences, the improvement of the tracking precision and momentum resolution and the reduced material budget. In the framework of the CERN RD50 Collaboration, we have developed p-n diode detectors on membranes obtained by locally thinning the silicon substrate by means of tetra-methyl ammonium hydroxide etching from the wafer backside. Diodes of different shapes and sizes have been fabricated on 57 and 99mum thick membranes. They have been tested, showing a very low leakage current ( less than 0.4nA/cm**2) and, as expected, a very low depletion voltage ( less than 1V for the 57mum membrane). The paper describes the technological approach used for devices fabrication and reports selected results from the electrical characterization.

  14. Silicon nitride coated silicon thin film on three dimensions current collector for lithium ion battery anode

    Science.gov (United States)

    Wu, Cheng-Yu; Chang, Chun-Chi; Duh, Jenq-Gong

    2016-09-01

    Silicon nitride coated silicon (N-Si) has been synthesized by two-step DC sputtering on Cu Micro-cone arrays (CMAs) at ambient temperature. The electrochemical properties of N-Si anodes with various thickness of nitride layer are investigated. From the potential window of 1.2 V-0.05 V, high rate charge-discharge and long cycle test have been executed to investigate the electrochemical performances of various N-Si coated Si-based lithium ion batteries anode materials. Higher specific capacity can be obtained after 200 cycles. The cycling stability is enhanced via thinner nitride layer coating as silicon nitride films are converted to Li3N with covered Si thin films. These N-Si anodes can be cycled under high rates up to 10 C due to low charge transfer resistance resulted from silicon nitride films. This indicates that the combination of silicon nitride and silicon can effectively endure high current and thus enhance the cycling stability. It is expected that N-Si is a potential candidate for batteries that can work effectively under high power.

  15. Silicon nanocrystals on amorphous silicon carbide alloy thin films: Control of film properties and nanocrystals growth

    Energy Technology Data Exchange (ETDEWEB)

    Barbe, Jeremy, E-mail: jeremy.barbe@hotmail.com [CEA, Liten, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, 31062 Toulouse (France); Xie, Ling; Leifer, Klaus [Department of Engineering Sciences, Uppsala University, Box 534, S-751 21 Uppsala (Sweden); Faucherand, Pascal; Morin, Christine; Rapisarda, Dario; De Vito, Eric [CEA, Liten, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Makasheva, Kremena; Despax, Bernard [Universite de Toulouse, UPS, INPT, LAPLACE (Laboratoire Plasma et Conversion d' Energie), 118 route de Narbonne, 31062 Toulouse (France); CNRS, LAPLACE, F-31062 Toulouse (France); Perraud, Simon [CEA, Liten, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2012-11-01

    The present study demonstrates the growth of silicon nanocrystals on amorphous silicon carbide alloy thin films. Amorphous silicon carbide films [a-Si{sub 1-x}C{sub x}:H (with x < 0.3)] were obtained by plasma enhanced chemical vapor deposition from a mixture of silane and methane diluted in hydrogen. The effect of varying the precursor gas-flow ratio on the film properties was investigated. In particular, a wide optical band gap (2.3 eV) was reached by using a high methane-to-silane flow ratio during the deposition of the a-Si{sub 1-x}C{sub x}:H layer. The effect of short-time annealing at 700 Degree-Sign C on the composition and properties of the layer was studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. It was observed that the silicon-to-carbon ratio in the layer remains unchanged after short-time annealing, but the reorganization of the film due to a large dehydrogenation leads to a higher density of SiC bonds. Moreover, the film remains amorphous after the performed short-time annealing. In a second part, it was shown that a high density (1 Multiplication-Sign 10{sup 12} cm{sup -2}) of silicon nanocrystals can be grown by low pressure chemical vapor deposition on a-Si{sub 0.8}C{sub 0.2} surfaces at 700 Degree-Sign C, from silane diluted in hydrogen. The influence of growth time and silane partial pressure on nanocrystals size and density was studied. It was also found that amorphous silicon carbide surfaces enhance silicon nanocrystal nucleation with respect to SiO{sub 2}, due to the differences in surface chemical properties. - Highlights: Black-Right-Pointing-Pointer Silicon nanocrystals (Si-NC) growth on amorphous silicon carbide alloy thin films Black-Right-Pointing-Pointer Plasma deposited amorphous silicon carbide films with well-controlled properties Black-Right-Pointing-Pointer Study on the thermal effect of 700 Degree-Sign C short-time annealing on the layer properties Black-Right-Pointing-Pointer Low pressure

  16. 非晶纳米晶软磁材料在高效电机中的应用%Applications of amorphous/nanocrystalline soft magnetic materials in high efficient motors

    Institute of Scientific and Technical Information of China (English)

    陈国钧; 涂国超; 吕玮

    2012-01-01

    The Am-motor with amorphous/nanocrystalline stator (rotor) has an efficiency of above 95%, and has a considerable energy saving potential. The advantages of Am-motor compared with traditional motors, the amorphous/nanocrystalline materials for making Am-motor, and the manufacture methods for bulk stator (rotor) are comprehensively reviewed in the paper.%以非晶纳米晶作为定(转)子铁心的非晶电机( Am-Motor)运行效率一般可达95%以上,其节能潜力非常可观.较全面地评述了非晶电机与传统材料电机相比的优越性、用于制作非晶电机的非晶纳米晶材料及其定(转)子块体器件的加工制作方法.

  17. Characteristics of Disorder and Defect in Hydrogenated Amorphous Silicon Nitride Thin Films Containing Silicon Nanograins

    Institute of Scientific and Technical Information of China (English)

    DING Wen-ge; YU Wei; ZHANG Jiang-yong; HAN Li; FU Guang-sheng

    2006-01-01

    The hydrogenated amorphous silicon nitride (SiNx) thin films embedded with nano-structural silicon were prepared and the microstructures at the interface of silicon nano-grains/SiNx were identified by the optical absorption and Raman scattering measurements. Characterized by the exponential tail of optical absorption and the band-width of the Raman scattering TO mode, the disorder in the interface region increases with the gas flow ratio increasing. Besides, as reflected by the sub-gap absorption coefficients, the density of interface defect states decreases, which can be attributed to the structural mismatch in the interface region and also the changes of hydrogen content in the deposited films. Additional annealing treatment results in a significant increase of defects and degree of disorder, for which the hydrogen out-diffusion in the annealing process would be responsible.

  18. Valley-engineered ultra-thin silicon for high-performance junctionless transistors

    Science.gov (United States)

    Kim, Seung-Yoon; Choi, Sung-Yool; Hwang, Wan Sik; Cho, Byung Jin

    2016-07-01

    Extremely thin silicon show good mechanical flexibility because of their 2-D like structure and enhanced performance by the quantum confinement effect. In this paper, we demonstrate a junctionless FET which reveals a room temperature quantum confinement effect (RTQCE) achieved by a valley-engineering of the silicon. The strain-induced band splitting and a quantum confinement effect induced from ultra-thin-body silicon are the two main mechanisms for valley engineering. These were obtained from the extremely well-controlled silicon surface roughness and high tensile strain in silicon, thereupon demonstrating a device mobility increase of ~500% in a 2.5 nm thick silicon channel device.

  19. Synthesis of silicon carbide thin films with polycarbosilane (PCS)

    Energy Technology Data Exchange (ETDEWEB)

    Colombo, P. [Univ. di Padova (Italy). Dept. di Ingegneria Meccanica-Settore Materiali; Paulson, T.E.; Pantano, C.G. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering

    1997-09-01

    Polycarbosilane (PCS) thin films were deposited on silicon (and other) substrates and heat treated under vacuum ({approximately}10{sup {minus}6} torr) at temperatures in the range of 200--1,200 C. At temperatures in the range of 1,000--1,200 C, the initially amorphous PCS films transformed to polycrystalline {beta}-silicon carbide ({beta}-SiC). Although PCS films could be deposited at thickness up to 2 {micro}m, the films with thicknesses >1 {micro}m could not be transformed to SiC without extensive cracking. The resulting SiC coatings were characterized using Fourier transform infrared spectroscopy, glancing-angle X-ray diffractometry, secondary-ion mass spectroscopy, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The temperature and time dependence of the amorphous-to-crystalline transition could be associated with the evolution of free carbon, oxygen, and hydrogen in the films.

  20. Odd electron diffraction patterns in silicon nanowires and silicon thin films explained by microtwins and nanotwins

    Energy Technology Data Exchange (ETDEWEB)

    Cayron, Cyril; Latu-Romain, Laurence; Mouchet, Celine; Secouard, Christopher; Rouviere, Emmanuelle; Simonato, Jean-Pierre [CEA DRT, LITEN, Minatec, 38 - Grenoble (France); Den Hertog, Martien; Rouviere, Jean-Luc [CEA, DSM, INAC, Minatec, 38 - Grenoble (France)

    2009-04-15

    Odd electron diffraction patterns (EDPs) have been obtained by transmission electron microscopy (TEM) on silicon nanowires grown via the vapour-liquid- solid method and on silicon thin films deposited by electron beam evaporation. Many explanations have been given in the past, without consensus among the scientific community: size artifacts, twinning artifacts or, more widely accepted, the existence of new hexagonal Si phases. In order to resolve this issue, the microstructures of Si nanowires and Si thin films have been characterized by TEM, high-resolution transmission electron microscopy (HRTEM) and highresolution scanning transmission electron microscopy. Despite the differences in the geometries and elaboration processes, the EDPs of the materials show great similarities. The different hypotheses reported in the literature have been investigated. It was found that the positions of the diffraction spots in the EDPs could be reproduced by simulating a hexagonal structure with c/a=12(2/3){sup 1/2}, but the intensities in many EDPs remained unexplained. Finally, it was established that all the experimental data, i.e. EDPs and HRTEM images, agree with a classical cubic silicon structure containing two microstructural defects: (i) overlapping {sigma}3 microtwins which induce extra spots by double diffraction, and (ii) nanotwins which induce extra spots as a result of streaking effects. It is concluded that there is no hexagonal phase in the Si nanowires and the Si thin films presented in this work. (orig.)

  1. Odd electron diffraction patterns in silicon nanowires and silicon thin films explained by microtwins and nanotwins

    Science.gov (United States)

    Cayron, Cyril; Den Hertog, Martien; Latu-Romain, Laurence; Mouchet, Céline; Secouard, Christopher; Rouviere, Jean-Luc; Rouviere, Emmanuelle; Simonato, Jean-Pierre

    2009-01-01

    Odd electron diffraction patterns (EDPs) have been obtained by transmission electron microscopy (TEM) on silicon nanowires grown via the vapour–liquid–solid method and on silicon thin films deposited by electron beam evaporation. Many explanations have been given in the past, without consensus among the scientific community: size artifacts, twinning artifacts or, more widely accepted, the existence of new hexagonal Si phases. In order to resolve this issue, the microstructures of Si nanowires and Si thin films have been characterized by TEM, high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning transmission electron microscopy. Despite the differences in the geometries and elaboration processes, the EDPs of the materials show great similarities. The different hypotheses reported in the literature have been investigated. It was found that the positions of the diffraction spots in the EDPs could be reproduced by simulating a hexagonal structure with c/a = 12(2/3)1/2, but the intensities in many EDPs remained unexplained. Finally, it was established that all the experimental data, i.e. EDPs and HRTEM images, agree with a classical cubic silicon structure containing two microstructural defects: (i) overlapping Σ3 microtwins which induce extra spots by double diffraction, and (ii) nanotwins which induce extra spots as a result of streaking effects. It is concluded that there is no hexagonal phase in the Si nanowires and the Si thin films presented in this work. PMID:22477767

  2. Microstructure and tribological properties of Zr-based amorphous-nanocrystalline coatings deposited on the surface of titanium alloys by Electrospark Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Xiang; Tan, Yefa, E-mail: tanyefa7651@163.com; Zhou, Chunhua; Xu, Ting; Zhang, Zhongwei

    2015-11-30

    Highlights: • Zr-based amorphous-nanocrystalline coatings were well prepared on TC11 titanium alloys. • High glass forming ability of alloy system and high cooling rate of Electrospark Deposition process are beneficial for the generation of amorphous phase. • A model has been applied to investigate the generation of nanocrystalline phases in amorphous coating. • Excellent wear properties obtained due to nanocrystalline phases distributed in amorphous organization. - Abstract: In order to improve the wear resistance of titanium alloys, the Zr-based amorphous-nanocrystalline coatings were prepared by Electrospark Deposition (ESD) on the surface of TC11. The microstructure of the coatings was analyzed and the tribological behavior and mechanism of the coatings were investigated. The results show that the coating is mainly composed of amorphous phase Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} and distributed a large number of nano particles with the diameter between 2 nm and 4 nm such as CuZr{sub 3}, Ni{sub 2}Zr{sub 3}, NiZr{sub 2}, etc. The new alloy system made up of molten electrode material of Zr-based alloy and TC11 substrate has a large glass forming ability, which transforms to amorphous phase in the rapid heating and cooling ESD process. The long-range diffusions of atoms such as Zr and Cu in amorphous microstructure play an important role in nano nucleation growth. The coating is dense, uniform, bonding with TC11 substrate metallurgically. The thickness of the coating is from 55 μm to 60 μm and the average microhardness is 801.3 HV{sub 0.025}. The coating has good friction-reducing and anti-wear properties. The friction coefficient of the coating changes between 0.13 and 0.21 with small fluctuation, decreasing about 60% compared to that of TC11 substrate. And the wear resistance of the coating is increased by 57% than that of TC11 substrate. The main wear mechanism of the coating is micro-cutting wear accompanied with oxidation wear.

  3. Structure and Optical Properties of Silicon Nanocrystals Embedded in Amorphous Silicon Thin Films Obtained by PECVD

    Directory of Open Access Journals (Sweden)

    B. M. Monroy

    2011-01-01

    Full Text Available Silicon nanocrystals embedded in amorphous silicon matrix were obtained by plasma enhanced chemical vapor deposition using dichlorosilane as silicon precursor. The RF power and dichlorosilane to hydrogen flow rate ratio were varied to obtain different crystalline fractions and average sizes of silicon nanocrystals. High-resolution transmission electron microscopy images and RAMAN measurements confirmed the existence of nanocrystals embedded in the amorphous matrix with average sizes between 2 and 6 nm. Different crystalline fractions (from 12% to 54% can be achieved in these films by regulating the selected growth parameters. The global optical constants of the films were obtained by UV-visible transmittance measurements. Effective band gap variations from 1.78 to 2.3 eV were confirmed by Tauc plot method. Absorption coefficients higher than standard amorphous silicon were obtained in these thin films for specific growth parameters. The relationship between the optical properties is discussed in terms of the different internal nanostructures of the samples.

  4. Transparent Conductive Oxides for Thin-Film Silicon Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Loeffler, J.

    2005-04-25

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination with a highly reflective back contact leads to an increase in optical path length of the light. Multiple (total) internal reflectance leads to virtual 'trapping' of the light in the solar cell structure, allowing a further decrease in absorber thickness and thus thin-film silicon solar cell devices with higher and more stable efficiency. Here, the optical mechanisms involved in the light trapping in thin-film silicon solar cells have been studied, and two types of front TCO materials have been investigated with respect to their suitability as front TCO in thin-film silicon pin type solar cells. Undoped and aluminum doped zinc oxide layers have been fabricated for the first time by the expanding thermal plasma chemical vapour deposition (ETP CVD) technique at substrate temperatures between 150C and 350C, and successfully implemented as a front electrode material for amorphous silicon pin superstrate type solar cells. Solar cells with efficiencies comparable to cells on Asahi U-type reference TCO have been reproducibly obtained. A higher haze is needed for the ZnO samples studied here than for Asahi U-type TCO in order to achieve comparable long wavelength response of the solar cells. This is attributed to the different angular distribution of the scattered light, showing higher scattering intensities at large angles for the Asahi U-type TCO. A barrier at the TCO/p interface and minor collection problems may explain the slightly lower fill factors obtained for the

  5. Transparent conductive oxides for thin-film silicon solar cells

    Science.gov (United States)

    Löffler, J.

    2005-04-01

    This thesis describes research on thin-film silicon solar cells with focus on the transparent conductive oxide (TCO) for such devices. In addition to the formation of a transparent and electrically conductive front electrode for the solar cell allowing photocurrent collection with low ohmic losses, the front TCO plays an important role for the light enhancement of thin-film silicon pin type solar cells. If the TCO is rough, light scattering at rough interfaces in the solar cell in combination with a highly reflective back contact leads to an increase in optical path length of the light. Multiple (total) internal reflectance leads to virtual 'trapping' of the light in the solar cell structure, allowing a further decrease in absorber thickness and thus thin-film silicon solar cell devices with higher and more stable efficiency. Here, the optical mechanisms involved in the light trapping in thin-film silicon solar cells have been studied, and two types of front TCO materials have been investigated with respect to their suitability as front TCO in thin-film silicon pin type solar cells. Undoped and aluminum doped zinc oxide layers have been fabricated for the first time by the expanding thermal plasma chemical vapour deposition (ETP CVD) technique at substrate temperatures between 150 º C and 350 º C, and successfully implemented as a front electrode material for amorphous silicon pin superstrate type solar cells. Solar cells with efficiencies comparable to cells on Asahi U-type reference TCO have been reproducibly obtained. A higher haze is needed for the ZnO samples studied here than for Asahi U-type TCO in order to achieve comparable long wavelength response of the solar cells. This is attributed to the different angular distribution of the scattered light, showing higher scattering intensities at large angles for the Asahi U-type TCO. A barrier at the TCO/p interface and minor collection problems may explain the slightly lower fill factors obtained for the cells

  6. Silicon Oxynitride Thin Film Barriers for PV Packaging (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    del Cueto, J. A.; Glick, S. H.; Terwilliger, K. M.; Jorgensen, G. J.; Pankow, J. W.; Keyes, B. M.; Gedvilas, L. M.; Pern, F. J.

    2006-10-03

    Dielectric, adhesion-promoting, moisture barriers comprised of silicon oxynitride thin film materials (SiOxNy with various material stoichiometric compositions x,y) were applied to: 1) bare and pre-coated soda-lime silicate glass (coated with transparent conductive oxide SnO2:F and/or aluminum), and polymer substrates (polyethylene terephthalate, PET, or polyethylene napthalate, PEN); plus 2) pre- deposited photovoltaic (PV) cells and mini-modules consisting of amorphous silicon (a-Si) and copper indium gallium diselenide (CIGS) thin-film PV technologies. We used plasma enhanced chemical vapor deposition (PECVD) process with dilute silane, nitrogen, and nitrous oxide/oxygen gas mixtures in a low-power (< or = 10 milliW per cm2) RF discharge at ~ 0.2 Torr pressure, and low substrate temperatures < or = 100(degrees)C, over deposition areas ~ 1000 cm2. Barrier properties of the resulting PV cells and coated-glass packaging structures were studied with subsequent stressing in damp-heat exposure at 85(degrees)C/85% RH. Preliminary results on PV cells and coated glass indicate the palpable benefits of the barriers in mitigating moisture intrusion and degradation of the underlying structures using SiOxNy coatings with thicknesses in the range of 100-200 nm.

  7. XPS study of palladium sensitized nano porous silicon thin film

    Indian Academy of Sciences (India)

    J Kanungo; L Selegård; C Vahlberg; K Uvdal; H Saha; S Basu

    2010-12-01

    Nano porous silicon (PS) was formed on -type monocrystalline silicon of 2–5 cm resistivity and (100) orientation by electrochemical anodization method using HF and ethanol as the electrolytes. High density of surface states, arising due to its nano structure, is responsible for the uncontrolled oxidation in air and for the deterioration of the PS surface with time. To stabilize the material PS surface was modified by a simple and low cost chemical method using PdCl2 solution at room temperature. X-ray photoelectron spectroscopy (XPS) was performed to reveal the chemical composition and the relative concentration of palladium on the nanoporous silicon thin films. An increase of SiO2 formation was observed after PdCl2 treatment and presence of palladium was also detected on the modified surface. – characteristics of Al/PS junction were studied using two lateral Al contacts and a linear relationship was obtained for Pd modified PS surface. Stability of the contact was studied for a time period of around 30 days and no significant ageing effect could be observed.

  8. Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ben Dkhil, S., E-mail: sadok.bendekhil@gmail.com [Laboratoire Physique des Materiaux, Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Ingenierie des Materiaux Polymeres, IMP, UMR CNRS 5223, Universite Claude Bernard - Lyon 1, 15, boulevard Latarjet, 69622 Villeurbanne (France); Bourguiga, R. [Laboratoire Physique des Materiaux, Structures et Proprietes Groupe Physique des Composants et Dispositifs Nanometriques, 7021 Jarzouna, Bizerte (Tunisia); Davenas, J. [Ingenierie des Materiaux Polymeres, IMP, UMR CNRS 5223, Universite Claude Bernard - Lyon 1, 15, boulevard Latarjet, 69622 Villeurbanne (France); Cornu, D. [Institut Europeen des Membranes, UMR CNRS 5635, Ecole Nationale superieure de Chimie, Universite de Montpellier, 1919 route de Mende, F34000 Montpellier (France)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Hybrid solar cells based on blends of poly(N-vinylcarbazole) and silicon nanowires have been fabricated. Black-Right-Pointing-Pointer We have investigated the charge transfer between PVK and SiNWs by the way of the quenching of the PVK photoluminescence. Black-Right-Pointing-Pointer The relation between the morphology of the composite thin films and the charge transfer between SiNWs and PVK has been examined. Black-Right-Pointing-Pointer We have investigated the effects of SiNWs concentration on the photovoltaic characteristics leading to the optimization of a critical SiNWs concentration. - Abstract: Hybrid thin films combining the high optical absorption of a semiconducting polymer film and the electronic properties of silicon fillers have been investigated in the perspective of the development of low cost solar cells. Bulk heterojunction photovoltaic materials based on blends of a semiconductor polymer poly(N-vinylcarbazole) (PVK) as electron donor and silicon nanowires (SiNWs) as electron acceptor have been studied. Composite PVK/SiNWs films were cast from a common solvent mixture. UV-visible spectrometry and photoluminescence of the composites have been studied as a function of the SiNWs concentration. Photoluminescence spectroscopy (PL) shows the existence of a critical SiNWs concentration of about 10 wt % for PL quenching corresponding to the most efficient charge pair separation. The photovoltaic (PV) effect has been studied under illumination. The optimum open-circuit voltage V{sub oc} and short-circuit current density J{sub sc} are obtained for 10 wt % SiNWs whereas a degradation of these parameters is observed at higher SiNWs concentrations. These results are correlated to the formation of aggregates in the composite leading to recombination of the photogenerated charge pairs competing with the dissociation mechanism.

  9. Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells

    Science.gov (United States)

    Winans, Joshua David

    As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

  10. Silicon-Light: a European FP7 Project Aiming at High Efficiency Thin Film Silicon Solar Cells on Foil

    DEFF Research Database (Denmark)

    Soppe, W.; Haug, F.-J.; Couty, P.

    2011-01-01

    Silicon-Light is a European FP7 project, which started January 1st, 2010 and aims at development of low cost, high-efficiency thin film silicon solar cells on foil. Three main routes are explored to achieve these goals: a) advanced light trapping by implementing nanotexturization through UV Nano...... calculations of ideal nanotextures for light trapping in thin film silicon solar cells; the fabrication of masters and the replication and roll-to-roll fabrication of these nanotextures. Further, results on ITO variants with improved work function are presented. Finally, the status of cell fabrication on foils...

  11. Thin film silicon modules: contributions to low cost industrial production

    Energy Technology Data Exchange (ETDEWEB)

    Shah, A. [Universite de Neuchatel, Neuchatel (Switzerland)

    2005-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) discusses the research work done during the two-year period 2003-04 at the Thin-Film Solar Cell Laboratory of the Institute of Microtechnology (IMT) at the University of Neuchatel in Switzerland. The transition from fundamental research work to concrete industrialisation issues, and changes within the research staff are discussed. The main results of the work done are presented, including basic techniques for the production of p-i-n solar cells on glass, new technologies for the deposition of n-i-p cells on low-cost flexible substrates and the optimisation of zinc oxide deposition methods. The key role played by substrate chemistry and roughness in the nucleation and growth of micro-crystalline silicon layers is looked at and diagnostic tools for the analysis of micro-crystalline solar cells are discussed.

  12. Reduction Bending of Thin Crystalline Silicon Solar Cells

    Institute of Scientific and Technical Information of China (English)

    SHEN Lan-xian; LIU Zu-ming; LIAO Hua; TU Jie-lei; DENG Shu-kang

    2009-01-01

    Reported are the results of reduction the bending of thin crystalline silicon solar ceils after printing and sintering of back electrode by changing the back electrode paste and adjusting the screen printing parameters without effecting the electrical properties of the cell. Theory and experiments showed that the bending of the cell is changed with its thickness of suhstrate, the thinner cell, the more serious bending. The bending of the cell is decreased with the thickness decrease of the back contact paste. The substrate with the thickness of 190μm printing with sheet aluminum paste shows a relatively lower bend compared with that of the substrate printing with ordinary aluminum paste, and the minimum bend is 0.55 mm which is reduced by52%.

  13. Optical limiting effects in nanostructured silicon carbide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Borshch, A A; Starkov, V N; Volkov, V I; Rudenko, V I; Boyarchuk, A Yu [Institute of Physics, National Academy of Sciences of Ukraine, Kiev (Ukraine); Semenov, A V [Institute for Single Crystals of NAS of Ukraine (Ukraine)

    2013-12-31

    We present the results of experiments on the interaction of nanosecond laser radiation at 532 and 1064 nm with nanostructured silicon carbide thin films of different polytypes. We have found the effect of optical intensity limiting at both wavelengths. The intensity of optical limiting at λ = 532 nm (I{sub cl} ∼ 10{sup 6} W cm{sup -2}) is shown to be an order of magnitude less than that at λ = 1064 nm (I{sub cl} ∼ 10{sup 7} W cm{sup -2}). We discuss the nature of the nonlinearity, leading to the optical limiting effect. We have proposed a method for determining the amount of linear and two-photon absorption in material media. (nonlinear optical phenomena)

  14. Thin tantalum-silicon-oxygen/tantalum-silicon-nitrogen films as high-efficiency humidity diffusion barriers for solar cell encapsulation

    Energy Technology Data Exchange (ETDEWEB)

    Heuer, H. [Institut fuer Halbleiter-und Mikrosystemtechnik (IHM) Technische Universitaet Dresden, Helmholtzstrasse 10, 01062 Dresden (Germany)]. E-mail: Henning.Heuer@izfp-d.fraunhofer.de; Wenzel, C. [Institut fuer Halbleiter-und Mikrosystemtechnik (IHM) Technische Universitaet Dresden, Helmholtzstrasse 10, 01062 Dresden (Germany); Herrmann, D. [Institut fuer Halbleiter-und Mikrosystemtechnik (IHM) Technische Universitaet Dresden, Helmholtzstrasse 10, 01062 Dresden (Germany); Zentrum fuer Sonnenenergie-und Wasserstoff-Forschung (ZSW) Industriestrasse 6, 70565 Stuttgart (Germany); Huebner, R. [Institut fuer Halbleiter-und Mikrosystemtechnik (IHM) Technische Universitaet Dresden, Helmholtzstrasse 10, 01062 Dresden (Germany); Leibniz Institut fuer Festkoerper-und Werkstoffforschung Dresden (IFW) Helmholtzstrasse 20, 01069, Dresden (Germany); Zhang, Z.L. [Institut fuer Halbleiter-und Mikrosystemtechnik (IHM) Technische Universitaet Dresden, Helmholtzstrasse 10, 01062 Dresden (Germany); Max-Planck-Gesellschaft fuer Metallforschung (MPI) Heisenbergstrasse 3, 70569 Stuttgart (Germany); Bartha, J.W. [Institut fuer Halbleiter-und Mikrosystemtechnik (IHM) Technische Universitaet Dresden, Helmholtzstrasse 10, 01062 Dresden (Germany)

    2006-12-05

    Flexible thin-film solar cells require flexible encapsulation to protect the copper-indium-2 selenide (CIS) absorber layer from humidity and aggressive environmental influences. Tantalum-silicon-based diffusion barriers are currently a favorite material to prevent future semiconductor devices from copper diffusion. In this work tantalum-silicon-nitrogen (Ta-Si-N) and tantalum-silicon-oxygen (Ta-Si-O) films were investigated and optimized for thin-film solar cell encapsulation of next-generation flexible solar modules. CIS solar modules were coated with tantalum-based barrier layers. The performance of the thin-film barrier encapsulation was determined by measuring the remaining module efficiency after a 1000 h accelerated aging test. A significantly enhanced stability against humidity diffusion in comparison to non-encapsulated modules was reached with a reactively sputtered thin-film system consisting of 250 nm Ta-Si-O and 15 nm Ta-Si-N.

  15. Study of back reflectors for thin film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, H.; Mai, Y. [Baoding Tianwei Solarfilms Co., Ltd., Baoding 071051 (China); Wan, M. [Department of Chemistry and Material Science, Hunan Institute of Humanities, Science and Technology, Loudi 417000 (China); Gao, J.; Wang, Y.; He, T.; Feng, Y.; Yin, J.; Du, J.; Wang, J.; Sun, R. [Baoding Tianwei Solarfilms Co., Ltd., Baoding 071051 (China); Huang, Y., E-mail: y.huang@btw-solarfilms.com [Baoding Tianwei Solarfilms Co., Ltd., Baoding 071051 (China)

    2013-07-31

    In this study, the reflection properties of transparent conductive oxide (TCO) films i.e. aluminum doped zinc oxide (ZnO:Al) and boron doped zinc oxide (ZnO:B) films plus aluminum (Al) films or white polyvinyl butyral (PVB) foils, which are usually used as the combined back reflectors of thin film silicon solar cells, are investigated. Sputtered ZnO:Al films were etched in diluted hydrochloric acid (1%) to achieve rough surface structures while textured ZnO:B films were directly prepared by a low pressure chemical vapor deposition technique. It is found that the rough TCO/Al reflectors show a low total reflection, which is mainly due to the parasitic absorption by the surface plasmons at the rough TCO/Al interfaces as well as the absorption in the TCO films. Differently, the rough TCO/white PVB foil reflectors display a slightly high light reflection regardless of the influence of the rough interface without the excitation of surface plasmons. Thus, the TCO/white PVB foil back reflectors could be a good candidate with respect to light utilization when they are applied in thin film silicon solar cells. - Highlights: • White polyvinyl butyral and transparent conductive oxide materials are used. • The reflection properties of TCO/Al and TCO/white PVB foil reflectors are studied. • The ZnO:Al and ZnO:B films are used as two types of TCO materials. • TCO/white PVB foil reflector shows a high reflection compared to TCO/Al reflector.

  16. Tribology-Structure Relationships in Silicon Oxycarbide Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, Joseph V.; Colombo, Paolo; Howell, Jane A.; Pantano, C. G.

    2010-09-01

    Silicon oxycarbide is a versatile material system that is attractive for many applications because of its ability to tune properties such as chemical compatibility, refractive index, electrical conductivity, and optical band gap through changes in composition. One particularly intriguing application lies in the production of biocompatible coatings with good mechanical properties. In this paper, we report on the wide range of mechanical and tribological property values exhibited by silicon oxycarbide thin films deposited by reactive radio frequency magnetron sputtering. Through a change in oxygen partial pressure in the sputtering plasma, the composition of the films was controlled to produce relatively pure SiO2, carbon-doped SiC, and compositions between these limits. Hardness values were 8-20 GPa over this range and the elastic modulus was measured to be between 60 and 220 GPa. We call attention to the fit of the mechanical data to a simple additive bond-mixture model for property prediction. Tribological parameters were measured using a ball-on-disk apparatus and the samples exhibited the same general trends for friction coefficient and wear rate. One film is shown to produce variable low friction behavior and low wear rate, which suggests a solid-state self-lubrication process because of heterogeneity on the nanometer scale.

  17. Comparing n- and p-type polycrystalline silicon absorbers in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Deckers, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium); Bourgeois, E. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Jivanescu, M. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Abass, A. [Photonics Research Group (INTEC), Ghent University-imec, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Van Gestel, D.; Van Nieuwenhuysen, K.; Douhard, B. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); D' Haen, J.; Nesladek, M.; Manca, J. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Gordon, I.; Bender, H. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); Stesmans, A. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Mertens, R.; Poortmans, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium)

    2015-03-31

    We have investigated fine grained polycrystalline silicon thin films grown by direct chemical vapor deposition on oxidized silicon substrates. More specifically, we analyze the influence of the doping type on the properties of this model polycrystalline silicon material. This includes an investigation of defect passivation and benchmarking of minority carrier properties. In our investigation, we use a variety of characterization techniques to probe the properties of the investigated polycrystalline silicon thin films, including Fourier Transform Photoelectron Spectroscopy, Electron Spin Resonance, Conductivity Activation, and Suns-Voc measurements. Amphoteric silicon dangling bond defects are identified as the most prominent defect type present in these layers. They are the primary recombination center in the relatively lowly doped polysilicon thin films at the heart of the current investigation. In contrast with the case of solar cells based on Czochralski silicon or multicrystalline silicon wafers, we conclude that no benefit is found to be associated with the use of n-type dopants over p-type dopants in the active absorber of the investigated polycrystalline silicon thin-film solar cells. - Highlights: • Comparison of n- and p-type absorbers for thin-film poly-Si solar cells • Extensive characterization of the investigated layers' characteristics • Literature review pertaining the use of n-type and p-type dopants in silicon.

  18. Pulsed laser deposition of silicon dioxide thin films with silicone targets for fabricating waveguide devices

    Science.gov (United States)

    Okoshi, Masayuki; Kuramatsu, Masaaki; Inoue, Narumi

    2002-06-01

    Silicon dioxide (SiO2) thin films were deposited at room temperature by 193-nm ArF excimer laser ablation of silicone in oxygen atmosphere. Only the side chains of the target were photo-dissociated during ablation to deposit Si-O bonds on a substrate in high laser fluence at about 10 J/cm2. Oxygen gas worked to oxidize the Si-O bonds ejected from the target to from SiO2 thin films at the gas pressure of 4.4 X 10-2 Torr, in addition to reducing the isolated carbon mixed into the films. We also found that the deposited rate could control refractive index of the films. The refractive index of the film deposited at 0.05 nm/pulse is greater than that of the film at 0.1 nm/pulse. Thus, a 0.2-micrometers thick SiO2 cladding film deposited at 0.1 nm/pulse was firstly formed on the whole surface of a 100- micrometers -thick polyester film, and then a 0.6 micrometers -thick SiO2 core film at 0.05 nm/pulse was fabricated in a line on the sample. The sample functioned as a waveguide device for a 633-nm line of He-Ne laser.

  19. Large Area Thin Film Silicon: Synergy between Displays and Solar Cells

    NARCIS (Netherlands)

    Schropp, R.E.I.

    2012-01-01

    Thin-film silicon technology has changed our society, owing to the rapid advance of its two major application fields in communication (thin-film displays) and sustainable energy (thin-film solar cells). Throughout its development, advances in these application fields have always benefitted each othe

  20. Designing a stronger interface through graded structures in amorphous/nanocrystalline ZrCu/Cu multilayered films.

    Science.gov (United States)

    Chang, C H; Hsieh, C H; Huang, J C; Wang, C; Liao, Y C; Hsueh, C H; Du, X H; Wang, Z K; Wang, X

    2016-06-03

    Many multilayered nano-structures appear to fail due to brittle matter along the interfaces. In order to toughen them, in this study, the microstructure and interface strength of multilayered thin films consisting of amorphous ZrCu and nanocrystalline Cu (with sharp or graded interfaces) are examined and analyzed. The interface possesses a gradient nature in terms of composition, nanocrystalline phase size and volume fraction. The bending results extracted from the nano-scaled cantilever bending samples demonstrate that multilayered films with graded interfaces would have a much higher interface bending strength/strain/modulus, and an overall improvement upgrade of more than 50%. The simple graded interface design of multilayered thin films with improved mechanical properties can offer much more promising performance in structural and functional applications for MEMS or optical coating.

  1. Ultrasonic seam welding on thin silicon solar cells

    Science.gov (United States)

    Stofel, E. J.

    1982-01-01

    The ultrathin silicon solar cell has progressed to where it is a serious candidate for future light weight or radiation tolerant spacecraft. The ultrasonic method of producing welds was found to be satisfactory. These ultrathin cells could be handled without breakage in a semiautomated welding machine. This is a prototype of a machine capable of production rates sufficiently large to support spacecraft array assembly needs. For comparative purposes, this project also welded a variety of cells with thicknesses up to 0.23 mm as well as the 0.07 mm ultrathin cells. There was no electrical degradation in any cells. The mechanical pull strength of welds on the thick cells was excellent when using a large welding force. The mechanical strength of welds on thin cells was less since only a small welding force could be used without cracking these cells. Even so, the strength of welds on thin cells appears adequate for array application. The ability of such welds to survive multiyear, near Earth orbit thermal cycles needs to be demonstrated.

  2. Hydrogenated amorphous silicon thin film anode for proton conducting batteries

    Science.gov (United States)

    Meng, Tiejun; Young, Kwo; Beglau, David; Yan, Shuli; Zeng, Peng; Cheng, Mark Ming-Cheng

    2016-01-01

    Hydrogenated amorphous Si (a-Si:H) thin films deposited by chemical vapor deposition were used as anode in a non-conventional nickel metal hydride battery using a proton-conducting ionic liquid based non-aqueous electrolyte instead of alkaline solution for the first time, which showed a high specific discharge capacity of 1418 mAh g-1 for the 38th cycle and retained 707 mAh g-1 after 500 cycles. A maximum discharge capacity of 3635 mAh g-1 was obtained at a lower discharge rate, 510 mA g-1. This electrochemical discharge capacity is equivalent to about 3.8 hydrogen atoms stored in each silicon atom. Cyclic voltammogram showed an improved stability 300 mV below the hydrogen evolution potential. Both Raman spectroscopy and Fourier transform infrared spectroscopy studies showed no difference to the pre-existing covalent Si-H bond after electrochemical cycling and charging, indicating a non-covalent nature of the Si-H bonding contributing to the reversible hydrogen storage of the current material. Another a-Si:H thin film was prepared by an rf-sputtering deposition followed by an ex-situ hydrogenation, which showed a discharge capacity of 2377 mAh g-1.

  3. Microstructure and tribological properties of Zr-based amorphous-nanocrystalline coatings deposited on the surface of titanium alloys by Electrospark Deposition

    Science.gov (United States)

    Hong, Xiang; Tan, Yefa; Zhou, Chunhua; Xu, Ting; Zhang, Zhongwei

    2015-11-01

    In order to improve the wear resistance of titanium alloys, the Zr-based amorphous-nanocrystalline coatings were prepared by Electrospark Deposition (ESD) on the surface of TC11. The microstructure of the coatings was analyzed and the tribological behavior and mechanism of the coatings were investigated. The results show that the coating is mainly composed of amorphous phase Zr55Cu30Al10Ni5 and distributed a large number of nano particles with the diameter between 2 nm and 4 nm such as CuZr3, Ni2Zr3, NiZr2, etc. The new alloy system made up of molten electrode material of Zr-based alloy and TC11 substrate has a large glass forming ability, which transforms to amorphous phase in the rapid heating and cooling ESD process. The long-range diffusions of atoms such as Zr and Cu in amorphous microstructure play an important role in nano nucleation growth. The coating is dense, uniform, bonding with TC11 substrate metallurgically. The thickness of the coating is from 55 μm to 60 μm and the average microhardness is 801.3 HV0.025. The coating has good friction-reducing and anti-wear properties. The friction coefficient of the coating changes between 0.13 and 0.21 with small fluctuation, decreasing about 60% compared to that of TC11 substrate. And the wear resistance of the coating is increased by 57% than that of TC11 substrate. The main wear mechanism of the coating is micro-cutting wear accompanied with oxidation wear.

  4. Enhanced crystallization of amorphous silicon thin films using embedded silicon nanocrystals

    Science.gov (United States)

    Anderson, Curtis Michael

    This thesis is concerned with the production of silicon thin films for photovoltaic applications. Much research has been carried out to find a stable, more efficient alternative to amorphous silicon, resulting in a number of various amorphous/crystalline mixed-phase film structures with properties superior to amorphous silicon. This thesis work details a completely new approach to mixed-phase film deposition, focusing on the fast crystallization of these films. The deposition of amorphous silicon films with embedded nanocrystals was carried out via a dual-plasma system. It is known that plasma conditions to produce high quality films are much different from those to produce particles. Hence the experimental system used here involved two separate plasmas to allow the optimum production of the crystalline nanoparticles and the amorphous film. Both plasmas use 13.56 MHz excitation voltage with diluted silane as the silicon precursor. The nanoparticle production reactor is a flow-through device that can be altered to control the size of the particles from around 5--30 nm average diameter. The film production reactor is a parallel-plate capacitively-coupled plasma system, into which the aerosol-suspended nanoparticles were injected. The nanocrystals could either be "co-deposited" simultaneously with the amorphous film, or be deposited separately in a layer-by-layer technique; both approaches are discussed in detail. Measurements of the film conductivity provide for the first time unambiguous evidence that the presence of nanocrystallites above 5 nm in the amorphous film have a direct impact on the electronic properties of co-deposited films. Further measurements of the film structure by transmission electron microscopy (TEM) and Raman spectroscopy demonstrate clearly the effect of embedded nanocrystals on the annealed crystallization process; the immediate growth of the crystal seeds has been observed. Additionally, a newly discovered mechanism of film crystallization

  5. Sinusoidal nanotextures for light management in silicon thin-film solar cells

    Science.gov (United States)

    Köppel, G.; Rech, B.; Becker, C.

    2016-04-01

    Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

  6. Modulated surface textures for enhanced scattering in thin-film silicon solar cells

    NARCIS (Netherlands)

    Isabella, O.; Battaglia, C.; Ballif, C.; Zeman, M.

    2012-01-01

    Nano-scale randomly textured front transparent oxides are superposed on micro-scale etched glass substrates to form modulated surface textures. The resulting enhanced light scattering is implemented in single and double junction thin-film silicon solar cells.

  7. Ultra-Thin Deformable Silicon Substrates with Lateral Segmentation and Flexible Metal Interconnect

    NARCIS (Netherlands)

    Zoumpouidis, T.; Wang, L.; Bartek, M.; Jansen, K.M.B.; Ernst, L.J.

    2007-01-01

    Our progress in developing technology modules for deformable single-crystalline-silicon electronics is presented in this contribution. Additional deformability/reliability is accomplished by modifications of the previously reported ultra-thin and flexible CIRCONFLEX technology (1). The flexibility

  8. Temporomandibular joint ankylosis fixation technique with ultra thin silicon sheet

    Directory of Open Access Journals (Sweden)

    G S Kalra

    2011-01-01

    Full Text Available Background: Temporomandibular joint ankylosis is a highly distressing condition in which the joint space is obliterated by scar tissue and the patient has an inability to open the mouth. Different autogenous and alloplastic interposition materials have been used after the resection of the ankylotic bone to achieve desirable and long lasting results. The recurrence of disease is most distressing for both patients and surgeon. We have been using ultra thin silicon sheet as our preferred material for providing proper fixation and cover to the joint. We have been encouraged by good patient compliance, no implant extrusion and favourable outcome. Materials and Methods: The clinical study included 80 patients with temporomandibular joint ankylosis, treated between April 2001 and March 2009. In all patients, temporomandibular joint ankylosis had resulted following trauma. Diagnosis was based on clinical assessment supplemented by radiographic examination consisting of a panoramic radiograph, axial and coronal computer tomography. The technique of using ultra thin silicon sheet covering whole of the joint space fixed with non-absorbable nylon 3-0 suture both medially to medial pterygoid muscle and laterally to periosteum of zygomatic arch was employed in all patients. Results: A total of 80 patients were in this study (59 males and 21 females. The aetiology of temporomandibular joint ankylosis was post-traumatic in all cases. The patients′ age ranged from 5 to 45 years. The disease was unilateral in 61 cases and bilateral in 19 cases. Twelve patients, who had previous surgery done in the form of gap arthroplasty in 6 cases, costochondral graft in 4 cases and temporalis muscle in 2 cases, presented with recurrence on the same side. The pre-op inter-incisal mouth opening ranged from 4 to 12 mm. The intraoperative inter-incisal mouth opening ranged from 28 to 46 mm. An additional procedure was done in 13 patients, including placement of costochondral

  9. Silicon-Light: a European FP7 Project Aiming at High Efficiency Thin Film Silicon Solar Cells on Foil

    DEFF Research Database (Denmark)

    Soppe, W.; Haug, F.-J.; Couty, P.

    2011-01-01

    Silicon-Light is a European FP7 project, which started January 1st, 2010 and aims at development of low cost, high-efficiency thin film silicon solar cells on foil. Three main routes are explored to achieve these goals: a) advanced light trapping by implementing nanotexturization through UV Nano...... Imprinting Lithography (UV-NIL); b) growth of crack-free silicon absorber layers on highly textured substrates; c) development of new TCOs which should combine the best properties of presently available materials like ITO and AZO. The paper presents the midterm status of the project results, showing model...

  10. Crystalline Silicon Solar Cells with Thin Silicon Passivation Film Deposited prior to Phosphorous Diffusion

    Directory of Open Access Journals (Sweden)

    Ching-Tao Li

    2014-01-01

    Full Text Available We demonstrate the performance improvement of p-type single-crystalline silicon (sc-Si solar cells resulting from front surface passivation by a thin amorphous silicon (a-Si film deposited prior to phosphorus diffusion. The conversion efficiency was improved for the sample with an a-Si film of ~5 nm thickness deposited on the front surface prior to high-temperature phosphorus diffusion, with respect to the samples with an a-Si film deposited on the front surface after phosphorus diffusion. The improvement in conversion efficiency is 0.4% absolute with respect to a-Si film passivated cells, that is, the cells with an a-Si film deposited on the front surface after phosphorus diffusion. The new technique provided a 0.5% improvement in conversion efficiency compared to the cells without a-Si passivation. Such performance improvements result from reduced surface recombination as well as lowered contact resistance, the latter of which induces a high fill factor of the solar cell.

  11. High-efficient n-i-p thin-film silicon solar cells

    NARCIS (Netherlands)

    Yang, G.

    2015-01-01

    In this thesis we present results of the development of n-i-p thin-film silicon solar cells on randomly textured substrates, aiming for highly efficient micromorph solar cells (i.e., solar cells based on a μc-Si:H bottom cell and a-Si:H top cell). For the efficiency of n-i-p thin-film silicon solar

  12. High-efficient n-i-p thin-film silicon solar cells

    NARCIS (Netherlands)

    Yang, G.

    2015-01-01

    In this thesis we present results of the development of n-i-p thin-film silicon solar cells on randomly textured substrates, aiming for highly efficient micromorph solar cells (i.e., solar cells based on a μc-Si:H bottom cell and a-Si:H top cell). For the efficiency of n-i-p thin-film silicon solar

  13. Reversibility of silicidation of Ta filaments in HWCVD of thin film silicon

    NARCIS (Netherlands)

    van der Werf, C.H.M.; Li, H. B. T.; Verlaan, V.; Oliphant, C.J.; Bakker, R.; Houweling, Z.S.; Schropp, R.E.I.

    2009-01-01

    If tantalum filaments are used for the hot wire chemical vapour deposition (HWCVD) of thin film silicon, various types of tantalum silicides are formed, depending on the filament temperature. Under deposition conditions employed for device quality amorphous and microcrystalline silicon (Twire ≈ 1750

  14. A silicon-containing nanocomposite for a thin-film lithium-ion battery

    Science.gov (United States)

    Berdnikov, A. E.; Gerashchenko, V. N.; Gusev, V. N.; Kulova, T. L.; Metlitskaya, A. V.; Mironenko, A. A.; Rudyi, A. S.; Skundin, A. M.

    2013-04-01

    A technological basis for manufacturing of a thin-film anode based on a silicon-containing nano-composite for lithium-ion batteries is developed. The results of experimental studies of charge-discharge characteristics, morphology and phase composition for the silicon-containing nanocomposite are presented, confirming the promising character of its application as an anodic material.

  15. Highly stable, protein resistant thin films on SiC-modified silicon substrates.

    Science.gov (United States)

    Qin, Guoting; Zhang, Rui; Makarenko, Boris; Kumar, Amit; Rabalais, Wayne; López Romero, J Manuel; Rico, Rodrigo; Cai, Chengzhi

    2010-05-21

    Thin films terminated with oligo(ethylene glycol) (OEG) could be photochemically grafted onto ultrathin silicon carbide layers that were generated on silicon substrates via carbonization with acetylene at 820 degrees C. The OEG coating reduced the non-specific adsorption of fibrinogen on the substrates by 99.5% and remained resistant after storage in PBS for 4 weeks at 37 degrees C.

  16. Silicon-based thin-film transistors with a high stability

    NARCIS (Netherlands)

    Stannowski, Bernd

    2002-01-01

    Thin-Film Transistors (TFTs) are widely applied as pixel-addressing devices in large-area electronics, such as active-matrix liquid-crystal displays (AMLCDs) or sensor arrays. Hydrogenated amorphous silicon (a-Si:H) and silicon nitride (a-SiNx:H) are generally used as the semiconductor and the insul

  17. Formation of thin-film crystalline silicon on glass observed by in-situ XRD

    NARCIS (Netherlands)

    Westra, J.M.; Vavrunkova, V.; Sutta, P.; Van Swaaij, R.A.C.M.M.; Zeman, M.

    2010-01-01

    Thin-film poly-crystalline silicon (poly c-Si) on glass obtained by crystallization of an amorphous silicon (a-Si) film is a promising material for low cost, high efficiency solar cells. Our approach to obtain this material is to crystallize a-Si films on glass by solid phase crystallization (SPC).

  18. Silicon-based thin-film transistors with a high stability

    NARCIS (Netherlands)

    Stannowski, Bernd

    2002-01-01

    Thin-Film Transistors (TFTs) are widely applied as pixel-addressing devices in large-area electronics, such as active-matrix liquid-crystal displays (AMLCDs) or sensor arrays. Hydrogenated amorphous silicon (a-Si:H) and silicon nitride (a-SiNx:H) are generally used as the semiconductor and the

  19. High Efficiency, Low Cost Solar Cells Manufactured Using 'Silicon Ink' on Thin Crystalline Silicon Wafers

    Energy Technology Data Exchange (ETDEWEB)

    Antoniadis, H.

    2011-03-01

    Reported are the development and demonstration of a 17% efficient 25mm x 25mm crystalline Silicon solar cell and a 16% efficient 125mm x 125mm crystalline Silicon solar cell, both produced by Ink-jet printing Silicon Ink on a thin crystalline Silicon wafer. To achieve these objectives, processing approaches were developed to print the Silicon Ink in a predetermined pattern to form a high efficiency selective emitter, remove the solvents in the Silicon Ink and fuse the deposited particle Silicon films. Additionally, standard solar cell manufacturing equipment with slightly modified processes were used to complete the fabrication of the Silicon Ink high efficiency solar cells. Also reported are the development and demonstration of a 18.5% efficient 125mm x 125mm monocrystalline Silicon cell, and a 17% efficient 125mm x 125mm multicrystalline Silicon cell, by utilizing high throughput Ink-jet and screen printing technologies. To achieve these objectives, Innovalight developed new high throughput processing tools to print and fuse both p and n type particle Silicon Inks in a predetermined pat-tern applied either on the front or the back of the cell. Additionally, a customized Ink-jet and screen printing systems, coupled with customized substrate handling solution, customized printing algorithms, and a customized ink drying process, in combination with a purchased turn-key line, were used to complete the high efficiency solar cells. This development work delivered a process capable of high volume producing 18.5% efficient crystalline Silicon solar cells and enabled the Innovalight to commercialize its technology by the summer of 2010.

  20. Axial ion channeling patterns from ultra-thin silicon membranes

    Energy Technology Data Exchange (ETDEWEB)

    Motapothula, M., E-mail: g0801315@nus.edu.sg [Center for Ion Beam Applications, Physics Department, National University of Singapore, Lower Kent Ridge Road, Singapore 117542 (Singapore); Dang, Z.Y. [Center for Ion Beam Applications, Physics Department, National University of Singapore, Lower Kent Ridge Road, Singapore 117542 (Singapore); Venkatesan, T. [NanoCore, National University of Singapore, Singapore 117576 (Singapore); Breese, M.B.H. [Center for Ion Beam Applications, Physics Department, National University of Singapore, Lower Kent Ridge Road, Singapore 117542 (Singapore); SSLS, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Rana, M.A. [Physics Division, Directorate of Science, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Osman, A. [National Centre for Physics (NCP), Shahdara Valley Road, Islamabad (Pakistan)

    2012-07-15

    We present channeling patterns produced by MeV protons transmitted through 55 nm thick [0 0 1] silicon membranes showing the early evolution of the axially channeled beam angular distribution for small tilts away from the [0 0 1], [0 1 1] and [1 1 1] axes. Instead of a ring-like 'doughnut' distribution previously observed at small tilts to major axes in thicker membranes, geometric shapes such as squares and hexagons are observed along different axes in ultra-thin membranes. The different shapes arise because of the highly non-equilibrium transverse momentum distribution of the channeled beam during its initial propagation in the crystal and the reduced multiple scattering which allows the fine angular structure to be resolved. We describe a simple geometric construction of the intersecting planar channels at an axis to gain insight into the origin of the geometric shapes observed in such patterns and how they evolve into the 'doughnut' distributions in thicker crystals.

  1. Development of thin wraparound junction silicon solar cells

    Science.gov (United States)

    Ho, F.; Iles, P. A.

    1981-01-01

    The state of the art technologies was applied to fabricate 50 micro thick 2x4 cm, coplanar back contact (CBC) solar cells with AMO efficiency above 12%. A requirement was that the cells have low solar absorptance. A wraparound junction (WAJ) with wraparound metallization was chosen. This WAJ approach avoided the need for very complex fixturing, especially during rotation of the cells for providing adequate contacts over dielectric edge layers. The contact adhesion to silicon was considered better than to an insulator. It is indicated that shunt resistance caused by poor WAJ diode quality, and series resistance from the WAJ contact, give good cell performance. The cells developed reached 14 percent AMO efficiency (at 25 C), with solar absorptance values of 0.73. Space/cell environmental tests were performed on these cells and the thin CSC cells performed well. The optimized design configuration and process sequence were used to make 50 deliverable CBC cells. These cells were all above 12 percent efficiency and had an average efficiency of -13 percent. Results of environmental tests (humidity-temperature, thermal shock, and contact adherence) are also given.

  2. Ambipolar characteristics of microcrystalline silicon thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Kah-Yoong [IEF5-Photovoltaics, Research Center Juelich, 52425 Juelich (Germany); School of Engineering and Science, Jacobs University Bremen, 28759 Bremen (Germany); Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Gordijn, Aad [IEF5-Photovoltaics, Research Center Juelich, 52425 Juelich (Germany); Stiebig, Helmut [IEF5-Photovoltaics, Research Center Juelich, 52425 Juelich (Germany); Malibu GmbH and Co. KG, 33609 Bielefeld (Germany); Knipp, Dietmar [School of Engineering and Science, Jacobs University Bremen, 28759 Bremen (Germany)

    2010-04-15

    Hydrogenated microcrystalline silicon ({mu}c-Si:H) has recently attracted significant attention as a promising candidate for thin-film transistors (TFTs) in large-area electronics due to high electron and hole charge carrier mobilities. We report on top-gate ambipolar TFTs based on {mu}c-Si:H prepared by plasma-enhanced chemical vapor deposition at temperatures below 200 C. Electrons and holes are directly injected into the {mu}c-Si:H channel via chromium drain and source contacts. The TFTs exhibit electron and hole charge carrier mobilities of 30-50 cm{sup 2}/Vs and 10-15 cm{sup 2}/Vs, respectively. In this work, the electrical characteristics of the top-gate ambipolar {mu}c-Si:H TFTs are described by a simple analytical model that takes the ambipolar transport into account. The analytical expressions are used to model the transfer curves, the potential and the net surface charge along the channel of the TFTs. The electrical model provides insights into the electronic transport of ambipolar {mu}c-Si:H TFTs (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Structural, microstructural and magnetic properties of amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, L., E-mail: leilakarimi@iauahvaz.ac.ir [Materials Science and Engineering Department, Islamic Azad University of Ahvaz, Ahvaz (Iran, Islamic Republic of); Shokrollahi, H. [Materials Science and Engineering Department, Shiraz University of Technology, 71555-313, Shiraz (Iran, Islamic Republic of)

    2011-06-09

    Highlights: > The amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} magnetic powders were prepared by mechanical alloying. > The saturation magnetization decreases and the coercivity increases as a result of the electronic interactions and the grain size reduction. > The use of amorphous alloy is due to the lower magnetic losses and higher electrical resistivity compared with other magnetic material - Abstract: This paper focuses on the magnetic, structural and microstructural studies of amorphous/nanocrystalline Ni{sub 63}Fe{sub 13}Mo{sub 4}Nb{sub 20} powders prepared by mechanical alloying. The ball-milling of Ni, Fe, Mo and Nb powders leads to alloying the element powders, the nanocrystalline and an amorphization matrix with Mo element up to 120 h followed by the strain and thermal-induced nucleation of a single nanocrystalline Ni-based phase from the amorphous matrix at 190 h. The results showed that the saturation magnetization decreases as a result of the electronic interactions between magnetic and non-magnetic elements and finally increases by the partial crystallization of the amorphous matrix. The coercive force increases as the milling time increases and finally decreases due to sub-grains formation.

  4. Aluminum induced crystallization of strongly (111) oriented polycrystalline silicon thin film and nucleation analysis

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A polycrystalline silicon thin film was fabricated on glass substrate by means of aluminum induced crystallization (AIC). Al and α-Si layers were deposited by magnetron sputtering respectively and annealed at 480°C for 1 h to realize layer exchange. The polycrystalline silicon thin film was continuous and strongly (111) oriented. By analyzing the structure variation of the oxidation membrane and lattice mismatch between γ-Al2O3 and Si, it was concluded that aluminum promoted the formation of (111) oriented silicon nucleus by controlling the orientation of γ-Al2O3, which was formed at the early stage of annealing.

  5. New process for production of ultra-thin grain oriented silicon steel

    Institute of Scientific and Technical Information of China (English)

    GAO Xiuhua; LIU En; QIU Chunlin; QI Kemin; TIAN Yanwen

    2006-01-01

    The Hi-B silicon steels were cold rolled by cross shear rolling (CSR) with different mismatch speed ratio(MSR)s and conventional rolling(CR) respectively, followed by primary recrystallization annealing. The effects of MSR and annealing temperature on magnetic properties of ultra-thin grain oriented silicon steel were analyzed. Experimental results show that, with the increase of MSR, the magnetic properties can be remarkably improved. The higher the annealing temperature is, the higher the magnetic induction and the lower the iron loss in ultra-thin silicon steel is.

  6. Silicon nanomembranes as a means to evaluate stress evolution in deposited thin films

    Science.gov (United States)

    Anna M. Clausen; Deborah M. Paskiewicz; Alireza Sadeghirad; Joseph Jakes; Donald E. Savage; Donald S. Stone; Feng Liu; Max G. Lagally

    2014-01-01

    Thin-film deposition on ultra-thin substrates poses unique challenges because of the potential for a dynamic response to the film stress during deposition. While theoretical studies have investigated film stress related changes in bulk substrates, little has been done to learn how stress might evolve in a film growing on a compliant substrate. We use silicon...

  7. Effect of Hydrogen Dilution on Growth of Silicon Nanocrystals Embedded in Silicon Nitride Thin Film bv Plasma-Enhanced CVD

    Institute of Scientific and Technical Information of China (English)

    DING Wenge; ZHEN Lanfang; ZHANG Jiangyong; LI Yachao; YU Wei; FU Guangsheng

    2007-01-01

    An investigation was conducted into the effect of hydrogen dilution on the mi-crostructure and optical properties of silicon nanograins embedded in silicon nitride (Si/SiNx) thin film deposited by the helicon wave plasma-enhanced chemical vapour deposition technique. With Ar-diluted SiH4 and N2 as the reactant gas sources in the fabrication of thin film, the film was formed at a high deposition rate. There was a high density of defect at the amorphous silicon (a-Si)/SiNx interface and a relative low optical gap in the film. An addition of hydrogen into the reactant gas reduced the film deposition rate sharply. The silicon nanograins in the SiNx matrix were in a crystalline state, and the density of defects at the silicon nanocrystals (nc-Si)/SiNx interface decreased significantly and the optical gap of the films widened. These results suggested that hydrogen activated by the plasma could not only eliminate in the defects between the interface of silicon nanograins and SiNx matrix, but also helped the nanograins transform from the amorphous into crystalline state. By changing the hydrogen dilution ratio in the reactant gas sources, a tunable band gap from 1.87 eV to 3.32 eV was obtained in the Si/SiNx film.

  8. High efficiency back-contact back-junction thin-film monocrystalline silicon solar cells from the porous silicon process

    Science.gov (United States)

    Haase, F.; Kajari-Schröder, S.; Brendel, R.

    2013-11-01

    This work demonstrates the fabrication of a 45 μm thick back-contact back-junction thin-film monocrystalline silicon solar cell from the porous silicon process with an energy conversion efficiency of 18.9%. We demonstrate an efficiency improvement of 5.4% absolute compared to our prior record of 13.5% for back-contact back-junction thin-film monocrystalline silicon solar cells. This increase in efficiency is achieved by reducing the recombination at the base contact using a back surface field and by increasing the generation with a front texture. We investigate the loss mechanisms in the cell using finite element simulations. A free energy loss analysis based on experiments and simulations determines the dominating loss mechanisms. The efficiency loss by base recombination is 0.8% absolute and the loss by base contact recombination is 0.5% absolute in the 18.9% efficiency cell.

  9. Thin film polycrystalline silicon photoelectric converter and fabricating method; Hakumaku takkesho shirikon koden henkan sochi oyobi sono seizo hoho

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, K. [Kobe (Japan); Suzuki, T. [Kobe (Japan); Yoshimi, M. [Kobe (Japan)

    1995-04-07

    This invention relates to a fabricating method for a thin film polycrystalline silicon photoelectric converter which has a large area and can be produced at low cost. Successive formation of mono-conductive polycrystalline silicon thin film and reverse conducting polycrystalline silicon thin film on a translucent substrate requires no vapor phase epitaxial growth, and the film formation temperature for silicon thin film can be lowered. Orientation of the monocrystalline silicon thin film to any of the surface bearings of (100), (111), and (110) results in the function of determining the orientation of the reverse conducting polycrystalline silicon thin film formed thereon. This orientation is effective to obtain excellent characteristics, and results in effective surface orientation of the entire power generating area. In addition, the supporting substrate and the surface protective film of the solar cell can be combined by orienting the translucent substrate side to the light incident side. 2 figs., 1 tab.

  10. A new analytical model of high voltage silicon on insulator (SOI) thin film devices

    Institute of Scientific and Technical Information of China (English)

    Hu Sheng-Dong; Zhang Bo; Li Zhao-Ji

    2009-01-01

    A new analytical model of high voltage silicon on insulator (SOI) thin film devices is proposed, and a formula of silicon critical electric field is derived as a function of silicon film thickness by solving a 2D Poisson equation from an effective ionization rate, with a threshold energy taken into account for electron multiplying. Unlike a conventional silicon critical electric field that is constant and independent of silicon film thickness, the proposed silicon critical electric field increases sharply with silicon film thickness decreasing especially in the case of thin films, and can come to 141 V/μm at a film thickness of 0.1 μm which is much larger than the normal value of about 30 V/μm. From the proposed formula of silicon critical electric field, the expressions of dielectric layer electric field and vertical breakdown voltage (VB,V) are obtained. Based on the model, an ultra thin film can be used to enhance dielectric layer electric field and so increase vertical breakdown voltage for SOI devices because of its high silicon critical electric field, and with a dielectric layer thickness of 2 μm the vertical breakdown voltages reach 852 and 300V for the silicon film thicknesses of 0.1 and 5μm, respectively. In addition, a relation between dielectric layer thickness and silicon film thickness is obtained, indicating a minimum vertical breakdown voltage that should be avoided when an SOI device is designed. 2D simulated results and some experimental results are in good agreement with analytical results.

  11. Thin Single Crystal Silicon Solar Cells on Ceramic Substrates: November 2009 - November 2010

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.; Ravi, K. V.

    2011-06-01

    In this program we have been developing a technology for fabricating thin (< 50 micrometres) single crystal silicon wafers on foreign substrates. We reverse the conventional approach of depositing or forming silicon on foreign substrates by depositing or forming thick (200 to 400 micrometres) ceramic materials on high quality single crystal silicon films ~ 50 micrometres thick. Our key innovation is the fabrication of thin, refractory, and self-adhering 'handling layers or substrates' on thin epitaxial silicon films in-situ, from powder precursors obtained from low cost raw materials. This 'handling layer' has sufficient strength for device and module processing and fabrication. Successful production of full sized (125 mm X 125 mm) silicon on ceramic wafers with 50 micrometre thick single crystal silicon has been achieved and device process flow developed for solar cell fabrication. Impurity transfer from the ceramic to the silicon during the elevated temperature consolidation process has resulted in very low minority carrier lifetimes and resulting low cell efficiencies. Detailed analysis of minority carrier lifetime, metals analysis and device characterization have been done. A full sized solar cell efficiency of 8% has been demonstrated.

  12. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Prathap Pathi

    2017-01-01

    Full Text Available Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm and is slightly lower (by ~5% at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm silicon and just 1%–2% for thicker (>100 μm cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  13. Silicon Light: a European FP7 project aiming at high efficiency thin film silicon solar cells on foil. Monolithic series interconnection of flexible thin-film PV devices

    Energy Technology Data Exchange (ETDEWEB)

    Soppe, W. [ECN Solar Energy, P.O. Box 1, 1755 ZG Petten (Netherlands); Haug, F.J. [Ecole Polytechnique Federale de Lausanne EPFL, Photovoltaics and Thin Film Electronics Laboratory, Rue A.-L. Breguet 2, 2000 Neuchatel (Switzerland); Couty, P. [VHFTechnologies SA, Rue Edouard-Verdan 2, CH-1400 Yverdon-les-Bains (Switzerland); Duchamp, M. [Technical University of Denmark, Center for Electron Nanoscopy, DK-2800 Kongens Lyngby (Denmark); Schipper, W. [Nanoptics GmbH, Innungstr.5, 21244 Buchholz (Germany); Krc, J. [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, SI-1000 Ljubljana (Slovenia); Sanchez, G. [Universidad Politecnica de Valencia, I.U.I. Centro de Tecnologia Nanofotonica, 46022 Valencia (Spain); Leitner, K. [Umicore Thin Film Products AG, Balzers (Liechtenstein); Wang, Q. [Shanghai Jiaotong University, Research Institute of Micro/Nanometer Science and Technology, 800 Dongchuan Road, Min Hang, 200240 Shanghai (China)

    2011-09-15

    Silicon-Light is a European FP7 project, which started January 1st, 2010 and aims at development of low cost, high-efficiency thin film silicon solar cells on foil. Three main routes are explored to achieve these goals: (a) advanced light trapping by implementing nanotexturization through UV Nano Imprinting Lithography (UV-NIL); (b) growth of crack-free silicon absorber layers on highly textured substrates; (c) development of new TCOs which should combine the best properties of presently available materials like ITO and AZO. The paper presents the midterm status of the project results, showing model calculations of ideal nanotextures for light trapping in thin film silicon solar cells; the fabrication of masters and the replication and roll-to-roll fabrication of these nanotextures. Further, results on ITO variants with improved work function are presented. Finally, the status of cell fabrication on foils with nanotexture is shown. Microcrystalline and amorphous silicon single junction cells with stable efficiencies with more than 8% have been made, paving the way towards a-Si/{mu}c-Si tandem cells with more than 11% efficiency.

  14. Assembly of europium organic framework–gold nanoparticle composite thin films on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Deep, Akash, E-mail: dr.akashdeep@gmail.com [Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030 (India); Academy of Scientific and Innovative Research, CSIR-CSIO, Sector 30 C, Chandigarh 160030 (India); Kaur, Rajnish [Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030 (India); Academy of Scientific and Innovative Research, CSIR-CSIO, Sector 30 C, Chandigarh 160030 (India); Kumar, Parveen [Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030 (India); Kumar, Pawan; Paul, A.K. [Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030 (India); Academy of Scientific and Innovative Research, CSIR-CSIO, Sector 30 C, Chandigarh 160030 (India)

    2014-08-28

    Metal organic frameworks are a sub-class of coordination polymers and rapidly generating huge research interests in several technological areas. One of the emerging areas of their potential applications is the photovoltaics. The present study proposes the assembly of europium organic framework–gold nanoparticle nanocomposite thin film on silicon substrate. Microscopic, X-ray diffraction, surface area measurement and thermal studies have indicated the formation of the desired thin film. Spectral studies have been used to highlight their solid state optical property. Current–voltage studies have established semiconducting property of the above thin films. - Highlights: • Thin film of europium organic framework/gold nanoparticles is prepared on silicon. • Fairly homogeneous films with a roughness factor of 5–10 nm are obtained. • Above thin films offer solid-state photoluminescence and semiconducting properties.

  15. MIS solar cells on thin polycrystalline silicon. Progress report No. 3, September 1-November 30, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, W.A.

    1980-12-01

    The first task of this project involves electron-beam deposition of thin silicon films on low cost substrates. The goal is to obtain 20 ..mu..m thick films having 20 ..mu..m diameter crystallites which may be recrystallized to > 40 ..mu..m. Material characterization and device studies are to be included in efforts to reach a 6% conversion efficiency. The second task deals with MIS solar cell fabrication on various types of silicon including poly-Si, ribbon-Si, silicon on ceramic, and thin film silicon. Conduction mechanism studies, optimum engineering design, and modification of the fabrication process are to be used to achieve 13% efficiency on Xtal-Si and 11% efficiency on poly-Si. The third task involves more detailed test procedures and includes spectral response, interface and grain boundary effects, computer analysis, materials studies, and grain boundary passivation. Progress is detailed. (WHK)

  16. Growth of YBCO superconducting thin films on CaF sub 2 buffered silicon

    CERN Document Server

    Bhagwat, S S; Patil, J M; Shirodkar, V S

    2000-01-01

    CaF sub 2 films were grown on silicon using the neutral cluster beam deposition technique. These films were highly crystalline and c-axis oriented. Superconducting YBCO thin films were grown on the Ca F sub 2 buffered silicon using the laser ablation technique. These films showed T sub c (onset) at 90 K and Tc(zero) at 86 K. X-ray diffraction analysis showed that the YBCO films were also oriented along the c-axis.

  17. Towards the efficiency limits of silicon solar cells: how thin is too thin?

    CERN Document Server

    Kowalczewski, Piotr

    2015-01-01

    It is currently possible to fabricate crystalline silicon solar cells with the absorber thickness ranging from a few hundreds of micrometers (conventional wafer-based cells) to devices as thin as $1\\,\\mu\\mathrm{m}$. In this work, we use a model single-junction solar cell to calculate the limits of energy conversion efficiency and estimate the optimal absorber thickness. The limiting efficiency for cells in the thickness range between 40 and $500\\,\\mu\\mathrm{m}$ is very similar and close to 29%. In this regard, we argue that decreasing the thickness below around $40\\,\\mu\\mathrm{m}$ is counter-productive, as it significantly reduces the maximum achievable efficiency, even when optimal light trapping is implemented. We analyse the roles of incomplete light trapping and extrinsic (bulk and surface) recombination mechanisms. For a reasonably high material quality, consistent with present-day fabrication techniques, the optimal thickness is always higher than a few tens of micrometers. We identify incomplete light ...

  18. Sunlight-thin nanophotonic monocrystalline silicon solar cells

    Science.gov (United States)

    Depauw, Valérie; Trompoukis, Christos; Massiot, Inès; Chen, Wanghua; Dmitriev, Alexandre; Cabarrocas, Pere Roca i.; Gordon, Ivan; Poortmans, Jef

    2017-09-01

    Introducing nanophotonics into photovoltaics sets the path for scaling down the surface texture of crystalline-silicon solar cells from the micro- to the nanoscale, allowing to further boost the photon absorption while reducing silicon material loss. However, keeping excellent electrical performance has proven to be very challenging, as the absorber is damaged by the nanotexturing and the sensitivity to the surface recombination is dramatically increased. Here we realize a light-wavelength-scale nanotextured monocrystalline silicon cell with the confirmed efficiency of 8.6% and an effective thickness of only 830 nm. For this we adopt a self-assembled large-area and industry-compatible amorphous ordered nanopatterning, combined with an advanced surface passivation, earning strongly enhanced solar light absorption while retaining efficient electron collection. This prompts the development of highly efficient flexible and semitransparent photovoltaics, based on the industrially mature monocrystalline silicon technology.

  19. Multi-Objective Optimization of Thin-Film Silicon Solar Cells with Metallic and Dielectric Nanoparticles

    Directory of Open Access Journals (Sweden)

    Giovanni Aiello

    2017-01-01

    Full Text Available Thin-film solar cells enable a strong reduction of the amount of silicon needed to produce photovoltaic panels but their efficiency lowers. Placing metallic or dielectric nanoparticles over the silicon substrate increases the light trapping into the panel thanks to the plasmonic scattering from nanoparticles at the surface of the cell. The goal of this paper is to optimize the geometry of a thin-film solar cell with silver and silica nanoparticles in order to improve its efficiency, taking into account the amount of silver. An efficient evolutionary algorithm is applied to perform the optimization with a reduced computing time.

  20. Multi-resonant absorption in ultra-thin silicon solar cells with metallic nanowires.

    Science.gov (United States)

    Massiot, Inès; Colin, Clément; Sauvan, Christophe; Lalanne, Philippe; Cabarrocas, Pere Roca I; Pelouard, Jean-Luc; Collin, Stéphane

    2013-05-06

    We propose a design to confine light absorption in flat and ultra-thin amorphous silicon solar cells with a one-dimensional silver grating embedded in the front window of the cell. We show numerically that multi-resonant light trapping is achieved in both TE and TM polarizations. Each resonance is analyzed in detail and modeled by Fabry-Perot resonances or guided modes via grating coupling. This approach is generalized to a complete amorphous silicon solar cell, with the additional degrees of freedom provided by the buffer layers. These results could guide the design of resonant structures for optimized ultra-thin solar cells.

  1. Nanostructured silicon carbon thin films grown by plasma enhanced chemical vapour deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Coscia, U. [Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); CNISM Unita' di Napoli, Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); Ambrosone, G., E-mail: ambrosone@na.infn.it [Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); SPIN-CNR, Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); Basa, D.K. [Department of Physics, Utkal University, Bhubaneswar 751004 (India); Rigato, V. [INFN Laboratori Nazionali Legnaro, 35020 Legnaro (Padova) (Italy); Ferrero, S.; Virga, A. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2013-09-30

    Nanostructured silicon carbon thin films, composed of Si nanocrystallites embedded in hydrogenated amorphous silicon carbon matrix, have been prepared by varying rf power in ultra high vacuum plasma enhanced chemical vapour deposition system using silane and methane gas mixtures diluted in hydrogen. In this paper we have studied the compositional, structural and electrical properties of these films as a function of rf power. It is shown that with increasing rf power the atomic densities of carbon and hydrogen increase while the atomic density of silicon decreases, resulting in a reduction in the mass density. Further, it is demonstrated that carbon is incorporated into amorphous matrix and it is mainly bonded to silicon. The study has also revealed that the crystalline volume fraction decreases with increase in rf power and that the films deposited with low rf power have a size distribution of large and small crystallites while the films deposited with relatively high power have only small crystallites. Finally, the enhanced transport properties of the nanostructured silicon carbon films, as compared to amorphous counterpart, have been attributed to the presence of Si nanocrystallites. - Highlights: • The mass density of silicon carbon films decreases from 2.3 to 2 g/cm{sup 3}. • Carbon is incorporated in the amorphous phase and it is mainly bonded to silicon. • Nanostructured silicon carbon films are deposited at rf power > 40 W. • Si nanocrystallites in amorphous silicon carbon enhance the electrical properties.

  2. Silicon nitride and intrinsic amorphous silicon double antireflection coatings for thin-film solar cells on foreign substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Da; Kunz, Thomas [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Photovoltaics and Thermosensoric, Haberstr. 2a, 91058 Erlangen (Germany); Wolf, Nadine [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Energy Efficiency, Am Galgenberg 87, 97074 Wuerzburg (Germany); Liebig, Jan Philipp [Materials Science and Engineering, Institute I, University of Erlangen-Nuremberg, Martensstr. 5, 91058 Erlangen (Germany); Wittmann, Stephan; Ahmad, Taimoor; Hessmann, Maik T.; Auer, Richard [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Photovoltaics and Thermosensoric, Haberstr. 2a, 91058 Erlangen (Germany); Göken, Mathias [Materials Science and Engineering, Institute I, University of Erlangen-Nuremberg, Martensstr. 5, 91058 Erlangen (Germany); Brabec, Christoph J. [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Photovoltaics and Thermosensoric, Haberstr. 2a, 91058 Erlangen (Germany); Institute of Materials for Electronics and Energy Technology, University of Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen (Germany)

    2015-05-29

    Hydrogenated intrinsic amorphous silicon (a-Si:H) was investigated as a surface passivation method for crystalline silicon thin film solar cells on graphite substrates. The results of the experiments, including quantum efficiency and current density-voltage measurements, show improvements in cell performance. This improvement is due to surface passivation by an a-Si:H(i) layer, which increases the open circuit voltage and the fill factor. In comparison with our previous work, we have achieved an increase of 0.6% absolute cell efficiency for a 40 μm thick 4 cm{sup 2} aperture area on the graphite substrate. The optical properties of the SiN{sub x}/a-Si:H(i) stack were studied using spectroscopic ellipsometer techniques. Scanning transmission electron microscopy inside a scanning electron microscope was applied to characterize the cross section of the SiN{sub x}/a-Si:H(i) stack using focus ion beam preparation. - Highlights: • We report a 10.8% efficiency for thin-film silicon solar cell on graphite. • Hydrogenated intrinsic amorphous silicon was applied for surface passivation. • SiN{sub x}/a-Si:H(i) stacks were characterized by spectroscopic ellipsometer techniques. • Cross-section micrograph was obtained by scanning transmission electron microscopy. • Quantum efficiency and J-V measurements show improvements in the cell performance.

  3. Variation in the structure and optical properties of polymorphous silicon thin films using dichlorosilane as silicon precursor

    Energy Technology Data Exchange (ETDEWEB)

    Remolina, A.; Hamui, L.; Monroy, B.M.; Garcia-Sanchez, M.F.; Santana, G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, AP 70-360, Cd. Universitaria, Coyoacan, C. P. 04510, Mexico D. F. (Mexico); Ponce, A. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo 140, C. P. 25290, Saltillo, Coahuila (Mexico); Picquart, M. [Departamento de Fisica, Universidad Autonoma Metropolitana, AP 55-534, Av. Sn Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C.P. 09340, Mexico D. F. (Mexico)

    2011-03-15

    Polymorphous silicon thin films were obtained by plasma enhanced chemical vapor deposition using dichlorosilane as silicon precursor. The RF power and the dichlorosilane to hydrogen flow rate ratio were varied to obtain different crystalline fractions and average sizes of silicon nanocrystals embedded in the amorphous silicon matrix. Microscopy images confirmed the existence of nanocrystallites with averages sizes between 2 and 6 nm. Broader size distributions were obtained with increasing RF power. Raman results confirmed that different nanocrystalline fractions (from 12% to 54%) can be achieved in these films by regulating the selected growth parameters. The optical band gap calculated by the Tauc model from UV-visible transmittance measurements varies between 1.8 to 2.3 eV. The relationship between the optical properties is discussed in terms of the different nanostructures of the samples. Depending on their absorption properties and effective band gap, these materials can be suitable for application in thin film solar cell devices (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Silicon solar cell performance deposited by diamond like carbon thin film ;Atomic oxygen effects;

    Science.gov (United States)

    Aghaei, Abbas Ail; Eshaghi, Akbar; Karami, Esmaeil

    2017-09-01

    In this research, a diamond-like carbon thin film was deposited on p-type polycrystalline silicon solar cell via plasma-enhanced chemical vapor deposition method by using methane and hydrogen gases. The effect of atomic oxygen on the functioning of silicon coated DLC thin film and silicon was investigated. Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and attenuated total reflection-Fourier transform infrared spectroscopy were used to characterize the structure and morphology of the DLC thin film. Photocurrent-voltage characteristics of the silicon solar cell were carried out using a solar simulator. The results showed that atomic oxygen exposure induced the including oxidation, structural changes, cross-linking reactions and bond breaking of the DLC film; thus reducing the optical properties. The photocurrent-voltage characteristics showed that although the properties of the fabricated thin film were decreased after being exposed to destructive rays, when compared with solar cell without any coating, it could protect it in atomic oxygen condition enhancing solar cell efficiency up to 12%. Thus, it can be said that diamond-like carbon thin layer protect the solar cell against atomic oxygen exposure.

  5. Deposition and characterization of amorphous silicon with embedded nanocrystals and microcrystalline silicon for thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, R., E-mail: rambrosi@uacj.mx [Instituto Nacional de Astrofísica, Óptica y Electrónica, INAOE, Puebla (Mexico); Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, UACJ, C.J., Chihuahua (Mexico); Moreno, M.; Torres, A. [Instituto Nacional de Astrofísica, Óptica y Electrónica, INAOE, Puebla (Mexico); Carrillo, A. [Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, UACJ, C.J., Chihuahua (Mexico); Vivaldo, I.; Cosme, I. [Instituto Nacional de Astrofísica, Óptica y Electrónica, INAOE, Puebla (Mexico); Heredia, A. [Universidad Popular Autónoma del Estado de Puebla, Puebla (Mexico)

    2015-09-15

    Highlights: • Nanostructured silicon thin films were deposited by PECVD. • Polymorphous and microcrystalline were obtained varying the pressure and power. • Structural and optoelectronics properties were studied. • The σ{sub dark} changed by 5 order of magnitude under illumination, V{sub d} was at 2.5 A/s. • The evidence of embedded nanocrystals into the amorphous matrix was investigated. - Abstract: Amorphous silicon thin films with embedded nanocrystals and microcrystalline silicon were deposited by the standard Radio Frequency (RF) Plasma Enhanced Chemical Vapor Deposition (PECVD) technique, from SiH{sub 4}, H{sub 2}, Ar gas mixture at substrate temperature of 200 °C. Two series of films were produced varying deposition parameters as chamber pressure and RF power density. The chemical bonding in the films was characterized by Fourier transform infrared spectroscopy, where it was observed a correlation between the hydrogen content and the morphological and electrical properties in the films. Electrical and optical parameters were extracted in both series of films, as room temperature conductivity (σ{sub RT}), activation energy (E{sub a}), and optical band gap (E{sub g}). As well, structural analysis in the films was performed by Raman spectroscopy and Atomic Force Microscopy (AFM), which gives an indication of the films crystallinity. The photoconductivity changed in a range of 2 and 6 orders of magnitude from dark to AM 1.5 illumination conditions, which is of interest for thin film solar cells applications.

  6. Scattering of long wavelengths into thin silicon photovoltaic films by plasmonic silver nanoparticles

    Science.gov (United States)

    Osgood, R. M.; Bullion, K. M.; Giardini, S. A.; Carlson, J. B.; Stenhouse, P.; Kingsborough, R.; Liberman, V.; Parameswaran, L.; Rothschild, M.; Miller, O.; Kooi, S.; Joannopoulos, J.; Jeffrey, F.; Braymen, S.; Gill, H. Singh; Kumar, J.

    2014-10-01

    Nanoparticles and nanostructures with plasmonic resonances are currently being employed to enhance the efficiency of solar cells. 1-3 Ag stripe arrays have been shown theoretically to enhance the short-circuit current of thin silicon layers. 4 Monolayers of Ag nanoparticles with diameter d thin polymer layers with thicknesses thin (100 nm films deposited on glass and flexible polymer substrates, the latter originating in a roll-to-roll manufacturing process. Ag nanoparticles are held in place and aggregation is prevented with a polymer overcoat. We observe interesting wavelength shifts between maxima in specular and diffuse scattering that depend on particle size and shape, indicating that the nanoparticles substantially modify the scattering into the thin silicon film.

  7. Laser cleaning of the metallic thin films from silicon wafer surface with UV laser radiation

    Science.gov (United States)

    Apostol, Ileana; Apostol, Dan; Victor, Damian; Timcu, Adrian; Iordache, Iuliana; Castex, Marie-Claude C.; Galli, Roberta; Ulieru, Dumitru G.

    2004-10-01

    The interest to use laser surface processing in microtechnology as a friendly method from the technologic and environmental point of view lead our studies about laser radiation interaction with photo-resist and metallic thin films. In this view we have tried in our experiments to process metallic thin films deposited on silicon substrate by using laser radiation. To obtain a good quality of the metallic thin film removal from the silicon surface a careful selection of the incident laser intensity, number of pulses and irradiation geometry is needed. The threshold value for the laser cleaning intensity depends on the number of incident laser pulses. A careful experimental estimation of the cleaning conditions from the point of view of incident laser energy, fluence, intensity and irradiation geometry was realized for aluminum, copper, and chromium thin films.

  8. Modelling of an ultra-thin silicatene/silicon-carbide hybrid film

    Science.gov (United States)

    Schlexer, Philomena; Pacchioni, Gianfranco

    2016-09-01

    Recently, a well-ordered silicatene/silicon-carbide hybrid thin-film supported on Ru(0 0 0 1) has been reported (2015 Surf. Sci. 632 9-13). The thin-film consist of a monolayer of corner sharing (SiO4)-tetrahedra on top of a (Si2C3) monolayer supported on the Ru(0 0 0 1) surface. This silicatene/silicon-carbide hybrid system may exhibit interesting properties for nano-technological applications and represents another example of a 2D material. We explore the physical and chemical properties of the silicatene/silicon-carbide thin-film using DFT and compare the vibrational spectra with existing experimental data. The characteristics of the silicatene/silicon-carbide hybrid system are compared with those of the bilayer-silicatene (pure SiO2 film). We found large differences in the adsorption modes of the two thin-films on the Ru(0 0 0 1) support. Whereas the bilayer-silicatene physisorbs on the Ru(0 0 0 1) surface, the silicatene/silicon-carbide layer binds via chemisorption. The chemical properties of the two thin-films were probed by adsorption of H atoms at various positions, as well as by Al-doping and the formation of hydroxyl groups (Al-OH). These results show that despite the similar structure of the top layer and the identical metal support (Ru), the mixed silicatene/silicon-carbide system behaves quite differently from the pure silica two-layer counterpart.

  9. Thermal conductivity of silicon nanocrystals and polystyrene nanocomposite thin films

    Science.gov (United States)

    Bagja Juangsa, Firman; Muroya, Yoshiki; Ryu, Meguya; Morikawa, Junko; Nozaki, Tomohiro

    2016-09-01

    Silicon nanocrystals (SiNCs) are well known for their size-dependent optical and electronic properties; they also have the potential for low yet controllable thermal properties. As a silicon-based low-thermal conductivity material is required in microdevice applications, SiNCs can be utilized for thermal insulation. In this paper, SiNCs and polymer nanocomposites were produced, and their thermal conductivity, including the density and specific heat, was measured. Measurement results were compared with thermal conductivity models for composite materials, and the comparison shows a decreasing value of the thermal conductivity, indicating the effect of the size and presence of the nanostructure on the thermal conductivity. Moreover, employing silicon inks at room temperature during the fabrication process enables a low cost of fabrication and preserves the unique properties of SiNCs.

  10. Electrochemical Intercalation of Sodium into Silicon Thin Film

    Institute of Scientific and Technical Information of China (English)

    Dong-Yeon Kim; Hyo-Jun Ahn; Gyu-Bong Cho; Jong-Seon Kim; Ho-Suk Ryu; Ki-Won Kim; Jou-Hyeon Ahn; Won-Cheol Shin

    2008-01-01

    In order to investigate the possibility of Si thin film as an anode for Na battery, we studied the electrochemical intercalation of sodium into the Si film. Amorphous Si thin film electrode was prepared using DC magnetron sputtering. Sodium ion could intercalate into Si thin film upto Na0.52Si, i.e. 530mAh · g-1-Si. The first discharge capacity was 80mAh.·g-1-Si, which meant reversible amount of sodium intercalation. The discharge capacity slightly decreased to 70mAh · g-1-Si after 10 cycles.

  11. In and Ga Codoped ZnO Film as a Front Electrode for Thin Film Silicon Solar Cells

    OpenAIRE

    Duy Phong Pham; Huu Truong Nguyen; Bach Thang Phan; Thi My Dung Cao; Van Dung Hoang; Vinh Ai Dao; Junsin Yi; Cao Vinh Tran

    2014-01-01

    Doped ZnO thin films have attracted much attention in the research community as front-contact transparent conducting electrodes in thin film silicon solar cells. The prerequisite in both low resistivity and high transmittance in visible and near-infrared region for hydrogenated microcrystalline or amorphous/microcrystalline tandem thin film silicon solar cells has promoted further improvements of this material. In this work, we propose the combination of major Ga and minor In impurities codop...

  12. In-situ transmission measurements as process control for thin-film silicon solar cells

    NARCIS (Netherlands)

    Meier, M.; Muthmann, S.; Flikweert, A. J.; Dingemans, G.; M. C. M. van de Sanden,; Gordijn, A.

    2011-01-01

    In this work, in-situ transmission measurements using plasma as light source are presented for the determination of growth rate and crystallinity during silicon thin-film growth. The intensity of distinct plasma emission lines was measured at the backside of the transparent substrates on which silic

  13. Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

    NARCIS (Netherlands)

    de Jong, M.M.

    2013-01-01

    In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic subst

  14. Simulation of twin boundary effect on characteristics of single grain-silicon thin film transistors

    NARCIS (Netherlands)

    Yan, F.; Migliorato, P.; Ishihara, R.

    2007-01-01

    The influence of twin boundaries on the characteristics of single grain-silicon thin film transistors has been analyzed by three-dimensional simulation. The simulations show that the orientation and the location of a twin boundary could affect the field-effect mobility and the leakage current of a d

  15. Materials and Light Management for High-Efficiency Thin-Film Silicon Solar Cells

    NARCIS (Netherlands)

    Tan, H.

    2015-01-01

    Direct conversion of sunlight into electricity is one of the most promising approaches to provide sufficient renewable energy for humankind. Solar cells are such devices which can efficiently generate electricity from sunlight through the photovoltaic effect. Thin-film silicon solar cells, a type of

  16. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells

    Science.gov (United States)

    Pathi, Prathap; Peer, Akshit; Biswas, Rana

    2017-01-01

    Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping. PMID:28336851

  17. Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

    NARCIS (Netherlands)

    de Jong, M.M.

    2013-01-01

    In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic

  18. Nano-Photonic Structures for Light Trapping in Ultra-Thin Crystalline Silicon Solar Cells.

    Science.gov (United States)

    Pathi, Prathap; Peer, Akshit; Biswas, Rana

    2017-01-13

    Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm² photo-current and >20% efficiency. This architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhanced light-trapping.

  19. Designing optimized nano textures for thin-film silicon solar cells

    NARCIS (Netherlands)

    Jäger, K.; Fischer, M.; Van Swaaij, R.A.C.M.M.; Zeman, M.

    2013-01-01

    Thin-film silicon solar cells (TFSSC), which can be manufactured from abundant materials solely, contain nano-textured interfaces that scatter the incident light. We present an approximate very fast algorithm that allows optimizing the surface morphology of two-dimensional nano-textured interfaces.

  20. Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

    NARCIS (Netherlands)

    de Jong, M.M.|info:eu-repo/dai/nl/325844208

    2013-01-01

    In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic subst

  1. Materials and Light Management for High-Efficiency Thin-Film Silicon Solar Cells

    NARCIS (Netherlands)

    Tan, H.

    2015-01-01

    Direct conversion of sunlight into electricity is one of the most promising approaches to provide sufficient renewable energy for humankind. Solar cells are such devices which can efficiently generate electricity from sunlight through the photovoltaic effect. Thin-film silicon solar cells, a type of

  2. Ultrafast terahertz conductivity and transient optical absorption spectroscopy of silicon nanocrystal thin films

    DEFF Research Database (Denmark)

    Titova, Lyubov V.; Harthy, Rahma Al; Cooke, David

    We use time-resolved THz spectroscopy and transient optical absorption spectroscopy as two complementary techniques to study ultrafast carrier dynamics in silicon nanocrystal thin films. We find that the photoconductive dynamics in these materials is dominated by interface trapping, and we observe...... several different relaxation mechanisms for photoexcited carriers...

  3. Thin foil silicon solar cells with coplanar back contacts

    Science.gov (United States)

    Ho, F.; Iles, P. A.; Baraona, C. R.

    1981-01-01

    To fabricate 50 microns thick, coplanar back contact (CBC) silicon solar cells, wraparound junction design was selected and proved to be effective. The process sequence used, the cell design, and the cell performance are described. CBC cells with low solar absorptance have shown AMO efficiencies to 13%, high cells up to 14%; further improvements are projected with predictable optimization.

  4. Thin-film monocrystalline-silicon solar cells based on a seed layer approach with 11% efficiency

    Science.gov (United States)

    Gordon, I.; Qiu, Y.; Van Gestel, D.; Poortmans, J.

    2010-09-01

    Solar modules made from thin-film crystalline-silicon layers of high quality on glass substrates could lower the price of photovoltaic electricity substantially. Almost half of the price of wafer-based silicon solar modules is currently due to the cost of the silicon wafers themselves. Using crystalline-silicon thin-film as the active material would substantially reduce the silicon consumption while still ensuring a high cell-efficiency potential and a stable cell performance. One way to create a crystalline-silicon thin film on glass is by using a seed layer approach in which a thin crystalline-silicon layer is first created on a non-silicon substrate, followed by epitaxial thickening of this layer. In this paper, we present new solar cell results obtained on 10-micron thick monocrystalline-silicon layers, made by epitaxial thickening of thin seed layers on transparent glass-ceramic substrates. We used thin (001)-oriented silicon single-crystal seed layers on glass-ceramic substrates provided by Corning Inc. that are made by a process based on anodic bonding and implant-induced separation. Epitaxial thickening of these seed layers was realized in an atmospheric-pressure chemical vapor deposition system. Simple solar cell structures in substrate configuration were made from the epitaxial mono-silicon layers. The Si surface was plasma-textured to reduce the front-side reflection. No other light trapping features were incorporated. Efficiencies of up to 11% were reached with Voc values above 600 mV indicating the good electronic quality of the material. We believe that by further optimizing the material quality and by integrating an efficient light trapping scheme, the efficiency potential of these single-crystal silicon thin films on glass-ceramics should be higher than 15%.

  5. Ultra-thin silicon/electro-optic polymer hybrid waveguide modulators

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Feng; Spring, Andrew M. [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Sato, Hiromu [Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Maeda, Daisuke; Ozawa, Masa-aki; Odoi, Keisuke [Nissan Chemical Industries, Ltd., 2-10-1 Tuboi Nishi, Funabashi, Chiba 274-8507 (Japan); Aoki, Isao; Otomo, Akira [National Institute of Information and Communications Technology, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492 (Japan); Yokoyama, Shiyoshi, E-mail: s-yokoyama@cm.kyushu-u.ac.jp [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan); Department of Molecular and Material Sciences, Kyushu University, 6-1 Kasuga-koen Kasuga, Fukuoka 816-8580 (Japan)

    2015-09-21

    Ultra-thin silicon and electro-optic (EO) polymer hybrid waveguide modulators have been designed and fabricated. The waveguide consists of a silicon core with a thickness of 30 nm and a width of 2 μm. The cladding is an EO polymer. Optical mode calculation reveals that 55% of the optical field around the silicon extends into the EO polymer in the TE mode. A Mach-Zehnder interferometer (MZI) modulator was prepared using common coplanar electrodes. The measured half-wave voltage of the MZI with 7 μm spacing and 1.3 cm long electrodes is 4.6 V at 1550 nm. The evaluated EO coefficient is 70 pm/V, which is comparable to that of the bulk EO polymer film. Using ultra-thin silicon is beneficial in order to reduce the side-wall scattering loss, yielding a propagation loss of 4.0 dB/cm. We also investigated a mode converter which couples light from the hybrid EO waveguide into a strip silicon waveguide. The calculation indicates that the coupling loss between these two devices is small enough to exploit the potential fusion of a hybrid EO polymer modulator together with a silicon micro-photonics device.

  6. Growth and etch rate study of low temperature anodic silicon dioxide thin films.

    Science.gov (United States)

    Ashok, Akarapu; Pal, Prem

    2014-01-01

    Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics.

  7. Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

    Directory of Open Access Journals (Sweden)

    Akarapu Ashok

    2014-01-01

    Full Text Available Silicon dioxide (SiO2 thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs and microelectromechanical systems (MEMS. Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics.

  8. Nanophotonic devices on thin buried oxide Silicon-On-Insulator substrates

    CERN Document Server

    Sridaran, Suresh

    2009-01-01

    We demonstrate a silicon photonic platform using thin buried oxide silicon-on-insulator (SOI) substrates using localized substrate removal. We show high confinement silicon strip waveguides, micro-ring resonators and nanotapers using this technology. Propagation losses for the waveguides using the cutback method are 3.88 dB/cm for the quasi-TE mode and 5.06 dB/cm for the quasi-TM mode. Ring resonators with a loaded quality factor (Q) of 46,500 for the quasi-TM mode and intrinsic Q of 148,000 for the quasi-TE mode have been obtained. This process will enable the integration of photonic structures with thin buried oxide SOI based electronics.

  9. Silicon carbide thin films as nuclear ceramics grown by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Filipescu, M., E-mail: morarm@nipne.ro [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO 77125, Magurele - Bucharest (Romania); Velisa, G. [Horia Hulubei National Institute of Physics and Nuclear Engineering, P.O.BOX MG-6, Bucharest - Magurele (Romania); Ion, V.; Andrei, A. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO 77125, Magurele - Bucharest (Romania); Scintee, N.; Ionescu, P. [Horia Hulubei National Institute of Physics and Nuclear Engineering, P.O.BOX MG-6, Bucharest - Magurele (Romania); Stanciu, S.G. [Center for Microscopy- Microanalysis and Information Processing, University ' POLITEHNICA' of Bucharest, Bucharest (Romania); Pantelica, D. [Horia Hulubei National Institute of Physics and Nuclear Engineering, P.O.BOX MG-6, Bucharest - Magurele (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG 16, RO 77125, Magurele - Bucharest (Romania)

    2011-09-01

    Silicon carbide has been identified as a potential inert matrix candidate for advanced fuel. In this work, the growth of SiC thin films by pulsed laser deposition is reported. The stoicheometry and thickness of deposited films was investigated by non-Rutherford backscattering spectrometry. The influence of the deposition parameters, i.e. substrate temperature and laser fluence on the structure, morphology and optical properties of the deposited thin layers was studied. It was found that polycrystalline SiC thin films with uniform surface morphology were obtained at 873 K.

  10. Analysis of thin baked-on silicone layers by FTIR and 3D-Laser Scanning Microscopy.

    Science.gov (United States)

    Funke, Stefanie; Matilainen, Julia; Nalenz, Heiko; Bechtold-Peters, Karoline; Mahler, Hanns-Christian; Friess, Wolfgang

    2015-10-01

    Pre-filled syringes (PFS) and auto-injection devices with cartridges are increasingly used for parenteral administration. To assure functionality, silicone oil is applied to the inner surface of the glass barrel. Silicone oil migration into the product can be minimized by applying a thin but sufficient layer of silicone oil emulsion followed by thermal bake-on versus spraying-on silicone oil. Silicone layers thicker than 100nm resulting from regular spray-on siliconization can be characterized using interferometric profilometers. However, the analysis of thin silicone layers generated by bake-on siliconization is more challenging. In this paper, we have evaluated Fourier transform infrared (FTIR) spectroscopy after solvent extraction and a new 3D-Laser Scanning Microscopy (3D-LSM) to overcome this challenge. A multi-step solvent extraction and subsequent FTIR spectroscopy enabled to quantify baked-on silicone levels as low as 21-325μg per 5mL cartridge. 3D-LSM was successfully established to visualize and measure baked-on silicone layers as thin as 10nm. 3D-LSM was additionally used to analyze the silicone oil distribution within cartridges at such low levels. Both methods provided new, highly valuable insights to characterize the siliconization after processing, in order to achieve functionality.

  11. Composition of nanocomposites based on thin layers of tin on porous silicon formed by magnetron sputtering

    Science.gov (United States)

    Lenshin, A. S.; Kashkarov, V. M.; Domashevskaya, E. P.; Seredin, P. V.; Ryabtsev, S. V.; Bel'tyukov, A. N.; Gil'mutdinov, F. Z.

    2017-01-01

    Using scanning electron microscopy and X-ray photoelectron spectroscopy the features of morphology and peculiarities of the surface composition of nanocomposites made of thin tin layers by magnetron sputtering formed on porous silicon with pores size of 50-150 nm. Porous silicon was obtained on n-type conductivity crystalline silicon substrate. The obtained nanocomposites were found differ between themselves by the ratio of the main phases: tin dioxide, sub-oxide and metal tin in a dependence on the thickness of the deposited tin layer. Fraction of the oxidized tin in the phase composition of composites was reduced from the surface to the bulk of the sample. Moreover, it was determined that the deposition of tin nanolayers did not result in a considerable change of the phase composition of porous silicon substrate.

  12. Research on high-efficiency, single-junction, monolithic, thin-film amorphous silicon solar cells

    Science.gov (United States)

    Wiesmann, H.; Dolan, J.; Fricano, G.; Danginis, V.

    1987-02-01

    A study was undertaken of the optoelectronic properties of amorphous silicon-hydrogen thin films deposited from disilane at high deposition rates. The information derived from this study was used to fabricate amorphous silicon solar cells with efficiencies exceeding 7%. The intrinsic layer of these solar cells was deposited at 15 angstroms/second. Material properties investigated included dark conductivity, photoconductivity, minority carrier diffusion length, and density of states. The solar cells properties characterized were absolute quantum yield and simulated global AM 1.5 efficiencies. Investigations were undertaken utilizing optical and infrared spectroscopy to optimize the microstructures of the intrinsic amorphous silicon. That work was sponsored by the New York State Energy Research and Development Authority. The information was used to optimize the intrinsic layer of amorphous silicon solar cells, resulting in AM 1.5 efficiencies exceeding 7%.

  13. High deposition rate processes for the fabrication of microcrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Michard, S. [Institute of Energy and Climate Research 5 - Photovoltaik, Forschungszentrum Jülich, 52425 Jülich (Germany); Meier, M., E-mail: ma.meier@fz-juelich.de [Institute of Energy and Climate Research 5 - Photovoltaik, Forschungszentrum Jülich, 52425 Jülich (Germany); Grootoonk, B.; Astakhov, O.; Gordijn, A.; Finger, F. [Institute of Energy and Climate Research 5 - Photovoltaik, Forschungszentrum Jülich, 52425 Jülich (Germany)

    2013-05-15

    The increase of deposition rate of microcrystalline silicon absorber layers is an essential point for cost reduction in the mass production of thin-film silicon solar cells. In this work we explored a broad range of plasma enhanced chemical vapor deposition (PECVD) parameters in order to increase the deposition rate of intrinsic microcrystalline silicon layers keeping the industrial relevant material quality standards. We combined plasma excitation frequencies in the VHF band with the high pressure high power depletion regime using new deposition facilities and achieved deposition rates as high as 2.8 nm/s. The material quality evaluated from photosensitivity and electron spin resonance measurements is similar to standard microcrystalline silicon deposited at low growth rates. The influence of the deposition power and the deposition pressure on the electrical and structural film properties was investigated.

  14. Thermal recrystallization of physical vapor deposition based germanium thin films on bulk silicon (100)

    KAUST Repository

    Hussain, Aftab M.

    2013-08-16

    We demonstrate a simple, low-cost, and scalable process for obtaining uniform, smooth surfaced, high quality mono-crystalline germanium (100) thin films on silicon (100). The germanium thin films were deposited on a silicon substrate using plasma-assisted sputtering based physical vapor deposition. They were crystallized by annealing at various temperatures ranging from 700 °C to 1100 °C. We report that the best quality germanium thin films are obtained above the melting point of germanium (937 °C), thus offering a method for in-situ Czochralski process. We show well-behaved high-κ /metal gate metal-oxide-semiconductor capacitors (MOSCAPs) using this film. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Synchrotron radiation studies of the orientation of thin silicon phthalocyanine dichloride film on HOPG substrate

    Institute of Scientific and Technical Information of China (English)

    DENG Ju-Zhi; CHEN Rong; SEKIGUCHI Tetsuhiro; BABA Yuji; HIRAO Norie; HONDA Mitsunori

    2008-01-01

    Thin silicon Phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser.The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy.The orientation of the molecules in respect to the substrate plane Was investigated by measuring the silicon K-edge near edge X-ray absorption fine structure(NEXAFS).In the NEXAFS spectra of the thin sample,two clear peaks which were assigned to 1s→σ*Si-N and 1s→σ*Si-C1 appeared around 1847.2 eV and 1843.1 eV respectively.The intensities of the resonance peaks showed strong polarization dependence.A quantitative analysis of the polarization dependence revealed that the Si-N bond tended to lie down while the Si-C1 bond was out of the molecular plane.

  16. Coulomb blockade effects in silicon nanoparticles embedded in thin silicon-rich oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Sanchez, A; Barreto, J; Dominguez, C [IMB-CNM (CSIC), Campus UAB, Bellaterra 08193, Barcelona (Spain); Aceves, M; Yu, Z [INAOE, Electronics Department, Apartado 51, Puebla, 72000 (Mexico); Luna-Lopez, J A [CCMC, UNAM, Optics Department, Ensenada, BC, 22800 (Mexico)], E-mail: alfredo.morales@cnm.es

    2008-04-23

    Silicon nanoparticles (Si-nps) embedded in silicon oxide matrix were created using silicon-rich oxide (SRO) films deposited by low pressure chemical vapour deposition (LPCVD) followed by a thermal annealing at 1100 deg. C. The electrical properties were studied using metal-oxide-semiconductor (MOS) structures with the SRO films as the active layers. Capacitance versus voltage (C-V) exhibited downward and upward peaks in the accumulation region related to charge trapping and de-trapping effects of Si-nps, respectively. Current versus voltage (I-V) measurements showed fluctuations in the form of spike-like peaks and a clear staircase at room temperature. These effects have been related to the Coulomb blockade (CB) effect in the silicon nanoparticles embedded in SRO films. The observed quantum effects are due to 1 nm nanoparticles.

  17. Design of a 1200-V Thin-Silicon-Layer p-Channel SOI LDMOS Device

    Institute of Scientific and Technical Information of China (English)

    胡盛东; 张玲; 罗小蓉; 张波; 李肇基; 吴丽娟

    2011-01-01

    A 1200-V thin-silicon-layer p-channel silicon-on-insulator(SOI)lateral double-diffused metal-oxide-semiconductor (LDMOS)transistor is designed.The device named INI SO1 p-LDMOS is characterized by a series of equidistant high concentration n+ islands inserted at the interface of a top silicon layer and a buried oxide layer.Accumulation-mode holes,caused by the electric potential dispersion between the device surface and the substrate,are located in the spacing between two neighboring n+ islands,and greatly enhance the electric field of the buried oxide layer and therefore,effectively increase the device breakdown voltage.Based on a 2-μm-thick buried oxide layer and a 1.5-μm-thick top silicon layer,a breakdown voltage of 1224 V is obtained,resulting in the high electric field(608 V/μm)of the buried oxide layer.%A 1200-V thin-silicon-layer p-channel silicon-on-insulator (SOI) lateral double-diffused metal-oxide-semiconductor (LDMOS) transistor is designed. The device named INI SOI p-LDMOS is characterized by a series of equidistant high concentration n+ islands inserted at the interface of a top silicon layer and a buried oxide layer. Accumulation-mode holes, caused by the electric potential dispersion between the device surface and the substrate, are located in the spacing between two neighboring n+ islands, and greatly enhance the electric field of the buried oxide layer and therefore, effectively increase the device breakdown voltage. Based on a 2-[im-thick buried oxide layer and a 1.5-um-thick top silicon layer, a breakdown voltage of 1224 V is obtained, resulting in the high electric field (608 V/\\im) of the buried oxide layer.

  18. GigaTracker, a Thin and Fast Silicon Pixels Tracker

    CERN Document Server

    Velghe, Bob; Bonacini, Sandro; Ceccucci, Augusto; Kaplon, Jan; Kluge, Alexander; Mapelli, Alessandro; Morel, Michel; Noël, Jérôme; Noy, Matthew; Perktold, Lukas; Petagna, Paolo; Poltorak, Karolina; Riedler, Petra; Romagnoli, Giulia; Chiozzi, Stefano; Cotta Ramusino, Angelo; Fiorini, Massimiliano; Gianoli, Alberto; Petrucci, Ferruccio; Wahl, Heinrich; Arcidiacono, Roberta; Jarron, Pierre; Marchetto, Flavio; Gil, Eduardo Cortina; Nuessle, Georg; Szilasi, Nicolas

    2014-01-01

    GigaTracker, the NA62’s upstream spectrometer, plays a key role in the kinematically constrained background suppression for the study of the K + ! p + n ̄ n decay. It is made of three independent stations, each of which is a six by three cm 2 hybrid silicon pixels detector. To meet the NA62 physics goals, GigaTracker has to address challenging requirements. The hit time resolution must be better than 200 ps while keeping the total thickness of the sensor to less than 0.5 mm silicon equivalent. The 200 μm thick sensor is divided into 18000 300 μm 300 μm pixels bump-bounded to ten independent read-out chips. The chips use an end-of-column architecture and rely on time-over- threshold discriminators. A station can handle a crossing rate of 750 MHz. Microchannel cooling technology will be used to cool the assembly. It allows us to keep the sensor close to 0 C with 130 μm of silicon in the beam area. The sensor and read-out chip performance were validated using a 45 pixel demonstrator with a laser test setu...

  19. The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.

    Science.gov (United States)

    Gerlach, D; Wimmer, M; Wilks, R G; Félix, R; Kronast, F; Ruske, F; Bär, M

    2014-12-21

    The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization.

  20. Enhancement of photovoltaic properties of multicrystalline silicon solar cells by combination of buried metallic contacts and thin porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ben Rabha, M.; Bessais, B. [Laboratoire de Photovoltaique, Centre de Recherches et des Technologies de l' Energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia)

    2010-03-15

    Photovoltaic properties of buried metallic contacts (BMCs) with and without application of a front porous silicon (PS) layer on multicrystalline silicon (mc-Si) solar cells were investigated. A Chemical Vapor Etching (CVE) method was used to perform front PS layer and BMCs of mc-Si solar cells. Good electrical performance for the mc-Si solar cells was observed after combination of BMCs and thin PS films. As a result the current-voltage (I-V) characteristics and the internal quantum efficiency (IQE) were improved, and the effective minority carrier diffusion length (Ln) increases from 75 to 110 {mu}m after BMCs achievement. The reflectivity was reduced to 8% in the 450-950 nm wavelength range. This simple and low cost technology induces a 12% conversion efficiency (surface area = 3.2 cm{sup 2}). The obtained results indicate that the BMCs improve charge carrier collection while the PS layer passivates the front surface. (author)

  1. Fluorination of silicon carbide thin films using pure F{sub 2} gas or XeF{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Batisse, Nicolas [Laboratoire des Materiaux Inorganiques UMR UBP-CNRS 6002, Clermont Universite, Universite Blaise Pascal, Clermont-Ferrand (France); Guerin, Katia, E-mail: Katia.guerin@univ-bpclermont.f [Laboratoire des Materiaux Inorganiques UMR UBP-CNRS 6002, Clermont Universite, Universite Blaise Pascal, Clermont-Ferrand (France); Dubois, Marc; Hamwi, Andre; Spinelle, Laurent; Tomasella, Eric [Laboratoire des Materiaux Inorganiques UMR UBP-CNRS 6002, Clermont Universite, Universite Blaise Pascal, Clermont-Ferrand (France)

    2010-09-30

    Two fluorination methods: direct fluorination using F{sub 2} gas and fluorination by the decomposition of fluorinating agent XeF{sub 2} have been applied to silicon carbide SiC thin films in order to form a composite of carbide derived carbon film together with residual silicon carbide. Before and after fluorination, the thin films have been characterized by Scanning Electron Microscopy, Rutherford Backscattering spectroscopy, Fourier Transformed InfraRed and Raman spectroscopies. Whereas direct fluorination leads to irreversible damages into the thin films, XeF{sub 2} method allows a progressive etching of the silicon atoms and the formation of non-fluorinated carbon.

  2. A study of ZnO:B films for thin film silicon solar cells

    Science.gov (United States)

    Yin, J.; Zhu, H.; Wang, Y.; Wang, Z.; Gao, J.; Mai, Y.; Ma, Y.; Wan, M.; Huang, Y.

    2012-10-01

    Boron doped zinc oxide (ZnO:B) films with different thicknesses were prepared with low pressure chemical vapor deposition (LPCVD) technique and implemented in thin film silicon solar cells as front and back electrodes. It is found that thick back ZnO:B film electrode in thin film silicon solar cells leads to a high fill factors (FF), which is attributed to an improvement of the electrical properties of the thick ZnO:B films, and in the meanwhile a slightly low short circuit currents (Jsc) due to a high light absorption in the thick back ZnO:B films. Differently, the thicker front ZnO:B film electrodes result in a high Jsc but a low FF of solar cells compared to the thinner ones. The low FF of the solar cells may be caused by the local shunt originated from the pinholes or by the cracks (zones of non-dense material) formed in particular in microcrystalline silicon materials deposited on rough front ZnO:B films. As to the high Jsc, it is expected to be due to a good light trapping effect inside solar cells grown on rough front ZnO:B films. Moreover, the application of high reflective polyvinyl butyral (PVB) foils effectively enhances the utilization of incident light in solar cells. By optimizing deposition process of the ZnO:B films, high efficiencies of 8.8% and 10% for single junction thin film amorphous silicon solar cells (a-Si:H, intrinsic layer thickness < 200 nm) and amorphous/microcrystalline silicon tandem solar cells (a-Si:H/μc-Si:H, intrinsic amorphous silicon layer thickness < 220 nm), respectively, are achieved.

  3. Silicon wafer wettability and aging behaviors: Impact on gold thin-film morphology

    KAUST Repository

    Yang, Xiaoming

    2014-10-01

    This paper reports on the wettability and aging behaviors of the silicon wafers that had been cleaned using a piranha (3:1 mixture of sulfuric acid (H2SO4, 96%) and hydrogen peroxide (H2O 2, 30%), 120 °C), SC1 (1:1:5 mixture of NH4OH, H 2O2 and H2O, at 80°C) or HF solution (6 parts of 40% NH4F and 1 part of 49% HF, at room temperature) solution, and treated with gaseous plasma. The silicon wafers cleaned using the piranha or SC1 solution were hydrophilic, and the water contact angles on the surfaces would increase along with aging time, until they reached the saturated points of around 70°. The contact angle increase rate of these wafers in a vacuum was much faster than that in the open air, because of loss of water, which was physically adsorbed on the wafer surfaces. The silicon wafers cleaned with the HF solution were hydrophobic. Their contact angle decreased in the atmosphere, while it increased in the vacuum up to 95°. Gold thin films deposited on the hydrophilic wafers were smoother than that deposited on the hydrophobic wafers, because the numerous oxygen groups formed on the hydrophilic surfaces would react with gold adatoms in the sputtering process to form a continuous thin film at the nucleation stage. The argon, nitrogen, oxygen gas plasma treatments could change the silicon wafer surfaces from hydrophobic to hydrophilic by creating a thin (around 2.5 nm) silicon dioxide film, which could be utilized to improve the roughness and adhesion of the gold thin film. © 2014 Elsevier Ltd. All rights reserved.

  4. Vibrational Spectroscopy of Chemical Species in Silicon and Silicon-Rich Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Kirill O. Bugaev

    2012-01-01

    Full Text Available Vibrational properties of hydrogenated silicon-rich nitride (SiN:H of various stoichiometry (0.6≤≤1.3 and hydrogenated amorphous silicon (a-Si:H films were studied using Raman spectroscopy and Fourier transform infrared spectroscopy. Furnace annealing during 5 hours in Ar ambient at 1130∘C and pulse laser annealing were applied to modify the structure of films. Surprisingly, after annealing with such high-thermal budget, according to the FTIR data, the nearly stoichiometric silicon nitride film contains hydrogen in the form of Si–H bonds. From analysis of the FTIR data of the Si–N bond vibrations, one can conclude that silicon nitride is partly crystallized. According to the Raman data a-Si:H films with hydrogen concentration 15% and lower contain mainly Si–H chemical species, and films with hydrogen concentration 30–35% contain mainly Si–H2 chemical species. Nanosecond pulse laser treatments lead to crystallization of the films and its dehydrogenization.

  5. Ultrafast deposition of silicon nitride and semiconductor silicon thin films by Hot Wire Chemical Vapor Deposition

    NARCIS (Netherlands)

    Schropp, R.E.I.; van der Werf, C.H.M.; Verlaan, V.; Rath, J.K.; Li, H. B. T.

    2009-01-01

    The technology of Hot Wire Chemical Vapor Deposition (HWCVD) or Catalytic Chemical Vapor Deposition (Cat-CVD) has made great progress during the last couple of years. This review discusses examples of significant progress. Specifically, silicon nitride deposition by HWCVD (HW-SiNx) is highlighted, a

  6. Electrical breakdown of amorphous hydrogenated silicon rich silicon nitride thin film diodes

    NARCIS (Netherlands)

    Bijlsma, S.J.; Bijlsma, Sipke J.; van Kranenburg, H.; Nieuwesteeg, K.J.B.M.; Pitt, Michael G.; Verweij, Jan F.; Verweij, J.F.

    1996-01-01

    Electrical breakdown, both intrinsic and extrinsic, of thin film diodes used as switches in active matrix addressed liquid crystal displays has been studied using electrical measurements, thermal measurements, thermal 3D simulations, electrical simulations and post breakdown observations. The diodes

  7. Modeling the splitting of thin silicon films from porosified crystalline silicon upon high temperature annealing in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ghannam, Moustafa Y.; Raheem, Yaser Abdul; Alomar, Abdul Azeez [EE Department, College of Engineering and Petroleum, Kuwait University, Safat (Kuwait); Poortmans, Jef [IMEC, Leuven (Belgium)

    2012-10-15

    The role of hydrogen in promoting thin film splitting from crystalline silicon wafers with pores or trenches during high temperature annealing is investigated. During the treatment, trenches are transformed into spherical voids that may laterally channel and split off the substrate. It is shown that the conditions necessary for hydrogen to contribute to the establishment of high stress levels around transformed voids or of pressure inside the voids are usually not satisfied. Hence promoting void coalescence by substantial void volume growth resulting from stress enhanced vacancy diffusion and/or exfoliation of separated voids are unlikely to occur. Also, there are no experimental evidence that confirms the role of hydrogen in triggering premature void collapse by Griffith fracture at relatively lower stress levels in conjunction with reduced surface energy. Therefore, it is concluded that splitting occurs during high temperature annealing only when neighboring voids are close enough to systematically coalesce. In that case, hydrogen may react at high temperature with the internal silicon surface of the voids (walls) and contribute to breaking the thin straps separating the voids which promotes channelling and film splitting (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Effect of the Nd content on the structural and photoluminescence properties of silicon-rich silicon dioxide thin films

    Directory of Open Access Journals (Sweden)

    Debieu Olivier

    2011-01-01

    Full Text Available Abstract In this article, the microstructure and photoluminescence (PL properties of Nd-doped silicon-rich silicon oxide (SRSO are reported as a function of the annealing temperature and the Nd concentration. The thin films, which were grown on Si substrates by reactive magnetron co-sputtering, contain the same Si excess as determined by Rutherford backscattering spectrometry. Fourier transform infrared (FTIR spectra show that a phase separation occurs during the annealing because of the condensation of the Si excess resulting in the formation of silicon nanoparticles (Si-np as detected by high-resolution transmission electron microscopy and X-ray diffraction (XRD measurements. Under non-resonant excitation at 488 nm, our Nd-doped SRSO films simultaneously exhibited PL from Si-np and Nd3+ demonstrating the efficient energy transfer between Si-np and Nd3+ and the sensitizing effect of Si-np. Upon increasing the Nd concentration from 0.08 to 4.9 at.%, our samples revealed a progressive quenching of the Nd3+ PL which can be correlated with the concomitant increase of disorder within the host matrix as shown by FTIR experiments. Moreover, the presence of Nd-oxide nanocrystals in the highest Nd-doped sample was established by XRD. It is, therefore, suggested that the Nd clustering, as well as disorder, are responsible for the concentration quenching of the PL of Nd3+.

  9. Insights into electrical characteristics of silicon doped hafnium oxide ferroelectric thin films

    Science.gov (United States)

    Zhou, Dayu; Müller, J.; Xu, Jin; Knebel, S.; Bräuhaus, D.; Schröder, U.

    2012-02-01

    Silicon doped hafnium oxide thin films were recently discovered to exhibit ferroelectricity. In the present study, metal-ferroelectric-metal capacitors with Si:HfO2 thin films as ferroelectric material and TiN as electrodes have been characterized with respect to capacitance and current density as functions of temperature and applied voltage. Polarity asymmetry of the frequency dependent coercive field was explained by interfacial effects. No ferroelectric-paraelectric phase transition was observed at temperatures up to 478 K. Clear distinctions between current evolutions with or without polarization switching were correlated to the time competition between the measurement and the response of relaxation mechanisms.

  10. Buckling patterns of gold thin films on silicon substrates: Formation of superimposed blisters

    Science.gov (United States)

    Colin, J.; Coupeau, C.; Durinck, J.; Grilhé, J.

    2009-06-01

    Buckling phenomena leading to the formation of superimposed blisters have been experimentally observed with the help of a confocal interferometric microscope onto the surface of gold thin films deposited on silicon substrates. Assuming that residual folding effects resulting from plastic deformation mechanisms take place in the film during its morphological evolution, different probable scenarios for the formation of the observed buckling patterns are elaborated in the framework of the Föppl-von Karman's theory of thin plates. Multi-step buckling with growing interface delamination is considered for the first scenario while a single or multi-step buckling at a given delamination width is assumed for the other ones.

  11. Fabricating 40 µm-thin silicon solar cells with different orientations by using SLiM-cut method

    Science.gov (United States)

    Wang, Teng-Yu; Chen, Chien-Hsun; Shiao, Jui-Chung; Chen, Sung-Yu; Du, Chen-Hsun

    2017-10-01

    Thin silicon foils with different crystal orientations were fabricated using the stress induced lift-off (SLiM-cut) method. The thickness of the silicon foils was approximately 40 µm. The ≤ft foil had a smoother surface than the ≤ft foil. With surface passivation, the minority carrier lifetimes of the ≤ft and ≤ft silicon foil were 1.0 µs and 1.6 µs, respectively. In this study, 4 cm2-thin silicon solar cells with heterojunction structures were fabricated. The energy conversion efficiencies were determined to be 10.74% and 14.74% for the ≤ft and ≤ft solar cells, respectively. The surface quality of the silicon foils was determined to affect the solar cell character. This study demonstrated that fabricating the solar cell by using silicon foil obtained from the SLiM-cut method is feasible.

  12. Electrodeposition of magnetic thin films of cobalt on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Munford, M.L.; Seligman, L.; Sartorelli, M.L.; Voltolini, E.; Martins, L.F.O.; Schwarzacher, W.; Pasa, A.A. E-mail: pasa@fisica.ufsc.br

    2001-05-01

    To understand the electrodeposition of Co on Si, sulphate electrolytes containing two different Co ion concentrations were tested. Thin films with uniform thickness, ranging from 10 to 700 nm, low surface roughness, compact and metallic appearance were obtained for Co concentrations of 26 and 104 mM, respectively. Transverse MOKE measurements showed in-plane magnetization with the magnitude of the coercive field being dependent on the thickness of the deposited layers. VSM measurements with the applied field perpendicular to the surface allowed the observation of an out-of-plane remanent magnetization. These properties are of considerable interest for technological applications.

  13. Phase transitions from semiconductive amorphous to conductive polycrystalline in indium silicon oxide thin films

    Science.gov (United States)

    Mitoma, Nobuhiko; Da, Bo; Yoshikawa, Hideki; Nabatame, Toshihide; Takahashi, Makoto; Ito, Kazuhiro; Kizu, Takio; Fujiwara, Akihiko; Tsukagoshi, Kazuhito

    2016-11-01

    The enhancement in electrical conductivity and optical transparency induced by a phase transition from amorphous to polycrystalline in lightly silicon-doped indium oxide (InSiO) thin films is studied. The phase transition caused by simple thermal annealing transforms the InSiO thin films from semiconductors to conductors. Silicon atoms form SiO4 tetrahedra in InSiO, which enhances the overlap of In 5s orbitals as a result of the distortion of InO6 octahedral networks. Desorption of weakly bonded oxygen releases electrons from deep subgap states and enhances the electrical conductivity and optical transparency of the films. Optical absorption and X-ray photoelectron spectroscopy measurements reveal that the phase transition causes a Fermi energy shift of ˜0.2 eV.

  14. Polymorphous silicon thin films produced in dusty plasmas: application to solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Roca i Cabarrocas, Pere; Chaabane, N; Kharchenko, A V; Tchakarov, S [Laboratoire de Physique des Interfaces et des Couches Minces (UMR 7647), Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2004-12-01

    We summarize our current understanding of the optimization of PIN solar cells produced by plasma enhanced chemical vapour deposition from silane-hydrogen mixtures. To increase the deposition rate, the discharge is operated under plasma conditions close to powder formation, where silicon nanocrystals contribute to the deposition of so-called polymorphous silicon thin films. We show that the increase in deposition rate can be achieved via an accurate control of the plasma parameters. However, this also results in a highly defective interface in the solar cells due to the bombardment of the P-layer by positively charged nanocrystals during the deposition of the I-layer. We show that decreasing the ion energy by increasing the total pressure or by using silane-helium mixtures allows us to increase both the deposition rate and the solar cells efficiency, as required for cost effective thin film photovoltaics.

  15. Polymorphous silicon thin films produced in dusty plasmas: application to solar cells

    Science.gov (United States)

    Cabarrocas, Pere Roca i.; Chaâbane, N.; Kharchenko, A. V.; Tchakarov, S.

    2004-12-01

    We summarize our current understanding of the optimization of PIN solar cells produced by plasma enhanced chemical vapour deposition from silane hydrogen mixtures. To increase the deposition rate, the discharge is operated under plasma conditions close to powder formation, where silicon nanocrystals contribute to the deposition of so-called polymorphous silicon thin films. We show that the increase in deposition rate can be achieved via an accurate control of the plasma parameters. However, this also results in a highly defective interface in the solar cells due to the bombardment of the P-layer by positively charged nanocrystals during the deposition of the I-layer. We show that decreasing the ion energy by increasing the total pressure or by using silane helium mixtures allows us to increase both the deposition rate and the solar cells efficiency, as required for cost effective thin film photovoltaics.

  16. Incorporation of gold into silicon by thin film deposition and pulsed laser melting

    Science.gov (United States)

    Warrender, Jeffrey M.; Hudspeth, Quentin; Malladi, Girish; Efstathiadis, Harry; Mathews, Jay

    2016-12-01

    We report on the incorporation of gold into silicon at a peak concentration of 1.9 × 1020 at./cm3, four orders of magnitude above the equilibrium solubility limit, using pulsed laser melting of a thin film deposited on the silicon surface. We vary the film thickness and laser process parameters (fluence, number of shots) to quantify the range of concentrations that can be achieved. Our approach achieves gold concentrations comparable to those achieved with ion implantation followed by pulsed laser melting, in a layer with high crystalline quality. This approach offers an attractive alternative to ion implantation for forming high quality, high concentration layers of transition metals like gold in silicon.

  17. Nanoindentation of GaN/SiC thin films on silicon substrate

    Science.gov (United States)

    Grashchenko, A. S.; Kukushkin, S. A.; Osipov, A. V.; Redkov, A. V.

    2017-03-01

    The indentation process of thin gallium nitride film grown on SiC buffer layer on silicon was studied. SiC was obtained by the new method of substitution of atoms directly in a silicon substrate. Indentation data, atomic force microscopy and Raman spectroscopy were used to characterize the indented system. Mechanical properties of the film and the substrate were derived using single-layer Oliver-Pharr and Doerner-Nix approaches. Micro-Raman confocal microscopy was used to construct 3-dimensional maps of mechanical stresses and crystalline quality both of GaN and silicon near the indenter impression for different indentation depths. The anisotropy of propagation of the elastic stresses during indentation was investigated and it was shown, that distribution of stress in the substrate has a shape of trefoil. This process has been modeled by means of molecular dynamics.

  18. Infrared Insight into the Network of Hydrogenated Amorphous and Polycrystalline Silicon thin Films

    Directory of Open Access Journals (Sweden)

    Jarmila Mullerova

    2006-01-01

    Full Text Available IR measurements were carried out on both amorphous and polycrystalline silicon samples deposited by PECVDon glass substrate. The transition from amorphous to polycrystalline phase was achieved by increasing dilution of silaneplasma at the deposition process. The samples were found to be mixed phase materials. Commonly, infrared spectra ofhydrogenated silicon thin films yield information about microstructure, hydrogen content and hydrogen bonding to silicon. Inthis paper, additional understanding was retrieved from infrared response. Applying standard optical laws, effective mediatheory and Clausius-Mossoti approach concerning the Si-Si and Si-H bonds under IR irradiation as individual oscillators,refractive indices in the long wavelength limit, crystalline, amorphous and voids volume fractions and the mass density of thefilms were determined. The mass density was found to decrease with increasing crystalline volume fraction, which can beattributed to the void-dominated mechanism of network formation.

  19. Optical bandgap of ultra-thin amorphous silicon films deposited on crystalline silicon by PECVD

    Directory of Open Access Journals (Sweden)

    Yaser Abdulraheem

    2014-05-01

    Full Text Available An optical study based on spectroscopic ellipsometry, performed on ultrathin hydrogenated amorphous silicon (a-Si:H layers, is presented in this work. Ultrathin layers of intrinsic amorphous silicon have been deposited on n-type mono-crystalline silicon (c-Si wafers by plasma enhanced chemical vapor deposition (PECVD. The layer thicknesses along with their optical properties –including their refractive index and optical loss- were characterized by spectroscopic ellipsometry (SE in a wavelength range from 250 nm to 850 nm. The data was fitted to a Tauc-Lorentz optical model and the fitting parameters were extracted and used to compute the refractive index, extinction coefficient and optical bandgap. Furthermore, the a-Si:H film grown on silicon was etched at a controlled rate using a TMAH solution prepared at room temperature. The optical properties along with the Tauc-Lorentz fitting parameters were extracted from the model as the film thickness was reduced. The etch rate for ultrathin a-Si:H layers in TMAH at room temperature was found to slow down drastically as the c-Si interface is approached. From the Tauc-Lorentz parameters obtained from SE, it was found that the a-Si film exhibited properties that evolved with thickness suggesting that the deposited film is non-homogeneous across its depth. It was also found that the degree of crystallinity and optical (Tauc bandgap increased as the layers were reduced in thickness and coming closer to the c-Si substrate interface, suggesting the presence of nano-structured clusters mixed into the amorphous phase for the region close to the crystalline silicon substrate. Further results from Atomic Force Microscopy and Transmission Electron Microscopy confirmed the presence of an interfacial transitional layer between the amorphous film and the underlying substrate showing silicon nano-crystalline enclosures that can lead to quantum confinement effects. Quantum confinement is suggested to be the cause

  20. Optical bandgap of ultra-thin amorphous silicon films deposited on crystalline silicon by PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Abdulraheem, Yaser, E-mail: yaser.abdulraheem@kuniv.edu.kw [Electrical Engineering Department, College of Engineering and Petroleum, Kuwait University. P.O. Box 5969, 13060 Safat (Kuwait); Gordon, Ivan; Bearda, Twan; Meddeb, Hosny; Poortmans, Jozef [IMEC, Kapeldreef 75, 3001, Leuven (Belgium)

    2014-05-15

    An optical study based on spectroscopic ellipsometry, performed on ultrathin hydrogenated amorphous silicon (a-Si:H) layers, is presented in this work. Ultrathin layers of intrinsic amorphous silicon have been deposited on n-type mono-crystalline silicon (c-Si) wafers by plasma enhanced chemical vapor deposition (PECVD). The layer thicknesses along with their optical properties –including their refractive index and optical loss- were characterized by spectroscopic ellipsometry (SE) in a wavelength range from 250 nm to 850 nm. The data was fitted to a Tauc-Lorentz optical model and the fitting parameters were extracted and used to compute the refractive index, extinction coefficient and optical bandgap. Furthermore, the a-Si:H film grown on silicon was etched at a controlled rate using a TMAH solution prepared at room temperature. The optical properties along with the Tauc-Lorentz fitting parameters were extracted from the model as the film thickness was reduced. The etch rate for ultrathin a-Si:H layers in TMAH at room temperature was found to slow down drastically as the c-Si interface is approached. From the Tauc-Lorentz parameters obtained from SE, it was found that the a-Si film exhibited properties that evolved with thickness suggesting that the deposited film is non-homogeneous across its depth. It was also found that the degree of crystallinity and optical (Tauc) bandgap increased as the layers were reduced in thickness and coming closer to the c-Si substrate interface, suggesting the presence of nano-structured clusters mixed into the amorphous phase for the region close to the crystalline silicon substrate. Further results from Atomic Force Microscopy and Transmission Electron Microscopy confirmed the presence of an interfacial transitional layer between the amorphous film and the underlying substrate showing silicon nano-crystalline enclosures that can lead to quantum confinement effects. Quantum confinement is suggested to be the cause of the observed

  1. Microscratch testing method for systematic evaluation of the adhesion of atomic layer deposited thin films on silicon

    OpenAIRE

    Kilpi, Lauri; Ylivaara, Oili M.E.; Vaajoki, Antti; Malm, Jari; Sintonen, Sakari; Tuominen, Marko; Puurunen, Riikka L.; Ronkainen, Helena

    2016-01-01

    The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as LCSi1, LCSi2, LCALD1, and LCALD2, representing the failure p...

  2. Band engineering of amorphous silicon ruthenium thin film and its near-infrared absorption enhancement combined with nano-holes pattern on back surface of silicon substrate

    Science.gov (United States)

    Guo, Anran; Zhong, Hao; Li, Wei; Gu, Deen; Jiang, Xiangdong; Jiang, Yadong

    2016-10-01

    Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its bandgap limit. In this study, a narrow bandgap silicon rich semiconductor is achieved by introducing ruthenium (Ru) into amorphous silicon (a-Si) to form amorphous silicon ruthenium (a-Si1-xRux) thin films through co-sputtering. The increase of Ru concentration leads to an enhancement of light absorption and a narrower bandgap. Meanwhile, a specific light trapping technique is employed to realize high absorption of a-Si1-xRux thin film in a finite thickness to avoid unnecessary carrier recombination. A double-layer absorber comprising of a-Si1-xRux thin film and silicon random nano-holes layer is formed on the back surface of silicon substrates, and significantly improves near-infrared absorption while the leaky light intensity is less than 5%. This novel absorber, combining narrow bandgap thin film with light trapping structure, may have a potential application in near-infrared photoelectronic devices.

  3. Thin PZT-Based Ferroelectric Capacitors on Flexible Silicon for Nonvolatile Memory Applications

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-04-24

    A flexible version of traditional thin lead zirconium titanate ((Pb1.1Zr0.48Ti0.52O3)-(PZT)) based ferroelectric random access memory (FeRAM) on silicon shows record performance in flexible arena. The thin PZT layer requires lower operational voltages to achieve coercive electric fields, reduces the sol-gel coating cycles required (i.e., more cost-effective), and, fabrication wise, is more suitable for further scaling of lateral dimensions to the nano-scale due to the larger feature size-to-depth aspect ratio (critical for ultra-high density non-volatile memory applications). Utilizing the inverse proportionality between substrate\\'s thickness and its flexibility, traditional PZT based FeRAM on silicon is transformed through a transfer-less manufacturable process into a flexible form that matches organic electronics\\' flexibility while preserving the superior performance of silicon CMOS electronics. Each memory cell in a FeRAM array consists of two main elements; a select/access transistor, and a storage ferroelectric capacitor. Flexible transistors on silicon have already been reported. In this work, we focus on the storage ferroelectric capacitors, and report, for the first time, its performance after transformation into a flexible version, and assess its key memory parameters while bent at 0.5 cm minimum bending radius.

  4. Deposition of Low Stress Silicon Nitride Thin Film and Its Application in Surface Micromachining Device Structures

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

    Full Text Available Surface machining processes are responsible for creating microstructures that reside near the surfaces of a substrate and are characterized by the fabrication of micromechanical structures from deposited thin films. These films can be selectively removed to build three-dimensional structures whose functionality typically requires that they should be freed from the planar substrate. Silicon nitride thin film is one of these important materials. In this paper, by adjusting the SiH2Cl2/NH3 gaseous ratio, low stress silicon nitride (LS SiN is deposited by the low pressure chemical vapor deposition (LPCVD process. The internal stress generally in 135 MPa has been detected using an FLX-2320 film stress tester. Based on the wide application in surface micromachining devices, the mechanical properties of LS SiN are measured by nanoindentation, giving the value of Young’s modulus of 224 GPa and the hardness of 22.5 GPa, respectively. Dry etching and wet etching are utilized to fabricate the LS SiN thin film for structural layers. The etching rate compared with normal Si3N4 film by LPCVD is demonstrated for silicon chip manufacture.

  5. Functional Laser Trimming Of Thin Film Resistors On Silicon ICs

    Science.gov (United States)

    Mueller, Michael J.; Mickanin, Wes

    1986-07-01

    Modern Laser Wafer Trimming (LWT) technology achieves exceptional analog circuit performance and precision while maintain-ing the advantages of high production throughput and yield. Microprocessor-driven instrumentation has both emphasized the role of data conversion circuits and demanded sophisticated signal conditioning functions. Advanced analog semiconductor circuits with bandwidths over 1 GHz, and high precision, trimmable, thin-film resistors meet many of todays emerging circuit requirements. Critical to meeting these requirements are optimum choices of laser characteristics, proper materials, trimming process control, accurate modeling of trimmed resistor performance, and appropriate circuit design. Once limited exclusively to hand-crafted, custom integrated circuits, designs are now available in semi-custom circuit configurations. These are similar to those provided for digital designs and supported by computer-aided design (CAD) tools. Integrated with fully automated measurement and trimming systems, these quality circuits can now be produced in quantity to meet the requirements of communications, instrumentation, and signal processing markets.

  6. Degradation of a tantalum filament during the hot-wire CVD of silicon nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oliphant, C.J. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040 (South Africa); Arendse, C.J., E-mail: cjarendse@uwc.ac.za [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Muller, T.F.G. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Jordaan, W.A. [National Metrology Institute of South Africa, Private Bag X34, Lynwood Ridge, Pretoria 0040 (South Africa); Knoesen, D. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa)

    2015-01-30

    Electron backscatter diffraction revealed that during the hot-wire deposition of silicon nitride, a tantalum filament partially transformed to some of its nitrides and silicides. The deposition of an encapsulating silicon nitride layer occurred at the cooler filament ends. Time-of-flight secondary ion mass spectroscopy disclosed the presence of hydrogen, nitrogen and silicon containing ions within the aged filament bulk. Hardness measurements revealed that the recrystallized tantalum core experienced significant hardening, whereas the silicides and nitrides were harder but more brittle. Crack growth, porosity and the different thermal expansion amongst the various phases are all enhanced at the hotter centre regions, which resulted in failure at these areas. - Highlights: • Tantalum filament degrades and fails during hot-wire CVD of silicon nitride thin films. • An encapsulating silicon nitride layer is deposited at the cooler ends. • Electron backscatter diffraction reveals Ta-silicides and -nitrides with a Ta core. • Filament failure occurs at hot centre regions due to different mechanical properties of Ta, its silicides and nitrides.

  7. Porous silicon as an internal reflector in thin epitaxial solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kuzma-Filipek, I.; Duerinckx, F.; Nieuwenhuysen, K. van; Beaucarne, G.; Poortmans, J.; Mertens, R. [IMEC vzw, Leuven (Belgium)

    2007-05-15

    Thin film epitaxial silicon solar cells are considered a near future alternative to bulk silicon solar cells. However due to the limited thickness of the active layer they require efficient light trapping. Therefore we propose the development and implementation of such light confinement by means of a porous silicon (PS) intermediate reflector at the epi/substrate interface. The formation of the reflector is done by electrochemical etching of a highly doped Si substrate into a multilayer stack (Bragg-optical reflector), and is followed by epitaxial deposition of the active layer. The implementation of the PS reflector however requires detailed analysis of many problematic issues, foremost the optical optimisation of the stack for internal reflection at the Si/PS/Si interface. Other topics include the pore rearrangement during high-temperature CVD as well as the quality of the epitaxial layer grown on porous silicon. Another challenge is the resistance within the PS layers. For that purpose, SRP (Spreading Resistance Probe) and resistance measurements were performed to determine the conductive properties of rearranged PS. First cells with a 9-layer porous silicon reflector gave a very promising efficiency of 13.5% which is 1.5% higher compared to cells without internal reflector. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Size Control of Porous Silicon-Based Nanoparticles via Pore-Wall Thinning.

    Science.gov (United States)

    Secret, Emilie; Leonard, Camille; Kelly, Stefan J; Uhl, Amanda; Cozzan, Clayton; Andrew, Jennifer S

    2016-02-02

    Photoluminescent silicon nanocrystals are very attractive for biomedical and electronic applications. Here a new process is presented to synthesize photoluminescent silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. These nanoparticles are formed using a pore-wall thinning approach, where the as-etched porous silicon layer is partially oxidized to silica, which is dissolved by a hydrofluoric acid solution, decreasing the pore-wall thickness. This decrease in pore-wall thickness leads to a corresponding decrease in the size of the nanocrystals that make up the pore walls, resulting in the formation of smaller nanoparticles during sonication of the porous silicon. Particle diameters were measured using dynamic light scattering, and these values were compared with the nanocrystallite size within the pore wall as determined from X-ray diffraction. Additionally, an increase in the quantum confinement effect is observed for these particles through an increase in the photoluminescence intensity of the nanoparticles compared with the as-etched nanoparticles, without the need for a further activation step by oxidation after synthesis.

  9. Low-temperature technique of thin silicon ion implanted epitaxial detectors

    Science.gov (United States)

    Kordyasz, A. J.; Le Neindre, N.; Parlog, M.; Casini, G.; Bougault, R.; Poggi, G.; Bednarek, A.; Kowalczyk, M.; Lopez, O.; Merrer, Y.; Vient, E.; Frankland, J. D.; Bonnet, E.; Chbihi, A.; Gruyer, D.; Borderie, B.; Ademard, G.; Edelbruck, P.; Rivet, M. F.; Salomon, F.; Bini, M.; Valdré, S.; Scarlini, E.; Pasquali, G.; Pastore, G.; Piantelli, S.; Stefanini, A.; Olmi, A.; Barlini, S.; Boiano, A.; Rosato, E.; Meoli, A.; Ordine, A.; Spadaccini, G.; Tortone, G.; Vigilante, M.; Vanzanella, E.; Bruno, M.; Serra, S.; Morelli, L.; Guerzoni, M.; Alba, R.; Santonocito, D.; Maiolino, C.; Cinausero, M.; Gramegna, F.; Marchi, T.; Kozik, T.; Kulig, P.; Twaróg, T.; Sosin, Z.; Gaşior, K.; Grzeszczuk, A.; Zipper, W.; Sarnecki, J.; Lipiński, D.; Wodzińska, H.; Brzozowski, A.; Teodorczyk, M.; Gajewski, M.; Zagojski, A.; Krzyżak, K.; Tarasiuk, K. J.; Khabanowa, Z.; Kordyasz, Ł.

    2015-02-01

    A new technique of large-area thin ion implanted silicon detectors has been developed within the R&D performed by the FAZIA Collaboration. The essence of the technique is the application of a low-temperature baking process instead of high-temperature annealing. This thermal treatment is performed after B+ ion implantation and Al evaporation of detector contacts, made by using a single adjusted Al mask. Extremely thin silicon pads can be therefore obtained. The thickness distribution along the X and Y directions was measured for a prototype chip by the energy loss of α-particles from 241Am ( = 5.5 MeV). Preliminary tests on the first thin detector (area ≈ 20 × 20 mm2) were performed at the INFN-LNS cyclotron in Catania (Italy) using products emitted in the heavy-ion reaction 84Kr ( E = 35 A MeV) + 112Sn. The ΔE - E ion identification plot was obtained using a telescope consisting of our thin ΔE detector (21 μm thick) followed by a typical FAZIA 510 μm E detector of the same active area. The charge distribution of measured ions is presented together with a quantitative evaluation of the quality of the Z resolution. The threshold is lower than 2 A MeV depending on the ion charge.

  10. Low-temperature technique of thin silicon ion implanted epitaxial detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kordyasz, A.J.; Bednarek, A. [Warsaw University, Heavy Ion Laboratory, Warsaw (Poland); Le Neindre, N.; Bougault, R.; Lopez, O.; Merrer, Y.; Vient, E. [Universite de Caen, LPC, IN2P3-CNRS, ENSICAEN, Caen-Cedex (France); Parlog, M. [Universite de Caen, LPC, IN2P3-CNRS, ENSICAEN, Caen-Cedex (France); ' ' Horia Hulubei' ' National Institute of Physics and Nuclear Engineering (IFIN-HH), Bucharest Magurele (Romania); Casini, G.; Poggi, G.; Bini, M.; Valdre, S.; Scarlini, E.; Pasquali, G.; Pastore, G.; Piantelli, S.; Stefanini, A.; Olmi, A.; Barlini, S. [INFN Firenze, Sesto Fiorentino (Italy); Universita di Firenze, Sesto Fiorentino (Firenze) (Italy); Kowalczyk, M. [Warsaw University, Heavy Ion Laboratory, Warsaw (Poland); University of Warsaw, Institute of Experimental Physics, Warsaw (Poland); Frankland, J.D.; Bonnet, E.; Chbihi, A.; Gruyer, D. [CEA et IN2P3-CNRS, GANIL, Caen-Cedex 05 (France); Borderie, B.; Ademard, G.; Edelbruck, P.; Rivet, M.F.; Salomon, F. [IN2P3-CNRS, Institut de Physique Nucleaire, Orsay-Cedex (France); Boiano, A.; Rosato, E.; Meoli, A.; Ordine, A.; Spadaccini, G.; Tortone, G.; Vigilante, M.; Vanzanella, E. [Universita di Napoli ' ' Federico II' ' , Dipartimento di Scienze Fisiche, Napoli (Italy); INFN, Napoli (Italy); Bruno, M.; Serra, S.; Morelli, L.; Guerzoni, M. [INFN, Bologna (Italy); Universita di Bologna, Bologna (Italy); Alba, R.; Santonocito, D.; Maiolino, C. [INFN, Catania (Italy); Universita di Catania, LNS, Catania (Italy); Cinausero, M.; Gramegna, F.; Marchi, T. [INFN LNL Legnaro, Legnaro (Padova) (Italy); Kozik, T.; Kulig, P.; Twarog, T.; Sosin, Z. [Jagiellonian University, Cracow (Poland); Gasior, K.; Grzeszczuk, A.; Zipper, W. [University of Silesia, Silesian University, Katowice (Poland); Sarnecki, J.; Lipinski, D.; Wodzinska, H.; Brzozowski, A.; Teodorczyk, M.; Gajewski, M.; Zagojski, A.; Krzyzak, K. [Institute of Electronic Materials Technology, Warsaw (Poland); Tarasiuk, K.J. [University of Warsaw, Institute of Experimental Physics, Warsaw (Poland); Khabanowa, Z. [Faculty of Physics, Warsaw University of Technology, Warsaw (Poland); Kordyasz, L. [Warsaw University of Technology, Faculty of Mechatronics, Institute of Mikromechanics and Photonics, Department of Design of Precision Devices, Warsaw (Poland)

    2015-02-01

    A new technique of large-area thin ion implanted silicon detectors has been developed within the R and D performed by the FAZIA Collaboration. The essence of the technique is the application of a low-temperature baking process instead of high-temperature annealing. This thermal treatment is performed after B{sup +} ion implantation and Al evaporation of detector contacts, made by using a single adjusted Al mask. Extremely thin silicon pads can be therefore obtained. The thickness distribution along the X and Y directions was measured for a prototype chip by the energy loss of α-particles from {sup 241}Am (left angle E{sub α} right angle = 5.5 MeV). Preliminary tests on the first thin detector (area ∼ 20 x 20 mm{sup 2}) were performed at the INFN-LNS cyclotron in Catania (Italy) using products emitted in the heavy-ion reaction {sup 84}Kr (E = 35 A MeV) + {sup 112}Sn. The ΔE - E ion identification plot was obtained using a telescope consisting of our thin ΔE detector (21 μm thick) followed by a typical FAZIA 510 μm E detector of the same active area. The charge distribution of measured ions is presented together with a quantitative evaluation of the quality of the Z resolution. The threshold is lower than 2 A MeV depending on the ion charge. (orig.)

  11. Light Trapping in Thin Film Silicon Solar Cells on Plastic Substrates

    Science.gov (United States)

    de Jong, M. M.

    2013-01-01

    In the search for sustainable energy sources, solar energy can fulfil a large part of the growing demand. The biggest threshold for large-scale solar energy harvesting is the solar panel price. For drastic cost reductions, roll-to-roll fabrication of thin film silicon solar cells using plastic substrates can be a solution. In this thesis, we investigate the possibilities of depositing thin film solar cells directly onto cheap plastic substrates. Micro-textured glass and sheets, which have a wide range of applications, such as in green house, lighting etc, are applied in these solar cells for light trapping. Thin silicon films can be produced by decomposing silane gas, using a plasma process. In these types of processes, the temperature of the growing surface has a large influence on the quality of the grown films. Because plastic substrates limit the maximum tolerable substrate temperature, new methods have to be developed to produce device-grade silicon layers. At low temperature, polysilanes can form in the plasma, eventually forming dust particles, which can deteriorate device performance. By studying the spatially resolved optical emission from the plasma between the electrodes, we can identify whether we have a dusty plasma. Furthermore, we found an explanation for the temperature dependence of dust formation; Monitoring the formation of polysilanes as a function of temperature using a mass-spectrometer, we observed that the polymerization rate is indeed influenced by the substrate temperature. For solar cell substrate material, our choice was polycarbonate (PC), because of its low cost, its excellent transparency and its relatively high glass transition temperature of 130-140°C. At 130°C we searched for deposition recipes for device quality silicon, using a very high frequency plasma enhanced chemical deposition process. By diluting the feedstock silane with hydrogen gas, the silicon quality can be improved for amorphous silicon (a-Si), until we reach the

  12. Coplanar back contacts for thin silicon solar cells

    Science.gov (United States)

    Storti, G.; Scheinine, A.; Whitehouse, D.; Wohlgemuth, J.; Wrigley, C.; Giuliano, M.

    1981-01-01

    The type of coplanar back contact solar cell described was constructed with interdigitated n(+) and p(+) type regions on the back of the cell, such that both contacts are made on the back with no metallization grid on the front. This cell construction has several potential advantages over conventional cells for space use namely, convenience of interconnects, lower operating temperatures and higher efficiency due to the elimination of grid shadowing. However, the processing is more complex, and the cell is inherently more radiation sensitive. The latter problem can be reduced substantially by making the cells very thin (approximately 50 micrometers). Two types of interdigitated back contact cells are possible, the types being dependent on the character of the front surface. The front surface field cell has a front surface region that is of the same conductivity type as the bulk but is more heavily doped. This creates an electric field at the surface which repels the minority carriers. The tandem junction cell has a front surface region of a conductivity type that is opposite to that of the bulk. The junction thus created floats to open circuit voltage on illumination and injects carriers into the bulk which then can be collected at the rear junction. For space use, the front surface field cell is potentially more radiation resistant than the tandem junction cell because the flow of minority carriers (electrons) into the bulk will be less sensitive to the production of recombination centers, particularly in the space charge region at the front surface.

  13. Investigation of the degradation of a thin-film hydrogenated amorphous silicon photovoltaic module

    Energy Technology Data Exchange (ETDEWEB)

    van Dyk, E.E.; Audouard, A.; Meyer, E.L. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Woolard, C.D. [Department of Chemistry, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa)

    2007-01-23

    The degradation of a thin-film hydrogenated single-junction amorphous silicon (a-Si:H) photovoltaic (PV) module has been studied. We investigated the different modes of electrical and physical degradation of a-Si:H PV modules by employing a degradation and failure assessment procedure used in conjunction with analytical techniques, including, scanning electron microscopy (SEM) and thermogravimetry. This paper reveals that due to their thickness, thin films are very sensitive to the type of degradation observed. Moreover, this paper deals with the problems associated with the module encapsulant, poly(ethylene-co-vinylacetate) (EVA). The main objective of this study was to establish the influence of outdoor environmental conditions on the performance of a thin-film PV module comprising a-Si:H single-junction cells. (author)

  14. Defect annealing processes for polycrystalline silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Steffens, S., E-mail: simon.steffens@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Berlin (Germany); Becker, C. [Helmholtz-Zentrum Berlin, Berlin (Germany); Zollondz, J.-H., E-mail: hzollondz@masdarpv.com [CSG Solar AG, Thalheim (Germany); Chowdhury, A.; Slaoui, A. [L’Institut d’Électronique du Solide et des Systèmes, Strasbourg (France); Lindekugel, S. [Fraunhofer-Institut für Solare Energiesysteme, Freiburg (Germany); Schubert, U.; Evans, R. [Suntech R and D Australia Pty Ltd, Sydney (Australia); Rech, B. [Helmholtz-Zentrum Berlin, Berlin (Germany)

    2013-05-15

    Highlights: ► Defect annealing processes were applied to polycrystalline silicon thin films. ► Conventional rapid thermal annealing was compared to novel annealing processes using a laser system and a zone-melting recrystallization setup. ► The open circuit voltages could be enhanced from below 170 mV up to 482 mV. ► Increase in Sun's-V{sub OC} values with decrease in FWHM of the TO Raman phonon of crystalline silicon. ► Solar cells were fabricated for I–V-measurements: Best solar cell efficiency of 6.7%. -- Abstract: A variety of defect healing methods was analyzed for optimization of polycrystalline silicon (poly-Si) thin-film solar cells on glass. The films were fabricated by solid phase crystallization of amorphous silicon deposited either by plasma enhanced chemical vapor deposition (PECVD) or by electron-beam evaporation (EBE). Three different rapid thermal processing (RTP) set-ups were compared: A conventional rapid thermal annealing oven, a dual wavelength laser annealing system and a movable two sided halogen lamp oven. The two latter processes utilize focused energy input for reducing the thermal load introduced into the glass substrates and thus lead to less deformation and impurity diffusion. Analysis of the structural and electrical properties of the poly-Si thin films was performed by Suns-V{sub OC} measurements and Raman spectroscopy. 1 cm{sup 2} cells were prepared for a selection of samples and characterized by I–V-measurements. The poly-Si material quality could be extremely enhanced, resulting in increase of the open circuit voltages from about 100 mV (EBE) and 170 mV (PECVD) in the untreated case up to 480 mV after processing.

  15. In situ micro-Raman analysis and X-ray diffraction of nickel silicide thin films on silicon.

    Science.gov (United States)

    Bhaskaran, M; Sriram, S; Perova, T S; Ermakov, V; Thorogood, G J; Short, K T; Holland, A S

    2009-01-01

    This article reports on the in situ analysis of nickel silicide (NiSi) thin films formed by thermal processing of nickel thin films deposited on silicon substrates. The in situ techniques employed for this study include micro-Raman spectroscopy (microRS) and X-ray diffraction (XRD); in both cases the variations for temperatures up to 350 degrees C has been studied. Nickel silicide thin films formed by vacuum annealing of nickel on silicon were used as a reference for these measurements. In situ analysis was carried out on nickel thin films on silicon, while the samples were heated from room temperature to 350 degrees C. Data was gathered at regular temperature intervals and other specific points of interest (such as 250 degrees C, where the reaction between nickel and silicon to form Ni(2)Si is expected). The transformations from the metallic state, through the intermediate reaction states, until the desired metal-silicon reaction product is attained, are discussed. The evolution of nickel silicide from the nickel film can be observed from both the microRS and XRD in situ studies. Variations in the evolution of silicide from metal for different silicon substrates are discussed, and these include (100) n-type, (100) p-type, and (110) p-type silicon substrates.

  16. CW laser induced crystallization of thin amorphous silicon films deposited by EBE and PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Said-Bacar, Z., E-mail: zabardjade@yahoo.fr [InESS (UMR 7163 CNRS-UDS), 23 rue de Loess, 67037 Strasbourg Cedex 2 (France); Prathap, P. [InESS (UMR 7163 CNRS-UDS), 23 rue de Loess, 67037 Strasbourg Cedex 2 (France); Cayron, C. [CEA, LITEN, DEHT, Minatec, 17 rue des Martyrs, 38054 Cedex 9 (France); Mermet, F. [IREPA LASER, Pole API - Parc d' Innovation, 67400 Illkirch (France); Leroy, Y.; Antoni, F.; Slaoui, A.; Fogarassy, E. [InESS (UMR 7163 CNRS-UDS), 23 rue de Loess, 67037 Strasbourg Cedex 2 (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer The effect of hydrogen in CW laser crystallization of hydrogenated amorphous silicon thin films has been investigated. Black-Right-Pointing-Pointer Large hydrogen content results in decohesion of the films due to hydrogen effusion. Black-Right-Pointing-Pointer Very low hydrogen content or hydrogen free amorphous silicon film are suitable for crystallization induced by CW laser. Black-Right-Pointing-Pointer Grains of size between 20 and 100 {mu}m in width and about 200 {mu}m in long in scanning direction are obtained with these latter films. - Abstract: This work presents the Continuous Wave (CW) laser crystallization of thin amorphous silicon (a-Si) films deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and by Electron Beam Evaporation (EBE) on low cost glass substrate. The films are characterized by Elastic Recoil Detection Analysis (ERDA) and by Fourier-Transform Infrared (FTIR) spectroscopy to evaluate the hydrogen content. Analysis shows that the PECVD films contain a high hydrogen concentration ({approx}10 at.%) while the EBE films are almost hydrogen-free. It is found that the hydrogen is in a bonding configuration with the a-Si network and in a free form, requiring a long thermal annealing for exodiffusion before the laser treatment to avoid explosive effusion. The CW laser crystallization process of the amorphous silicon films was operated in liquid phase regime. We show by Electron Backscatter Diffraction (EBSD) that polysilicon films with large grains can be obtained with EBE as well as for the PECVD amorphous silicon provided that for the latest the hydrogen content is lower than 2 at.%.

  17. Silicon carbide thin films for high temperature microelectromechanical systems

    Science.gov (United States)

    Fleischman, Aaron Judah

    Silicon Carbide (SiC) was studied for use as a material in microelectromechanical systems (MEMS). An APCVD reactor was built to deposit SiC on 100-mm diameter substrates. 3C-SiC films were grown heteroepitaxially atop 100-mm Si wafers. SiC was deposited atop suitable sacrificial layers of polysilicon and thermal oxide. The reactor gas flow was modeled using finite element techniques. The gas flow formed a recirculating pattern, with fresh reactant gases injected at the top of the reactor, traveling down the inside sidewalls and introduced at the bottom of the wafer, forming a plume of heated gases rising to the top of the reactor. This recirculation pattern explains the gradually decreasing growth rate from the wafer's bottom to its top as reactant gases are gradually depleted as they rise. Intentional doping of 3C-SiC films was studied, using diborane and phosphine dopant sources. SIMS indicated that B and P could be incorporated into 3C-SiC films, however B doped films were electrically compensated due to trace amounts of nitrogen in the diborane. Boron concentrations above 3C-SiC's solid solubility caused the SiC to become polycrystalline. Phosphorus incorporation was less predictable and did not vary linearly with phosphine flow rates. A reactive ion etch (REE) process was developed to etch 3C-SiC. Addition of He to the plasma chemistry enhanced the etch rates and etch anisotropy of the 3C-SiC. The etch recipe also produced similar results for polycrystalline SiC on polysilicon and thermal oxide. A maximum SiC etch rate of 1,267 A/min with a selectivity of 1.4 to Si was obtained. Using the above methods, SiC resonant devices were fabricated using polysilicon and thermal oxide as sacrificial layers. Polysilicon resonant devices were fabricated for comparison. The devices were tested by measuring their resonant frequency at room and elevated temperatures to 900°C to determine Young's modulus and its temperature dependence. All devices showed resonant frequency

  18. The evolution of the fraction of Er ions sensitized by Si nanostructures in silicon-rich silicon oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Noe, P; Okuno, H; Jager, J-B; Delamadeleine, E; Demichel, O; Rouviere, J-L; Calvo, V [INAC/SP2M, Commissariat a l' Energie Atomique-MINATEC, 17 rue des Martyrs, F-38054 Grenoble Cedex (France); Maurizio, C; D' Acapito, F [CNR-INFM-OGG c/o ESRF, GILDA-CRG, BP 220, F-38043 Grenoble (France)

    2009-09-02

    Photoluminescence (PL) and time-resolved PL experiments as a function of the elaboration process are performed on Er-doped silicon-rich silicon oxide (SRO:Er) thin films grown under NH{sub 3} atmosphere. These PL measurements of the Er{sup 3+} emission at 1.54 {mu}m under non-resonant pumping with the Er f-f transitions are obtained for different Er{sup 3+} concentrations, ranging from 0.05 to 1.4 at.%, and various post-growth annealing temperatures of the layers. High resolution transmission electron microscopy (HRTEM) and energy-filtered TEM (EFTEM) analysis show a high density of Si nanostructures composed of amorphous and crystalline nanoclusters varying from 2.7 x 10{sup 18} to 10{sup 18} cm{sup -3} as a function of the post-growth annealing temperature. Measurements of PL lifetime and effective Er excitation cross section for all the samples under non-resonant optical excitation with the Er{sup 3+} atomic energy levels show that the number of Er{sup 3+} ions sensitized by the silicon-rich matrix decreases as the annealing temperature is increased from 500 to 1050 {sup 0}C. The origin of this effect is attributed to the reduction of the density of sensitizers for Er ions in the SRO matrix when the annealing temperature increases. Finally, extended x-ray absorption fine-structure spectroscopy (EXAFS) shows a strong correlation between the number of emitters and the mean local order around the erbium ions.

  19. A study of ZnO:B films for thin film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yin, J.; Zhu, H.; Wang, Y.; Wang, Z.; Gao, J.; Mai, Y.; Ma, Y. [Baoding Tianwei Solarfilms Co., Ltd., 071051, Baoding (China); Wan, M. [Department of Chemistry and Material science, Hunan Institute of Humanities, Science and Technology, 417000, Loudi (China); Huang, Y., E-mail: y.huang@btw-solarfilms.com [Baoding Tianwei Solarfilms Co., Ltd., 071051, Baoding (China)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer ZnO:B films with different thicknesses were prepared with LPCVD technique. Black-Right-Pointing-Pointer The thicker ZnO:B back electrodes lead to higher FF but slightly lower J{sub sc.} Black-Right-Pointing-Pointer Back polyvinyl butyral (PVB) foils improves the utilization of incident light in solar cells. Black-Right-Pointing-Pointer The thicker ZnO:B front electrode films result in high J{sub sc} but lower FF. - Abstract: Boron doped zinc oxide (ZnO:B) films with different thicknesses were prepared with low pressure chemical vapor deposition (LPCVD) technique and implemented in thin film silicon solar cells as front and back electrodes. It is found that thick back ZnO:B film electrode in thin film silicon solar cells leads to a high fill factors (FF), which is attributed to an improvement of the electrical properties of the thick ZnO:B films, and in the meanwhile a slightly low short circuit currents (J{sub sc}) due to a high light absorption in the thick back ZnO:B films. Differently, the thicker front ZnO:B film electrodes result in a high J{sub sc} but a low FF of solar cells compared to the thinner ones. The low FF of the solar cells may be caused by the local shunt originated from the pinholes or by the cracks (zones of non-dense material) formed in particular in microcrystalline silicon materials deposited on rough front ZnO:B films. As to the high J{sub sc}, it is expected to be due to a good light trapping effect inside solar cells grown on rough front ZnO:B films. Moreover, the application of high reflective polyvinyl butyral (PVB) foils effectively enhances the utilization of incident light in solar cells. By optimizing deposition process of the ZnO:B films, high efficiencies of 8.8% and 10% for single junction thin film amorphous silicon solar cells (a-Si:H, intrinsic layer thickness < 200 nm) and amorphous/microcrystalline silicon tandem solar cells (a-Si:H/{mu}c-Si:H, intrinsic amorphous silicon layer

  20. Self-assembled thin film of imidazolium ionic liquid on a silicon surface: Low friction and remarkable wear-resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Gusain, Rashi [CSIR-Indian Institute of Petroleum, Mohkampur, Dehardun 248005 (India); Academy of Scientific and Innovative Research, New Delhi 110025 (India); Kokufu, Sho [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan); Bakshi, Paramjeet S. [CSIR-Indian Institute of Petroleum, Mohkampur, Dehardun 248005 (India); Utsunomiya, Toru; Ichii, Takashi; Sugimura, Hiroyuki [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan); Khatri, Om P., E-mail: opkhatri@iip.res.in [CSIR-Indian Institute of Petroleum, Mohkampur, Dehardun 248005 (India); Academy of Scientific and Innovative Research, New Delhi 110025 (India)

    2016-02-28

    Graphical abstract: - Highlights: • Ionic liquid thin film is deposited on a silicon surface via covalent interaction. • Chemical and morphological features of ionic liquid thin film are probed by XPS and AFM. • Ionic liquid thin film exhibited low and steady friction along with remarkable wear-resistivity. - Abstract: Imidazolium-hexafluorophosphate (ImPF{sub 6}) ionic liquid thin film is prepared on a silicon surface using 3-chloropropyltrimethoxysilane as a bifunctional chemical linker. XPS result revealed the covalent grafting of ImPF{sub 6} thin film on a silicon surface. The atomic force microscopic images demonstrated that the ImPF{sub 6} thin film is composed of nanoscopic pads/clusters with height of 3–7 nm. Microtribological properties in terms of coefficient of friction and wear-resistivity are probed at the mean Hertzian contact pressure of 0.35–0.6 GPa under the rotational sliding contact. The ImPF{sub 6} thin film exhibited low and steady coefficient of friction (μ = 0.11) along with remarkable wear-resistivity to protect the underlying silicon substrate. The low shear strength of ImPF{sub 6} thin film, the covalent interaction between ImPF{sub 6} ionic liquid thin film and underlying silicon substrate, and its regular grafting collectively reduced the friction and improved the anti-wear property. The covalently grafted ionic liquid thin film further shows immense potential to expand the durability and lifetime of M/NEMS based devices with significant reduction of the friction.

  1. Electrical Transport in Thin Films of Doped Silicon Nanocrystals

    Science.gov (United States)

    Chen, Ting

    Colloidal semiconductor nanocrystals (NCs) have shown great potential for thin-film optoelectronics, such as solar cells and light emitting diodes (LEDs), due to their size-tunable electronic properties and solution processability. Significant progress has been made in developing synthetic methods to prepare high quality NCs, achieving controllable doping, and integrating NCs into high performance electronic devices. Most electronic applications rely on the electrical conduction through NC films, therefore, fundamental understanding of the carrier transport in NC films is required to further improve device performance and provide guide for future device design. My research is inspired by the successful achievement of a highly efficient LED with hydrosilylated Si NCs as the emissive layer. To better understand the electrical conduction in the Si NC system, a systematic study of the temperature and electric-field dependence of the film conductivity is performed. It shows that the conductivity of the Si NC film is limited by the ionization of rare NCs containing donor impurities and the carrier transport follows nearest neighbor hopping. The Si NCs are inherently doped with a very small concentration of impurities, about 1 donor per 1000 NCs. This is also the first study of carrier transport in a lightly doped NC system, and results obtained in this work can apply to other NC materials as well. The organic ligands used to passivate NC surface are necessary to achieve strong photoluminescence, however, they inhibit the carrier transport due to the resulting large tunneling barrier between neighboring NCs. The localization length estimated from the temperature data in the high electric field regime is about 1 nm. In addition, the activation energy required for conduction also depends on the surrounding medium of NCs, the electrical conduction can be improved by reducing the activation energy through engineering of the matrix of NC arrays. Doping is critical to enable

  2. Silicon induced stability and mobility of indium zinc oxide based bilayer thin film transistors

    Science.gov (United States)

    Chauhan, Ram Narayan; Tiwari, Nidhi; Liu, Po-Tsun; Shieh, Han-Ping D.; Kumar, Jitendra

    2016-11-01

    Indium zinc oxide (IZO), silicon containing IZO, and IZO/IZO:Si bilayer thin films have been prepared by dual radio frequency magnetron sputtering on glass and SiO2/Si substrates for studying their chemical compositions and electrical characteristics in order to ascertain reliability for thin film transistor (TFT) applications. An attempt is therefore made here to fabricate single IZO and IZO/IZO:Si bilayer TFTs to study the effect of film thickness, silicon incorporation, and bilayer active channel on device performance and negative bias illumination stress (NBIS) stability. TFTs with increasing single active IZO layer thickness exhibit decrease in carrier mobility but steady improvement in NBIS; the best values being μFE ˜ 27.0, 22.0 cm2/Vs and ΔVth ˜ -13.00, -6.75 V for a channel thickness of 7 and 27 nm, respectively. While silicon incorporation is shown to reduce the mobility somewhat, it raises the stability markedly (ΔVth ˜ -1.20 V). Further, IZO (7 nm)/IZO:Si (27 nm) bilayer based TFTs display useful characteristics (field effect mobility, μFE = 15.3 cm2/Vs and NBIS value, ΔVth =-0.75 V) for their application in transparent electronics.

  3. Photoluminescence, time-resolved emission and photoresponse of plasma-modified porous silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Benyahia, Be., E-mail: benyahiabedra@hotmail.com [Unité de Développement de la Technologie du Silicium, 2 Boulevard Frantz Fanon, B.P. 140, Alger-7 Merveilles, Algiers 16200 (Algeria); Guerbous, L. [Centre de Recherche Nucléaire d' Alger, 2 Boulevard Frantz Fanon, B.P. 399, Alger-Gare, Algiers 16000 (Algeria); Gabouze, N.; Mahmoudi, Br. [Unité de Développement de la Technologie du Silicium, 2 Boulevard Frantz Fanon, B.P. 140, Alger-7 Merveilles, Algiers 16200 (Algeria)

    2013-07-01

    Photoluminescence and photoelectrical study on plasma-modified porous silicon (PS) thin films is presented. Porous silicon passivated by hydrocarbon groups (CH{sub x}) shows an intense broad and stable photoluminescence (PL) band centered at 623 nm whereas the maximum of the photosensitivity spectrum is placed around 400 nm. Along with its potential utilization for silicon-based light emitters' fabrication, it could also represent an appealing option for the improvement of energy conversion efficiency in silicon-based solar cells whether by using its luminescence properties (photon down-conversion) or the excess photocurrent produced by an improved high-energy photon's absorption. Excitation spectra (PLE) under steady-state conditions are reported. PLE shows that visible PL is excited by light from UV region. The time-resolved photoluminescence of CH{sub x}/PS in the range of some tenth of μs are investigated at room temperature. The PL decay line shape, in CH{sub x}/PS is well described by stretched exponential. The photosensitivity spectroscopy shows a significant increase of absorption at high photon energy excitation. - Highlights: • Coating porous silicon (PS) by hydrocarbon (CH{sub x}) reduces nonradiative transition. • Drop of the photoluminescence (PL) intensity. • The PL of CH{sub x}/PS is due to radiative transitions at 1.8 and 1.87 eV. • Photosensitivity revealed an excess spectral response (SR) at high-energy excitation. • For photovoltaic PL and SR could be used for the evolution of the silicon solar cells.

  4. Ultrasmooth gold thin films by self-limiting galvanic displacement on silicon.

    Science.gov (United States)

    Gutés, Albert; Carraro, Carlo; Maboudian, Roya

    2011-05-01

    Galvanic displacement (GD), a type of electroless deposition, has been used to obtain ultrasmooth gold thin films on silicon . The novel aspect of the method presented herein is the absence of fluoride ions in the liquid phase, and its principal advantage when compared to previous efforts is that the process is inherently self-limiting. The self-limiting factor is due to the fact that in the absence of fluorinated species, no silicon oxide is removed during the process. Thus, the maximum gold film thickness is achieved when elemental silicon is no longer available once the surface is oxidized completely during the galvanic displacement process. X-ray photoelectron spectroscopy has been used as a tool for thickness measurement, using the gold to silicon ratio as an analytical signal. Three gold plating solutions with different concentrations of KAuCl₄ (2, 0.2, and 0.02 mM) have been used to obtain information about the formation rate of the gold film. This XPS analysis demonstrates the formation of gold films to a maximum thickness of ∼3.5 Å. Atomic force microscopy is used to confirm surface smoothness, suggesting that the monolayer growth does not follow the Volmer-Weber growth mode, in contrast to the GD process from aqueous conditions with fluorinated species.

  5. Low thermal budget rapid thermal annealing of hydrogenated PECVD silicon thin films for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    El-Gohary, H.G.; Farrokh-Baroughi, M.; Sivoththaman, S. [Waterloo Univ., ON (Canada). Dept. of Electrical and Computer Engineering

    2006-07-01

    The photovoltaic (PV) market is currently dominated by crystalline silicon solar cells, having a market share of more than 84 per cent. Half of the total price of the PV modules is attributed to the cost of silicon base materials. This paper presented a new approach towards low cost solar cell technologies. In particular, it presented a low temperature plasma enhanced chemical vapor deposition (PECVD) technique for emitter realization. The technique improves the junction quality by a medium temperature low thermal budget rapid thermal annealing (RTA) technique. The many advantages that RTA has for silicon processing was discussed with reference to rapid thermal processing (RTP) used for annealing low temperature deposited silicon thin films. Some of the attractive features of RTP include low cost, minimum overall thermal budget, low power consumption and high throughput. For all the annealed samples in this study which were deposited without hydrogen dilution, 90 per cent of the surface was full of pits caused mainly by hydrogen evolution from the films. It was suggested that high hydrogen dilution can enhance the film quality and reduce the number and size of pits for device applications, particularly for the solar cell applications. However, it was concluded that the growth mechanism of 91 per cent and 99 per cent hydrogen dilution on c-Si and glass substrates using the same process conditions are different and may lead to quasiepitaxial growth mechanism for the films deposited on the crystalline wafers. 21 tabs., 3 tabs., 9 figs.

  6. Thin, High Lifetime Silicon Wafers with No Sawing; Re-crystallization in a Thin Film Capsule

    Energy Technology Data Exchange (ETDEWEB)

    Emanuel Sachs

    2013-01-16

    The project fits within the area of renewable energy called photovoltaics (PV), or the generation of electricity directly from sunlight using semiconductor devices. PV has the greatest potential of any renewable energy technology. The vast majority of photovoltaic modules are made on crystalline silicon wafers and these wafers accounts for the largest fraction of the cost of a photovoltaic module. Thus, a method of making high quality, low cost wafers would be extremely beneficial to the PV industry The industry standard technology creates wafers by casting an ingot and then sawing wafers from the ingot. Sawing rendered half of the highly refined silicon feedstock as un-reclaimable dust. Being a brittle material, the sawing is actually a type of grinding operation which is costly both in terms of capital equipment and in terms of consumables costs. The consumables costs associated with the wire sawing technology are particularly burdensome and include the cost of the wire itself (continuously fed, one time use), the abrasive particles, and, waste disposal. The goal of this project was to make wafers directly from molten silicon with no sawing required. The fundamental concept was to create a very low cost (but low quality) wafer of the desired shape and size and then to improve the quality of the wafer by a specialized thermal treatment (called re-crystallization). Others have attempted to create silicon sheet by recrystallization with varying degrees of success. Key among the difficulties encountered by others were: a) difficulty in maintaining the physical shape of the sheet during the recrystallization process and b) difficulty in maintaining the cleanliness of the sheet during recrystallization. Our method solved both of these challenges by encapsulating the preform wafer in a protective capsule prior to recrystallization (see below). The recrystallization method developed in this work was extremely effective at maintaining the shape and the cleanliness of the

  7. Band engineering of amorphous silicon ruthenium thin film and its near-infrared absorption enhancement combined with nano-holes pattern on back surface of silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Anran; Zhong, Hao [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Li, Wei, E-mail: wli@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Gu, Deen; Jiang, Xiangdong [School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Jiang, Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-10-30

    Highlights: • The increase of Ru concentration leads to a narrower bandgap of a-Si{sub 1-x}Ru{sub x} thin film. • The absorption coefficient of a-Si{sub 1-x}Ru{sub x} is higher than that of SiGe. • A double-layer absorber comprising of a-Si{sub 1-x}Ru{sub x} film and Si nano-holes layer is achieved. - Abstract: Silicon is widely used in semiconductor industry but has poor performance in near-infrared photoelectronic devices because of its bandgap limit. In this study, a narrow bandgap silicon rich semiconductor is achieved by introducing ruthenium (Ru) into amorphous silicon (a-Si) to form amorphous silicon ruthenium (a-Si{sub 1-x}Ru{sub x}) thin films through co-sputtering. The increase of Ru concentration leads to an enhancement of light absorption and a narrower bandgap. Meanwhile, a specific light trapping technique is employed to realize high absorption of a-Si{sub 1-x}Ru{sub x} thin film in a finite thickness to avoid unnecessary carrier recombination. A double-layer absorber comprising of a-Si{sub 1-x}Ru{sub x} thin film and silicon random nano-holes layer is formed on the back surface of silicon substrates, and significantly improves near-infrared absorption while the leaky light intensity is less than 5%. This novel absorber, combining narrow bandgap thin film with light trapping structure, may have a potential application in near-infrared photoelectronic devices.

  8. Superior light trapping in thin film silicon solar cells through nano imprint lithography

    Energy Technology Data Exchange (ETDEWEB)

    Soppe, W.J.; Dorenkamper, M.S.; Schropp, R.E.I.; Pex, P.P.A.C.

    2013-10-15

    ECN and partners have developed a fabrication process based on nanoimprint lithography (NIL) of textures for light trapping in thin film solar cells such as thin-film silicon, OPV, CIGS and CdTe. The process can be applied in roll-to-roll mode when using a foil substrate or in roll-to-plate mode when using a glass substrate. The lacquer also serves as an electrically insulating layer for cells if steel foil is used as substrate, to enable monolithic series interconnection. In this paper we will show the superior light trapping in thin film silicon solar cells made on steel foil with nanotextured back contacts. We have made single junction a-Si and {mu}c-Si and a-Si/{mu}c-Si tandem cells, where we applied several types of nano-imprints with random and periodic structures. We will show that the nano-imprinted back contact enables more than 30% increase of current in comparison with non-textured back contacts and that optimized periodic textures outperform state-of-the-art random textures. For a-Si cells we obtained Jsc of 18 mA/cm{sup 2} and for {mu}c-Si cells more than 24 mA/cm{sup 2}. Tandem cells with a total Si absorber layer thickness of only 1350 nm have an initial efficiency of 11%.

  9. Sputtered Al-doped ZnO transparent conducting thin films suitable for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ayadi, Z., E-mail: Zouhaier.BenAyadi@fsg.rnu.tn [Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l' Environnement, Université de Gabès, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Mahdhi, H. [Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l' Environnement, Université de Gabès, Faculté des Sciences de Gabès, Cité Erriadh Manara Zrig, 6072 Gabès (Tunisia); Djessas, K. [Laboratoire Procédés, Matériaux et Energie Solaire (PROMES-CNRS), TECNOSUD, Rambla de la Thermodynamique, 66100 Perpignan (France); Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 68860, Perpignan Cedex9 (France); Gauffier, J.L. [Département de Génie Physique, INSA de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse cedex 4 (France); and others

    2014-02-28

    Highly transparent conducting Al-doped zinc oxide (AZO) thin films have been grown onto p-type porous silicon substrates by RF-magnetron sputtering at room temperature using aluminum doped nanocrystalline powder. The obtained AZO films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The films are highly transparent in the visible wavelength region with a transmittance higher than 85% and an electrical resistivity of 1.56 × 10{sup −4} Ω·cm was obtained at room temperature. On the other hand, we have studied the position of the p–n junction involved in the In{sub 2}O{sub 3}:SnO{sub 2}/(n)AZO/Si(p) structure, by electron-beam induced current technique. Current density–voltage characterizations in dark and under illumination were also investigated. The cell exhibits an efficiency of 5%. - Highlights: • Al-doped zinc oxide (AZO) thin films were grown by RF-magnetron sputtering. • AZO nanopowder compacted target was prepared by a sol–gel method. • AZO thin films are polycrystalline and have preferred orientation along c-axis. • We report a photovoltaic effect in Si(p)/porous silicon/AZO heterostructure. • The cell exhibits an efficiency of 5%.

  10. Combining light-harvesting with detachability in high-efficiency thin-film silicon solar cells.

    Science.gov (United States)

    Ram, Sanjay K; Desta, Derese; Rizzoli, Rita; Bellettato, Michele; Lyckegaard, Folmer; Jensen, Pia B; Jeppesen, Bjarke R; Chevallier, Jacques; Summonte, Caterina; Larsen, Arne Nylandsted; Balling, Peter

    2017-06-01

    Efforts to realize thin-film solar cells on unconventional substrates face several obstacles in achieving good energy-conversion efficiency and integrating light-management into the solar cell design. In this report a technique to circumvent these obstacles is presented: transferability and an efficient light-harvesting scheme are combined for thin-film silicon solar cells by the incorporation of a NaCl layer. Amorphous silicon solar cells in p-i-n configuration are fabricated on reusable glass substrates coated with an interlayer of NaCl. Subsequently, the solar cells are detached from the substrate by dissolution of the sacrificial NaCl layer in water and then transferred onto a plastic sheet, with a resultant post-transfer efficiency of 9%. The light-trapping effect of the surface nanotextures originating from the NaCl layer on the overlying solar cell is studied theoretically and experimentally. The enhanced light absorption in the solar cells on NaCl-coated substrates leads to significant improvement in the photocurrent and energy-conversion efficiency in solar cells with both 350 and 100 nm thick absorber layers, compared to flat-substrate solar cells. Efficient transferable thin-film solar cells hold a vast potential for widespread deployment of off-grid photovoltaics and cost reduction.

  11. Luminescent Nanocrystalline Silicon Carbide Thin Film Deposited by Helicon Wave Plasma Enhanced Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LU Wan-bing; YU Wei; WU Li-ping; CUI Shuang-kui; FU Guang-sheng

    2006-01-01

    Hydrogenated nanocrystalline silicon carbide (SiC) thin films were deposited on the single-crystal silicon substrate using the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. The influences of magnetic field and hydrogen dilution ratio on the structures of SiC thin film were investigated with the atomic force microscopy (AFM), the Fourier transform infrared absorption (FTIR) and the transmission electron microscopy (TEM). The results indicate that the high plasma activity of the helicon wave mode proves to be a key factor to grow crystalline SiC thin films at a relative low substrate temperature. Also, the decrease in the grain sizes from the level of microcrystalline to that of nanocrystalline can be achieved by increasing the hydrogen dilution ratios. Transmission electron microscopy measurements reveal that the size of most nanocrystals in the film deposited under the higher hydrogen dilution ratios is smaller than the doubled Bohr radius of 3C-SiC (approximately 5.4 nm), and the light emission measurements also show a strong blue photoluminescence at the room temperature, which is considered to be caused by the quantum confinement effect of small-sized SiC nanocrystals.

  12. Applications of Cubic MgZnO Thin Films in Metal-Insulator-Silicon Structures

    Institute of Scientific and Technical Information of China (English)

    LIANG Jun; WU Hui-Zhen; LAO Yan-Feng; QIU Dong-Jiang; CHEN Nai-Bo; XU Tian-Ning

    2004-01-01

    @@ Cubic Mgo.55Zno.45O thin film alloys have been deposited on Si substrates at low growth temperature. The topography of the cross section of the epitaxial film by scanning electronic microscope demonstrates good mor phology and high interfacial quality. The high (001) orientation and wide band-gap (Eg > 5.5 eV) of the cubic Mgo.55Zno.45 O thin films accord with the guidelines for metal-insulator-silicon (MIS) device applications. Using the cubic ternary thin films as insulators, MIS structures have been fabricated. The capacitance-voltage measurements show the flat band voltage shift VFB of11.8 V and mobile ion density Dmc of 5.57 × 1010 cm-2 for the MIS structure. Leakage current density as low as ~ 10-7 A/cm2 is obtained at E = 700 kV/cm by the currentvoltage measurements. These unique structural and electrical properties of the fabricated MIS devices indicate that cubic MgZnO materials could become a new candidate for high-κ dielectrics used in silicon integrated circuit technologies.

  13. Crystalline silicon surface passivation by thermal ALD deposited Al doped ZnO thin films

    Directory of Open Access Journals (Sweden)

    Jagannath Panigrahi

    2017-03-01

    Full Text Available The evidence of good quality silicon surface passivation using thermal ALD deposited Al doped zinc oxide (AZO thin films is demonstrated. AZO films are prepared by introducing aluminium precursor in between zinc and oxygen precursors during the deposition. The formation of AZO is confirmed by ellipsometry, XRD and Hall measurements. Effective minority carrier lifetime (τeff greater than 1.5ms at intermediate bulk injection levels is realized for symmetrically passivated p-type silicon surfaces under optimised annealing conditions of temperature and time in hydrogen ambient. The best results are realised at 450°C annealing for >15min. Such a layer may lead to implied open circuit voltage gain of 80mV.

  14. Silicon surface passivation using thin HfO2 films by atomic layer deposition

    Science.gov (United States)

    Gope, Jhuma; Vandana; Batra, Neha; Panigrahi, Jagannath; Singh, Rajbir; Maurya, K. K.; Srivastava, Ritu; Singh, P. K.

    2015-12-01

    Hafnium oxide (HfO2) is a potential material for equivalent oxide thickness (EOT) scaling in microelectronics; however, its surface passivation properties particularly on silicon are not well explored. This paper reports investigation on passivation properties of thermally deposited thin HfO2 films by atomic layer deposition system (ALD) on silicon surface. As-deposited pristine film (∼8 nm) shows better passivation with <100 cm/s surface recombination velocity (SRV) vis-à-vis thicker films. Further improvement in passivation quality is achieved with annealing at 400 °C for 10 min where the SRV reduces to ∼20 cm/s. Conductance measurements show that the interface defect density (Dit) increases with film thickness whereas its value decreases after annealing. XRR data corroborate with the observations made by FTIR and SRV data.

  15. Integration of field emitter array and thin-film transistor using polycrystalline silicon process technology

    CERN Document Server

    Song, Y H; Kang, S Y; Park Jeong Man; Cho, K I

    1998-01-01

    We present the monolithic integration of a gated polycrystalline silicon field emitter array (poly-Si FEA) and a thin-film transistor(TFT) on an insulating substrate for active-matrix field emission displays (AMFEDs). The TFT was designed to have low off-state currents even at a high drain voltage. Amorphous silicon has been used as a starting material of the poly-Si FEA for improving surface smoothness and uniformity of the tips, and the gate holes have been formed by using an etch-back process. The integrated poly-Si TFT controlled electron emissions of the poly-Si FEA actively, resulting in great improvement in the emission reliability along with a low-voltage control, below 15 V, of field emission, The developed technology has potential applications in AMFEDs on glass substrates.

  16. Thin-film scintillators for extended ultraviolet /UV/ response silicon detectors

    Science.gov (United States)

    Viehmann, W.

    1979-01-01

    The preparation and radiometric properties of silicon detectors coated with fluorescent thin films are described. The films are deposited from solutions of clear plastics, such as acrylic resins, polyvinyl toluene or polystyrene, and of organic laser dyes in a common solvent. They are optically clear, mechanically and chemically stable, yet easily applied and removed. Multiple doped films of a few microns thickness exhibit broad-band absorption from less than 250 nm to about 450 nm and narrow band emissions with peaks ranging from 380 nm to 600 nm. Internal quantum efficiencies are close to 100 percent and fluorescence decay times are in the nanosecond range. When deposited on optically denser media, a large fraction of the fluorescent emission is trapped in the substrate. Silicon photodiodes coated with multiple doped films exhibit high external quantum efficiencies and virtually flat photon response in the near UV.

  17. Non-classical crystallization of silicon thin films during hot wire chemical vapor deposition

    Science.gov (United States)

    Jung, Jae-Soo; Lee, Sang-Hoon; Kim, Da-Seul; Kim, Kun-Su; Park, Soon-Won; Hwang, Nong-Moon

    2017-01-01

    The deposition behavior of silicon films by hot wire chemical vapor deposition (HWCVD) was approached by non-classical crystallization, where the building block of deposition is a nanoparticle generated in the gas phase of the reactor. The puzzling phenomenon of the formation of an amorphous incubation layer on glass could be explained by the liquid-like property of small charged nanoparticles (CNPs), which are generated in the initial stage of the HWCVD process. Using the liquid-like property of small CNPs, homo-epitaxial growth as thick as 150 nm could be successfully grown on a silicon wafer at 600 °C under the processing condition where CNPs as small as possible could be supplied steadily by a cyclic process which periodically resets the process. The size of CNPs turned out to be an important parameter in the microstructure evolution of thin films.

  18. Thin-film scintillators for extended ultraviolet /UV/ response silicon detectors

    Science.gov (United States)

    Viehmann, W.

    1979-01-01

    The preparation and radiometric properties of silicon detectors coated with fluorescent thin films are described. The films are deposited from solutions of clear plastics, such as acrylic resins, polyvinyl toluene or polystyrene, and of organic laser dyes in a common solvent. They are optically clear, mechanically and chemically stable, yet easily applied and removed. Multiple doped films of a few microns thickness exhibit broad-band absorption from less than 250 nm to about 450 nm and narrow band emissions with peaks ranging from 380 nm to 600 nm. Internal quantum efficiencies are close to 100 percent and fluorescence decay times are in the nanosecond range. When deposited on optically denser media, a large fraction of the fluorescent emission is trapped in the substrate. Silicon photodiodes coated with multiple doped films exhibit high external quantum efficiencies and virtually flat photon response in the near UV.

  19. Absorption coefficient modeling of microcrystalline silicon thin film using Maxwell-Garnett effective medium theory.

    Science.gov (United States)

    Chen, Sheng-Hui; Wang, Hsuan-Wen; Chang, Ting-Wei

    2012-03-12

    Considering the Mott-Davis density of state model and Rayleigh scattering effect, we present an approach to model the absorption profile of microcrystalline silicon thin films in this paper. Maxwell-Garnett effective medium theory was applied to analyze the absorption curves. To validate the model, several experimental profiles have been established and compared with those results from the model. With the assistance of the genetic algorithm, our results show that the absorption curves from the model are in good agreement with the experiments. Our findings also indicate that, as the crystal volume fraction increases, not only do the defects in amorphous silicon reduce, but the bulk scattering effect is gradually enhanced as well.

  20. Thin-film monocrystalline-silicon solar cells made by a seed layer approach on glass-ceramic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, I.; Beaucarne, G.; Poortmans, J. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Vallon, S. [Corning European Technology Center, 7bis avenue de Valvins, 77210 Avon (France); Mayolet, A. [Corning Incorporated, SP-FR02-12, Corning, NY 14831 (United States)

    2010-02-15

    Solar modules made from thin-film crystalline-silicon layers of high quality on glass substrates could lower the price of photovoltaic electricity substantially. One way to create crystalline-silicon thin films on non-silicon substrates is to use the so-called ''seed layer approach'', in which a thin crystalline-silicon seed layer is first created, followed by epitaxial thickening of this seed layer. In this paper, we present the first solar cell results obtained on 10-{mu}m-thick monocrystalline-silicon (mono-Si) layers obtained by a seed layer approach on transparent glass-ceramic substrates. The seed layers were made using implant-induced separation and anodic bonding. These layers were then epitaxially thickened by thermal CVD. Simple solar cell structures without integrated light trapping features showed efficiencies of up to 7.5%. Compared to polycrystalline-silicon layers made by aluminum-induced crystallization of amorphous silicon and thermal CVD, the mono-Si layers have a much higher bulk diffusion lifetime. (author)

  1. Systematic process development towards high performance transferred thin silicon solar cells based on epitaxially grown absorbers

    Science.gov (United States)

    Murcia Salazar, Clara Paola

    The value of thin crystalline silicon (c-Si) solar cells is the potential for higher performance compared to conventional wafer approaches. Thin silicon solar cells can outperform thick cells with the same material properties because the smaller active volume causes a reduced bulk recombination leading to higher voltages while efficient light trapping structures ensure all photons are absorbed. Efficiencies above 20+% can be achieved with less than 20um of c-Si with current silicon solar cell processing technologies. In a thin solar cell, factors that will lead to high efficiency include high minority carrier lifetime, low surface recombination, and good optical confinement. Independently optimizing surface optical and electrical properties in a thin solar cell can achieve this higher performance. In addition, re-utilizing a c-Si wafer with a process that allows optimization of both surfaces is a path to higher performance at lower cost. The challenge in the fabrication of this high performance concept is to separately analyze critical parameters through fabrication and transfer and establish the design rules for high performance. This work contributes to the design and systematic fabrication approach of a 20 mum thick epitaxial silicon solar cell. State-of-the-art thin absorbers of less than 30um have reported 655mV (on a textured front surface with antireflection coating), and efficiencies near 17%. We report near 640mV (on a planar front surface with antireflection coating) for 20 mum thick absorbers. It is found that previously reported efficiencies are tightly related to solar cell's active thickness. In the case of transferred solar cells, the thinnest epitaxial transferred cell reported is near 24 mum thick with an efficiency of 15.4% (transparent front handle, textured with ARC and metallic back reflector). Recently, a c-Si transferred solar cell of 43 mum has reported 19.1% efficiency (with a front texture and ARC with localized back contact and reflector

  2. Thermal oxidation of silicon in a residual oxygen atmosphere—the RESOX process—for self-limiting growth of thin silicon dioxide films

    Science.gov (United States)

    Wright, Jason T.; Carbaugh, Daniel J.; Haggerty, Morgan E.; Richard, Andrea L.; Ingram, David C.; Kaya, Savas; Jadwisienczak, Wojciech M.; Rahman, Faiz

    2016-10-01

    We describe in detail the growth procedures and properties of thermal silicon dioxide grown in a limited and dilute oxygen atmosphere. Thin thermal oxide films have become increasingly important in recent years due to the continuing down-scaling of ultra large scale integration metal oxide silicon field effect transistors. Such films are also of importance for organic transistors where back-gating is needed. The technique described here is novel and allows self-limited formation of high quality thin oxide films on silicon surfaces. This technique is easy to implement in both research laboratory and industrial settings. Growth conditions and their effects on film growth have been described. Properties of the resulting oxide films, relevant for microelectronic device applications, have also been investigated and reported here. Overall, our findings are that thin, high quality, dense silicon dioxide films of thicknesses up to 100 nm can be easily grown in a depleted oxygen environment at temperatures similar to that used for usual silicon dioxide thermal growth in flowing dry oxygen.

  3. Strain dependence of the direct energy bandgap in thin silicon on insulator layers

    OpenAIRE

    Munguía, J; Bluet, J-M; Chouaib, H.; Bremond, G.; Mermoux, Michel; Bru-Chevallier, C

    2010-01-01

    Abstract Photoreflectance spectroscopy is applied on tensilely-strained silicon on insulator (sSOI) thin layers in order to evaluate the biaxial strain effect on the Si direct bandgap. The measured redshift of the transition (i.e. direct bandgap) with strain (~ -100 meV/%), corresponds to theoretical predictions. The hydrostatic and valence band deformation potential parameters for E 1 (i.e. transition close to L-point along the ?-direction) are also measured: and ' 0 E eV D 5. 0 5 . 7 1 1...

  4. Plasma monitoring and PECVD process control in thin film silicon-based solar cell manufacturing

    Directory of Open Access Journals (Sweden)

    Gabriel Onno

    2014-02-01

    Full Text Available A key process in thin film silicon-based solar cell manufacturing is plasma enhanced chemical vapor deposition (PECVD of the active layers. The deposition process can be monitored in situ by plasma diagnostics. Three types of complementary diagnostics, namely optical emission spectroscopy, mass spectrometry and non-linear extended electron dynamics are applied to an industrial-type PECVD reactor. We investigated the influence of substrate and chamber wall temperature and chamber history on the PECVD process. The impact of chamber wall conditioning on the solar cell performance is demonstrated.

  5. Thin metal layer as transparent electrode in n-i-p amorphous silicon solar cells

    Directory of Open Access Journals (Sweden)

    Theuring Martin

    2014-07-01

    Full Text Available In this paper, transparent electrodes, based on a thin silver film and a capping layer, are investigated. Low deposition temperature, flexibility and low material costs are the advantages of this type of electrode. Their applicability in structured n-i-p amorphous silicon solar cells is demonstrated in simulation and experiment. The influence of the individual layer thicknesses on the solar cell performance is discussed and approaches for further improvements are given. For the silver film/capping layer electrode, a higher solar cell efficiency could be achieved compared to a reference ZnO:Al front contact.

  6. Low temperature NbSi thin film thermometers on Silicon Nitride membranes for bolometer applications

    Energy Technology Data Exchange (ETDEWEB)

    Camus, Ph. E-mail: camus@csnsm.in2p3.fr; Berge, L.; Dumoulin, L.; Marnieros, S.; Torre, J.P

    2000-04-07

    We report the design of amorphous NbSi thin film bolometer thermometers on Silicon Nitride membranes. Due to the low-thermal conductivity of Si{sub 3}N{sub 4}, this material has several applications in millimeter wavelength bolometers and microcalorimetry. Compared to NTD-Ge thermometers, similar sensitivities are obtained with a 50 times lesser volume. The smallest realized films have a rectangular surface (100x400 {mu}m{sup 2}) and are 100 nm thick. Optimization of the thermometer shape, NbSi composition and electrical material contact is discussed. The goal of this development is to manufacture a complete array of bolometers by photolithography techniques.

  7. Bound exciton photoluminescence from ion‑implanted phosphorus in thin silicon layers.

    Science.gov (United States)

    Sumikura, Hisashi; Nishiguchi, Katsuhiko; Ono, Yukinori; Fujiwara, Akira; Notomi, Masaya

    2011-12-01

    We report the observation of clear bound exciton (BE) emission from ion-implanted phosphorus. Shallow implantation and high-temperature annealing successfully introduce active donors into thin silicon layers. The BE emission at a wavelength of 1079 nm shows that a part of the implanted donors are definitely activated and isolated from each other. However, photoluminescence and electron spin resonance studies find a cluster state of the activated donors. The BE emission is suppressed by this cluster state rather than the nonradiative processes caused by ion implantation. Our results provide important information about ion implantation for doping quantum devices with phosphorus quantum bits.

  8. Diode behavior in ultra-thin low temperature ALD grown zinc-oxide on silicon

    Directory of Open Access Journals (Sweden)

    Nazek El-Atab

    2013-10-01

    Full Text Available A thin-film ZnO(n/Si(p+ heterojunction diode is demonstrated. The thin film ZnO layer is deposited by Atomic Layer Deposition (ALD at different temperatures on a p-type silicon substrate. Atomic force microscopy (AFM AC-in-Air method in addition to conductive AFM (CAFM were used for the characterization of ZnO layer and to measure the current-voltage characteristics. Forward and reverse bias n-p diode behavior with good rectification properties is achieved. The diode with ZnO grown at 80°C exhibited the highest on/off ratio with a turn-on voltage (VON ∼3.5 V. The measured breakdown voltage (VBR and electric field (EBR for this diode are 5.4 V and 3.86 MV/cm, respectively.

  9. Deterministic aperiodic composite lattice-structured silicon thin films for photon management

    CERN Document Server

    Xavier, Jolly; Becker, Christiane

    2016-01-01

    Exotic manipulation of the flow of photons in nanoengineered semiconductor materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced and industrially viable broadband photonic technologies. Through a generic deterministic nanotechnological route, in addition to periodic, transversely quasicrystallographic or disordered random photonic lattices, here we show scalable nanostructured semiconductor thin films on large area nanoimprinted substrates up to 4cm^2 with advanced functional features of aperiodic composite nanophotonic lattices having tailorable supercell tiles. The richer Fourier spectra of the presented artificially nanostructured materials with well-defined lattice point morphologies are designed functionally akin to two-dimensional incommensurate intergrowth aperiodic lattices-comprising periodic photonic crystals and in-plane quasicrystals as subgroups. The composite photonic lattice-structured crystalline silicon thin films with tapered nanoholes or nanocone...

  10. Amorphous silicon pixel radiation detectors and associated thin film transistor electronics readout

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Mendez, V.; Drewery, J.; Hong, W.S.; Jing, T.; Kaplan, S.N.; Lee, H.; Mireshghi, A.

    1994-10-01

    We describe the characteristics of thin (1 {mu}m) and thick (>30 {mu}m) hydrogenated amorphous silicon p-i-n diodes which are optimized for detecting and recording the spatial distribution of charged particles, x-rays and {gamma} rays. For x-ray, {gamma} ray, and charged particle detection we can use thin p-i-n photosensitive diode arrays coupled to evaporated layers of suitable scintillators. For direct detection of charged particles with high resistance to radiation damage, we use the thick p-i-n diode arrays. Deposition techniques using helium dilution, which produce samples with low stress are described. Pixel arrays for flux exposures can be readout by transistor, single diode or two diode switches. Polysilicon charge sensitive pixel amplifiers for single event detection are described. Various applications in nuclear, particle physics, x-ray medical imaging, neutron crystallography, and radionuclide chromatography are discussed.

  11. Pulsed laser deposition of tungsten carbide thin films on silicon (100) substrate

    Science.gov (United States)

    Suda, Y.; Nakazono, T.; Ebihara, K.; Baba, K.

    1997-01-01

    A method of synthesizing tungsten carbide (WC) thin films by a pulsed YAG laser deposition is investigated. WC thin films are deposited on silicon (100) substrates by using WC5%Co alloy targets. Glancing angle X-ray diffraction shows that the strong peaks of W 2C appear at the substrate temperature of 500°C. Beside the strong peaks of W 2C, weak peaks of WC and W 3Co 3C appear at the substrate temperature of 650°C. Auger electron spectroscopy shows that the almost stoichiometric WC films are deposited at the methane gas pressure of 1.0 Pa. Morphological features of the samples have been obtained by employing the technique of scanning electron microscopy. X-ray photoelectron spectroscopy has been used to obtain structural and compositional information about the samples.

  12. Mechanical alloying of Cu/Al plates and preparation of bulk amorphous/nanocrystalline composite by thermoplastic deformation%搅拌摩擦法制备Cu-Al非晶/纳米晶复合材料

    Institute of Scientific and Technical Information of China (English)

    徐红霞; 段辉平; 宋洪海

    2013-01-01

    利用搅拌摩擦技术,使叠放在一起的Cu、Al板材发生强烈的热塑性变形.对搅拌区产物的显微结构分析表明:Cu、Al板材被搅拌破碎并充分混合在一起,Cu、Al元素发生扩散并实现合金化;在搅拌区中有许多尺寸> 1μm的非晶相和非晶/纳米晶复合相,非晶相的基体中含有平均尺寸约为5nm的纳米晶.热塑性变形技术不仅可用于块体金属材料的机械合金化,也可用于制备块体非晶/纳米晶复合材料.%Strong thermoplastic deformation of overlapped Cu and Al plates had been realized by stir friction processing. Transmission electron microscopy investigation on the microstructure of the stirred zone demonstrate that the Cu and Al plates are torn into shreds and well-mixed in the stirred zone. The inter-diffusion between Cu and Al shreds happens, resulting in the mechanical alloying of Cu/Al plates. There are many amorphous phases with size of more than 1 micron and amorphous/nanocrystalline composite phases in the deformation zone. The average size of the nanocrystallines surrounded by amorphous phases, is about 5 nanometers. Experimental results strongly suggest that the thermoplastic deformation technique can not only be used to do mechanical alloying for bulk metallic materials but also to fabricate bulk amorphous/crystalline materials.

  13. Asymmetric electrostatic and hydrophobic-hydrophilic interaction forces between mica surfaces and silicone polymer thin films.

    Science.gov (United States)

    Donaldson, Stephen H; Das, Saurabh; Gebbie, Matthew A; Rapp, Michael; Jones, Louis C; Roiter, Yuri; Koenig, Peter H; Gizaw, Yonas; Israelachvili, Jacob N

    2013-11-26

    We have synthesized model hydrophobic silicone thin films on gold surfaces by a two-step covalent grafting procedure. An amino-functionalized gold surface reacts with monoepoxy-terminated polydimethylsiloxane (PDMS) via a click reaction, resulting in a covalently attached nanoscale thin film of PDMS, and the click chemistry synthesis route provides great selectivity, reproducibility, and stability in the resulting model hydrophobic silicone thin films. The asymmetric interaction forces between the PDMS thin films and mica surfaces were measured with the surface forces apparatus in aqueous sodium chloride solutions. At an acidic pH of 3, attractive interactions are measured, resulting in instabilities during both approach (jump-in) and separation (jump-out from adhesive contact). Quantitative analysis of the results indicates that the Derjaguin-Landau-Verwey-Overbeek theory alone, i.e., the combination of electrostatic repulsion and van der Waals attraction, cannot fully describe the measured forces and that the additional measured adhesion is likely due to hydrophobic interactions. The surface interactions are highly pH-dependent, and a basic pH of 10 results in fully repulsive interactions at all distances, due to repulsive electrostatic and steric-hydration interactions, indicating that the PDMS is negatively charged at high pH. We describe an interaction potential with a parameter, known as the Hydra parameter, that can account for the extra attraction (low pH) due to hydrophobicity as well as the extra repulsion (high pH) due to hydrophilic (steric-hydration) interactions. The interaction potential is general and provides a quantitative measure of interfacial hydrophobicity/hydrophilicity for any set of interacting surfaces in aqueous solution.

  14. Thin film polycrystalline silicon: Promise and problems in displays and solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fonash, S.J. [Pennsylvania State Univ., University Park, PA (United States)

    1995-08-01

    Thin film polycrystalline Si (poly-Si) with its carrier mobilities, potentially good stability, low intragrain defect density, compatibility with silicon processing, and ease of doping activation is an interesting material for {open_quotes}macroelectronics{close_quotes} applications such as TFTs for displays and solar cells. The poly-Si films needed for these applications can be ultra-thin-in the 500{Angstrom} to 1000{Angstrom} thickness range for flat panel display TFTs and in the 4{mu}m to 10{mu}m thickness range for solar cells. Because the films needed for these microelectronics applications can be so thin, an effective approach to producing the films is that of crystallizing a-Si precursor material. Unlike cast materials, poly-Si films made this way can be produced using low temperature processing. Unlike deposited poly-Si films, these crystallized poly-Si films can have grain widths that are much larger than the film thickness and almost atomically smooth surfaces. This thin film poly-Si crystallized from a-Si precursor films, and its promise and problems for TFTs and solar cells, is the focus of this discussion.

  15. Thin film reactions on silicon surfaces and the quality of metal-semiconductor interfaces

    Science.gov (United States)

    Morgen, P.; Jørgensen, B.; Rasmussen, J.; Labunov, V. A.; Nylandsted Larsen, A.

    1986-03-01

    We have studied the formation of thin silicide layers on silicon surfaces by thermal treatments of thin evaporated metal films. Examples are given for Pt/Si, V/Si, and Ti/Si. The treatments studied were vacuum furnace annealing, electron-beam annealing, and xenon lamp illumination. The compositional depth profiles of the resulting structures were analyzed with RBS and Auger/ sputter profiling. Impurities, oxygen and carbon, are present in Ti and V before annealing, and may also become incorporated during the treatment. Thus the quality of the annealing procedures depends strongly on the thermodynamics of the ternary or quarternary mixtures of metal, silicon and impurities. Best results, in terms of silicide homogeneity, purity, and interface sharpness (epitaxy) were obtained for PtSi, xenon lamp annealed for very short times. Also for V and Ti, rapid thermal annealing was found to produce much better structures than vacuum furnace annealing. The influence of oxygen in the systems studied is discussed in terms of ternary phase diagrams.

  16. Amorphous silicon thin-film solar cells on glass fiber textiles

    Energy Technology Data Exchange (ETDEWEB)

    Plentz, Jonathan, E-mail: jonathan.plentz@leibniz-ipht.de; Andrä, Gudrun; Pliewischkies, Torsten; Brückner, Uwe; Eisenhawer, Björn; Falk, Fritz

    2016-02-15

    Graphical abstract: - Highlights: • Amorphous silicon solar cells on textile glass fiber fabrics are demonstrated. • Open circuit voltages of 883 mV show shunt-free contacting on non-planar fabrics. • Short-circuit current densities of 3.7 mA/cm{sup 2} are limited by transmission losses. • Fill factors of 43.1% and pseudo fill factors of 70.2% show high series resistance. • Efficiencies of 1.4% and pseudo efficiencies of 2.1% realized on textile fabrics. - Abstract: In this contribution, amorphous silicon thin-film solar cells on textile glass fiber fabrics for smart textiles are prepared and the photovoltaic performance is characterized. These solar cells on fabrics delivered open circuit voltages up to 883 mV. This shows that shunt-free contacting of the solar cells was successful, even in case of non-planar fabrics. The short-circuit current densities up to 3.7 mA/cm{sup 2} are limited by transmission losses in a 10 nm thin titanium layer, which was used as a semi-transparent contact. The low conductivity of this layer limits the fill factor to 43.1%. Pseudo fill factors, neglecting the series resistance, up to 70.2% were measured. Efficiencies up to 1.4% and pseudo efficiencies up to 2.1% were realized on textile fabrics. A transparent conductive oxide could further improve the efficiency to above 5%.

  17. Growth of nanocrystalline silicon carbide thin films by plasma enhanced chemical vapor deposition

    CERN Document Server

    Lee, S W; Moon, J Y; Ahn, S S; Kim, H Y; Shin, D H

    1999-01-01

    Nanocrystalline silicon carbide thin films have been deposited by plasma enhanced chemical vapor deposition (PECVD) using SiH sub 4 , CH sub 4 , and H sub 2 gases. The effects of gas mixing ratio (CH sub 4 /SiH sub 4), deposition temperature, and RF power on the film properties have been studied. The growth rate, refractive index, and the optical energy gap depends critically on the growth conditions. The dependence of the growth rate on the gas flow ratio is quite different from the results obtained for the growth using C sub 2 H sub 2 gas instead of CH sub 4. As the deposition temperature is increased from 300 .deg. C to 600 .deg. C, hydrogen and carbon content in the film decreases and as a result the optical gap decreases. At the deposition temperature of 600 .deg. C and RF power of 150 W, the film structure si nanocrystalline, As the result of the nanocrystallization the dark conductivity is greatly improved. The nanocrystalline silicon carbide thin films may be used for large area optoelectronic devices...

  18. Growth of (100)-highly textured BaBiO{sub 3} thin films on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ferreyra, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); Departamento de Física, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1, Ciudad Universitaria, Buenos Aires (Argentina); Marchini, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Departamento de Química Inorgánica, Analítica y Química-Física, INQUIMAE-CONICET, Facultad Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, Buenos Aires (Argentina); Granell, P. [INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Golmar, F. [Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); INTI, CMNB, Av. Gral Paz 5445, B1650KNA San Martín, Buenos Aires (Argentina); Escuela de Ciencia y Tecnología, UNSAM, Campus Miguelete, 1650 San Martín, Buenos Aires (Argentina); Albornoz, C. [GIyA and INN, CNEA, Av. Gral Paz 1499, 1650 San Martín, Buenos Aires (Argentina); and others

    2016-08-01

    We report on the growth and characterization of non-epitaxial but (100)-highly textured BaBiO{sub 3} thin films on silicon substrates. We have found the deposition conditions that optimize the texture, and show that the textured growth is favoured by the formation of a BaO layer at the first growth stages. X-ray diffraction Φ-scans, together with the observation that the same textured growth is found on films grown on Pt and SiO{sub 2} buffered Si, demonstrate the absence of epitaxy. Finally, we have shown that our (100)-oriented BaBiO{sub 3} films can be used as suitable buffers for the growth of textured heterostructures on silicon, which could facilitate the integration of potential devices with standard electronics. - Highlights: • BaBiO{sub 3} thin films were grown on Si substrates and characterized. • Films prepared using optimized conditions are highly textured in the (100) direction. • The absence of in-plane texture was demonstrated by X-ray diffraction. • Our films are suitable buffers for the growth of (100)-textured oxide heterostructures.

  19. Large-area monocrystalline silicon thin films by annealing of macroporous arrays: Understanding and tackling defects in the material

    Science.gov (United States)

    Depauw, Valérie; Gordon, Ivan; Beaucarne, Guy; Poortmans, Jef; Mertens, Robert; Celis, Jean-Pierre

    2009-08-01

    A concept that could provide a thin monocrystalline-silicon absorber layer without resorting to the expensive step of epitaxy would be very appealing for reducing the cost of solar cells. The empty-space-in-silicon technique by which thin films of silicon can be formed by reorganization of regular arrays of cylindrical voids at high temperature may be such a concept if the high quality of the thin film could be ensured on centimeter-large areas. While previous works mainly investigated the influence of the porous array on the final structure, this work focuses on the practical aspects of the high-temperature step and its application to large areas. An insight into the defects that may form is given and the origin of these defects is discussed, providing recommendations on how to avoid them. Surface roughening, pitting, formation of holes, and silicon pillars could be attributed to the nonuniform reactions between Si, SiO2, and SiO. Hydrogen atmospheres are therefore preferred for reorganization of macroporous arrays. Argon atmospheres, however, may provide high-quality silicon thin films as well, possibly even more easily transferable, as long as annealing is performed in controlled, clean, and oxygen-free conditions. Our experiments on large areas also highlight the importance of kinetics, which had not been considered up to now and which will require further understanding to ensure a complete reorganization over any wafer area.

  20. Fabrication of Solid State Nanopore in Thin Silicon Membrane Using Low Cost Multistep Chemical Etching

    Directory of Open Access Journals (Sweden)

    Muhammad Shuja Khan

    2015-11-01

    Full Text Available Nanopore-based analysis is currently an area of great interest in many disciplines with the potential for exceptionally versatile applications in medicine. This work presents a novel step towards fabrication of a single solid-state nanopore (SSSN in a thin silicon membrane. Silicon nanopores are realized using multistep processes on both sides of n-type silicon-on-insulator (SOI <100> wafer with resistivity 1–4 Ω·cm. An electrochemical HF etch with low current density (0.47 mA/cm2 is employed to produce SSSN. Blue LED is considered to emit light in a narrow band region which facilitates the etching procedure in a unilateral direction. This helps in production of straight nanopores in n-type Si. Additionally, a variety of pore diameters are demonstrated using different HF concentrations. Atomic force microscopy is used to demonstrate the surface morphology of the fabricated pores in non-contact mode. Pore edges exhibit a pronounced rounded shape and can offer high stability to fluidic artificial lipid bilayer to study membrane proteins. Electrochemically-fabricated SSSN has excellent smoothness and potential applications in diagnostics and pharmaceutical research on transmembrane proteins and label free detection.

  1. Dual-side and three-dimensional microelectrode arrays fabricated from ultra-thin silicon substrates

    Science.gov (United States)

    Du, Jiangang; Roukes, Michael L.; Masmanidis, Sotiris C.

    2009-07-01

    A method for fabricating planar implantable microelectrode arrays was demonstrated using a process that relied on ultra-thin silicon substrates, which ranged in thickness from 25 to 50 µm. The challenge of handling these fragile materials was met via a temporary substrate support mechanism. In order to compensate for putative electrical shielding of extracellular neuronal fields, separately addressable electrode arrays were defined on each side of the silicon device. Deep reactive ion etching was employed to create sharp implantable shafts with lengths of up to 5 mm. The devices were flip-chip bonded onto printed circuit boards (PCBs) by means of an anisotropic conductive adhesive film. This scalable assembly technique enabled three-dimensional (3D) integration through formation of stacks of multiple silicon and PCB layers. Simulations and measurements of microelectrode noise appear to suggest that low impedance surfaces, which could be formed by electrodeposition of gold or other materials, are required to ensure an optimal signal-to-noise ratio as well a low level of interchannel crosstalk.

  2. Thermal annealing of thin PECVD silicon-oxide films for airgap-based optical filters

    Science.gov (United States)

    Ghaderi, M.; de Graaf, G.; Wolffenbuttel, R. F.

    2016-08-01

    This paper investigates the mechanical and optical properties of thin PECVD silicon-oxide layers for optical applications. The different deposition parameters in PECVD provide a promising tool to manipulate and control the film structure. Membranes for use in optical filters typically are of ~λ/4n thickness and should be slightly tensile for remaining flat, thus avoiding scattering. The effect of the thermal budget of the process on the mechanical characteristics of the deposited films was studied. Films with compressive stress ranging from  -100 to 0 MPa were deposited. Multiple thermal annealing cycles were applied to wafers and the in situ residual stress and ex situ optical properties were measured. The residual stress in the films was found to be highly temperature dependent. Annealing during the subsequent process steps results in tensile stress from 100 to 300 MPa in sub-micron thick PECVD silicon-oxide films. However, sub-100 nm thick PECVD silicon-oxide layers exhibit a lower dependence on the thermal annealing cycles, resulting in lower stress variations in films after the annealing. It is also shown that the coefficient of thermal expansion, hence the residual stress in layers, varies with the thickness. Finally, several free-standing membranes were fabricated and the results are compared.

  3. Design, fabrication and optical characterization of photonic crystal assisted thin film monocrystalline-silicon solar cells.

    Science.gov (United States)

    Meng, Xianqin; Depauw, Valérie; Gomard, Guillaume; El Daif, Ounsi; Trompoukis, Christos; Drouard, Emmanuel; Jamois, Cécile; Fave, Alain; Dross, Frédéric; Gordon, Ivan; Seassal, Christian

    2012-07-02

    In this paper, we present the integration of an absorbing photonic crystal within a monocrystalline silicon thin film photovoltaic stack fabricated without epitaxy. Finite difference time domain optical simulations are performed in order to design one- and two-dimensional photonic crystals to assist crystalline silicon solar cells. The simulations show that the 1D and 2D patterned solar cell stacks would have an increased integrated absorption in the crystalline silicon layer would increase of respectively 38% and 50%, when compared to a similar but unpatterned stack, in the whole wavelength range between 300 nm and 1100 nm. In order to fabricate such patterned stacks, we developed an effective set of processes based on laser holographic lithography, reactive ion etching and inductively coupled plasma etching. Optical measurements performed on the patterned stacks highlight the significant absorption increase achieved in the whole wavelength range of interest, as expected by simulation. Moreover, we show that with this design, the angle of incidence has almost no influence on the absorption for angles as high as around 60°.

  4. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    Science.gov (United States)

    Ghoneim, Mohamed T.; Fahad, Hossain M.; Hussain, Aftab M.; Rojas, Jhonathan P.; Torres Sevilla, Galo A.; Alfaraj, Nasir; Lizardo, Ernesto B.; Hussain, Muhammad M.

    2015-12-01

    In today's digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical "through silicon" micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  5. MOCVD ZnO/Screen Printed Ag Back Reflector for Flexible Thin Film Silicon Solar Cell Application

    OpenAIRE

    Amornrat Limmanee; Patipan Krudtad; Sasiwimon Songtrai; Suttinan Jaroensathainchok; Taweewat Krajangsang; Jaran Sritharathikhun; Kobsak Sriprapha

    2014-01-01

    We have prepared Ag back electrode by screen printing technique and developed MOCVD ZnO/screen printed Ag back reflector for flexible thin film silicon solar cell application. A discontinuity and poor contact interface between the MOCVD ZnO and screen printed Ag layers caused poor open circuit voltage (Voc) and low fill factor (FF); however, an insertion of a thin sputtered ZnO layer at the interface could solve this problem. The n type hydrogenated amorphous silicon (a-Si:H) film is preferab...

  6. Low temperature deposition of polycrystalline silicon thin films on a flexible polymer substrate by hot wire chemical vapor deposition

    Science.gov (United States)

    Lee, Sang-hoon; Jung, Jae-soo; Lee, Sung-soo; Lee, Sung-bo; Hwang, Nong-moon

    2016-11-01

    For the applications such as flexible displays and solar cells, the direct deposition of crystalline silicon films on a flexible polymer substrate has been a great issue. Here, we investigated the direct deposition of polycrystalline silicon films on a polyimide film at the substrate temperature of 200 °C. The low temperature deposition of crystalline silicon on a flexible substrate has been successfully made based on two ideas. One is that the Si-Cl-H system has a retrograde solubility of silicon in the gas phase near the substrate temperature. The other is the new concept of non-classical crystallization, where films grow by the building block of nanoparticles formed in the gas phase during hot-wire chemical vapor deposition (HWCVD). The total amount of precipitation of silicon nanoparticles decreased with increasing HCl concentration. By adding HCl, the amount and the size of silicon nanoparticles were reduced remarkably, which is related with the low temperature deposition of silicon films of highly crystalline fraction with a very thin amorphous incubation layer. The dark conductivity of the intrinsic film prepared at the flow rate ratio of RHCl=[HCl]/[SiH4]=3.61 was 1.84×10-6 Scm-1 at room temperature. The Hall mobility of the n-type silicon film prepared at RHCl=3.61 was 5.72 cm2 V-1s-1. These electrical properties of silicon films are high enough and could be used in flexible electric devices.

  7. Influence of intermediate layers on the surface condition of laser crystallized silicon thin films and solar cell performance

    Science.gov (United States)

    Höger, Ingmar; Himmerlich, Marcel; Gawlik, Annett; Brückner, Uwe; Krischok, Stefan; Andrä, Gudrun

    2016-01-01

    The intermediate layer (IL) between glass substrate and silicon plays a significant role in the optimization of multicrystalline liquid phase crystallized silicon thin film solar cells on glass. This study deals with the influence of the IL on the surface condition and the required chemical surface treatment of the crystallized silicon (mc-Si), which is of particular interest for a-Si:H heterojunction thin film solar cells. Two types of IL were investigated: sputtered silicon nitride (SiN) and a layer stack consisting of silicon nitride and silicon oxide (SiN/SiO). X-ray photoelectron spectroscopy measurements revealed the formation of silicon oxynitride (SiOxNy) or silicon oxide (SiO2) layers at the surface of the mc-Si after liquid phase crystallization on SiN or SiN/SiO, respectively. We propose that SiOxNy formation is governed by dissolving nitrogen from the SiN layer in the silicon melt, which segregates at the crystallization front during crystallization. This process is successfully hindered, when additional SiO layers are introduced into the IL. In order to achieve solar cell open circuit voltages above 500 mV, a removal of the formed SiOxNy top layer is required using sophisticated cleaning of the crystallized silicon prior to a-Si:H deposition. However, solar cells crystallized on SiN/SiO yield high open circuit voltage even when a simple wet chemical surface treatment is applied. The implementation of SiN/SiO intermediate layers facilitates the production of mesa type solar cells with open circuit voltages above 600 mV and a power conversion efficiency of 10%.

  8. Influence of intermediate layers on the surface condition of laser crystallized silicon thin films and solar cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Höger, Ingmar, E-mail: ingmar.hoeger@ipht-jena.de; Gawlik, Annett; Brückner, Uwe; Andrä, Gudrun [Leibniz-Institut für Photonische Technologien, PF 100239, 07702 Jena (Germany); Himmerlich, Marcel; Krischok, Stefan [Institut für Mikro-und Nanotechnologien, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau (Germany)

    2016-01-28

    The intermediate layer (IL) between glass substrate and silicon plays a significant role in the optimization of multicrystalline liquid phase crystallized silicon thin film solar cells on glass. This study deals with the influence of the IL on the surface condition and the required chemical surface treatment of the crystallized silicon (mc-Si), which is of particular interest for a-Si:H heterojunction thin film solar cells. Two types of IL were investigated: sputtered silicon nitride (SiN) and a layer stack consisting of silicon nitride and silicon oxide (SiN/SiO). X-ray photoelectron spectroscopy measurements revealed the formation of silicon oxynitride (SiO{sub x}N{sub y}) or silicon oxide (SiO{sub 2}) layers at the surface of the mc-Si after liquid phase crystallization on SiN or SiN/SiO, respectively. We propose that SiO{sub x}N{sub y} formation is governed by dissolving nitrogen from the SiN layer in the silicon melt, which segregates at the crystallization front during crystallization. This process is successfully hindered, when additional SiO layers are introduced into the IL. In order to achieve solar cell open circuit voltages above 500 mV, a removal of the formed SiO{sub x}N{sub y} top layer is required using sophisticated cleaning of the crystallized silicon prior to a-Si:H deposition. However, solar cells crystallized on SiN/SiO yield high open circuit voltage even when a simple wet chemical surface treatment is applied. The implementation of SiN/SiO intermediate layers facilitates the production of mesa type solar cells with open circuit voltages above 600 mV and a power conversion efficiency of 10%.

  9. Polycrystalline silicon thin-film solar cells with plasmonic-enhanced light-trapping.

    Science.gov (United States)

    Varlamov, Sergey; Rao, Jing; Soderstrom, Thomas

    2012-07-02

    One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach. The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles. To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 μm thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm(2), which can be increased up to 17-18 mA/cm(2) (~25% higher) after application of a simple diffuse back reflector made of a white paint. To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23°C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing

  10. Amorphous and microcrystalline silicon applied in very thin tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schicho, Sandra

    2011-07-28

    Thin-film solar cells are fabricated by low-cost production processes, and are therefore an alternative to conventionally used wafer solar cells based on crystalline silicon. Due to the different band gaps, tandem cells that consist of amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) single junction solar cells deposited on top of each other use the solar spectrum much more efficient than single junction solar cells. The silicon layers are usually deposited on TCO (Transparent Conductive Oxide)-coated glass and metal- or plastic foils. Compared to the CdTe and CIGS based thin-film technologies, silicon thin-film solar cells have the advantage that no limitation of raw material supply is expected and no toxic elements are used. Nevertheless, the production cost per Wattpeak is the decisive factor concerning competitiveness and can be reduced by, e.g., shorter deposition times or reduced material consumption. Both cost-reducing conceptions are simultaneously achieved by reducing the a-Si:H and {mu}c-Si:H absorber layer thicknesses in a tandem device. In the work on hand, the influence of an absorber layer thickness reduction up to 77% on the photovoltaic parameters of a-Si:H/{mu}c-Si:H tandem solar cells was investigated. An industry-oriented Radio Frequency Plasma-Enhanced Chemical Vapour Deposition (RF-PECVD) system was used to deposit the solar cells on glass substrates coated with randomly structured TCO layers. The thicknesses of top and bottom cell absorber layers were varied by adjusting the deposition time. Reduced layer thicknesses lead to lower absorption and, hence, to reduced short-circuit current densities which, however, are partially balanced by higher open-circuit voltages and fill factors. Furthermore, by using very thin amorphous top cells, the light-induced degradation decreases tremendously. Accordingly, a thickness reduction of 75% led to an efficiency loss of only 21 %. By adjusting the parameters for the deposition of a-Si:H top cells, a

  11. Light-trapping design of graphene transparent electrodes for efficient thin-film silicon solar cells.

    Science.gov (United States)

    Zhao, Yongxiang; Chen, Fei; Shen, Qiang; Zhang, Lianmeng

    2012-09-01

    In this paper, the performance of solar cells with graphene transparent electrodes is compared with cells using conventional indium tin oxide (ITO) electrodes, and it is demonstrated the optical absorption of solar cells with bare graphene structure is worse than that of bare ITO structure because of the higher refractive index of graphene. To enhance the light trapping of graphene-based thin-film solar cells, a simple two-layer SiO(2)/SiC structure is proposed as antireflection coatings deposited on top of graphene transparent electrodes, and the thickness of each layer is optimized by differential evolution in order to enhance the optical absorption of a-Si:H thin-film solar cells to the greatest degree. The optimization results demonstrate the optimal SiO(2)/SiC/graphene structure can obtain 37.30% enhancement with respect to bare ITO structure, which has obviously exceeded the light-trapping enhancement of 34.15% for the optimal SiO(2)/SiC/ITO structure. Therefore, with the aid of the light-trapping structure, the graphene films are a very promising indium-free transparent electrode substitute for the conventional ITO electrode for use in cost-efficient thin-film silicon solar cells.

  12. ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

    Directory of Open Access Journals (Sweden)

    Peter Pikna

    2014-10-01

    Full Text Available Thin film polycrystalline silicon (poly-Si solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ. Tested temperature of the sample (55°C – 110°C was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

  13. Crystalline silicon for thin film solar cells. Final report; Kristallines Silizium fuer Duennschichtsolarzellen. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, H.

    2001-07-01

    Thin film solar cells based on silicon are of great interest for cost-effective conversion of solar energy into electric power. In order to reach this goal, intensive research is still necessary, pointing, e.g., to a further enhancement of the conversion efficiency, an improvement of stability and a reduction of the production time. Aim of the project work was the achievement of knowledge on microcrystalline silicon and its application in thin film solar cells by means of a broad research and development program. Material research focused on growth processes of the microcrystalline material, the incorporation and stability of hydrogen, the electronic transport and defects. In particular the transition from amorphous to microcrystalline material which is obtained for the present deposition methods by minor variations of the deposition parameters as well as the enhancement of the deposition rate were intensively studies. Another focus of research aimed toward the development and improvement of zinc oxide films which are of central importance for this type of solar cells for the application as transparent contacts. A comprehensive understanding was achieved. The films were incorporated in thin film solar cells and with conversion efficiencies >8% for single cells (at relatively high deposition rate) and 10% (stable) for tandem cells with amorphous silicon, top values were achieved by international standards. The project achievements serve as a base for a further development of this type of solar cell and for the transfer of this technology to industry. (orig.) [German] Duennschichtsolarzellen auf der Basis von Silizium sind von grossem Interesse fuer eine kostenguenstige Umwandlung von Sonnenenergie in elektrischen Strom. Um dieses Ziel zu erreichen, ist jedoch noch intensive Forschung, u.a. zur weiteren Steigerung des Wirkungsgrades, zur Verbesserung der Stabilitaet und zur Verkuerzung des Produktionsprozesses erforderlich. Ziel der Projektarbeiten war, durch ein

  14. Silicon nitride gradient film as the underlayer of ultra-thin tetrahedral amorphous carbon overcoat for magnetic recording slider

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guigen, E-mail: wanggghit@yahoo.com [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Kuang Xuping; Zhang Huayu; Zhu Can [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Han Jiecai [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Zuo Hongbo [Center for Composite Materials, Harbin Institute of Technology, Harbin 150080 (China); Ma Hongtao [SAE Technologies Development (Dongguan) Co., Ltd., Dongguan 523087 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The ultra-thin carbon films with different silicon nitride (Si-N) film underlayers were prepared. Black-Right-Pointing-Pointer It highlighted the influences of Si-N underlayers. Black-Right-Pointing-Pointer The carbon films with Si-N underlayers obtained by nitriding especially at the substrate bias of -150 V, can exhibit better corrosion protection properties - Abstract: There are higher technical requirements for protection overcoat of magnetic recording slider used in high-density storage fields for the future. In this study, silicon nitride (Si-N) composition-gradient films were firstly prepared by nitriding of silicon thin films pre-sputtered on silicon wafers and magnetic recording sliders, using microwave electron cyclotron resonance plasma source. The ultra-thin tetrahedral amorphous carbon films were then deposited on the Si-N films by filtered cathodic vacuum arc method. Compared with amorphous carbon overcoats with conventional silicon underlayers, the overcoats with Si-N underlayers obtained by plasma nitriding especially at the substrate bias of -150 V, can provide better corrosion protection for high-density magnetic recording sliders.

  15. Substrate bias effect on crystallinity of polycrystalline silicon thin films prepared by pulsed ion-beam evaporation method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Fazlat; Gunji, Michiharu; Yang, Sung-Chae; Suzuki, Tsuneo; Suematsu, Hisayuki; Jiang, Weihua; Yatsui, Kiyoshi [Nagaoka Univ. of Technology, Extreme Energy-Density Research Inst., Nagaoka, Niigata (Japan)

    2002-06-01

    The deposition of polycrystalline silicon thin films has been tried by a pulsed ion-beam evaporation method, where high crystallinity and deposition rate have been achieved without heating the substrate. The crystallinity and the deposition rate were improved by applying bias voltage to the substrate, where instantaneous substrate heating might have occurred by ion-bombardment. (author)

  16. Gas phase considerations for the deposition of thin film silicon solar cells by VHF-PECVD at low substrate temperatures

    NARCIS (Netherlands)

    Rath, J.K.; Verkerk, A.D.; Brinza, M.; Schropp, R.E.I.; Goedheer, W.J.; Krzhizhanovskaya, V.V.; Gorbachev, Y.E.; Orlov, K.E.; Khilkevitch, E.M.; Smirnov, A.S.

    2008-01-01

    Fabrication of thin film silicon solar cells on cheap plastics or paper-like substrate requires deposition process at very low substrate temperature, typically ≤ 100 °C. In a chemical vapor deposition process, low growth temperatures lead to materials with low density, high porosity, high disorder a

  17. Ferroelectric properties of epitaxial Pb(Zr, Ti)O3 thin films on silicon by control of crystal orientation

    NARCIS (Netherlands)

    Dekkers, Jan M.; Nguyen, Duc Minh; Steenwelle, Ruud Johannes Antonius; te Riele, P.M.; Blank, David H.A.; Rijnders, Augustinus J.H.M.

    2009-01-01

    Crystalline Pb(Zr,Ti)O3 (PZT) thin films between metallic-oxide SrRuO3 (SRO) electrodes were prepared using pulsed laser deposition on CeO2/yttria-stabilized zirconia buffered silicon (001) substrates. Different deposition conditions for the initial layers of the bottom SRO electrode result in an or

  18. Gas phase considerations for the deposition of thin film silicon solar cells by VHF-PECVD at low substrate temperatures

    NARCIS (Netherlands)

    Rath, J.K.; Verkerk, A.D.; Brinza, M.; Schropp, R.E.I.; Goedheer, W.J.; Krzhizhanovskaya, V.V.; Gorbachev, Y.E.; Orlov, K.E.; Khilkevitch, E.M.; Smirnov, A.S.

    2008-01-01

    Fabrication of thin film silicon solar cells on cheap plastics or paper-like substrate requires deposition process at very low substrate temperature, typically ≤ 100 °C. In a chemical vapor deposition process, low growth temperatures lead to materials with low density, high porosity, high disorder

  19. A novel structured plastic substrate for light confinement in thin film silicon solar cells by a geometric optical effect

    NARCIS (Netherlands)

    Sonneveld, Piet; Hamers, E.A.G.; Rijn, C.J.M. van; Baggerman, J.; Holterman, H.J.; Swinkels, Gert-Jan; Schropp, R.E.I.; Rath, J.K.; Jong, M.M. de

    2012-01-01

    We present a novel method to achieve light trapping in thin film silicon solar cells. Unlike the commonly used surface textures, such as Asahi U-type TCO, that rely on light scattering phenomena, we employ embossed periodically arranged micro-pyramidal structures with feature sizes much larger than

  20. A novel structured plastic substrate for light confinement in thin film silicon solar cells by a geometric optical effect

    NARCIS (Netherlands)

    de Jong, M.M.; Rath, J.K.; Schropp, R.E.I.; Sonneveld, P.J.; Swinkels, G.L.A.M.; Holterman, H.J.; Baggerman, J.; van Rijn, C.J.M.; Hamers, E.A.G.

    2011-01-01

    We present a novel method to achieve light trapping in thin film silicon solar cells. Unlike the commonly used surface textures, such as Asahi U-type TCO, that rely on light scattering phenomena, we employ embossed periodically arranged micro-pyramidal structures with feature sizes much larger than

  1. Unravelling a simple method for the low temperature synthesis of silicon nanocrystals and monolithic nanocrystalline thin films

    Science.gov (United States)

    Kim, Ka-Hyun; Johnson, Erik V.; Kazanskii, Andrey G.; Khenkin, Mark V.; Roca I Cabarrocas, Pere

    2017-01-01

    In this work, we present new results on the plasma processing and structure of hydrogenated polymorphous silicon (pm-Si:H) thin films. pm-Si:H thin films consist of a low volume fraction of silicon nanocrystals embedded in a silicon matrix with medium range order, and they possess this morphology as a significant contribution to their growth comes from the impact on the substrate of silicon clusters and nanocrystals synthesized in the plasma. Quadrupole mass spectrometry, ion flux measurements, and material characterization by transmission electron microscopy (TEM) and atomic force microscopy all provide insight on the contribution to the growth by silicon nanocrystals during PECVD deposition. In particular, cross-section TEM measurements show for the first time that the silicon nanocrystals are uniformly distributed across the thickness of the pm-Si:H film. Moreover, parametric studies indicate that the best pm-Si:H material is obtained at the conditions after the transition between a pristine plasma and one containing nanocrystals, namely a total gas pressure around 2 Torr and a silane to hydrogen ratio between 0.05 to 0.1. From a practical point of view these conditions also correspond to the highest deposition rate achievable for a given RF power and silane flow rate.

  2. Unravelling a simple method for the low temperature synthesis of silicon nanocrystals and monolithic nanocrystalline thin films

    Science.gov (United States)

    Kim, Ka-Hyun; Johnson, Erik V.; Kazanskii, Andrey G.; Khenkin, Mark V.; Roca i Cabarrocas, Pere

    2017-01-01

    In this work, we present new results on the plasma processing and structure of hydrogenated polymorphous silicon (pm-Si:H) thin films. pm-Si:H thin films consist of a low volume fraction of silicon nanocrystals embedded in a silicon matrix with medium range order, and they possess this morphology as a significant contribution to their growth comes from the impact on the substrate of silicon clusters and nanocrystals synthesized in the plasma. Quadrupole mass spectrometry, ion flux measurements, and material characterization by transmission electron microscopy (TEM) and atomic force microscopy all provide insight on the contribution to the growth by silicon nanocrystals during PECVD deposition. In particular, cross-section TEM measurements show for the first time that the silicon nanocrystals are uniformly distributed across the thickness of the pm-Si:H film. Moreover, parametric studies indicate that the best pm-Si:H material is obtained at the conditions after the transition between a pristine plasma and one containing nanocrystals, namely a total gas pressure around 2 Torr and a silane to hydrogen ratio between 0.05 to 0.1. From a practical point of view these conditions also correspond to the highest deposition rate achievable for a given RF power and silane flow rate. PMID:28091562

  3. Effect of argon flow on promoting boron doping for in-situ grown silicon nitride thin films containing silicon quantum dots

    Science.gov (United States)

    Liu, Jia; Liu, Bin; Zhang, Xisheng; Guo, Xiaojia; (Frank Liu, Shengzhong

    2017-07-01

    Boron-doped silicon nitride thin films (SiNx) containing silicon quantum dots (Si QD) were prepared in situ by plasma enhanced chemical vapor deposition. With the aim of optimizing the performance of thin films, the mixed gas including argon and hydrogen was applied as dilution. The effects of Ar flow on the structural, electrical and optical properties of B-doped SiNx thin films were systemically studied through various characterizations. By tuning the Ar flow, the properties, such as QD size, crystallinity and optical band gap, can be effectively controlled. The B-doping efficiency in thin films was proved to be promoted by introducing moderate Ar flow. The maximum values of dark conductivity (1.52 S cm-1) and carrier concentration (2.41 × 1019 cm-3) were obtained for the B-doped SiNx thin films at the Ar flow of 200 sccm. Furthermore, the mechanism on the promotion in B-doping was illustrated in detail in this paper.

  4. Hot-wire chemical vapor deposition prepared aluminum doped p-type microcrystalline silicon carbide window layers for thin film silicon solar cells

    Science.gov (United States)

    Chen, Tao; Köhler, Florian; Heidt, Anna; Carius, Reinhard; Finger, Friedhelm

    2014-01-01

    Al-doped p-type microcrystalline silicon carbide (µc-SiC:H) thin films were deposited by hot-wire chemical vapor deposition at substrate temperatures below 400 °C. Monomethylsilane (MMS) highly diluted in hydrogen was used as the SiC source in favor of SiC deposition in a stoichiometric form. Aluminum (Al) introduced from trimethylaluminum (TMAl) was used as the p-type dopant. The material property of Al-doped p-type µc-SiC:H thin films deposited with different deposition pressure and filament temperature was investigated in this work. Such µc-SiC:H material is of mainly cubic (3C) SiC polytype. For certain conditions, like high deposition pressure and high filament temperature, additional hexagonal phase and/or stacking faults can be observed. P-type µc-SiC:H thin films with optical band gap E04 ranging from 2.0 to 2.8 eV and dark conductivity ranging from 10-5 to 0.1 S/cm can be prepared. Such transparent and conductive p-type µc-SiC:H thin films were applied in thin film silicon solar cells as the window layer, resulting in an improved quantum efficiency at wavelengths below 480 nm.

  5. Mechanical measurements on lithium phosphorous oxynitride coated silicon thin film electrodes for lithium-ion batteries during lithiation and delithiation

    Science.gov (United States)

    Al-Obeidi, Ahmed; Kramer, Dominik; Boles, Steven T.; Mönig, Reiner; Thompson, Carl V.

    2016-08-01

    The development of large stresses during lithiation and delithiation drives mechanical and chemical degradation processes (cracking and electrolyte decomposition) in thin film silicon anodes that complicate the study of normal electrochemical and mechanical processes. To reduce these effects, lithium phosphorous oxynitride (LiPON) coatings were applied to silicon thin film electrodes. Applying a LiPON coating has two purposes. First, the coating acts as a stable artificial solid electrolyte interphase. Second, it limits mechanical degradation by retaining the electrode's planar morphology during cycling. The development of stress in LiPON-coated electrodes was monitored using substrate curvature measurements. LiPON-coated electrodes displayed highly reproducible cycle-to-cycle behavior, unlike uncoated electrodes which had poorer coulombic efficiency and exhibited a continual loss in stress magnitude with continued cycling due to film fracture. The improved mechanical stability of the coated silicon electrodes allowed for a better investigation of rate effects and variations of mechanical properties during electrochemical cycling.

  6. Experimental investigation of nucleate boiling and thin-film evaporation on enhanced silicon surfaces

    Science.gov (United States)

    Malla, Shailesh

    The present work consists of two major studies. The first study investigates the effects of surface energy or wettability on nucleate pool boiling and the second study investigates the thin-film evaporative cooling for near junction thermal management. For the first study, effects of surface energy or wettability on critical heat flux (CHF) and boiling heat transfer (BHT) of smooth heated surfaces was studied in saturated pool boiling of water at 1 atm. For this purpose hydrophilic and hydrophobic surfaces were created on one side of 1cm x 1cm double-side polished silicon substrates. A resistive heating layer was applied on the opposite side of each substrate. The surface energies of the created surfaces were characterized by measuring the static contact angles of water sessile drops. To provide a wide range of surface energies, surfaces were made of Teflon (hydrophobic), bare silicon (hydrophilic) and aluminum oxide (most hydrophilic). The measured contact angles on these surfaces were ˜108, ˜57 and ˜13 degrees respectively. The results of pool boiling tests on these surfaces clearly illustrate the connection between surface energy and CHF. CHF was shown to linearly decrease with contact angle increase, from ˜125 W/cm2 on aluminum oxide (most hydrophilic) to nearly one tenth of this value on Teflon (hydrophobic). The most hydrophilic surface also produced increasingly better BHT than plain silicon and Teflon as heat flux increased. However, below ˜5 W/cm2 the hydrophobic surface demonstrated better heat transfer due to earlier onset of nucleate boiling, reducing surface superheats by up to ˜5 degrees relative to the other two surfaces. Above ˜5 W/cm2 the BHT of the hydrophobic surface rapidly deteriorated as superheat increased towards the value at CHF. To further understand the effect of surface energy on pool boiling performance, the growth and departure of bubbles from single nucleating sites on each surface were analyzed from high-speed video recordings

  7. Breakdown voltage model and structure realization of a thin silicon layer with linear variable doping on a silicon on insulator high voltage device with multiple step field plates

    Institute of Scientific and Technical Information of China (English)

    Qiao Ming; Zhuang Xiang; Wu Li-Juan; Zhang Wen-Tong; Wen Heng-Juan; Zhang Bo; Li Zhao-Ji

    2012-01-01

    Based on the theoretical and experimental investigation of a thin silicon layer (TSL) with linear variable doping (LVD) and further research on the TSL LVD with a multiple step field plate (MSFP),a breakdown voltage (BV) model is proposed and experimentally verified in this paper.With the two-dimensional Poisson equation of the silicon on insulator (SOI) device,the lateral electric field in drift region of the thin silicon layer is assumed to be constant.For the SOI device with LVD in the thin silicon layer,the dependence of the BV on impurity concentration under the drain is investigated by an enhanced dielectric layer field (ENDIF),from which the reduced surface field (RESURF) condition is deduced.The drain in the centre of the device has a good self-isolation effect but the problem of the high voltage interconnection (HVI) line will become serious.The two step field plates including the source field plate and gate field plate can be adopted to shield the HVI adverse effect on the device.Based on this model,the TSL LVD SOI n-channel lateral double-diffused MOSFET (nLDMOS) with MSFP is realized.The experimental breakdown voltage (BV) and specific on-resistance (Ron,sp) of the TSL LVD SOI device are 694 V and 21.3 Ω.mm2 with a drift region length of 60 μm,buried oxide layer of 3 μm,and silicon layer of 0.15 μm,respectively.

  8. Deposition and characterization of silicon thin-films by aluminum-induced crystallization

    Science.gov (United States)

    Ebil, Ozgenc

    Polycrystalline silicon (poly-Si) as a thin-film solar cell material could have major advantages compared to non-silicon thin-film technologies. In theory, thin-film poly-Si may retain the performance and stability of c-Si while taking advantage of established manufacturing techniques. However, poly-Si films deposited onto foreign substrates at low temperatures typically have an average grain size of 10--50 nm. Such a grain structure presents a potential problem for device performance since it introduces an excessive number of grain boundaries which, if left unpassivated, lead to poor solar cell properties. Therefore, for optimum device performance, the grain size of the poly-Si film should be at least comparable to the thickness of the films. For this project, the objectives were the deposition of poly-Si thin-films with 2--5 mum grain size on glass substrates using in-situ and conventional aluminum-induced crystallization (AIC) and the development of a model for AIC process. In-situ AIC experiments were performed using Hot-Wire Chemical Vapor Deposition (HWCVD) both above and below the eutectic temperature (577°C) of Si-Al binary system. Conventional AIC experiments were performed using a-Si layers deposited on aluminum coated glass substrates by Electron-beam deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD) and HWCVD. Continuous poly-Si films with an average grain size of 10 mum on glass substrates were achieved by both in-situ and conventional aluminum-induced crystallization of Si below eutectic temperature. The grain size was determined by three factors; the grain structure of Al layer, the nature of the interfacial oxide, and crystallization temperature. The interface oxide was found to be crucial for AIC process but not necessary for crystallization itself. The characterization of interfacial oxide layer formed on Al films revealed a bilayer structure containing Al2O3 and Al(OH)3 . The effective activation energy for AIC process was determined

  9. The stability of tin silicon oxide thin-film transistors with different annealing temperatures

    Science.gov (United States)

    Yang, Jianwen; Fu, Ruofan; Han, Yanbing; Meng, Ting; Zhang, Qun

    2016-07-01

    The influence of annealing temperature on the electrical properties of tin silicon oxide (TSO) thin-film transistors (TFTs) and the corresponding bias stress stability have been investigated. With increasing annealing temperature, the TSO films present a structure which is closer to crystallization, and it is conducive to the improvement of the mobility of TSO TFTs. Meanwhile, the positive bias stress (PBS) stability of TSO TFTs is ameliorated due to the decreasing traps at the interface of dielectric layer and channel layer. The threshold voltage shifts in opposite direction after being stressed under negative bias stress (NBS), which is due to the competition between electrons captured by defects related to oxygen vacancies in the channel layer and water molecule adsorption on the back channel.

  10. A thin silicon thermoelectric nanowire characterization platform (TNCP) equipped with nanoporous electrodes for electrical contact formation

    Science.gov (United States)

    Hoda Moosavi, S.; Kroener, Michael; Frei, Maxi; Frick, Fabian; Kerzenmacher, Sven; Woias, Peter

    2016-10-01

    We report on the fabrication of a silicon platform for the thermoelectric and structural characterization of single nanowires, equipped with nanoporous electrodes. Controlled wafer thinning to a thickness of 160 μm results in platform chips, which can be inserted into Transmission Electron Microscopes (TEM) for the nanowire's structural composition analysis. Our fabrication approach comprises the Bosch process (ICP), and "dicing before grinding" techniques to achieve this small thickness. To study the idea of developing a “plug-and-measure” platform, we have developed a novel approach for selfadhesion between a contact electrode and a nanowire by nanoporous electrodes. Due to the increased surface-to-volume ratio and increased van-der-Walls forces nanowires stick firmly to the electrodes for a good thermal and electrical connection. This innovative technique does also avoids, in best case, separate steps for contact formation.

  11. Dual interface gratings design for absorption enhancement in thin crystalline silicon solar cells

    Science.gov (United States)

    Zhang, Jinqiannan; Yu, Zhongyuan; Liu, Yumin; Chai, Hongyu; Hao, Jing; Ye, Han

    2017-09-01

    We numerically study and analyze the light absorption enhancement in thin crystalline silicon solar cell with dual interface gratings. The structure combines the front dielectric nanowalls and the sinusoidal plasmonic grating at back reflector. We show that having specific interfaces with well-chosen period, fill factor and height can allow more efficient dielectric and plasmonic modes coupling into active layer and can improve the solar cell performance. For 1 μm active layer case, the optimal result for the proposed structure achieves short-circuit current of 23.6 mA/cm2, which performs over 50% better than flat solar cell structure, the short-circuit current of which is 15.5 mA/cm2. In addition, the active layer thickness and angular analysis show that the proposed structure maintains its advantage over flat structure.

  12. Thin film silicon solar cells: advanced processing and characterization - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ballif, Ch.

    2008-04-15

    This final report elaborated for the Swiss Federal Office of Energy (SFOE) takes a look at the results of a project carried out at the photovoltaics laboratory at the University of Neuchatel in Switzerland. The project aimed to demonstrate the production of high-efficiency thin-film silicon devices on flexible substrates using low cost processes. New ways of improving processing and characterisation are examined. The process and manufacturing know-how necessary to provide support for industrial partners within the framework of further projects is discussed. The authors state that the efficiency of most devices was significantly improved, both on glass substrates and on flexible plastic foils. The process reproducibility was also improved and the interactions between the different layers in the device are now said to be better understood. The report presents the results obtained and discusses substrate materials, transparent conductors, defect analyses and new characterisation tools. Finally, the laboratory infrastructure is described.

  13. Aluminum–Titanium Alloy Back Contact Reducing Production Cost of Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Hsin-Yu Wu

    2016-11-01

    Full Text Available In this study, metal films are fabricated by using an in-line reactive direct current magnetron sputtering system. The aluminum–titanium (AlTi back contacts are prepared by changing the pressure from 10 mTorr to 25 mTorr. The optical, electrical and structural properties of the metal back contacts are investigated. The solar cells with the AlTi had lower contact resistance than those with the silver (Ag back contact, resulting in a higher fill factor. The AlTi contact can achieve a solar cell conversion efficiency as high as that obtained from the Ag contact. These findings encourage the potential adoption of AlTi films as an alternative back contact to silver for silicon thin-film solar cells.

  14. Analysis of the laser ablation processes for thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Stefan; Schoepe, Gunnar; Zahren, Christoph [Research Centre Juelich (Germany). Institute of Energy Research 5 - Photovoltaic; Stiebig, Helmut [Malibu GmbH and Co. KG, Bielefeld (Germany)

    2008-09-15

    A detailed analysis of the monolithical series connection of thin-film silicon modules with ZnO/Ag back contact is presented. In this study, pulsed lasers with wavelengths of 1064 nm and 532 nm were used. The influence of various laser parameters like laser power, pulse overlap, etc., on the different patterning steps is discussed. The focus of this study was on the back contact patterning process. Here (i) the flake formation process during the ablation and (ii) the influence of a NIR-laser source as an alternative approach to the green laser were investigated in detail. The latter would reduce system costs if only one NIR-laser source could be used for all patterning steps. (orig.)

  15. Research on the optimum hydrogenated silicon thin films for application in solar cells

    Institute of Scientific and Technical Information of China (English)

    Lei Qing-Song; Wu Zhi-Meng; Geng Xin-Hua; Zhao Ying; Sun Jian; Xi Jian-Ping

    2006-01-01

    Hydrogenated silicon (Si:H) thin films for application in solar cells were deposited by using very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at a substrate temperature of about 170 ℃. The electrical,structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage (Ⅰ - Ⅴ) characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.

  16. Design and operation of grid-interactive thin-film silicon PV systems

    Science.gov (United States)

    Marion, Bill; Atmaram, Gobind; Lashway, Clin; Strachan, John W.

    Results are described from the operation of 11 thin-film amorphous silicon photovoltaic systems at three test facilities: the Florida Solar Energy Center, the New Mexico Solar Energy Institute, and Sandia National Laboratories. Commercially available modules from four US manufacturers are used in these systems, with array sizes from 133 to 750 W peak. Measured array efficiencies are from 3.1 to 4.8 percent. Except for one manufacturer, array peak power is in agreement with the calculated design ratings. For certain grid-connected systems, nonoptimal operation exists because the array peak power voltage is below the lower voltage limit of the power conditioning system. Reliability problems are found in two manufacturers' modules when shorts to ground and terminal corrosion occur. Array leakage current data are presented.

  17. Abnormal Crystallization of Silicon Thin Films Deposited by ICP-CVD

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; YIN Min; WANG Jin-Xiao; HE De-Yan

    2005-01-01

    @@ Silicon thin films are deposited by inductively coupled plasma chemical vapour deposition (ICP-CVD) at a low temperature of 350℃ using a mixture of SiH4 and H2. The structures of the films are characterized by x-ray diffraction and Raman spectra. Under the optimum experimental conditions, we observe that the crystallinity of Si films becomes more excellent and the preferred orientation changes from (111) to (220) with the decreasing dilution of SiH4 in H2. Such an abnormal crystallization is tentatively interpreted in term of the high density,low electron temperature and spatial confinement of the plasma in the process of ICP-CVD.

  18. Leakage current mechanisms and their dependence on composition in silicon carbonitride thin films

    Science.gov (United States)

    Vijayakumar, Vishnuvardhanan; Varadarajan, Bhadri

    2015-04-01

    Electrical conduction in amorphous silicon carbonitride (a-SiCN:H) thin films deposited by plasma enhanced chemical vapor deposition (PECVD) is investigated for varying carbon to nitrogen ratios at room temperature. Films deposited with a lower carbon/nitrogen ratio showed two modes of electrical conduction; namely, Schottky emission mode below 2.3 MV cm-1 electric field and Poole-Frenkel mode from 2.3 MV cm-1 up to the breakdown field. Films with higher carbon/nitrogen ratios showed only Poole-Frenkel mode of conduction throughout the entire range of operation up to the breakdown field. The carbon rich films exhibited higher leakage currents attributed to its shallow defect energy levels leading to its higher Poole-Frenkel conductivity.

  19. Localized plasmonic losses at metal back contacts of thin-film silicon solar cells

    Science.gov (United States)

    Paetzold, U. W.; Hallermann, F.; Pieters, B. E.; Rau, U.; Carius, R.; von Plessen, G.

    2010-05-01

    Investigations of optical losses induced by localized plasmons in protrusions on silver back contacts of thin-film silicon solar cells are presented. The interaction of electromagnetic waves with nanoprotrusions on flat silver layers is simulated with a three-dimensional numerical solver of Maxwell's equations. Spatial absorption profiles and spatial electric field profiles as well as the absorption inside the protrusions are calculated. The results presented here show that the absorption of irradiated light at nanorough silver layers can be strongly enhanced by localized plasmonic resonances in Ag nanoprotrusions. Especially, localized plasmons in protrusions with a radius below 60 nm induce strong absorption, which can be several times the energy irradiated on the protrusion's cross section. The localized plasmonic resonances in single protrusions on Ag layers are observed to shift to longer wavelengths with increasing refractive index of the surrounding material. At wavelengths above 500 nm localized plasmonic resonances will increase the absorption of nanorough μc-Si:H/Ag interfaces. The localized plasmon induced absorption at nanorough ZnO/Ag interfaces lies at shorter wavelengths due to the lower refractive index of ZnO. For wavelengths above 500 nm, a high reflectivity of the silver back contacts is essential for the light-trapping of thin-film silicon solar cells. Localized-plasmon induced losses at silver back contacts can explain the experimentally observed increase of the solar cell performance when applying a ZnO/Ag back contact in comparison to a μc-Si:H/Ag back contact.

  20. High rate particle tracking and ultra-fast timing with a thin hybrid silicon pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Fiorini, M., E-mail: Massimiliano.Fiorini@cern.ch [CERN, CH-1211 Geneva 23 (Switzerland); Aglieri Rinella, G. [CERN, CH-1211 Geneva 23 (Switzerland); Carassiti, V. [INFN Sezione di Ferrara (Italy); Ceccucci, A. [CERN, CH-1211 Geneva 23 (Switzerland); Cortina Gil, E. [Université Catholique de Louvain, Louvain-la-Neuve (Belgium); Cotta Ramusino, A. [INFN Sezione di Ferrara (Italy); Dellacasa, G.; Garbolino, S.; Jarron, P. [INFN Sezione di Torino (Italy); Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A. [CERN, CH-1211 Geneva 23 (Switzerland); Martin, E. [Université Catholique de Louvain, Louvain-la-Neuve (Belgium); Mazza, G. [INFN Sezione di Torino (Italy); Morel, M.; Noy, M. [CERN, CH-1211 Geneva 23 (Switzerland); Nuessle, G. [Université Catholique de Louvain, Louvain-la-Neuve (Belgium); Perktold, L.; Petagna, P. [CERN, CH-1211 Geneva 23 (Switzerland); and others

    2013-08-01

    The Gigatracker (GTK) is a hybrid silicon pixel detector designed for the NA62 experiment at CERN. The beam spectrometer, made of three GTK stations, has to sustain high and non-uniform particle rate (∼1GHz in total) and measure momentum and angles of each beam track with a combined time resolution of 150 ps. In order to reduce multiple scattering and hadronic interactions of beam particles, the material budget of a single GTK station has been fixed to 0.5% X{sub 0}. The expected fluence for 100 days of running is 2×10{sup 14} 1 MeV n{sub eq}/cm{sup 2}, comparable to the one foreseen in the inner trackers of LHC detectors during 10 years of operation. To comply with these requirements, an efficient and very low-mass (<0.15%X{sub 0}) cooling system is being constructed, using a novel microchannel cooling silicon plate. Two complementary read-out architectures have been produced as small-scale prototypes: one is based on a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other makes use of a constant-fraction discriminator followed by an on-pixel TDC. The read-out ASICs are produced in 130 nm IBM CMOS technology and will be thinned down to 100μm or less. An overview of the Gigatracker detector system will be presented. Experimental results from laboratory and beam tests of prototype bump-bonded assemblies will be described as well. These results show a time resolution of about 170 ps for single hits from minimum ionizing particles, using 200μm thick silicon sensors.

  1. Characterization of thin irradiated epitaxial silicon sensors for the CMS phase II pixel upgrade

    CERN Document Server

    Centis Vignali, Matteo; Eichhorn, Thomas; Garutti, Erika; Junkes, Alexandra; Steinbrueck, Georg

    2015-01-01

    The high-luminosity upgrade fo the large hadron collider foreseen for 2023 resulted in the decision to replace the tracker system of the CMS experiment. The innermost layer of the new pixel detector will experience fluences in the order of $\\phi_{eq} \\approx 10^{16}$~cm$^{-2}$ and a dose of $\\approx 5$~MGy after an integrated luminosity of 3000~fb$^{-1}$. Several materials and designs are under investigation in order to build a detector that can withstand such high fluences. Thin planar silicon sensors are good canditates to achieve this goal since the degradation of the signal produced by traversing particles is less severe than for thicker devices. A study has been carried out in order to characterize highly irradiated planar epitaxial silicon sensors with an active thickness of 100~$\\mu$m. The investigation includes pad diodes and strip detectors irradiated up to a fluence of $\\phi_{eq} = 1.3 \\times 10^{16}$~cm$^{-2}$. The electrical properties of diodes have bee...

  2. Enhanced cooling in mono-crystalline ultra-thin silicon by embedded micro-air channels

    KAUST Repository

    Ghoneim, Mohamed T.

    2015-12-11

    In today’s digital world, complementary metal oxide semiconductor (CMOS) technology enabled scaling of bulk mono-crystalline silicon (100) based electronics has resulted in their higher performance but with increased dynamic and off-state power consumption. Such trade-off has caused excessive heat generation which eventually drains the charge of battery in portable devices. The traditional solution utilizing off-chip fans and heat sinks used for heat management make the whole system bulky and less mobile. Here we show, an enhanced cooling phenomenon in ultra-thin (>10 μm) mono-crystalline (100) silicon (detached from bulk substrate) by utilizing deterministic pattern of porous network of vertical “through silicon” micro-air channels that offer remarkable heat and weight management for ultra-mobile electronics, in a cost effective way with 20× reduction in substrate weight and a 12% lower maximum temperature at sustained loads. We also show the effectiveness of this event in functional MOS field effect transistors (MOSFETs) with high-κ/metal gate stacks.

  3. Loss analysis of back-contact back-junction thin-film monocrystalline silicon solar cells

    Science.gov (United States)

    Haase, F.; Eidelloth, S.; Horbelt, R.; Bothe, K.; Garralaga Rojas, E.; Brendel, R.

    2011-12-01

    We investigate power losses in back-contact back-junction monocrystalline thin-film silicon solar cells fabricated using the porous silicon layer transfer process. Our loss analysis combines two-dimensional finite element modeling and resistance network simulations. The input parameters of the finite element modeling are determined experimentally by measuring saturation current densities and sheet resistances on test samples prepared identically to the solar cells. Characteristic solar cell parameters such as short circuit current, open circuit voltage, fill factor, and efficiency of measured and network simulated current voltage characteristics investigated in this study match within an uncertainty of 5%. Free energy loss analysis serves as comparison of all losses in units of power per area at the maximum power point. The largest loss is bulk recombination due to a carrier lifetime of 2 μs in the epitaxial Si layer. Further significant losses result from recombination at the base contacts characterized by a diode saturation current density of 50 000 fA cm-2 as well as resistive losses due to lateral majority carrier current flows within the solar cell base and contact resistance losses.

  4. Scintillation light read-out by thin photodiodes in silicon wells

    CERN Document Server

    Allier, C P; Sarro, P M; Eijk, C W E

    2000-01-01

    Several applications of X-ray and gamma ray imaging detectors, e.g. in medical diagnostics, require millimeter or sub-millimeter spatial resolution and good energy resolution. In order to achieve such features we have proposed a new type of camera, which takes advantage of micromachining technology. It consists of an array of scintillator crystals encapsulated in silicon wells with photodiodes at the bottom. Several parameters of the photodiode need to be optimised: uniformity and efficiency of the light detection, gain, electronic noise and breakdown voltage. In order to evaluate these parameters we have processed 3x3 arrays of 1.8 mm sup 2 , approx 10 mu m thick photodiodes using (1 0 0) wafers etched in a KOH solution. Their optical response at 675 nm wavelength is comparable to that of a 500 mu m thick silicon PIN diode. Their low light detection efficiency is compensated by internal amplification. Several scintillator materials have been positioned in the wells on top of the thin photodiodes, i.e. a 200 ...

  5. Low-temperature silicon nitride for thin-film electronics on polyimide foil substrates

    Science.gov (United States)

    Gleskova, H.; Wagner, S.; Gašparík, V.; Kováč, P.

    2001-05-01

    We optimized silicon nitride (SiN x) layers, deposited by 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) at 150°C, to provide a high quality gate dielectric layer for the amorphous silicon thin film technology on polyimide foils. The layers were deposited from mixtures of silane, ammonia, and hydrogen. We varied the H 2 flow rate from 55 to 220 sccm and the rf power from 5 to 50 W, while the pressure was kept at 500 mTorr and the ratio of ammonia to silane flow at 10:1. The best film was obtained from the gas composition of SiH 4:NH 3:H 2=1:10:44 and the rf power of ˜20 W. This film grows at the rate of 1.5 Å/s, has a refractive index n=1.80, a dielectric constant ɛ=7.46, a dielectric breakdown field >3.4 MV/cm, a Si/N ratio of ˜0.67, and a hydrogen content of ˜2×10 22 cm -3, and etches in 10:1 buffered HF at a rate of 61 Å/s.

  6. Silicon-based thin films as bottom electrodes in chalcogenide nonvolatile memories

    Science.gov (United States)

    Lee, Seung-Yun; Yoon, Sung-Min; Choi, Kyu-Jeong; Lee, Nam-Yeal; Park, Young-Sam; Ryu, Sang-Ouk; Yu, Byoung-Gon; Kim, Sang-Hoon; Lee, Sang-Heung

    2007-10-01

    The effect of the electrical resistivity of a silicon-germanium (SiGe) thin film on the phase transition in a GeSbTe (GST) chalcogenide alloy and the manufacturing aspect of the fabrication process of a chalcogenide memory device employing the SiGe film as bottom electrodes were investigated. While p-type SiGe bottom electrodes were formed using in situ doping techniques, n-type ones could be made in a different manner where phosphorus atoms diffused from highly doped silicon underlayers to undoped SiGe films. The p-n heterojunction did not form between the p-type GST and n-type SiGe layers, and the semiconduction type of the SiGe alloys did not influence the memory device switching. It was confirmed that an optimum resistivity value existed for memory operation in spite of proportionality of Joule heating to electrical resistivity. The very high resistivity of the SiGe film had no effect on the reduction of reset current, which might result from the resistance decrease of the SiGe alloy at high temperatures.

  7. Silicon-based thin films as bottom electrodes in chalcogenide nonvolatile memories

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Yun [IT Convergence and Components Laboratory, Electronics and Telecommunications Research Institute (ETRI), Yuseong-gu, Daejeon 305-350 (Korea, Republic of)], E-mail: seungyun@etri.re.kr; Yoon, Sung-Min; Choi, Kyu-Jeong; Lee, Nam-Yeal; Park, Young-Sam; Ryu, Sang-Ouk; Yu, Byoung-Gon; Kim, Sang-Hoon; Lee, Sang-Heung [IT Convergence and Components Laboratory, Electronics and Telecommunications Research Institute (ETRI), Yuseong-gu, Daejeon 305-350 (Korea, Republic of)

    2007-10-31

    The effect of the electrical resistivity of a silicon-germanium (SiGe) thin film on the phase transition in a GeSbTe (GST) chalcogenide alloy and the manufacturing aspect of the fabrication process of a chalcogenide memory device employing the SiGe film as bottom electrodes were investigated. While p-type SiGe bottom electrodes were formed using in situ doping techniques, n-type ones could be made in a different manner where phosphorus atoms diffused from highly doped silicon underlayers to undoped SiGe films. The p-n heterojunction did not form between the p-type GST and n-type SiGe layers, and the semiconduction type of the SiGe alloys did not influence the memory device switching. It was confirmed that an optimum resistivity value existed for memory operation in spite of proportionality of Joule heating to electrical resistivity. The very high resistivity of the SiGe film had no effect on the reduction of reset current, which might result from the resistance decrease of the SiGe alloy at high temperatures.

  8. Density profile in thin films of polybutadiene on silicon oxide substrates: a TOF-NR study.

    Science.gov (United States)

    Hoppe, E Tilo; Sepe, Alessandro; Haese-Seiller, Martin; Moulin, Jean-François; Papadakis, Christine M

    2013-08-27

    We have investigated thin films from fully deuterated polybutadiene (PB-d6) on silicon substrates with the aim of detecting and characterizing a possible interphase in the polymer film near the substrate using time-of-flight neutron reflectometry (TOF-NR). As substrates, thermally oxidized silicon wafers were either used as such or they were coated with triethylethoxysilyl modified 1,2-PB prior to deposition of the PB-d6 film. TOF-NR reveals that, for both substrates, the scattering length density (SLD) of the PB films decreases near the solid interface. The reduction of SLD is converted to an excess fraction of free volume. To further verify the existence of the interphase in PB-d6, we attempt to model the TOF-NR curves with density profiles which do not feature an interphase. These density profiles do not describe the TOF-NR curves adequately. We conclude that, near the solid interface, an interphase having an SLD lower than the bulk of the film is present.

  9. Charge collection mapping of a novel ultra-thin silicon strip detector for hadrontherapy beam monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Bouterfa, Mohamed, E-mail: mohamed.bouterfa@uclouvain.be [ICTEAM Institute, Universite catholique de Louvain, Louvain-la-Neuve (Belgium); Alexandre, Geoffrey; Cortina Gil, Eduardo [IRPM Institute, Universite catholique de Louvain, Louvain-la-Neuve (Belgium); Flandre, Denis [ICTEAM Institute, Universite catholique de Louvain, Louvain-la-Neuve (Belgium)

    2013-12-21

    In precise hadrontherapy treatments, the particle beam must be monitored in real time without being degraded. Silicon strip detectors have been fabricated over an area as large as 4.5×4.5 cm{sup 2} with ultra low thickness of 20μm. These offer the following considerable advantages: significantly reduced beam scattering, higher radiation hardness which leads to improved detector lifetime, and much better collection efficiency. In a previous work, the novel sensor has been described and a global macroscopic dosimetry characterization has been proposed. This provides practical information for the detector daily use but not about the local microscopic knowledge of the sensor. This work therefore presents a micrometric-accuracy charge-collection characterization of this new generation of ultra-thin silicon strip detectors. This goal is reached thanks to a 1060 nm-wavelength micrometric-sized laser that can be positioned relatively to the sensor with a submicron precision for the three different axes. This study gives a much better knowledge of the inefficient areas of the sensor and allows therefore optimization for future designs.

  10. Charge collection mapping of a novel ultra-thin silicon strip detector for hadrontherapy beam monitoring

    Science.gov (United States)

    Bouterfa, Mohamed; Alexandre, Geoffrey; Cortina Gil, Eduardo; Flandre, Denis

    2013-12-01

    In precise hadrontherapy treatments, the particle beam must be monitored in real time without being degraded. Silicon strip detectors have been fabricated over an area as large as 4.5×4.5 cm2 with ultra low thickness of 20 μm. These offer the following considerable advantages: significantly reduced beam scattering, higher radiation hardness which leads to improved detector lifetime, and much better collection efficiency. In a previous work, the novel sensor has been described and a global macroscopic dosimetry characterization has been proposed. This provides practical information for the detector daily use but not about the local microscopic knowledge of the sensor. This work therefore presents a micrometric-accuracy charge-collection characterization of this new generation of ultra-thin silicon strip detectors. This goal is reached thanks to a 1060 nm-wavelength micrometric-sized laser that can be positioned relatively to the sensor with a submicron precision for the three different axes. This study gives a much better knowledge of the inefficient areas of the sensor and allows therefore optimization for future designs.

  11. Second-harmonic generation in periodically-poled thin film lithium niobate wafer-bonded on silicon

    Science.gov (United States)

    Rao, Ashutosh; Malinowski, Marcin; Honardoost, Amirmahdi; Talukder, Javed Rouf; Rabiei, Payam; Delfyett, Peter; Fathpour, Sasan

    2016-12-01

    Second-order optical nonlinear effects (second-harmonic and sum-frequency generation) are demonstrated in the telecommunication band by periodic poling of thin films of lithium niobate wafer-bonded on silicon substrates and rib-loaded with silicon nitride channels to attain ridge waveguide with cross-sections of ~ 2 {\\mu}m2. The compactness of the waveguides results in efficient second-order nonlinear devices. A nonlinear conversion of 8% is obtained with a pulsed input in 4 mm long waveguides. The choice of silicon substrate makes the platform potentially compatible with silicon photonics, and therefore may pave the path towards on-chip nonlinear and quantum-optic applications.

  12. Second-harmonic generation in periodically-poled thin film lithium niobate wafer-bonded on silicon

    CERN Document Server

    Rao, Ashutosh; Honardoost, Amirmahdi; Talukder, Javed Rouf; Rabiei, Rayam; Delfyett, Peter; Fathpour, Sasan

    2016-01-01

    Second-order optical nonlinear effects (second-harmonic and sum-frequency generation) are demonstrated in the telecommunication band by periodic poling of thin films of lithium niobate wafer-bonded on silicon substrates and rib-loaded with silicon nitride channels to attain ridge waveguide with cross-sections of ~ 2 {\\mu}m2. The compactness of the waveguides results in efficient second-order nonlinear devices. A nonlinear conversion of 8% is obtained with a pulsed input in 4 mm long waveguides. The choice of silicon substrate makes the platform potentially compatible with silicon photonics, and therefore may pave the path towards on-chip nonlinear and quantum-optic applications.

  13. Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures.

    Science.gov (United States)

    Hilali, Mohamed M; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S V

    2012-10-12

    In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent.

  14. Amorphous and microcrystalline silicon applied in very thin tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schicho, Sandra

    2011-07-28

    Thin-film solar cells are fabricated by low-cost production processes, and are therefore an alternative to conventionally used wafer solar cells based on crystalline silicon. Due to the different band gaps, tandem cells that consist of amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) single junction solar cells deposited on top of each other use the solar spectrum much more efficient than single junction solar cells. The silicon layers are usually deposited on TCO (Transparent Conductive Oxide)-coated glass and metal- or plastic foils. Compared to the CdTe and CIGS based thin-film technologies, silicon thin-film solar cells have the advantage that no limitation of raw material supply is expected and no toxic elements are used. Nevertheless, the production cost per Wattpeak is the decisive factor concerning competitiveness and can be reduced by, e.g., shorter deposition times or reduced material consumption. Both cost-reducing conceptions are simultaneously achieved by reducing the a-Si:H and {mu}c-Si:H absorber layer thicknesses in a tandem device. In the work on hand, the influence of an absorber layer thickness reduction up to 77% on the photovoltaic parameters of a-Si:H/{mu}c-Si:H tandem solar cells was investigated. An industry-oriented Radio Frequency Plasma-Enhanced Chemical Vapour Deposition (RF-PECVD) system was used to deposit the solar cells on glass substrates coated with randomly structured TCO layers. The thicknesses of top and bottom cell absorber layers were varied by adjusting the deposition time. Reduced layer thicknesses lead to lower absorption and, hence, to reduced short-circuit current densities which, however, are partially balanced by higher open-circuit voltages and fill factors. Furthermore, by using very thin amorphous top cells, the light-induced degradation decreases tremendously. Accordingly, a thickness reduction of 75% led to an efficiency loss of only 21 %. By adjusting the parameters for the deposition of a-Si:H top cells, a

  15. Synthesis of Poly-Silicon Thin Films on Glass Substrate Using Laser Initiated Metal Induced Crystallization of Amorphous Silicon for Space Power Application

    Science.gov (United States)

    Abu-Safe, Husam H.; Naseem, Hameed A.; Brown, William D.

    2007-01-01

    Poly-silicon thin films on glass substrates are synthesized using laser initiated metal induced crystallization of hydrogenated amorphous silicon films. These films can be used to fabricate solar cells on low cost glass and flexible substrates. The process starts by depositing 200 nm amorphous silicon films on the glass substrates. Following this, 200 nm of sputtered aluminum films were deposited on top of the silicon layers. The samples are irradiated with an argon ion cw laser beam for annealing. Laser power densities ranging from 4 to 9 W/cm2 were used in the annealing process. Each area on the sample is irradiated for a different exposure time. Optical microscopy was used to examine any cracks in the films and loss of adhesion to the substrates. X-Ray diffraction patterns from the initial results indicated the crystallization in the films. Scanning electron microscopy shows dendritic growth. The composition analysis of the crystallized films was conducted using Energy Dispersive x-ray Spectroscopy. The results of poly-silicon films synthesis on space qualified flexible substrates such as Kapton are also presented.

  16. Atomic-Resolution Observations of Semi-Crystalline IntegranularThin Films in Silicon Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Alexander; Idrobo, Juan C.; Cinibulk, Michael K.; Kisielowski, Christian; Browning, Nigel D.; Ritchie, Robert O.

    2005-08-01

    The thin intergranular phase in a silicon nitride (Si3N4)ceramic, which has been regarded for decades as having an entirely amorphous morphology, is shown to have a semi-crystalline structure. Using two different but complementary high-resolution electron microscopy methods, the intergranular atomic structure was directly imaged at the atomic level. These high-resolution images show that the atomic arrangement of the dopand element cerium takes very periodic positions not only along the interface between the intergranular phase and the Si3N4 matrix grains, but it arranges in a semi-crystalline structure that spans the entire width of the intergranular phase between two adjacent matrix grains, in principle connecting the two separate matrix grains. The result will have implications on the approach of understanding the materials properties of ceramics, most significantly on the mechanical properties and the associated computational modeling of the atomic structure of the thin intergranular phase in Si3N4 ceramics.

  17. Radiation hardness and charge collection efficiency of lithium irradiated thin silicon diodes

    CERN Document Server

    Boscardin, Maurizio; Bruzzi, Mara; Candelori, Andrea; Focardi, Ettore; Khomenkov, Volodymyr P; Piemonte, Claudio; Ronchin, S; Tosi, C; Zorzi, N

    2005-01-01

    Due to their low depletion voltage, even after high particle fluences, improved tracking precision and momentum resolution, and reduced material budget, thin substrates are one of the possible choices to provide radiation hard detectors for future high energy physics experiments. In the framework of the CERN RD50 Collaboration, we have developed PIN diode detectors on membranes obtained by locally thinning the silicon substrate by means of TMAH etching from the wafer backside. Diodes of different shapes and sizes have been fabricated on 50- mu m and 100- mu m thick membranes and tested, showing a low leakage current (of 300 nA/cm/sup 3/) and a very low depletion voltage (in the order of 1 V for the 50 mu m membrane) before irradiation. Radiation damage tests have been performed with 58 MeV lithium (Li) ions up to the fluence of 10/sup 14/ Li/cm/sup 2/ in order to determine the depletion voltage and leakage current density increase after irradiation. Charge collection efficiency tests carried out with a beta /...

  18. Texture-Etched SnO2 Glasses Applied to Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Bing-Rui Wu

    2014-01-01

    Full Text Available Transparent electrodes of tin dioxide (SnO2 on glasses were further wet-etched in the diluted HCl:Cr solution to obtain larger surface roughness and better light-scattering characteristic for thin-film solar cell applications. The process parameters in terms of HCl/Cr mixture ratio, etching temperature, and etching time have been investigated. After etching process, the surface roughness, transmission haze, and sheet resistance of SnO2 glasses were measured. It was found that the etching rate was increased with the additions in etchant concentration of Cr and etching temperature. The optimum texture-etching parameters were 0.15 wt.% Cr in 49% HCl, temperature of 90°C, and time of 30 sec. Moreover, silicon thin-film solar cells with the p-i-n structure were fabricated on the textured SnO2 glasses using hot-wire chemical vapor deposition. By optimizing the texture-etching process, the cell efficiency was increased from 4.04% to 4.39%, resulting from the increment of short-circuit current density from 14.14 to 15.58 mA/cm2. This improvement in cell performances can be ascribed to the light-scattering effect induced by surface texturization of SnO2.

  19. Ultra-thin distributed Bragg reflectors via stacked single-crystal silicon nanomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Minkyu; Seo, Jung-Hun; Lee, Jaeseong; Mi, Hongyi; Kim, Munho; Ma, Zhenqiang, E-mail: mazq@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Zhao, Deyin; Zhou, Weidong [Nanophotonics Lab, Department of Electrical Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States); Yin, Xin; Wang, Xudong [Department of Material Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-05-04

    In this paper, we report ultra-thin distributed Bragg reflectors (DBRs) via stacked single-crystal silicon (Si) nanomembranes (NMs). Mesh hole-free single-crystal Si NMs were released from a Si-on-insulator substrate and transferred to quartz and Si substrates. Thermal oxidation was applied to the transferred Si NM to form high-quality SiO{sub 2} and thus a Si/SiO{sub 2} pair with uniform and precisely controlled thicknesses. The Si/SiO{sub 2} layers, as smooth as epitaxial grown layers, minimize scattering loss at the interface and in between the layers. As a result, a reflection of 99.8% at the wavelength range from 1350 nm to 1650 nm can be measured from a 2.5-pair DBR on a quartz substrate and 3-pair DBR on a Si substrate with thickness of 0.87 μm and 1.14 μm, respectively. The high reflection, ultra-thin DBRs developed here, which can be applied to almost any devices and materials, holds potential for application in high performance optoelectronic devices and photonics applications.

  20. FTIR Characterization of Fluorine Doped Silicon Dioxide Thin Films Deposited by Plasma Enhanced Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Peng-Fei; DING Shi-Jin; ZHANG Wei; ZHANG Jian-Yun; WANGJi-Tao; WEI William Lee

    2000-01-01

    Fluorine doped silicon dioxide (SiOF) thin films have been prepared by plasma enhanced chemical vapor depo sition. The Fourier transform infrared spectrometry (FTIR) spectra of SiOF films are deliberated to reveal the structure change of SiO2 and the mechanism of dielectric constant reduction after doping fluorine. When F is doped in SiO2 films, the Si-O stretching absorption peak will have a blue-shift due to increase of the partial charge of the O atom. The FTIR spectra indicate that some Si-OH components in the thin film can be removed after doping fluorine. These changes reduce the ionic and orientational polarization, and result in the reduction in dielectric constant of the film. According to Gaussian fitting, it is found that the Si-F2 bonds will appear in the SiOF film with increase of the fluorine content. The Si-F2 structures are liable to react with water, and cause the same increase of absorbed moisture in the film.

  1. Simulation of polycrystalline silicon thin film solar cells - model calibration and sensitivity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Teodoreanu, Ana-Maria; Leendertz, Caspar; Sontheimer, Tobias; Rech, Bernd [Helmholtz-Zentrum Berlin, Kekulestr. 5. 12489 Berlin (Germany)

    2011-07-01

    To gain a better insight into the efficiency-limiting processes in polycrystalline silicon (poly-Si) thin film solar cells, we developed a simulation model for the J-V characteristics and minority carrier lifetime based on experimental results using the numerical 1D simulation program AFORS-HET. The calibration of the model has been achieved through simultaneously fitting the measured dark and light J-V curves of twelve poly-Si thin film minimodules with dissimilar thickness and absorber doping concentration. Effective defect density, capture cross section products of 10..100 cm{sup -1} have been determined in the poly-Si absorber by this procedure. Transient photoconductance decay measurements of the poly-Si absorbers have also been conducted in the low injection regime (4.5.10{sup 14} cm{sup -3}). High lifetimes of 100 {mu} s have been found which can be explained within our simulation model by field effect passivation. Furthermore simulations indicate that this field effect leads to a strong injection-dependence of carrier lifetime in the operation range of the solar cell. The sensitivity analysis performed with our calibrated model shows that the defects in the absorber layer are crucial for the cell efficiency. Thus, the improvement of the emitter and back surface field layers becomes important only if the absorber itself is of better quality. Moreover we discuss the optimum absorber thickness subject to different doping levels and absorber defect densities.

  2. Synthesis and characterization of large-grain solid-phase crystallized polycrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avishek, E-mail: avishek.kumar@nus.edu.sg, E-mail: dalapatig@imre.a-star.edu.sg [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Law, Felix; Widenborg, Per I. [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 (Singapore); Dalapati, Goutam K., E-mail: avishek.kumar@nus.edu.sg, E-mail: dalapatig@imre.a-star.edu.sg; Subramanian, Gomathy S.; Tan, Hui R. [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore); Aberle, Armin G. [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Block E3A, #06-01, Singapore 117574 and Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore)

    2014-11-01

    n-type polycrystalline silicon (poly-Si) films with very large grains, exceeding 30 μm in width, and with high Hall mobility of about 71.5 cm{sup 2}/V s are successfully prepared by the solid-phase crystallization technique on glass through the control of the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio. The effect of this gas flow ratio on the electronic and structural quality of the n-type poly-Si thin film is systematically investigated using Hall effect measurements, Raman microscopy, and electron backscatter diffraction (EBSD), respectively. The poly-Si grains are found to be randomly oriented, whereby the average area weighted grain size is found to increase from 4.3 to 18 μm with increase of the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio. The stress in the poly-Si thin films is found to increase above 900 MPa when the PH{sub 3} (2% in H{sub 2})/SiH{sub 4} gas flow ratio is increased from 0.025 to 0.45. Finally, high-resolution transmission electron microscopy, high angle annular dark field-scanning tunneling microscopy, and EBSD are used to identify the defects and dislocations caused by the stress in the fabricated poly-Si films.

  3. Carrier collection losses in interface passivated amorphous silicon thin-film solar cells

    Science.gov (United States)

    Neumüller, A.; Bereznev, S.; Ewert, M.; Volobujeva, O.; Sergeev, O.; Falta, J.; Vehse, M.; Agert, C.

    2016-07-01

    In silicon thin-film solar cells the interface between the i- and p-layer is the most critical. In the case of back diffusion of photogenerated minority carriers to the i/p-interface, recombination occurs mainly on the defect states at the interface. To suppress this effect and to reduce recombination losses, hydrogen plasma treatment (HPT) is usually applied. As an alternative to using state of the art HPT we apply an argon plasma treatment (APT) before the p-layer deposition in n-i-p solar cells. To study the effect of APT, several investigations were applied to compare the results with HPT and no plasma treatment at the interface. Carrier collection losses in resulting solar cells were examined with spectral response measurements with and without bias voltage. To investigate single layers, surface photovoltage and X-ray photoelectron spectroscopy (XPS) measurements were conducted. The results with APT at the i/p-interface show a beneficial contribution to the carrier collection compared with HPT and no plasma treatment. Therefore, it can be concluded that APT reduces the recombination centers at the interface. Further, we demonstrate that carrier collection losses of thin-film solar cells are significantly lower with APT.

  4. Ion beam treatment of functional layers in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wendi

    2013-10-01

    In silicon thin-film solar cells, transparent conductive layers have to fulfill the following requirements: high conductivity as effective contact, high transparency to transmit the light into the cell, and a textured surface which provides light scattering. Magnetron sputtered and wet-chemically textured aluminum doped zinc oxide (ZnO:Al) films are widely used as the transparent conductor. The technological goal of this dissertation is to develop an alternative to the wet etching process for light trapping in the thin silicon absorber layers through modification of the glass/ZnO:Al or ZnO:Al/Si interfaces by ion beam treatment. The study focuses on the textured growth of ZnO:Al films on ion beam pretreated glass substrates, and the preparation and application of textured glass for light trapping. The technological aspects such as the etch rates of the glass substrate and ZnO:Al films with different ion beam configurations were studied. The experimental etch rates are compared with simulated and theoretically predicted values. With regard to the ion beam treatment of glass substrate, the influence of the ion pretreated glass on the growth of ZnO:Al films was investigated. The ZnO:Al films grown on ion beam pretreated glass substrates exhibit self-textured morphology with surface roughness of 40 nm while remaining highly conductive. Silicon thin-film solar cells prepared on the as-grown rough ZnO:Al films show that this front contact can provide excellent light trapping effect. The highest initial efficiencies for amorphous single junction solar cells on as-grown rough ZnO:Al films was 9.4%. The as-grown rough morphology was attributed to large conical ZnO:Al grains initiated from the ion pretreated glass surface. It was found that the roughness of the as-grown rough ZnO:Al film is proportional to the number of O dangling bonds created by ion beam treatment on the glass substrate. A growth model was proposed to explain the growth mechanism of ZnO:Al films on Zn- and

  5. Crystalline silicon thin-film solar cells. Final report; Duennschicht-Solarzellen aus kristallinem Silizium. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Raeuber, A.; Wettling, W.; Eyer, A.; Faller, F.; Hebling, C.; Hurrle, A.; Lautenschlager, H.; Luedemann, R.; Lutz, F.; Reber, S.; Schetter, C.; Schillinger, N.; Schindler, R.; Schumacher, J.O.; Warta, W.

    1998-09-01

    Activities under the project covered all the processes involved in the fabrication of a crystalline silicon thin-film solar cell applying the high-temperature method, so that R and D work was carried out from testing of materials suitable for the dielectric and semiconductive layers required, development of the process sequences for fabrication of the solar cells, simulation and optimisation of the cell design through to final characterisation of the thin films and solar cells. Several cell designs were tested in parallel for intercomparison. Several high-temperature resistant materials were tested for their suitability to serve as substrate materials.The final project report presents the basic research work and studies on the physical and technological aspects of the crystalline thin-film solar cell as well as the major results of specific development work. The report shows that significant progress could be achieved. The efficiencies of all solar cell designs developed under the project are between 9 and 11%, including those using substrate materials easily available in industry, and it could be demonstrated that the solar cells are equal in potential to the wafer-based silicon cell. (orig./CB) [Deutsch] Es wurden alle wesentlichen Teilprozesse, die fuer die Entwicklung einer kristallinen Silicium Duennschicht-Solarzelle nach dem Hochtemperaturverfahren wichtig sind, bearbeitet. Der Projektrahmen reichte von der Materialentwicklung fuer die dielektrischen und halbleitenden Schichten ueber die Entwicklung der Solarzellenprozessschritte, die Simulation und Optimierung des Zellendesigns bis zur Charakterisierung von Schichten und Solarzellen. Dabei wurden mehrere verschiedene Zellentypen parallel untersucht und miteinander verglichen. In einer Studie wurden verschiedene hochtemperaturfeste Materialien auf ihre Eignung als Substrate hin untersucht. In dem hier vorgelegten Abschlussbericht werden die erarbeiteten Grundlagen zur Physik und Technologie der kristallinen

  6. MOCVD ZnO/Screen Printed Ag Back Reflector for Flexible Thin Film Silicon Solar Cell Application

    Directory of Open Access Journals (Sweden)

    Amornrat Limmanee

    2014-01-01

    Full Text Available We have prepared Ag back electrode by screen printing technique and developed MOCVD ZnO/screen printed Ag back reflector for flexible thin film silicon solar cell application. A discontinuity and poor contact interface between the MOCVD ZnO and screen printed Ag layers caused poor open circuit voltage (Voc and low fill factor (FF; however, an insertion of a thin sputtered ZnO layer at the interface could solve this problem. The n type hydrogenated amorphous silicon (a-Si:H film is preferable for the deposition on the surface of MOCVD ZnO film rather than the microcrystalline film due to its less sensitivity to textured surface, and this allowed an improvement in the FF. The n-i-p flexible amorphous silicon solar cell using the MOCVD ZnO/screen printed Ag back reflector showed an initial efficiency of 6.2% with Voc=0.86 V, Jsc=12.4 mA/cm2, and FF = 0.58 (1 cm2. The identical quantum efficiency and comparable performance to the cells using conventional sputtered Ag back electrode have verified the potential of the MOCVD ZnO/screen printed Ag back reflector and possible opportunity to use the screen printed Ag thick film for flexible thin film silicon solar cells.

  7. 多晶硅薄膜太阳电池%Polycrystalline Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    何海洋; 陈诺夫; 李宁; 白一鸣; 仲琳; 弭辙; 辛雅焜; 吴强; 高征

    2013-01-01

    Polycrystalline silicon (poly-Si) thin film solar cells are attracted much attention due to their low material consumption, low cost, high stability, and the mature technology of poly-Si thin film microelectronic devices. The structure and preparation processes of poly-Si thin film solar cells are reviewed in detail, and it is pointed out that the suitable substrate selection and high quality materials realization are the key research directions of poly-Si thin film solar cells at present. Then the principles, characteristics, advantages and disadvantages of the preparation methods are introduced systematically, including the chemical vapor deposition (CVD), magnetron sputtering (MS), solid-phase crystallization (SPC), laser crystallization (LC) and rapid thermal annealing (RTA). Finally, the development status of the technologies above is elaborated, and the application prospects of these methods in poly-Si thin film solar cells are reviewed objectively.%多晶硅薄膜太阳电池因兼具低材料消耗、低成本、高稳定性及多晶硅薄膜微电子器件的成熟工艺而备受瞩目.对多晶硅薄膜太阳电池的结构和制备工艺流程进行了详细阐述,指出当前多晶硅薄膜太阳电池的关键研究方向,即衬底的选择和高质量多晶硅薄膜的实现.特别是针对高质量多晶硅薄膜的制备,系统地介绍了化学气相沉积(CVD)、磁控溅射(MS)、固相晶化(SPC)、激光晶化(LC)以及快速热退火(RTA)等制备方法的工作原理、特点和优劣.综合阐述了各项技术的发展现状,并对上述技术及其在多晶硅薄膜太阳电池中的应用前景进行了客观评述与展望.

  8. Optical Absorption and Visible Photoluminescence from Thin Films of Silicon Phthalocyanine Derivatives

    Science.gov (United States)

    Rodríguez Gómez, Arturo; Moises Sánchez-Hernández, Carlos; Fleitman-Levin, Ilán; Arenas-Alatorre, Jesús; Carlos Alonso-Huitrón, Juan; Elena Sánchez Vergara, María

    2014-01-01

    The interest of microelectronics industry in new organic compounds for the manufacture of luminescent devices has increased substantially in the last decade. In this paper, we carried out a study of the usage feasibility of three organic bidentate ligands (2,6-dihydroxyanthraquinone, anthraflavic acid and potassium derivative salt of anthraflavic acid) for the synthesis of an organic semiconductor based in silicon phthalocyanines (SiPcs). We report the visible photoluminescence (PL) at room temperature obtained from thermal-evaporated thin films of these new materials. The surface morphology of these films was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM indicated that the thermal evaporation technique is an excellent resource in order to obtain low thin film roughness when depositing these kinds of compounds. Fourier transform infrared spectroscopy (FTIR) spectroscopy was employed to investigate possible changes in the intra-molecular bonds and to identify any evidence of crystallinity in the powder compounds and in the thin films after their deposition. FTIR showed that there was not any important change in the samples after the thermal deposition. The absorption coefficient (α) in the absorption region reveals non-direct transitions. Furthermore, the PL of all the investigated samples were observed with the naked eye in a bright background and also measured by a spectrofluorometer. The normalized PL spectra showed a Stokes shift ≈ 0.6 eV in two of our three samples, and no PL emission in the last one. Those results indicate that the Vis PL comes from a recombination of charge carriers between conduction band and valence band preceded by a non-radiative relaxation in the conduction band tails. PMID:28788200

  9. Optical Absorption and Visible Photoluminescence from Thin Films of Silicon Phthalocyanine Derivatives

    Directory of Open Access Journals (Sweden)

    Arturo Rodríguez Gómez

    2014-09-01

    Full Text Available The interest of microelectronics industry in new organic compounds for the manufacture of luminescent devices has increased substantially in the last decade. In this paper, we carried out a study of the usage feasibility of three organic bidentate ligands (2,6-dihydroxyanthraquinone, anthraflavic acid and potassium derivative salt of anthraflavic acid for the synthesis of an organic semiconductor based in silicon phthalocyanines (SiPcs. We report the visible photoluminescence (PL at room temperature obtained from thermal-evaporated thin films of these new materials. The surface morphology of these films was analyzed by atomic force microscopy (AFM and scanning electron microscopy (SEM. AFM indicated that the thermal evaporation technique is an excellent resource in order to obtain low thin film roughness when depositing these kinds of compounds. Fourier transform infrared spectroscopy (FTIR spectroscopy was employed to investigate possible changes in the intra-molecular bonds and to identify any evidence of crystallinity in the powder compounds and in the thin films after their deposition. FTIR showed that there was not any important change in the samples after the thermal deposition. The absorption coefficient (α in the absorption region reveals non-direct transitions. Furthermore, the PL of all the investigated samples were observed with the naked eye in a bright background and also measured by a spectrofluorometer. The normalized PL spectra showed a Stokes shift ≈ 0.6 eV in two of our three samples, and no PL emission in the last one. Those results indicate that the Vis PL comes from a recombination of charge carriers between conduction band and valence band preceded by a non-radiative relaxation in the conduction band tails.

  10. Pyroelectric response of lead zirconate titanate thin films on silicon: Effect of thermal stresses

    Energy Technology Data Exchange (ETDEWEB)

    Kesim, M. T.; Zhang, J.; Alpay, S. P. [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Trolier-McKinstry, S. [Department of Materials Science and Engineering and Materials Research Institute, Pennsylvania State University, Pennsylvania 16802 (United States); Mantese, J. V. [United Technologies Research Center, East Hartford, Connecticut 06118 (United States); Whatmore, R. W. [Tyndall National Institute, Lee Maltings, Dyke Parade, Cork City, County Cork (Ireland)

    2013-11-28

    Ferroelectric lead zirconate titanate [Pb(Zr{sub x}Ti{sub 1-x}O){sub 3}, (PZT x:1-x)] has received considerable interest for applications related to uncooled infrared devices due to its large pyroelectric figures of merit near room temperature, and the fact that such devices are inherently ac coupled, allowing for simplified image post processing. For ferroelectric films made by industry-standard deposition techniques, stresses develop in the PZT layer upon cooling from the processing/growth temperature due to thermal mismatch between the film and the substrate. In this study, we use a non-linear thermodynamic model to investigate the pyroelectric properties of polycrystalline PZT thin films for five different compositions (PZT 40:60, PZT 30:70, PZT 20:80, PZT 10:90, PZT 0:100) on silicon as a function of processing temperature (25–800 °C). It is shown that the in-plane thermal stresses in PZT thin films alter the out-of-plane polarization and the ferroelectric phase transformation temperature, with profound effect on the pyroelectric properties. PZT 30:70 is found to have the largest pyroelectric coefficient (0.042 μC cm{sup −2} °C{sup −1}, comparable to bulk values) at a growth temperature of 550 °C; typical to what is currently used for many deposition processes. Our results indicate that it is possible to optimize the pyroelectric response of PZT thin films by adjusting the Ti composition and the processing temperature, thereby, enabling the tailoring of material properties for optimization relative to a specific deposition process.

  11. Ultrafast carrier dynamics and the role of grain boundaries in polycrystalline silicon thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Titova, Lyubov V.; Cocker, Tyler L.; Xu, Sijia; Baribeau, Jean-Marc; Wu, Xiaohua; Lockwood, David J.; Hegmann, Frank A.

    2016-10-01

    We have used time-resolved terahertz spectroscopy to study microscopic photoconductivity and ultrafast photoexcited carrier dynamics in thin, pure, non-hydrogenated silicon films grown by molecular beam epitaxy on quartz substrates at temperatures ranging from 335 °C to 572 °C. By controlling the growth temperature, thin silicon films ranging from completely amorphous to polycrystalline with minimal amorphous phase can be achieved. Film morphology, in turn, determines its photoconductive properties: in the amorphous phase, carriers are trapped in bandtail states on sub-picosecond time scales, while the carriers excited in crystalline grains remain free for tens of picoseconds. We also find that in polycrystalline silicon the photoexcited carrier mobility is carrier-density-dependent, with higher carrier densities mitigating the effects of grain boundaries on inter-grain transport. In a film grown at the highest temperature of 572 °C, the morphology changes along the growth direction from polycrystalline with needles of single crystals in the bulk of the film to small crystallites interspersed with amorphous silicon at the top of the film. Depth profiling using different excitation wavelengths shows corresponding differences in the photoconductivity: the photoexcited carrier lifetime and mobility are higher in the first 100-150 nm from the substrate, suggesting that thinner, low-temperature grown polycrystalline silicon films are preferable for photovoltaic applications.

  12. Evolution of infrared spectra and optical emission spectra in hydrogenated silicon thin films prepared by VHF-PECVD

    Science.gov (United States)

    Hou, Guo-Fu; Geng, Xin-Hua; Zhang, Xiao-Dan; Sun, Jian; Zhang, Jian-Jun; Zhao, Ying

    2011-07-01

    A series of hydrogenated silicon thin films with varying silane concentrations have been deposited by using very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The deposition process and the silicon thin films are studied by using optical emission spectroscopy (OES) and Fourier transfer infrared (FTIR) spectroscopy, respectively. The results show that when the silane concentration changes from 10% to 1%, the peak frequency of the Si-H stretching mode shifts from 2000 cm-1 to 2100 cm-1, while the peak frequency of the Si—H wagging—rocking mode shifts from 650 cm-1 to 620 cm-1. At the same time the SiH/Hα intensity ratio in the plasma decreases gradually. The evolution of the infrared spectra and the optical emission spectra demonstrates a morphological phase transition from amorphous silicon (a-Si:H) to microcrystalline silicon (μc-Si:H). The structural evolution and the μc-Si:H formation have been analyzed based on the variation of Hα and SiH intensities in the plasma. The role of oxygen impurity during the plasma process and in the silicon films is also discussed in this study.

  13. Effect of silane flow rate on structural, electrical and optical properties of silicon thin films grown by VHF PECVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Gope, Jhuma [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumar, Sushil, E-mail: skumar@nplindia.org [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Sudhakar, S.; Rauthan, C.M.S. [Physics of Energy Harvesting Division, CSIR-Network of Institutes for Solar Energy, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, P.C. [Department of Physics, Banaras Hindu University, Varanasi 221005 (India)

    2013-08-15

    Hydrogenated silicon thin films deposited by VHF PECVD process for various silane flow rates have been investigated. The silane flow rate was varied from 5 sccm to 30 sccm, maintaining all other parameters constant. The electrical, structural and optical properties of these films were systematically studied as a function of silane flow rate. These films were characterized by Raman spectroscopy, Scanning Electron Microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and UV–visible (UV–Vis) spectroscopy. Different crystalline volume fraction (22%–60%) and band gap (∼1.58 eV–∼1.96 eV) were achieved for silicon thin films by varying the silane concentration. A transition from amorphous to nanocrystalline silicon has been confirmed by Raman and FTIR analysis. The film grown at this transition region shows the high conductivity in the order of 10{sup −4} Ω{sup −1} cm{sup −1}. - Highlights: • Silicon films grown using VHF PECVD at various F{sub silane} (silane flow rate). • Amorphous to nanocrystalline silicon transition at F{sub silane} ∼5 sccm–10 sccm. • Deposition rate increases with the increase of F{sub silane}. • Powder formation occurred beyond 20 sccm of F{sub silane}. • Film grown at 20 sccm shows max. crystalline fraction ∼60% with E{sub g} ∼1.58 eV.

  14. The Combination of Direct and Confined Laser Ablation Mechanisms for the Selective Structuring of Thin Silicon Nitride Layers

    Science.gov (United States)

    Rapp, Stephan; Heinrich, Gerrit; Domke, Matthias; Huber, Heinz P.

    In the production process of microelectronic devices and high efficiency solar cells, local openings in thin dielectric layers are required. Instead of photolithographic, laser based processing enables to open these dielectric layers locally in a low-cost mass production step. In this work, thin silicon nitride layers deposited on planar silicon wafers are processed by single infrared Gaussian shaped 660 fs laser pulses. The transparent silicon nitride layer, becoming absorptive at fluences higher than 0.3 J/cm2, is selectively removed by confined ablation at fluences below that value. At pulse peak fluences exceeding 1.0 J/cm2 a "SiNx island"is created by direct ablation in the spot center. In this article, theselective SiNx ablation by a combination of confined and direct laser ablation at the medium pulse peak fluence of 0.5 J/cm2 is investigated. To clarify the influence of the nonlinear absorption in the pulse center, the ablation behavior is investigated by time- and space-resolved pump-probe microscopy experiments. The results showphase changes in the silicon and in the silicon nitride in the first picoseconds after excitation, the ablation onset at around 10 ps and the subsequent mechanical materialmotion after a few nanoseconds. The actual silicon nitride layer removal starts after around 10 ns, whereas confined ablation processes are the driving mechanisms even in the nonlinearly absorbing spot center. A comparison of the energetic ablation efficiency of the SiNx layer system to further dielectric thin films shows no detrimental influence of the nonlinear absorbance.

  15. Boron Doped Nanocrystalline Film with Improved Work Function as a Buffer Layer in Thin Film Silicon Solar Cells.

    Science.gov (United States)

    Park, Jinjoo; Shin, Chonghoon; Park, Hyeongsik; Jung, Junhee; Lee, Youn-Jung; Bong, Sungjae; Dao, Vinh Ai; Balaji, Nagarajan; Yi, Junsin

    2015-03-01

    We investigated thin film silicon solar cells with boron doped hydrogenated nanocrystalline silicon/ hydrogenated amorphous silicon oxide [p-type nc-Si:H/a-SiOx:H] layer. First, we researched the bandgap engineering of diborane (B2H6) doped wide bandgap hydrogenated nanocryslline silicon (p-type nc-Si:H) films, which have excellent electrical properties of high dark conductivity, and low activation energy. The films prepared with lower doping ratio and higher hydrogen dilution ratio had higher optical gap (Eg), with higher dark conductivity (σ(d)), and lower activation energy (Ea). We controlled Eg from 2.10 eV to 1.75 eV, with σ(d) from 1.1 S/cm to 7.59 x 10(-3) S/cm, and Ea from 0.040 eV to 0.128 eV. Next, we focused on the fabrication of thin film silicon solar cells. By inserting p-type nc-Si:H film into the thin film silicon solar cells, we achieved a remarkable increase in the built-in potential from 0.803 eV to 0.901 eV. By forming p-type nc-Si:H film between SnO2:F/ZnO:Al (30 nm) and p-type a-SiOx:H layer, the solar cell properties of open circuit voltage (Voc), short circuit current density (Jsc), and efficiency (η) were improved by 3.7%, 9.2%, and 9.8%, respectively.

  16. Galvanic corrosion of structural non-stoichiometric silicon nitride thin films and its implications on reliability of microelectromechanical devices

    Energy Technology Data Exchange (ETDEWEB)

    Broas, M., E-mail: mikael.broas@aalto.fi; Mattila, T. T.; Paulasto-Kröckel, M. [Department of Electrical Engineering and Automation, Aalto University, Espoo, P.O. Box 13500, FIN-00076 Aalto (Finland); Liu, X.; Ge, Y. [Department of Materials Science and Engineering, Aalto University, Espoo, P.O. Box 16200, FIN-00076 Aalto (Finland)

    2015-06-28

    This paper describes a reliability assessment and failure analysis of a poly-Si/non-stoichiometric silicon nitride thin film composite structure. A set of poly-Si/SiN{sub x} thin film structures were exposed to a mixed flowing gas (MFG) environment, which simulates outdoor environments, for 90 days, and an elevated temperature and humidity (85 °C/95% R.H.) test for 140 days. The mechanical integrity of the thin films was observed to degrade during exposure to the chemically reactive atmospheres. The degree of degradation was analyzed with nanoindentation tests. Statistical analysis of the forces required to initiate a fracture in the thin films indicated degradation due to the exposure to the MFG environment in the SiN{sub x} part of the films. Scanning electron microscopy revealed a porous-like reaction layer on top of SiN{sub x}. The morphology of the reaction layer resembled that of galvanically corroded poly-Si. Transmission electron microscopy further clarified the microstructure of the reaction layer which had a complex multi-phase structure extending to depths of ∼100 nm. Furthermore, the layer was oxidized two times deeper in a 90 days MFG-tested sample compared to an untested reference. The formation of the layer is proposed to be caused by galvanic corrosion of elemental silicon in non-stoichiometric silicon nitride during hydrofluoric acid etching. The degradation is proposed to be due uncontrolled oxidation of the films during the stress tests.

  17. Chemical vapor deposition and characterization of polysilanes polymer based thin films and their applications in compound semiconductors and silicon devices

    Science.gov (United States)

    Oulachgar, El Hassane

    . This work has demonstrated that a polysilane polymeric source can be used to deposit a wide range of thin film materials exhibiting similar properties with conventional ceramic materials such as silicon carbide (SiC), silicon oxynitride (SiON), silicon oxycarbide (SiOC) silicon dioxide (SiO2) and silicon nitride (Si3N4). The strict control of the deposition process allows precise control of the electrical, optical and chemical properties of polymer-based thin films within a broad range. This work has also demonstrated for the first time that poly(dimethylsilmaes) polymers deposited by CVD can be used to effectively passivate both silicon and gallium arsenide MOS devices. This finding makes polymer-based thin films obtained by CVD very promising for the development of high-kappa dielectric materials for next generation high-mobility CMOS technology. Keywords. Thin films, Polymers, Vapor Phase Deposition, CVD, Nanodielectrics, Organosilanes, Polysilanes, GaAs Passivation, MOSFET, Silicon Oxynitride, Integrated Waveguide, Silicon Carbide, Compound Semiconductors.

  18. Stoichiometric silicon oxynitride thin films reactively sputtered in Ar/N2O plasmas by HiPIMS

    Science.gov (United States)

    Hänninen, Tuomas; Schmidt, Susann; Wissting, Jonas; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2016-04-01

    Silicon oxynitride (SiO x N y , x=0.2-1.3, y=0.2 -0.7) thin films were synthesized by reactive high power impulse magnetron sputtering from a pure silicon target in Ar/N2O atmospheres. It was found that the composition of the material can be controlled by the reactive gas flow and the average target power. X-ray photoelectron spectroscopy (XPS) shows that high average powers result in more silicon-rich films, while lower target powers yield silicon-oxide-like material due to more pronounced target poisoning. The amount of nitrogen in the films can be controlled by the percentage of nitrous oxide in the working gas. The nitrogen content remains at a constant level while the target is operated in the transition region between metallic and poisoned target surface conditions. The extent of target poisoning is gauged by the changes in peak target current under the different deposition conditions. XPS also shows that varying concentrations and ratios of oxygen and nitrogen in the films result in film chemical bonding structures ranging from silicon-rich to stoichiometric silicon oxynitrides having no observable Si-Si bond contributions. Spectroscopic ellipsometry shows that the film optical properties depend on the amount and ratio of oxygen and nitrogen in the compound, with film refractive indices measured at 633 nm ranging between those of SiO2 and Si3N4.

  19. High rate particle tracking and ultra-fast timing with a thin hybrid silicon pixel detector

    Science.gov (United States)

    Fiorini, M.; Aglieri Rinella, G.; Carassiti, V.; Ceccucci, A.; Cortina Gil, E.; Cotta Ramusino, A.; Dellacasa, G.; Garbolino, S.; Jarron, P.; Kaplon, J.; Kluge, A.; Marchetto, F.; Mapelli, A.; Martin, E.; Mazza, G.; Morel, M.; Noy, M.; Nuessle, G.; Perktold, L.; Petagna, P.; Petrucci, F.; Poltorak, K.; Riedler, P.; Rivetti, A.; Statera, M.; Velghe, B.

    2013-08-01

    The Gigatracker (GTK) is a hybrid silicon pixel detector designed for the NA62 experiment at CERN. The beam spectrometer, made of three GTK stations, has to sustain high and non-uniform particle rate (∼ 1 GHz in total) and measure momentum and angles of each beam track with a combined time resolution of 150 ps. In order to reduce multiple scattering and hadronic interactions of beam particles, the material budget of a single GTK station has been fixed to 0.5% X0. The expected fluence for 100 days of running is 2 ×1014 1 MeV neq /cm2, comparable to the one foreseen in the inner trackers of LHC detectors during 10 years of operation. To comply with these requirements, an efficient and very low-mass (architectures have been produced as small-scale prototypes: one is based on a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other makes use of a constant-fraction discriminator followed by an on-pixel TDC. The read-out ASICs are produced in 130 nm IBM CMOS technology and will be thinned down to 100 μm or less. An overview of the Gigatracker detector system will be presented. Experimental results from laboratory and beam tests of prototype bump-bonded assemblies will be described as well. These results show a time resolution of about 170 ps for single hits from minimum ionizing particles, using 200 μm thick silicon sensors.

  20. Enhanced tunability of the composition in silicon oxynitride thin films by the reactive gas pulsing process

    Science.gov (United States)

    Aubry, Eric; Weber, Sylvain; Billard, Alain; Martin, Nicolas

    2014-01-01

    Silicon oxynitride thin films were sputter deposited by the reactive gas pulsing process. Pure silicon target was sputtered in Ar, N2 and O2 mixture atmosphere. Oxygen gas was periodically and solely introduced using exponential signals. In order to vary the injected O2 quantity in the deposition chamber during one pulse at constant injection time (TON), the tau mounting time τmou of the exponential signals was systematically changed for each deposition. Taking into account the real-time measurements of the discharge voltage and the I(O*)/I(Ar*) emission lines ratio, it is shown that the oscillations of the discharge voltage during the TON and TOFF times (injection of O2 stopped) are attributed to the preferential adsorption of the oxygen compared to that of the nitrogen. The sputtering mode alternates from a fully nitrided mode (TOFF time) to a mixed mode (nitrided and oxidized mode) during the TON time. For the highest injected O2 quantities, the mixed mode tends toward a fully oxidized mode due to an increase of the trapped oxygen on the target. The oxygen (nitrogen) concentration in the SiOxNy films similarly (inversely) varies as the oxygen is trapped. Moreover, measurements of the contamination speed of the Si target surface are connected to different behaviors of the process. At low injected O2 quantities, the nitrided mode predominates over the oxidized one during the TON time. It leads to the formation of Si3N4-yOy-like films. Inversely, the mixed mode takes place for high injected O2 quantities and the oxidized mode prevails against the nitrided one producing SiO2-xNx-like films.

  1. Effect of back reflectors on photon absorption in thin-film amorphous silicon solar cells

    Science.gov (United States)

    Hossain, Mohammad I.; Qarony, Wayesh; Hossain, M. Khalid; Debnath, M. K.; Uddin, M. Jalal; Tsang, Yuen Hong

    2017-08-01

    In thin-film solar cells, the photocurrent conversion productivity can be distinctly boosted-up utilizing a proper back reflector. Herein, the impact of different smooth and textured back reflectors was explored and effectuated to study the optical phenomena with interface engineering strategies and characteristics of transparent contacts. A unique type of wet-chemically textured glass-substrate 3D etching mask used in superstrate (p-i-n) amorphous silicon-based solar cell along with legitimated back reflector permits joining the standard light-trapping methodologies, which are utilized to upgrade the energy conversion efficiency (ECE). To investigate the optical and electrical properties of solar cell structure, the optical simulations in three-dimensional measurements (3D) were performed utilizing finite-difference time-domain (FDTD) technique. This design methodology allows to determine the power losses, quantum efficiencies, and short-circuit current densities of various layers in such solar cell. The short-circuit current densities for different reflectors were varied from 11.50 to 13.27 and 13.81 to 16.36 mA/cm2 for the smooth and pyramidal textured solar cells, individually. Contrasted with the comparable flat reference cell, the short-circuit current density of textured solar cell was increased by around 24%, and most extreme outer quantum efficiencies rose from 79 to 86.5%. The photon absorption was fundamentally improved in the spectral region from 600 to 800 nm with no decrease of photocurrent shorter than 600-nm wavelength. Therefore, these optimized designs will help to build the effective plans next-generation amorphous silicon-based solar cells.

  2. Direct measurement of free-energy barrier to nucleation of crystallites in amorphous silicon thin films

    Science.gov (United States)

    Shi, Frank G.

    1994-01-01

    A method is introduced to measure the free-energy barrier W(sup *), the activation energy, and activation entropy to nucleation of crystallites in amorphous solids, independent of the energy barrier to growth. The method allows one to determine the temperature dependence of W(sup *), and the effect of the preparation conditions of the initial amorphous phase, the dopants, and the crystallization methds on W(sup *). The method is applied to determine the free-energy barrier to nucleation of crystallites in amorphous silicon (a-Si) thin films. For thermally induced nucleation in a-Si thin films with annealing temperatures in the range of from 824 to 983 K, the free-energy barrier W(sup *) to nucleation of silicon crystals is about 2.0 - 2.1 eV regardless of the preparation conditions of the films. The observation supports the idea that a-Si transforms into an intermediate amorphous state through the structural relaxation prior to the onset of nucleation of crystallites in a-Si. The observation also indicates that the activation entropy may be an insignificant part of the free-energy barrier for the nucleation of crystallites in a-Si. Compared with the free-energy barrier to nucleation of crystallites in undoped a-Si films, a significant reduction is observed in the free-energy barrier to nucleation in Cu-doped a-Si films. For a-Si under irradiation of Xe(2+) at 10(exp 5) eV, the free-energy barrier to ion-induced nucleation of crystallites is shown to be about half of the value associated with thermal-induced nucleation of crystallites in a-Si under the otherwise same conditions, which is much more significant than previously expected. The present method has a general kinetic basis; it thus should be equally applicable to nucleation of crystallites in any amorphous elemental semiconductors and semiconductor alloys, metallic and polymeric glasses, and to nucleation of crystallites in melts and solutions.

  3. Microscratch testing method for systematic evaluation of the adhesion of atomic layer deposited thin films on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kilpi, Lauri, E-mail: Lauri.Kilpi@vtt.fi; Ylivaara, Oili M. E.; Vaajoki, Antti; Puurunen, Riikka L.; Ronkainen, Helena [VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT (Finland); Malm, Jari [Department of Physics, University of Jyväskylä, P.O. Box 35, Jyväskylä 40014 (Finland); Sintonen, Sakari [Department of Micro- and Nanosciences, Aalto University School of Electrical Engineering, P.O. Box 13500, FI-00076 AALTO (Finland); Tuominen, Marko [ASM Microchemistry Oy, Pietari Kalmin katu 1 F 2, FIN-00560 Helsinki (Finland)

    2016-01-15

    The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as L{sub CSi1}, L{sub CSi2}, L{sub CALD1}, and L{sub CALD2}, representing the failure points of the silicon substrate and the coating delamination points of the ALD coating. The adhesion performance of the ALD Al{sub 2}O{sub 3}, TiO{sub 2}, TiN, and TaCN+Ru coatings with a thickness range between 20 and 600 nm and deposition temperature between 30 and 410 °C on silicon wafers was investigated. In addition, the impact of the annealing process after deposition on adhesion was evaluated for selected cases. The tests carried out using scratch and Scotch tape test showed that the coating deposition and annealing temperature, thickness of the coating, and surface pretreatments of the Si wafer had an impact on the adhesion performance of the ALD coatings on the silicon wafer. There was also an improved load carrying capacity due to Al{sub 2}O{sub 3}, the magnitude of which depended on the coating thickness and the deposition temperature. The tape tests were carried out for selected coatings as a comparison. The results show that the scratch test is a useful and applicable tool for adhesion evaluation of ALD coatings, even when carried out for thin (20 nm thick) coatings.

  4. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrakellis, P.; Amanatides, E., E-mail: lef@plasmatech.gr; Mataras, D. [Department of Chemical Engineering, Plasma Technology Laboratory, University of Patras, P.O. Box 140, 26504 Patras (Greece); Kalampounias, A. G. [University of Ioannina, Dep. of Chemistry, 45110, Ioannina (Greece); Spiliopoulos, N. [Department of Physics, University of Patras, P.O. Box 140, 26504 Patras (Greece); Lahootun, V.; Coeuret, F.; Madec, A. [Air Liquide CRCD,1 chemin de la porte des Loges, Les Loges en Josas, 78354 Jouy en Josas (France)

    2016-07-15

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  5. Quantification of Power Losses of the Interdigitated Metallization of Crystalline Silicon Thin-Film Solar Cells on Glass

    OpenAIRE

    Gress, Peter J.; Sergey Varlamov

    2012-01-01

    The metallization grid pattern is one of the most important design elements for high-efficiency solar cells. This paper presents a model based on the unit cell approach to accurately quantify the power losses of a specialized interdigitated metallization scheme for polycrystalline silicon thin-film solar cells on glass superstrates. The sum of the power losses can be minimized to produce an optimized grid-pattern design for a cell with specific parameters. The model is simulated with the stan...

  6. Finite element analysis of temperature distribution of polycrystalline silicon thin film transistors under self-heating stress

    Institute of Scientific and Technical Information of China (English)

    Huaisheng WANG; Mingxiang WANG; Zhenyu YANG

    2009-01-01

    The temperature distribution of typical n-type polycrystalline silicon thin film transistors under selfheating (SH) stress is studied by finite element analysis.From both steady-state and transient thermal simulation,the influence of device power density, substrate material,and channel width on device temperature distribution is analyzed. This study is helpful to understand the mechanism of SH degradation, and to effectively alleviate the SH effect in device operation.

  7. Neutron-activated determination of chlorine, using the /sup 35/Cl(n,p)/sup 35/S reaction as the basis, in thin coatings of silicon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Perezhogin, G.A.

    1988-01-10

    The neutron-activation determination of chlorine in thin coatings of silicon dioxide on silicon has been shown to be possible through the use of the /sup 55/Cl(n, P)/sup 35/S reaction. The detection limit of chlorine is 3 x 10/sup -9/ g (5 x 10/sup 13/ atoms).

  8. Growth of HT-LiCoO2 thin films on Pt-metalized silicon substrates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yao; CHUNG Chiyuen; ZHU Min

    2008-01-01

    Layered LiCoO2 (HT-LiCoO2) films were grown on Pt-metalized silicon (PMS) substrates and polished bulk nickel (PBN) substrates by pulsed laser deposition. The effects of substrate temperature, oxygen pressure, and substrate surface roughness on the microstructure of LiCoO2 films were investigated. It has been found that a higher substrate temperature and a higher oxygen pressure favor the formation of better crystallized and less lithium-deficient HT-LiCoO2 films. The HT-LiCoO2 film deposited on PBN substrates consists of large randomly orientated equiaxial grains, whereas on PMS substrate, it is made up of loosely packed highly [001] preferential orientated triangular shaped grains with the average grain size less than 100nm. Electrochemical measurements show that the highly [001] preferentially orientated nanostructured HT-LiCoO2 thin film grown on PMS substrate has good structural stability upon lithium insertion/extraction and can deliver an initial discharge capacity of approximately 45 μA·h·cm-2μm-1 with a cycling efficiency of above 99% at the charge/discharge rate of 0.5C.

  9. Internal friction study of microplasticity of aluminum thin films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, Y.; Tanahashi, K.; Asano, S. [Nagoya Institute of Technology, Nagoya (Japan)

    1995-12-01

    Internal friction in aluminum thin films 0.2 to 2.0 {mu}m thick on silicon substrates has been investigated between 180 and 360 K as a function of strain amplitude by means of a free-decay method of flexural vibration. According to the constitutive equation, the internal friction in the film alone can be evaluated separately from the data on the film/substrate composite. The amplitude-dependent part of internal friction in aluminum films is found in the strain range approximately two orders of magnitude higher than that for bulk aluminum. On the basis of the microplasticity theory, the amplitude-dependent internal friction can be converted into the plastic strain as a function of the effective stress on dislocation motion. The mechanical responses thus obtained for aluminum films show that the plastic strain of the order of 10-9 in creases nonlinearly with increasing stress. These curves tend to shift to a higher stress with decreasing film thickness and also with decreasing temperature, both indicating a suppression of the microplastic deformation. At all temperatures examined, the microflow stress at a constant level of the plastic strain varies inversely with the film thickness, which qualitatively agrees with the variation in macroscopic yield stress. 36 refs., 7 figs.

  10. Modeling and Analysis of Entropy Generation in Light Heating of Nanoscaled Silicon and Germanium Thin Films

    Directory of Open Access Journals (Sweden)

    José Ernesto Nájera-Carpio

    2015-07-01

    Full Text Available In this work, the irreversible processes in light heating of Silicon (Si and Germanium (Ge thin films are examined. Each film is exposed to light irradiation with radiative and convective boundary conditions. Heat, electron and hole transport and generation-recombination processes of electron-hole pairs are studied in terms of a phenomenological model obtained from basic principles of irreversible thermodynamics. We present an analysis of the contributions to the entropy production in the stationary state due to the dissipative effects associated with electron and hole transport, generation-recombination of electron-hole pairs as well as heat transport. The most significant contribution to the entropy production comes from the interaction of light with the medium in both Si and Ge. This interaction includes two processes, namely, the generation of electron-hole pairs and the transferring of energy from the absorbed light to the lattice. In Si the following contribution in magnitude comes from the heat transport. In Ge all the remaining contributions to entropy production have nearly the same order of magnitude. The results are compared and explained addressing the differences in the magnitude of the thermodynamic forces, Onsager’s coefficients and transport properties of Si and Ge.

  11. Fabrication and its characteristics of low-temperature polycrystalline silicon thin films

    Institute of Scientific and Technical Information of China (English)

    LASSAUT; J

    2009-01-01

    In order to reduce the cost of solar cells or flat-panel display, it is very important to synthesis poly-crystalline silicon films on low cost substrate such as glass at low temperature. In this work, electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (PECVD) system was successfully applied to synthesize poly-Si thin-film on common glass substrate using H2 as the plasma source and SiH4 (Ar:SiH4=19:1) as the precursor gas at low temperature. Since the multicusp cav- ity-coupling ECR plasma source was adopted to provide active precursors, the growth temperature decreased to lower than 200℃. In the plasma, the electron temperatures kTe are ~2―3 eV and the ion temperatures kTi≤1 eV. This leads to non-remarkable ion impacts during the film deposition. The characteristic of poly-Si films was investigated. It was shown that the crystalline fraction Xc of the films can be up to 90% even deposit at room temperature, and the film was (220) preferably oriented. The growth behaviors of the film between the interface of glass and Si films were also discussed in detail.

  12. Thin pixel development for the SuperB silicon vertex tracker

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, G., E-mail: giuliana.rizzo@pi.infn.it [INFN-Pisa and Universita di Pisa (Italy); Avanzini, C.; Batignani, G.; Bettarini, S.; Bosi, F.; Ceccanti, M.; Cenci, R.; Cervelli, A.; Crescioli, F.; Dell' Orso, M.; Forti, F.; Giannetti, P.; Giorgi, M.A. [INFN-Pisa and Universita di Pisa (Italy); Lusiani, A. [Scuola Normale Superiore and INFN-Pisa (Italy); Gregucci, S.; Mammini, P.; Marchiori, G.; Massa, M.; Morsani, F.; Neri, N. [INFN-Pisa and Universita di Pisa (Italy); and others

    2011-09-11

    The high luminosity SuperB asymmetric e{sup +}e{sup -} collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 10{sup 36} cm{sup -2} s{sup -1} with moderate beam currents and a reduced center of mass boost with respect to earlier B-Factories. An improved vertex resolution is required for precise time-dependent measurements and the SuperB Silicon Vertex Tracker will be equipped with an innermost layer of small radius (about 1.5 cm), resolution of 10-15{mu}m in both coordinates, low material budget (<1% X0), and able to withstand a background rate of several tens of MHz/cm{sup 2}. The ambitious goal of designing a thin pixel device with these stringent requirements is being pursued with specific R and D programs on different technologies: hybrid pixels, CMOS MAPS and pixel sensors developed with vertical integration technology. The latest results on the various pixel options for the SuperB SVT will be presented.

  13. The 30-band k ṡ p theory of valley splitting in silicon thin layers

    Science.gov (United States)

    Čukarić, Nemanja A.; Partoens, Bart; Tadić, Milan Ž.; Arsoski, Vladimir V.; Peeters, F. M.

    2016-05-01

    The valley splitting of the conduction-band states in a thin silicon-on-insulator layer is investigated using the 30-band k ṡ p theory. The system composed of a few nm thick \\text{Si} layer embedded within thick SiO2 layers is analyzed. The valley split states are found to cross periodically with increasing quantum well width, and therefore the energy splitting is an oscillatory function of the quantum well width, with period determined by the wave vector K 0 of the conduction band minimum. Because the valley split states are classified by parity, the optical transition between the ground hole state and one of those valley split conduction band states is forbidden. The oscillations in the valley splitting energy decrease with electric field and with smoothing of the composition profile between the well and the barrier by diffusion of oxygen from the SiO2 layers to the Si quantum well. Such a smoothing also leads to a decrease of the interband transition matrix elements. The obtained results are well parametrized by the effective two-valley model, but are found to disagree from previous 30-band calculations. This discrepancy could be traced back to the fact that the basis for the numerical solution of the eigenproblem must be restricted to the first Brillouin zone in order to obtain quantitatively correct results for the valley splitting.

  14. Improvement of small-area, amorphous-silicon thin-film photovoltaics on polymer substrate

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.F. (Minnesota Mining and Mfg. Co., St. Paul, MN (USA). Applied Technologies Lab.)

    1990-02-01

    This report describes a contract to produce, using roll-to-roll deposition on polyamide substrate, a small-area amorphous-silicon p-i-n photovoltaic (PV) cell with an energy conversion efficiency of 10% under air mass 1.5 insolation. Three improvements were attempted to achieve this goal: (1) zinc oxide, a transparent conducting oxide, was used as a top contact; the zinc oxide conductivity was improved to 8--9 ohms/square sheet resistance with less than 8% average optical absorption. (2) The red light response was improved with dielectric enhanced metal reflecting electrodes, which increased the short-circuit current density by more than 1 mA/Cm{sup 2}; a three-layer dielectric mirror coating was also designed that can increase the current density by another 1 mA/cm{sup 2}. (3) Improving the fill factor of the n-i-p (reverse structured) devices was also achieved in a multichamber deposition system. The overall energy conversion efficiency of the PV cell was 8.36%. Major obstacles to higher efficiencies are (1) controlling the thin-film defects that cause electrical shunts in devices fabricated on enhanced reflection electrodes, and (2) controlling impurities and introducing dopant profiles near the p/i interface in a continuous web deposition system.

  15. Fabrication and its characteristics of low-temperature polycrystalline silicon thin films

    Institute of Scientific and Technical Information of China (English)

    WU AiMin; DENG WanTing; QIN FuWen; LI BoHai; LASSAUT J; JIANG Xin; DONG Chuang

    2009-01-01

    In order to reduce the cost of solar cells or flat-panel display, it is very important to synthesis poly-crystalline silicon films on low cost substrate such as glass at low temperature. In this work, electron cyclotron resonance (ECR) plasma enhanced chemical vapor deposition (PECVD) system was suc-cessfully applied to synthesize poly-Si thin-film on common glass substrate using H2 as the plasma source and SiH4 (Ar'SiH4=19:1) as the precursor gas at low temperature. Since the multicusp cav-ity-coupling ECR plasma source was adopted to provide active precursors, the growth temperature decreased to lower than 200℃. In the plasma, the electron temperatures kTe are -2--3 eV and the ion temperatures kTi≤1 eV. This leads to non-remarkable ion impacts during the film deposition. The characteristic of poly-Si films was investigated. It was shown that the crystalline fraction Xc of the films can be up to 90% even deposit at room temperature, and the film was (220) preferably oriented. The growth behaviors of the film between the interface of glass and Si films were also discussed in detail.

  16. Numerical 3D-simulation of micromorph silicon thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Geissendoerfer, Stefan; Lacombe, Juergen; Maydell, Karsten von; Agert, Carsten [EWE-Forschungszentrum fuer Energietechnologie e.V. NEXT ENERGY, Carl-von-Ossietzky-Str. 15, 26129 Oldenburg (Germany)

    2011-07-01

    In this contribution 3-dimensional simulations of micromorph silicon thin film solar cells, which have a tandem structure consisting of amorphous and microcrystalline subcells, are presented. The variety of different active layers leads to a very complex structure. Additionally, randomly textured surfaces and interfaces have to be taken into account. Our goal is to create physical models to describe the coupled optical and electrical behaviour of the whole structure in three dimensions to determine the theoretical limits and dominant material parameters. To simulate solar cells with rough interfaces, the surfaces topography was measured via atomic force microscopy (AFM) and transferred to the commercial software Sentaurus TCAD from the company Synopsys. The virtual structure includes layer thicknesses and optoelectronic parameters. Results of the space resolved optical generation rates by using the optical solver ''Raytracer'' are presented. The space resolved optical generation rate inside the semiconductor layers depends on the structure of the TCO interface. Therefore, regions with higher charge carrier densities can be observed which has an influence on the current transport through the stack. These investigations and the influence to the IV characteristic are presented.

  17. Semi-coherent optical modelling of thin film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Walder, Cordula; Lacombe, Juergen; Maydell, Karsten von; Agert, Carsten [EWE-Forschungszentrum fuer Energietechnologie e.V., Carl-von-Ossietzky-Strasse 15, 26129 Oldenburg (Germany)

    2011-07-01

    At NEXT ENERGY the experimental investigation of thin film silicon solar cells is combined with numerical simulations using the software Sentaurus TCAD from Synopsys. We present the results of optical modelling with Sentaurus TCAD based on the one-dimensional semi-coherent optical model by Janez Krc. The idea of this model is that after interacting with a rough interface the incident light is split into a direct coherent part treated as electromagnetic waves and in a diffuse incoherent part treated as light beams. The proportion of either direct or diffuse part is determined by the haze parameter which can be obtained from spectrometer data. In order to describe the scattering effects at rough interfaces the intensities of the diffuse light are scaled with angular distribution functions. These functions are obtained from angle resolved scattering measurements. The optical model will be verified by experimental data and compared to the Raytracer and the Transfer Matrix Model. Furthermore the influence of different angles of incidence and of the spectral dependency on the solar cell performance will be investigated.

  18. Photonic and plasmonic structures for enhancing efficiency of thin film silicon solar cells

    Science.gov (United States)

    Pattnaik, Sambit

    Crystalline silicon solar cells use high cost processing techniques as well as thick materials that are ˜ 200µm thick to convert solar energy into electricity. From a cost viewpoint, it is highly advantageous to use thin film solar cells which are generally made in the range of 0.1-3µm in thickness. Due to this low thickness, the quantity of material is greatly reduced and so is the number and complexity of steps involved to complete a device, thereby allowing a continuous processing capability improving the throughput and hence greatly decreasing the cost. This also leads to faster payback time for the end user of the photovoltaic panel. In addition, due to the low thickness and the possibility of deposition on flexible foils, the photovoltaic (PV) modules can be flexible. Such flexible PV modules are well suited for building-integrated applications and for portable, foldable, PV power products. For economical applications of solar cells, high efficiency is an important consideration. Since Si is an indirect bandgap material, a thin film of Si needs efficient light trapping to achieve high optical absorption. The previous work in this field has been mostly based on randomly textured back reflectors. In this work, we have used a novel approach, a periodic photonic and plasmonic structure, to optimize current density of the devices by absorbing longer wavelengths without hampering other properties. The two dimensional diffraction effect generated by a periodic structure with the plasmonic light concentration achieved by silver cones to efficiently propagate light in the plane at the back surface of a solar cell, achieves a significant increase in optical absorption. Using such structures, we achieved a 50%+ increase in short circuit current in a nano-crystalline (nc-Si) solar cell relative to stainless steel. In addition to nc-Si solar cells on stainless steel, we have also used the periodic photonic structure to enhance optical absorption in amorphous cells and

  19. Finite Element Analysis of Silicon Thin Films on Soft Substrates as Anodes for Lithium Ion Batteries

    Science.gov (United States)

    Shaffer, Joseph

    2011-12-01

    The wide-scale use of green technologies such as electric vehicles has been slowed due to insufficient means of storing enough portable energy. Therefore it is critical that efficient storage mediums be developed in order to transform abundant renewable energy into an on-demand source of power. Lithium (Li) ion batteries are seeing a stream of improvements as they are introduced into many consumer electronics, electric vehicles and aircraft, and medical devices. Li-ion batteries are well suited for portable applications because of their high energy-to-weight ratios, high energy densities, and reasonable life cycles. Current research into Li-ion batteries is focused on enhancing its energy density, and by changing the electrode materials, greater energy capacities can be realized. Silicon (Si) is a very attractive option because it has the highest known theoretical charge capacity. Current Si anodes, however, suffer from early capacity fading caused by pulverization from the stresses induced by large volumetric changes that occur during charging and discharging. An innovative system aimed at resolving this issue is being developed. This system incorporates a thin Si film bonded to an elastomeric substrate which is intended to provide the desired stress relief. Non-linear finite element simulations have shown that a significant amount of deformation can be accommodated until a critical threshold of Li concentration is reached; beyond which buckling is induced and a wavy structure appears. When compared to a similar system using rigid substrates where no buckling occurs, the stress is reduced by an order of magnitude, significantly prolonging the life of the Si anode. Thus the stress can be released at high Li-ion diffusion induced strains by buckling the Si thin film. Several aspects of this anode system have been analyzed including studying the effects of charge rate and thin film plasticity, and the results are compared with preliminary empirical measurements to

  20. Research and development of photovoltaic power system. Development of novel technologies for fabrication of high quality silicon thin films for solar cells; Taiyoko hatsuden system no kenkyu kaihatsu. Kohinshitsu silicon usumaku sakusei gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, T. [Kanazawa University, Ishikawa (Japan). Faculty of Engineering

    1994-12-01

    Described herein are the results of the FY1994 research program for development of novel technologies for fabrication of high quality thin films of silicon for solar cells. The study on the mechanisms and effects of chemical annealing reveals that the film structure greatly varies depending on substrate temperature during the hydrotreatment process, based on the tests with substrate temperature, deposition of superthin film (T1) and hydrotreatment (T2) as the variable parameters. Chemical annealing at low temperature produces a high-quality a-Si:H film of low defect content. The study on fabrication of thin polycrystalline silicon films at low temperature observes on real time the process of deposition of the thin films on polycrystalline silicon substrates, where a natural oxide film is removed beforehand from the substrate. The results indicate that a thin polycrystalline silicon film of 100% crystallinity can be formed even on a polycrystalline silicon substrate by controlling starting gas composition and substrate temperature. The layer-by-layer method is used as the means for forming the seed crystals on a glass substrate, where deposition and hydrotreatment are repeated alternately, to produce the thin crystalline silicon films of high crystallinity. 3 figs.

  1. Grazing incidence X-ray fluorescence analysis of buried interfaces in periodically structured crystalline silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Eisenhauer, David; Preidel, Veit; Becker, Christiane [Young Investigator Group Nanostructured Silicon for Photovoltaic and Photonic Implementations (Nano-SIPPE), Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Pollakowski, Beatrix; Beckhoff, Burkhard [Physikalisch-Technische Bundesanstalt, Berlin (Germany); Baumann, Jonas; Kanngiesser, Birgit [Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin (Germany); Amkreutz, Daniel; Rech, Bernd [Institut Silizium Photovoltaik, Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Back, Franziska; Rudigier-Voigt, Eveline [SCHOTT AG, Mainz (Germany)

    2015-03-01

    We present grazing incidence X-ray fluorescence (GIXRF) experiments on 3D periodically textured interfaces of liquid phase crystallized silicon thin-film solar cells on glass. The influence of functional layers (SiO{sub x} or SiO{sub x}/SiC{sub x}) - placed between glass substrate and silicon during crystallization - on the final carbon and oxygen contaminations inside the silicon was analyzed. Baring of the buried structured silicon surface prior to GIXRF measurement was achieved by removal of the original nano-imprinted glass substrate by wet-chemical etching. A broad angle of incidence distribution was determined for the X-ray radiation impinging on this textured surface. Optical simulations were performed in order to estimate the incident radiation intensity on the structured surface profile considering total reflection and attenuation effects. The results indicate a much lower contamination level for SiO{sub x} compared to the SiO{sub x}/SiC{sub x} interlayers, and about 25% increased contamination when comparing structured with planar silicon layers, both correlating with the corresponding solar cell performances. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Effects of neutral particle beam on nano-crystalline silicon thin films, with application to thin film transistor backplane for flexible active matrix organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jin Nyoung; Song, Byoung Chul; Lee, Dong Hyeok [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of); Yoo, Suk Jae; Lee, Bonju [National Fusion Research Institute, 52, Yuseong-Gu, Deajeon, 305-333 (Korea, Republic of); Hong, MunPyo, E-mail: goodmoon@korea.ac.kr [Dept. of Display and Semiconductor Physics, Korea University, Chungnam (Korea, Republic of)

    2011-08-01

    A novel deposition process for nano-crystalline silicon (nc-Si) thin films was developed using neutral beam assisted chemical vapor deposition (NBaCVD) technology for the application of the thin film transistor (TFT) backplane of flexible active matrix organic light emitting diode (AMOLED). During the formation of a nc-Si thin film, the energetic particles enhance nano-sized crystalline rather microcrystalline Si in thin films. Neutral Particle Beam (NPB) affects the crystallinity in two ways: (1) NPB energy enhances nano-crystallinity through kinetic energy transfer and chemical annealing, and (2) heavier NPB (such as Ar) induces damage and amorphization through energetic particle impinging. Nc-Si thin film properties effectively can be changed by the reflector bias. As increase of NPB energy limits growing the crystalline, the performance of TFT supports this NPB behavior. The results of nc-Si TFT by NBaCVD demonstrate the technical potentials of neutral beam based processes for achieving high stability and reduced leakage in TFT backplanes for AMOLEDs.

  3. Effect of annealing temperature on optical and electrical properties of metallophthalocyanine thin films deposited on silicon substrate

    Directory of Open Access Journals (Sweden)

    Skonieczny R.

    2016-09-01

    Full Text Available The cobalt phthalocyanine (CoPc thin films (300 nm thick deposited on n-type silicon substrate have been studied using micro-Raman spectroscopy, atomic force spectroscopy (AFM and I-V measurement. The CoPc thin layers have been deposited at room temperature by the quasi-molecular beam evaporation technique. The micro-Raman spectra of CoPc thin films have been recorded in the spectral range of 1000 cm-1 to 1900 cm-1 using 488 nm excitation wavelength. Moreover, using surface Raman mapping it was possible to obtain information about polymorphic forms distribution (before and after annealing of metallophthalocyanine (α and β form from polarized Raman spectra. The I-V characteristics of the Au/CoPc/n-Si/Al Schottky barrier were also investigated. The obtained results showed that influence of the annealing process plays a crucial role in the ordering and electrical conductivity of the molecular structure of CoPc thin films deposited on n-type silicon substrate.

  4. OPTICAL CHARACTERIZATION OF TiO2 THIN FILM ON SILICON SUBSTRATE DEPOSITED BY DC REACTIVE MAGNETRON SPUTTERING

    Institute of Scientific and Technical Information of China (English)

    H.Q. Wang; H. Shen; D.C. Ba; B.W. Wang; L.S. Wen; D. Chen

    2005-01-01

    TiO2 thin film has attracted considerable attention in recent years, due to its different refractive index and transparency with amorphous and different crystals in the visible and near-infrared wavelength region, high dielectric constant, wide band gap, high wear resistance and stability, etc, for which make it being used in many fields. This paper aims to investigate the optical characterization of thin film TiO2 on silicon wafer. The TiO2 thin films were prepared by DC reactive magnetron sputtering process from Ti target. The reflectivity of the films was measured by UV-3101PC, and the index of refraction (n) and extinction coefficient (k) were measured by n & k Analyzer 1200.

  5. Effective Light Trapping in Thin Film Silicon Solar Cells with Nano- and Microscale Structures on Glass Substrate.

    Science.gov (United States)

    Bong, Sungjae; Ahn, Shihyun; Anh, Le Huy Tuan; Kim, Sunbo; Park, Hyeongsik; Shin, Chonghoon; Park, Jinjoo; Lee, Younjung; Yi, Junsin

    2016-05-01

    For thin film silicon-based solar cells, effective light trapping at a broad range of wavelengths (400-1100 nm) is necessary. Normally, etching is only carried out with TCOs, such as SnO2:F and impurity doped ZnO, to form nano-sized craters in the surface morphology to confer a light trapping effect. However, in this study, prior to ZnO:Al etching, periodic structures on the glass substrates were made by photolithography and wet etching to increase the light scattering and internal reflection. The use of periodic structures on the glass substrate resulted in higher haze ratios in the range from 550 nm to 1100 nm, which is the optical absorption wavelength region for thin film silicon solar cells, than obtained by simple ZnO:Al etching. The periodically textured glass with micro-sized structures compensates for the low haze ratio at the middle and long wavelengths of wet etched ZnO:Al. ZnO:Al was deposited on the periodically textured glass, after which the ZnO:Al surface was also etched randomly using a mixed acid solution to form nano-sized craters. The thin film silicon solar cells with 350-nm-thick amorphous silicon absorber layer deposited on the periodic structured glass and etched ZnO:Al generated up to 10.68% more photocurrent, with 11.2% increase of the conversion efficiency compared to the cell deposited on flat glass and etched ZnO:Al.

  6. Structural characterisation of BaTiO{sub 3} thin films deposited on SrRuO{sub 3}/YSZ buffered silicon substrates and silicon microcantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Colder, H.; Jorel, C., E-mail: corentin.jorel@unicaen.fr; Méchin, L. [GREYC, UMR 6072, CNRS, ENSICAEN, UCBN, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Domengès, B. [LAMIPS, CRISMAT-NXP Semiconductors-Presto Engineering laboratory, CNRS-UMR 6508, ENSICAEN, UCBN, 2 rue de la Girafe, 14 000 Caen (France); Marie, P.; Boisserie, M. [CIMAP, UMR 6252, CNRS, ENSICAEN, UCBN, CEA, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Guillon, S.; Nicu, L. [LAAS, CNRS, Univ de Toulouse, 7 avenue du Colonel Roche, 31400 Toulouse (France); Galdi, A. [GREYC, UMR 6072, CNRS, ENSICAEN, UCBN, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Department of Industrial Engineering, CNR-SPIN Salerno, Università di Salerno, 84084 Fisciano, Salerno (Italy)

    2014-02-07

    We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO{sub 3} (BTO) thin films were deposited at two different oxygen pressures, 5.10{sup −2} mbar and 5.10{sup −3} mbar, on SrRuO{sub 3}/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO{sub 3} electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10{sup −2} mbar strain was mostly localized inside the BTO grains whereas at 5.10{sup −3} mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O{sub 2} pressure of 5.10{sup −3} mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission electron microscopy (TEM) was used to investigate the epitaxial quality of the layers and their epitaxial relationship on plain silicon wafers as well as on released microcantilevers, thanks to Focused-Ion-Beam TEM lamella preparation.

  7. Surface and interface characterization of thin-film silicon solar cell structures

    Energy Technology Data Exchange (ETDEWEB)

    Gerlach, Dominic

    2013-02-21

    The properties of Si thin films for solar cells, the interaction with different substrates and the influence of dopants are examined with synchrotron based x-ray spectroscopy - primarily X-ray emission spectroscopy (XES) and hard X-ray photoelectron spectroscopy (HAXPES). The films are studied as-deposited (i.e., amorphous, a-Si) and after conversion into polycrystalline (poly-Si) employing solid phase crystallization (SPC). Si L{sub 2,3} XES spectra of thin-film Si samples can be described by a superposition of a-Si and monocrystalline Si-wafer (c-Si) reference spectra. According to a quantification based on that superposition principle, none of the investigated samples are completely crystallized - a measurable a-Si component always remains (5-20 %) regardless of deposition and treatment conditions. Based on additional results from electron back scattering diffraction different models are developed which may explain this finding. According to these models, the remnant a-Si component can be attributed to amorphous/disordered material at the grain boundaries. Using one of these models, the thickness of this grain-surrounding material s could be approximated to be (1.5 {+-} 0.5) nm. Further investigations of the SPC process reveal a faster crystallization for boron-doped samples, and a slower crystallization for phosphorous-doped samples, when compared to the crystallization of undoped a Si:H thin films. The peculiarities of B K XES spectra (and observed changes upon SPC) indicate that boron could act as a nucleation center promoting crystallization. Si L{sub 2,3} XES spectra of a-Si:H and P-doped poly-Si exhibit spectral features above the valence band maximum at 100 eV that could be attributed to a-Si defect states and n{sup +}-dopant states, respectively. The SPC crystallization velocity of Si thin films on ZnO:Al/glass is found to be faster than that on SiNx/glass substrate. Multiple indications for oxidization at the poly-Si/ZnO:Al interface are found based on

  8. The mechanical properties of 3C thin-film silicon carbide

    Science.gov (United States)

    Jackson, Kamili Moja

    Thin-film silicon carbide is a promising material for microelectromechanical systems (MEMS) because of its resistance to high temperatures and corrosive environments. However, more knowledge of its mechanical properties is needed to produce optimum MEMS devices with this material. Microsample tensile tests have been performed on this material to provide basic mechanical properties. Tests were conducted using tensile specimens with a gage width of 600 mum, gage length of 4 mm, and different thicknesses. The specimens were tested with a custom-built microsample testing machine comprised of specially designed grips, a piezoelectric actuator, and a miniature load cell. Strain was measured with a direct strain measurement system, the Interferometric Strain Displacement Gage. Obstacles to specimen fabrication resulted in a decrease in the amount and quality of the data. Material from Case Western Reserve University (CWRU) and Massachusetts Institute of Technology (MIT) was used; each material had unique fabrication challenges. The CWRU material had difficulties with adhesion of metal for strain measurement and excess material on some specimens. MIT fabrication was time consuming with low yield and required the collaboration of four institutions. Results from tests on epitaxially grown material from CWRU show an elastic modulus of 428 +/- 42 GPa, no Poisson's ratio results, and strengths of 1.13 +/- 0.48 GPa and 1.65 +/- 0.24 GPa for two different batches of material. The elastic modulus is lower than the calculated modulus of 456--466 GPa, but agrees well with previous bulge tests. Results from tests on polycrystalline material from MIT show an average elastic modulus of 428 GPa, strength of 0.49 +/- 0.20 GPa, and an average Poisson's ratio of 0.24 for Batch One. Batch Two, a material with a different texture, resulted in an average elastic modulus of 448 GPa, strength of 0.81 +/- 0.23 GPa, and an average Poisson's ratio of 0.17.

  9. Spatial resolution in thin film deposition on silicon surfaces by combining silylation and UV/ozonolysis

    Science.gov (United States)

    Guo, Lei; Zaera, Francisco

    2014-12-01

    A simple procedure has been developed for the processing of silicon wafers in order to facilitate the spatially resolved growth of thin solid films on their surfaces. Specifically, a combination of silylation and UV/ozonolysis was tested as a way to control the concentration of the surface hydroxo groups required for subsequent atomic layer deposition (ALD) of metals or oxides. Water contact angle measurements were used to evaluate the hydrophilicity/hydrophobicity of the surface, a proxy for OH surface coverage, and to optimize the UV/ozonolysis treatment. Silylation with hexamethyldisilazane, trichloro(octadecyl)silane, or trimethylchlorosilane was found to be an efficient way to block the hydroxo sites and to passivate the underlying surface, and UV/O3 treatments were shown to effectively remove the silylation layer and to regain the surface reactivity. Both O3 and 185 nm UV radiation were determined necessary for the removal of the silylation layer, and additional 254 nm radiation was found to enhance the process. Attenuated total reflection-infrared absorption spectroscopy was employed to assess the success of the silylation and UV/O3 removal steps, and atomic force microscopy data provided evidence for the retention of the original smoothness of the surface. Selective growth of HfO2 films via TDMAHf + H2O ALD was seen only on the UV/O3 treated surfaces; total inhibition of the deposition was observed on the untreated silylated surfaces (as determined by x-ray photoelectron spectroscopy and ellipsometry). Residual film growth was still detected on the latter if the ALD was carried out at high temperatures (250 °C), because the silylation layer deteriorates under such harsh conditions and forms surface defects that act as nucleation sites for the growth of oxide grains (as identified by electron microscopy and scanning electron microscopy). We believe that the silylation-UV/O3 procedure advanced here could be easily implemented for the patterning of surfaces

  10. High-rate deposition of nano-crystalline silicon thin films on plastics

    Energy Technology Data Exchange (ETDEWEB)

    Marins, E.; Guduru, V.; Cerqueira, F.; Alpuim, P. [Centro de Fisica, Universidade do Minho, 4800-058 Guimaraes, 4710-057 Braga (Portugal); Ribeiro, M. [Centro de Nanotecnologia e Materiais Tecnicos, Funcionais e Inteligentes (CeNTI), 4760-034 Vila Nova de Famalicao (Portugal); Bouattour, A. [Institut fuer Physikalische Elektronik (ipe), Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2011-03-15

    Nanocrystalline silicon (nc-Si:H) is commonly used in the bottom cell of tandem solar cells. With an indirect bandgap, nc-Si:H requires thicker ({proportional_to}1 {mu}m) films for efficient light harvesting than amorphous Si (a-Si:H) does. Therefore, thin-film high deposition rates are crucial for further cost reduction of highly efficient a-Si:H based photovoltaic technology. Plastic substrates allow for further cost reduction by enabling roll-to-roll inline deposition. In this work, high nc-Si:H deposition rates on plastic were achieved at low substrate temperature (150 C) by standard Radio-frequency (13.56 MHz) Plasma Enhanced Chemical Vapor Deposition. Focus was on the influence of deposition pressure, inter-electrode distance (1.2 cm) and high power coupled to the plasma, on the hydrogen-to-silane dilution ratios (HD) necessary to achieve the amorphous-to-nanocrystalline phase transition and on the resulting film deposition rate. For each pressure and rf-power, there is a value of HD for which the films start to exhibit a certain amount of crystalline fraction. For constant rf-power, this value increases with pressure. Within the parameter range studied the deposition rate was highest (0.38 nm/s) for nc-Si:H films deposited at 6 Torr, 700 mW/cm{sup 2} using HD of 98.5%. Decreasing the pressure to 3 Torr (1.5 Torr) and rf-power to 350 mW/cm{sup 2} using HD - 98.5% deposition rate is 0.12 nm/s (0.076 nm/s). Raman crystalline fraction of these films is 72, 62 and 53% for the 6, 3 and 1.5 Torr films, respectively (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Vanadium dioxide thin films prepared on silicon by low temperature MBE growth and ex-situ annealing

    Science.gov (United States)

    Homm, Pia; van Bilzen, Bart; Menghini, Mariela; Locquet, Jean-Pierre; Ivanova, Todora; Sanchez, Luis; Sanchis, Pablo

    Vanadium dioxide (VO2) is a material that shows an insulator to metal transition (IMT) near room temperature. This property can be exploited for applications in field effect devices, electro-optical switches and nonlinear circuit components. We have prepared VO2 thin films on silicon wafers by combining a low temperature MBE growth with an ex-situ annealing at high temperature. We investigated the structural, electrical and optical characteristics of films with thicknesses ranging from 10 to 100 nm. We have also studied the influence of the substrate cleaning. The films grown with our method are polycrystalline with a preferred orientation in the (011) direction of the monoclinic phase. For the films produced on silicon with a native oxide, an IMT at around 75 °C is observed. The magnitude of the resistance change across the IMT decreases with thickness while the refractive index at room temperature corresponds with values reported in the literature for thin films. The successful growth of VO2 films on silicon with good electrical and optical properties is an important step towards the integration of VO2 in novel devices. The authors acknowledge financial support from the FWO project G052010N10 and EU-FP7 SITOGA project. PH acknowledges support from Becas Chile - CONICYT.

  12. Mechanical measurements on lithium phosphorous oxynitride coated silicon thin film electrodes for lithium-ion batteries during lithiation and delithiation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Obeidi, Ahmed, E-mail: alobeidi@mit.edu; Thompson, Carl V., E-mail: reiner.moenig@kit.edu, E-mail: cthomp@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Kramer, Dominik, E-mail: dominik.kramer@kit.edu; Mönig, Reiner, E-mail: reiner.moenig@kit.edu, E-mail: cthomp@mit.edu [Institute for Applied Materials, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU), Helmholtzstraße 11, 89081 Ulm (Germany); Boles, Steven T., E-mail: steven.t.boles@polyu.edu.hk [Institute for Applied Materials, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Hong Kong Polytechnic University, 11 Yuk Choi Rd, Hung Hom (Hong Kong)

    2016-08-15

    The development of large stresses during lithiation and delithiation drives mechanical and chemical degradation processes (cracking and electrolyte decomposition) in thin film silicon anodes that complicate the study of normal electrochemical and mechanical processes. To reduce these effects, lithium phosphorous oxynitride (LiPON) coatings were applied to silicon thin film electrodes. Applying a LiPON coating has two purposes. First, the coating acts as a stable artificial solid electrolyte interphase. Second, it limits mechanical degradation by retaining the electrode's planar morphology during cycling. The development of stress in LiPON-coated electrodes was monitored using substrate curvature measurements. LiPON-coated electrodes displayed highly reproducible cycle-to-cycle behavior, unlike uncoated electrodes which had poorer coulombic efficiency and exhibited a continual loss in stress magnitude with continued cycling due to film fracture. The improved mechanical stability of the coated silicon electrodes allowed for a better investigation of rate effects and variations of mechanical properties during electrochemical cycling.

  13. Highly conductive boron doped micro/nanocrystalline silicon thin films deposited by VHF-PECVD for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Juneja, Sucheta; Sudhakar, S., E-mail: sudhakars@nplindia.org; Gope, Jhuma; Lodhi, Kalpana; Sharma, Mansi; Kumar, Sushil

    2015-09-15

    Graphical abstract: AFM images of boron doped micro/nanocrystalline silicon films at different diborane gas flow. - Highlights: • High deposition rate of 10 Å/s was achieved for boron doped silicon films. • Wide range of optical band gap from 1.32 eV to 1.84 eV observed for the deposited films. - Abstract: Boron doped hydrogenated micro/nanocrystalline silicon (μc/nc-Si:H) thin films have been deposited by plasma enhanced chemical vapor deposition technique (PECVD) using silane (SiH{sub 4}) diluted in argon. Diborane (B{sub 2}H{sub 6}) was used as the dopant gas and deposition was carried out at substrate temperature of 200 °C. The diborane flow (F{sub B}) varied in the range 0.00–0.30. Here, we report the effects of B{sub 2}H{sub 6} doping on electronic, optical and structural properties of hydrogenated micro/nanocrystalline silicon films. The structural properties were analyzed by atomic force microscopy (AFM) and X-ray diffraction (XRD). The doped micro/nano crystalline silicon films presented a crystallographic orientation preferentially in the (1 1 1) and (2 2 0) plane. We resolve the deposition parameters that lead to the formation of p-type micro/nanocrystalline silicon thin films with very high value of conductivity and lower optical band gap. Correlations between structural and electrical properties were also studied. Based on temperature dependent conductivity measurements, it has been observed that the room temperature dark conductivity varies in the range 1.45 × 10{sup −4} Ω{sup −1} cm{sup −1} to 2.02 Ω{sup −1} cm{sup −1} for the B-doped films. Meanwhile, the corresponding value of activation energies decreased to 0.06 eV for the B-doped films, which indicates the doped μc/nc-Si films with high conductivity can be achieved and these films prove to be a very good candidate for application in amorphous and micro/nano crystalline silicon solar cells as a p-type window layer.

  14. Realization of dual-heterojunction solar cells on ultra-thin ∼25 μm, flexible silicon substrates

    KAUST Repository

    Onyegam, Emmanuel U.

    2014-04-14

    Silicon heterojunction (HJ) solar cells with different rear passivation and contact designs were fabricated on ∼ 25 μ m semiconductor-on-metal (SOM) exfoliated substrates. It was found that the performance of these cells is limited by recombination at the rear-surface. Employing the dual-HJ architecture resulted in the improvement of open-circuit voltage (Voc) from 605 mV (single-HJ) to 645 mV with no front side intrinsic amorphous silicon (i-layer) passivation. Addition of un-optimized front side i-layer passivation resulted in further enhancement in Voc to 662 mV. Pathways to achieving further improvement in the performance of HJ solar cells on ultra-thin SOM substrates are discussed. © 2014 AIP Publishing LLC.

  15. Irreversible lithium storage during lithiation of amorphous silicon thin film electrodes studied by in-situ neutron reflectometry

    Science.gov (United States)

    Jerliu, Bujar; Hüger, Erwin; Horisberger, Michael; Stahn, Jochen; Schmidt, Harald

    2017-08-01

    Amorphous silicon is a promising high-capacity anode material for application in lithium-ion batteries. However, a huge drawback of the material is that the large capacity losses taking place during cycling lead to an unstable performance. In this study we investigate the capacity losses occurring during galvanostatic lithiation of amorphous silicon thin film electrodes by in-situ neutron reflectometry experiments for the first ten cycles. As determined from the analysis of the neutron scattering length density and of the film thickness, the capacity losses are due to irreversible storage of lithium in the electrode. The amount of stored lithium increases during cycling to 20% of the maximum theoretical capacity after the 10th cycle. Possible explanations are discussed.

  16. Surface morphology and structure of ultra-thin magnesium oxide grown on (100) silicon by atomic layer deposition oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Rochdi, N., E-mail: rochdi.nabil@gmail.com [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS UPR 3118, Aix-Marseille Universite, Case 913, Campus de Luminy, 13288 Marseille cedex 9 (France); Liudvikouskaya, K. [Belarusian State University of Informatics and Radioelectronics, P. Browka 6, 220013 Minsk (Belarus); Descoins, M.; Raissi, M.; Coudreau, C.; Lazzari, J.-L. [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS UPR 3118, Aix-Marseille Universite, Case 913, Campus de Luminy, 13288 Marseille cedex 9 (France); Oughaddou, H. [Commissariat a l' Energie Atomique, DSM-IRAMIS-SPCSI, Bat. 462, Saclay, 91191, Gif-sur-Yvette cedex (France); Universite de Cergy-Pontoise, LAMAp, 95000 Cergy-Pontoise cedex (France); D' Avitaya, F. Arnaud [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS UPR 3118, Aix-Marseille Universite, Case 913, Campus de Luminy, 13288 Marseille cedex 9 (France)

    2011-07-29

    Ultra-thin magnesium oxide layers were elaborated by atomic layer deposition and oxidation process on silicon (100) starting from (2 x 1) thermally-reconstructed or hydrogen-terminated Si surfaces. Low-energy electron diffraction experiments show (2 x 3) and (3 x 3) reconstructions while depositing a magnesium monolayer on Si clean surfaces, and a 3-dimentional growth of the oxide as confirmed by ex-situ atomic force microscopy. For hydrogen-terminated or clean surfaces previously physisorbed by oxygen, uniform cobalt/magnesium-oxide/silicon stacks of layers are observed by transmission electron microscopy. Annealing above 150 deg. C leads to MgO dissolution and formation of an interfacial complex compound by inter-diffusion of Si and Co.

  17. Behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic modules under outdoor long term exposure.

    Science.gov (United States)

    Kichou, Sofiane; Silvestre, Santiago; Nofuentes, Gustavo; Torres-Ramírez, Miguel; Chouder, Aissa; Guasch, Daniel

    2016-06-01

    Four years׳ behavioral data of thin-film single junction amorphous silicon (a-Si) photovoltaic (PV) modules installed in a relatively dry and sunny inland site with a Continental-Mediterranean climate (in the city of Jaén, Spain) are presented in this article. The shared data contributes to clarify how the Light Induced Degradation (LID) impacts the output power generated by the PV array, especially in the first days of exposure under outdoor conditions. Furthermore, a valuable methodology is provided in this data article permitting the assessment of the degradation rate and the stabilization period of the PV modules. Further discussions and interpretations concerning the data shared in this article can be found in the research paper "Characterization of degradation and evaluation of model parameters of amorphous silicon photovoltaic modules under outdoor long term exposure" (Kichou et al., 2016) [1].

  18. Quantification of Power Losses of the Interdigitated Metallization of Crystalline Silicon Thin-Film Solar Cells on Glass

    Directory of Open Access Journals (Sweden)

    Peter J. Gress

    2012-01-01

    Full Text Available The metallization grid pattern is one of the most important design elements for high-efficiency solar cells. This paper presents a model based on the unit cell approach to accurately quantify the power losses of a specialized interdigitated metallization scheme for polycrystalline silicon thin-film solar cells on glass superstrates. The sum of the power losses can be minimized to produce an optimized grid-pattern design for a cell with specific parameters. The model is simulated with the standard parameters of a polycrystalline silicon solar cell, and areas for efficiency improvements are identified, namely, a reduction in emitter finger widths and a shift toward series-interconnected, high-voltage modules with very small cell sizes. Using the model to optimize future grid-pattern designs, higher cell and module efficiencies of such devices can be achieved.

  19. Selected area laser-crystallized polycrystalline silicon thin films by a pulsed Nd:YAG laser with 355 nm wavelength

    Institute of Scientific and Technical Information of China (English)

    Duan Chunyan; Liu Chao; Ai Bin; Lai Jianjun; Deng Youjun; Shen Hui

    2011-01-01

    Selected area laser-crystallized polycrystalline silicon(p-Si)thin films were prepared by the third harmonics(355 nm wavelength)generated by a solid-state pulsed Nd:YAG laser.Surface morphologies of 400 nm thick films after laser irradiation were analyzed.Raman spectra show that film crystallinity is improved with increase of laser energy.The optimum laser energy density is sensitive to the film thickness.The laser energy density for efficiently crystallizing amorphous silicon films is between 440-634 mJ/cm2 for 300 nm thick films and between 777-993 mJ/cm2 for 400 nm thick films.The optimized laser energy density is 634,975 and 1571 mJ/cm2 for 300,400 and 500 nm thick films,respectively.

  20. Chemical interaction at the buried silicon/zinc oxide thin-film solar cell interface as revealed by hard X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wimmer, M., E-mail: mark.wimmer@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Gerlach, D.; Wilks, R.G.; Scherf, S.; Félix, R. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Lupulescu, C. [Institute for Optics and Atomic Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Ruske, F.; Schondelmaier, G.; Lips, K. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Hüpkes, J. [Institute for Energy Research, Forschungszentrum Jülich GmbH, Leo-Brandt-Straße, 52425 Jülich (Germany); Gorgoi, M. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Eberhardt, W. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Institute for Optics and Atomic Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Rech, B. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Bär, M., E-mail: marcus.baer@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Institut für Physik und Chemie, Brandenburgische Technische Universität Cottbus, Konrad-Wachsmann-Allee 1, 03046 Cottbus (Germany)

    2013-10-15

    Highlights: •We used HAXPES to identify chemical interactions at the buried silicon/aluminum-doped zinc oxide thin-film solar cell interface. •The results indicate a diffusion of zinc and aluminum into the silicon upon annealing procedures which are part of the solar cell processing. •The contamination of the silicon may be detrimental for the solar cell performance. -- Abstract: Hard X-ray photoelectron spectroscopy (HAXPES) is used to identify chemical interactions (such as elemental redistribution) at the buried silicon/aluminum-doped zinc oxide thin-film solar cell interface. Expanding our study of the interfacial oxidation of silicon upon its solid-phase crystallization (SPC), in which we found zinc oxide to be the source of oxygen, in this investigation we address chemical interaction processes involving zinc and aluminum. In particular, we observe an increase of zinc- and aluminum-related HAXPES signals after SPC of the deposited amorphous silicon thin films. Quantitative analysis suggests an elemental redistribution in the proximity of the silicon/aluminum-doped zinc oxide interface – more pronounced for aluminum than for zinc – as explanation. Based on these insights the complex chemical interface structure is discussed.

  1. Light-trapping design for thin-film silicon-perovskite tandem solar cells

    Science.gov (United States)

    Foster, Stephen; John, Sajeev

    2016-09-01

    Using finite-difference time-domain simulations, we investigate the optical properties of tandem silicon/perovskite solar cells with a photonic crystal architecture, consisting of a square-lattice array of inverted pyramids with a center-to-center spacing of 2.5 μm. We demonstrate that near-perfect light-trapping and absorption can be achieved over the 300-1100 nm wavelength range with this architecture, using less than 10 μm (equivalent bulk thickness) of crystalline silicon. Using a one-diode model, we obtain projected efficiencies of over 30% for the two-terminal tandem cell under a current-matching condition, well beyond the current record for single-junction silicon solar cells. The architecture is amenable to mass fabrication through wet-etching and uses a fraction of the silicon of traditional designs, making it an attractive alternative to other silicon-perovskite tandem designs.

  2. Growth direction of oblique angle electron beam deposited silicon monoxide thin films identified by optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Vejling Andersen, Søren; Lund Trolle, Mads; Pedersen, Kjeld [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Øst (Denmark)

    2013-12-02

    Oblique angle deposited (OAD) silicon monoxide (SiO) thin films forming tilted columnar structures have been characterized by second-harmonic generation. It was found that OAD SiO leads to a rotationally anisotropic second-harmonic response, depending on the optical angle of incidence. A model for the observed dependence of the second-harmonic signal on optical angle of incidence allows extraction of the growth direction of OAD films. The optically determined growth directions show convincing agreement with cross-sectional scanning electron microscopy images. In addition to a powerful characterization tool, these results demonstrate the possibilities for designing nonlinear optical devices through SiO OAD.

  3. Substrate bias effects on collector resistance in SiGe heterojunction bipolar transistors on thin film silicon-on-insulator

    Institute of Scientific and Technical Information of China (English)

    Xu Xiao-Bo; Zhang He-Ming; Hu Hui-Yong; Qu Jiang-Tao

    2011-01-01

    An analytical expression for the collector resistance of a novel vertical SiGe heteroj unction bipolar transistor (HBT)on thin film silicon-on-insulator (SOI) is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μm millimeter-wave SiGe SOI BiCMOS devices.

  4. Large-Scale PV Module Manufacturing Using Ultra-Thin Polycrystalline Silicon Solar Cells: Final Subcontract Report, 1 April 2002--28 February 2006

    Energy Technology Data Exchange (ETDEWEB)

    Wohlgemuth, J.; Narayanan, M.

    2006-07-01

    The major objectives of this program were to continue advances of BP Solar polycrystalline silicon manufacturing technology. The Program included work in the following areas. (1) Efforts in the casting area to increase ingot size, improve ingot material quality, and improve handling of silicon feedstock as it is loaded into the casting stations. (2) Developing wire saws to slice 100-..mu..m-thick silicon wafers on 290-..mu..m-centers. (3) Developing equipment for demounting and subsequent handling of very thin silicon wafers. (4) Developing cell processes using 100-..mu..m-thick silicon wafers that produce encapsulated cells with efficiencies of at least 15.4% at an overall yield exceeding 95%. (5) Expanding existing in-line manufacturing data reporting systems to provide active process control. (6) Establishing a 50-MW (annual nominal capacity) green-field Mega-plant factory model template based on this new thin polycrystalline silicon technology. (7) Facilitating an increase in the silicon feedstock industry's production capacity for lower-cost solar-grade silicon feedstock..

  5. Cathodic cage plasma deposition of TiN and TiO{sub 2} thin films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Romulo R. M. de [Department of Mechanics, Federal Institute of Education, Science, and Technology of Piaui, Praça da Liberdade, 1597, CEP 64000-040 Teresina, Piaui, Brazil and Department of Mechanical Engineering, Federal University of Piaui, Campus Min. Petronio Portela, Ininga, CEP 64049-550 Teresina, Piaui (Brazil); Sato, Patricia S.; Nascente, Pedro A. P., E-mail: nascente@ufscar.br [Department of Materials Engineering, Federal University of Sao Carlos, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, Sao Paulo (Brazil); Viana, Bartolomeu C. [Department of Physics, Federal University of Piaui, Campus Min. Petronio Portela, Ininga, CEP 64049-550 Teresina, Piaui (Brazil); Alves, Clodomiro [Department of Exact and Natural Sciences, Federal Rural University of Semi Arido, Avenida Francisco Mota, 572, CEP 59625-900 Mossoro, Rio Grande do Norte (Brazil); Nishimoto, Akio [Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2015-07-15

    Cathodic cage plasma deposition (CCPD) was used for growing titanium nitride (TiN) and titanium dioxide (TiO{sub 2}) thin films on silicon substrates. The main advantages of the CCPD technique are the uniformity, tridimensionality, and high rate of the film deposition that occurs at higher pressures, lower temperatures, and lower treatment times than those used in conventional nitriding treatments. In this work, the influence of the temperature and gas atmosphere upon the characteristics of the deposited films was investigated. The TiN and TiO{sub 2} thin films were characterized by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to analyze their chemical, structural, and morphological characteristics, and the combination of these results indicates that the low-cost CCPD technique can be used to produce even and highly crystalline TiN and TiO{sub 2} films.

  6. Structural and optical characterization of ZrO2 thin films grown on silicon and quartz substrates

    Science.gov (United States)

    Hojabri, Alireza

    2016-09-01

    Zirconium oxide thin films were grown successfully by thermal annealing of zirconium thin films deposited on quartz and silicon substrates by direct current magnetron sputtering technique. The structural and optical properties in relation to thermal annealing times were investigated. The X-ray diffraction patterns revealed that structure of films changes from amorphous to crystalline by increase of annealing times in range 60-240 min. The composition of films was determined by Rutherford back scattering spectroscopy. Atomic force microscopy results exhibited that surface morphology and roughness of films depend on the annealing time. The refractive index of the films was calculated using Swanepoel's method. The optical band gap energy of annealed films decreased from 5.50 to 5.34 eV with increasing thermal annealing time.

  7. PVD Silicon Carbide as a Thin Film Packaging Technology for Antennas on LCP Substrates for Harsh Environments

    Science.gov (United States)

    Scardelletti, Maximilian C.; Stanton, John W.; Ponchak, George E.; Jordan, Jennifer L.; Zorman, Christian A.

    2010-01-01

    This paper describes an effort to develop a thin film packaging technology for microfabricated planar antennas on polymeric substrates based on silicon carbide (SiC) films deposited by physical vapor deposition (PVD). The antennas are coplanar waveguide fed dual frequency folded slot antennas fabricated on liquid crystal polymer (LCP) substrates. The PVD SiC thin films were deposited directly onto the antennas by RF sputtering at room temperature at a chamber pressure of 30 mTorr and a power level of 300 W. The SiC film thickness is 450 nm. The return loss and radiation patterns were measured before and after the SiC-coated antennas were submerged into perchloric acid for 1 hour. No degradation in RF performance or physical integrity of the antenna was observed.

  8. Hadron-therapy beam monitoring: Towards a new generation of ultra-thin p-type silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bouterfa, M.; Aouadi, K. [Inst. of Information and Communication Technologies, Electronics and Applied Mathematics ICTEAM, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Bertrand, D. [Particle Therapy Dept., Ion Beam Application IBA, 1348 Louvain-la-Neuve (Belgium); Olbrechts, B.; Delamare, R. [Inst. of Information and Communication Technologies, Electronics and Applied Mathematics ICTEAM, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Raskin, J. P.; Gil, E. C. [Institut de Recherche en Mathematique et Physique IRMP, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium); Flandre, D. [Inst. of Information and Communication Technologies, Electronics and Applied Mathematics ICTEAM, Universite Catholique de Louvain, 1348 Louvain-la-Neuve (Belgium)

    2011-07-01

    Hadron-therapy has gained increasing interest for cancer treatment especially within the last decade. System commissioning and quality assurance procedures impose to monitor the particle beam using 2D dose measurements. Nowadays, several monitoring systems exist for hadron-therapy but all show a relatively high influence on the beam properties: indeed, most devices consist of several layers of materials that degrade the beam through scattering and energy losses. For precise treatment purposes, ultra-thin silicon strip detectors are investigated in order to reduce this beam scattering. We assess the beam size increase provoked by the Multiple Coulomb Scattering when passing through Si, to derive a target thickness. Monte-Carlo based simulations show a characteristic scattering opening angle lower than 1 mrad for thicknesses below 20 {mu}m. We then evaluated the fabrication process feasibility. We successfully thinned down silicon wafers to thicknesses lower than 10 {mu}m over areas of several cm{sup 2}. Strip detectors are presently being processed and they will tentatively be thinned down to 20 {mu}m. Moreover, two-dimensional TCAD simulations were carried out to investigate the beam detector performances on p-type Si substrates. Additionally, thick and thin substrates have been compared thanks to electrical simulations. Reducing the pitch between the strips increases breakdown voltage, whereas leakage current is quite insensitive to strips geometrical configuration. The samples are to be characterized as soon as possible in one of the IBA hadron-therapy facilities. For hadron-therapy, this would represent a considerable step forward in terms of treatment precision. (authors)

  9. Technology development of the nano-crystalline silicon thin film materials%纳米晶硅薄膜材料的技术发展

    Institute of Scientific and Technical Information of China (English)

    吴大维; 吴越侠; 唐志斌

    2012-01-01

    The recent development of the nano - crystalline silicon thin film material is reviewed in this paper. Some ideas is proposed to promote advances of the silicon thin film solar cells. In this paper, we make come discussions on the development of silicon thin film solar cells and predict the prospect of latest ones.%本文综述了硅基薄膜材料的发展历程;提出了一些促进硅基薄膜电池技术进步的思路;并对硅 基薄膜电池的发展进行了有益的探讨,对最新的硅基薄膜太阳能电池作了展望.

  10. Analysis of light propagation for a crossing of thin silicon wires using vertical tunnelling coupling with a thick optical channel waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Tsarev, A V; Kolosovskii, E A [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2013-08-31

    Using silicon photonic wires in a silicon-on-insulator structure as an example, we examine the problem of crossings of thin, high-index-contrast channel waveguides. To ensure high optical wave transmission efficiency at as low a level of parasitic scattering as possible, we propose using a structure with vertical coupling between a thin tapered silicon waveguide and a thick polymer waveguide, separated by a thin buffer oxide layer. Numerical simulation is used to find conditions under which such a structure (3 × 90 μm in dimensions) ensures 98 % and 99 % transmission efficiency at ∼1.55 μm in 35- and 26-nm spectral ranges, respectively, for direct propagation and 99.99 % transmission in the transverse direction. The optical element in question is proposed for use in optical microchips with multiple channel waveguide crossings. (integrated optical waveguides)

  11. Ultra-thin crystalline silicon films produced by plasma assisted epitaxial growth on silicon wafers and their transfer to foreign substrates*

    Directory of Open Access Journals (Sweden)

    Cabarrocas P. Roca i

    2010-10-01

    Full Text Available We have developed a new process to produce ultra-thin crystalline silicon films with thicknesses in the range of 0.1 − 1 μm on flexible substrates. A crystalline silicon wafer was cleaned by SiF4 plasma exposure and without breaking vacuum, an epitaxial film was grown from SiF4, H2 and Ar gas mixtures at low substrate temperature (Tsub ≈ 200 °C in a standard RF PECVD reactor. We found that H2 dilution is a key parameter for the growth of high quality epitaxial films and modification of the structural composition of the interface with the c-Si wafer, allowing one to switch from a smooth interface at low hydrogen flow rates to a fragile one, composed of hydrogen-rich micro-cavities, at high hydrogen flow rates. This feature can be advantageously used to separate the epitaxial film from the crystalline Si wafer. As a example demonstration, we show that by depositing a metal film followed by a spin-coated polyimide layer and applying a moderate thermal treatment to the stack, the fragile interface breaks down and allows one to obtain an ultrathin crystalline wafer on the flexible polyimide support.

  12. Study of nanoparticles TiO2 thin films on p-type silicon substrate using different alcoholic solvents

    Science.gov (United States)

    Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

    2016-07-01

    In this paper, sol-gel method spin coating technique is adopted to prepare nanoparticles titanium dioxide (TiO2) thin films. The prepared TiO2 sol was synthesized using titanium butoxide act as a precursor and subjected to deposited on the p-type silicon oxide (p-SiO2) and glass slide substrates under room temperature. The effect of different alcoholic solvents of methanol and ethanol on the structural, morphological, optical and electrical properties were systematically investigated. The coated TiO2 thin films were annealed in furnace at 773 K for 1 h. The structural properties of the TiO2 films were examined with X-ray Diffraction (XRD). From the XRD analysis, both solvents showing good crystallinity with anatase phase were the predominant structure. Atomic Force Microscopy (AFM) was employed to study the morphological of the thin films. The optical properties were investigated by Ultraviolet-visible (UV-Vis) spectroscopy were found that ethanol as a solvent give a higher optical transmittance if compare to the methanol solvent. The electrical properties of the nanoparticles TiO2 thin films were measured using two-point-probe technique.

  13. Recent progress in thin-film-silicon photovoltaic devices at CIEMAT; Recientes progresos en la tecnologia de dispositivos fotovoltaicos de silicio en lamina delgada en el CIEMAT

    Energy Technology Data Exchange (ETDEWEB)

    Gandia, J. J.; Carabe, J.

    2011-07-01

    Solar photovoltaic energy has evolved in the last 50 years on the basis of the co-existence of two fundamental technological paths: that of wafer-based silicon, dominating the market, and that of thin films, representing an important part of the options for the future of this energy-conversion field. More recently new concepts have gained significance, such as concentration photovoltaic (CPV), dye-sensitised solar cells (DSSC), organic cells, silicon-heterojunction (SHJ) cells and thin-crystalline silicon devices among others. over 90% of all these PV technologies are based on the use of either of the forms of the most abundant element of the earth crust: silicon. CIEMAT, being aware of the relevant role renewable energies and post-vocalic in particular must play in dinging solutions to the energy and environmental problem, has several action lines within this discipline. Among them is the one developed at the laboratory for Deposited-silicon Devices (DSD), entirely devoted to acquiring by own means the technology required for the fabrication of thin-film-silicon-based PV devices in order to be in conditions to give a maximum support to the Spanish industry in this field. Within the context of the historic evolution of PV technology in the world, this paper describes the progress of the DSD lab in the last years, according to a plan aimed at developing technology of the maximum strategic value. such a working scheme, supported by valuable collaborations, has led the group to a reference position in the areas of thin-film-silicon p-i-n devices on glass, silicon-heterojunction cells and p-i-n devices on flexible substrates. (Author) 5 refs.

  14. Impact of contamination on hydrogenated amorphous silicon thin films and solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Woerdenweber, Jan

    2011-09-26

    This thesis deals with atmospheric contamination and cross-contamination of boron (single-chamber process) of the intrinsic absorber layer (i-layer) of p-i-n thin film solar cells based on hydrogenated amorphous silicon. The atmospheric contaminations were introduced by means of intentional leaks. Hereby, the focus is on the influence of contamination species (oxygen and nitrogen), quantity of contamination (leak flow), source of contamination (leaks at chamber wall or in the process gas pipe), and plasma power on the properties of solar cells. Thereby, the minimum requirements for the purity of vacuum and process gas as well as leak conditions of the recipient and gas pipe system have been determined. Additionally, deposition regimes were developed, where the incorporation of impurities is significantly suppressed. For standard processes critical levels of nitrogen and oxygen contamination are determined to be {proportional_to} 4 x 10{sup 18} cm{sup -3} and {proportional_to} 2 x 10{sup 19} cm{sup -3}, respectively, for a leak situated at the chamber wall. Above these concentrations the solar cell efficiency deteriorates. In literature, incorporation of oxygen and nitrogen in doping configuration is assumed to be the reason for the cell deterioration. This assumption is supported by additional material studies of contaminated absorber layers done in this work. The difference in critical concentration is due to the higher doping efficiency of nitrogen compared to that for oxygen. Nevertheless, applying an air leak the critical concentrations of O and N are reached almost simultaneously since the incorporation probability of oxygen is about one order of magnitude higher compared to that for nitrogen. Applying a leak in the process gas pipe the critical oxygen contamination level increases to {proportional_to} 2 x 10{sup 20} cm{sup -3} whereas the critical nitrogen level remains unchanged compared to a chamber wall leak. Applying a deposition regime with a very high

  15. Electron spin resonance investigaton of semiconductor materials for application in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lihong

    2012-07-01

    In the present work, hydrogenated silicon and its alloys silicon carbide and silicon oxide have been investigated using electron spin resonance (ESR). The microstructure of these materials ranges from highly crystalline to amorphous. The correlation between the paramagnetic defects, microstructure, optical and electrical properties has been discussed. Correspondingly, these properties were characterized by the spin density (N{sub S}), g-value and the lineshape of ESR spectra, Infrared (I{sup IR}{sub C}) and/or Raman crystallinity (I{sup RS}{sub C}) as well as optical absorption and electrical dark conductivity ({sigma}{sub D}). 1. As the light absorber, Si layers essentially should have low defect density and good stability against light exposure. The spin density (N{sub S}) measured by ESR is often used as a measure for the paramagnetic defect density (N{sub D}) in the material. However, ESR sample preparation procedures can potentially cause discrepancy between N{sub S} and N{sub D}. Using Mo-foil, Al-foil and ZnO:Al-covered glass as sacrificial substrates, {mu}c-Si:H and a-Si:H films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and ESR powder samples have been prepared with corresponding procedures. Possible preparation-related metastability and instability effects have been investigated in terms of substrate dependence, HCl-etching and atmosphere exposure. A sequence of 'preparation - annealing - air-exposure - annealing' has been designed to investigate the metastability and instability effects. N{sub S} after post-preparation air exposure is higher than in the annealed states, especially for the highly crystalline {mu}c-Si:H material the discrepancy reached one order of magnitude. Low temperature ESR measurements at 40 K indicated that atmospheric exposure leads to a redistribution of the defect states which in turn influence the evaluated N{sub S}. In annealed conditions the samples tend to have lower N{sub S} presumably due

  16. Electron spin resonance investigaton of semiconductor materials for application in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lihong

    2012-07-01

    In the present work, hydrogenated silicon and its alloys silicon carbide and silicon oxide have been investigated using electron spin resonance (ESR). The microstructure of these materials ranges from highly crystalline to amorphous. The correlation between the paramagnetic defects, microstructure, optical and electrical properties has been discussed. Correspondingly, these properties were characterized by the spin density (N{sub S}), g-value and the lineshape of ESR spectra, Infrared (I{sup IR}{sub C}) and/or Raman crystallinity (I{sup RS}{sub C}) as well as optical absorption and electrical dark conductivity ({sigma}{sub D}). 1. As the light absorber, Si layers essentially should have low defect density and good stability against light exposure. The spin density (N{sub S}) measured by ESR is often used as a measure for the paramagnetic defect density (N{sub D}) in the material. However, ESR sample preparation procedures can potentially cause discrepancy between N{sub S} and N{sub D}. Using Mo-foil, Al-foil and ZnO:Al-covered glass as sacrificial substrates, {mu}c-Si:H and a-Si:H films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and ESR powder samples have been prepared with corresponding procedures. Possible preparation-related metastability and instability effects have been investigated in terms of substrate dependence, HCl-etching and atmosphere exposure. A sequence of 'preparation - annealing - air-exposure - annealing' has been designed to investigate the metastability and instability effects. N{sub S} after post-preparation air exposure is higher than in the annealed states, especially for the highly crystalline {mu}c-Si:H material the discrepancy reached one order of magnitude. Low temperature ESR measurements at 40 K indicated that atmospheric exposure leads to a redistribution of the defect states which in turn influence the evaluated N{sub S}. In annealed conditions the samples tend to have lower N{sub S} presumably due

  17. Development of Thin Film Amorphous Silicon Tandem Junction Based Photocathodes Providing High Open-Circuit Voltages for Hydrogen Production

    Directory of Open Access Journals (Sweden)

    F. Urbain

    2014-01-01

    Full Text Available Hydrogenated amorphous silicon thin film tandem solar cells (a-Si:H/a-Si:H have been developed with focus on high open-circuit voltages for the direct application as photocathodes in photoelectrochemical water splitting devices. By temperature variation during deposition of the intrinsic a-Si:H absorber layers the band gap energy of a-Si:H absorber layers, correlating with the hydrogen content of the material, can be adjusted and combined in a way that a-Si:H/a-Si:H tandem solar cells provide open-circuit voltages up to 1.87 V. The applicability of the tandem solar cells as photocathodes was investigated in a photoelectrochemical cell (PEC measurement set-up. With platinum as a catalyst, the a-Si:H/a-Si:H based photocathodes exhibit a high photocurrent onset potential of 1.76 V versus the reversible hydrogen electrode (RHE and a photocurrent of 5.3 mA/cm2 at 0 V versus RHE (under halogen lamp illumination. Our results provide evidence that a direct application of thin film silicon based photocathodes fulfills the main thermodynamic requirements to generate hydrogen. Furthermore, the presented approach may provide an efficient and low-cost route to solar hydrogen production.

  18. Optical modeling of thin film silicon solar cells by combination of the transfer-matrix method and the Raytracer algorithm

    Science.gov (United States)

    Walder, Cordula; Lacombe, Jürgen; von Maydell, Karsten; Agert, Carsten

    2012-06-01

    This article deals with an optical model which describes silicon thin film solar cells with rough interfaces in a fast and easy way. In order to simulate thin layer stacks with rough interfaces diffuse scattering as well as interference effects have to be taken into account. Algorithms like the Finite-Difference Time-Domain method (FDTD) solve the Maxwell Equations and therefore fulfil these demands. Yet they take up a considerable amount of simulation time and computation capacity. To overcome these drawbacks an optical model was developed which combines the Transfer- Matrix-Method (TMM) and the Raytracer algorithm. The fraction of TMM and Raytracer in the model is determined by a separating function which can be interpreted as the integral haze. In order to verify the combined optical model a series of amorphous silicon single cells with varying intrinsic layer thicknesses was produced on two different kinds of textured substrates. The results of the combined optical model are compared to measured data as well as to the simulation results of the FDTD method. It can be shown that the combined optical model yields good results at low simulation time.

  19. 非晶硅锗电池性能的调控研究%Modification to the performance of hydrogenated amorphous silicon germanium thin film solar cell

    Institute of Scientific and Technical Information of China (English)

    刘伯飞; 白立沙; 魏长春; 孙建; 侯国付; 赵颖; 张晓丹

    2013-01-01

    采用射频等离子体增强化学气相沉积技术,研究了非晶硅锗薄膜太阳电池。针对非晶硅锗薄膜材料的本身特性,通过调控硅锗合金中硅锗的比例,实现了对硅锗薄膜太阳电池中开路电压和短路电流密度的分别控制。借助于本征层硅锗材料帯隙梯度的设计,获得了可有效用于多结叠层电池中的非晶硅锗电池。%In this paper, we study hydrogenated amorphous silicon germanium thin film solar cells prepared by the radio frequency plasma-enhanced chemical vapor deposition. In the light of the inherent characteristics of hydrogenated amorphous silicon germanium mate-rial, the modulation of the germanium/silicon ratio in silicon germanium alloys can separately control open circuit voltage (Voc) and short circuit current density (Jsc) of a-SiGe:H thin film solar cells. By the structural design of band gap profiling in the amorphous silicon germanium intrinsic layer, hydrogenated amorphous silicon germanium thin film solar cells, which can be used efficiently as the component cell of multi-junction solar cells, are obtained.

  20. Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.

    Science.gov (United States)

    Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

    2014-10-01

    A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell.

  1. Synthesis of nanocrystalline silicon thin films using the increase of the deposition pressure in the hot-wire chemical vapour deposition technique

    Directory of Open Access Journals (Sweden)

    J.K. Rath

    2010-01-01

    Full Text Available Nanostructured thin silicon-based films have been deposited using the hot-wire chemical vapour deposition (HWCVD technique at the University of the Western Cape. A variety of techniques including optical and infrared spectroscopy, Raman scattering spectroscopy, X-rays diffraction (XRD and transmission electron microscopy (TEM have been used for characterisation of the films. The electrical measurements show that the films have good values of photoresponse, and the photocurrent remains stable after several hours of light soaking. This contribution will discuss the characteristics of the hydrogenated nanocrystalline silicon thin films deposited using increased process chamber pressure at a fixed hydrogen dilution ratio in monosilane gas.

  2. CMOS compatible fabrication of flexible and semi-transparent FeRAM on ultra-thin bulk monocrystalline silicon (100) fabric

    KAUST Repository

    Ghoneim, Mohamed T.

    2014-08-01

    Commercialization of flexible electronics requires reliable, high performance, ultra-compact and low power devices. To achieve them, we fabricate traditional electronics on bulk mono-crystalline silicon (100) and transform the top portion into an ultra-thin flexible silicon fabric with prefabricated devices, preserving ultra-large-scale-integration density and same device performance. This can be done in a cost effective manner due to its full compatibility with standard CMOS processes. In this paper, using the same approach, for the first time we demonstrate a ferroelectric random access memory (FeRAM) cell on flexible silicon fabric platform and assess its functionality and practical potential.

  3. Polycrystalline silicon thin-film solar cells prepared by layered laser crystallization with 540 mV open circuit voltage

    Energy Technology Data Exchange (ETDEWEB)

    Plentz, Jonathan, E-mail: jonathan.plentz@ipht-jena.de [Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena (Germany); Experimental Physics I, Institute of Physics, Ilmenau University of Technology, Weimarer Str. 32, 98693 Ilmenau (Germany); Andrä, Gudrun; Gawlik, Annett; Höger, Ingmar; Jia, Guobin; Falk, Fritz [Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena (Germany)

    2014-07-01

    Polycrystalline silicon thin film solar cells on a glass substrate are investigated. The solar cell layer structure was generated by a two-step process in which first a 100–600 nm thin seed layer is formed by diode laser crystallization of electron beam evaporated amorphous silicon. In a second step this layer is epitaxially thickened to 2–3.5 μm by layered laser crystallization. In this process further amorphous silicon is deposited and in situ repeatedly is irradiated by excimer laser pulses. The polycrystalline layer consists of grains several hundreds of microns long and several tens of microns wide and it contains a p{sup +}–p–n{sup +} doping profile. After deposition a rapid thermal annealing and hydrogen passivation steps follow. The back and front contacts are prepared after mesa structuring. The influence of the seed layer thickness on the solar cell performance was investigated. In addition, the absorber contamination due to the background pressure during absorber deposition and its influence on the short circuit current density was investigated. The best parameters reached for various solar cells are 540 mV open circuit voltage, 20.3 mA/cm{sup 2} short circuit current density (without light trapping), 75% fill factor, and 5.2% efficiency. - Highlights: • Layered laser crystallization leads to grain sizes of 10–300 μm on glass. • Open circuit voltage of 540 mV and efficiency of 5.2% are achieved. • Short circuit current is influenced by background pressure during deposition. • Short circuit current density of 20.3 mA/cm{sup 2} is reached without light trapping. • Progress requires pressures below 10{sup −7} hPa and deposition rates over 100 nm/min.

  4. Enhancement of silicon using micro-patterned surfaces of thin films

    Directory of Open Access Journals (Sweden)

    E Kaivosoja

    2010-04-01

    Full Text Available Micro-textured biomaterials might enhance cytocompatibility of silicon-based micro-electro-mechanical system (bio-MEMS dummies. Photolithography-physical vapour deposition was used to produce diamond-like carbon (DLC or Ti squares and circles on silicon, and also their inverse replicas; then DLC and Ti were compared for their guiding potential, using a SaOS-2 cell model. Scanning electron microscopy at 48 hours indicated cells were well-spread on large-sized patterns (several cells on one pattern and assumed the geometrical architecture of underlying features. Medium-sized patterns (slightly smaller than solitary indicator cells were inhabited by singular cells, which stretched from one island to another, assuming longitudinal or branching morphologies. On small-sized patterns (much smaller than individual cells cells covered large micro-textured areas, but cellular filopodia bypassed the bare silicon. Immunofluorescence and confocal laser scanning microscopy indicated that the actin cytoskeleton and vinculin-containing adhesion junctions were present on the patterned areas, but not on the bare silicon. Cell density/coverage disclosed a 3.4-3.7-fold preference for the biomaterial patterns over silicon substrate (p < 0.001. Differences in the cellular response between materials were lost at 120 hours when cells were confluent. The working hypothesis was proven; enhancement by micro-patterning depends on the pattern size, shape and material and can be used to improve biocompatibility during the initial integration phase of the device.

  5. Optimization of optical absorption in thin layers of amorphous silicon enhanced by silver nanospheres

    CERN Document Server

    Omelyanovich, Mikhail; Simovski, Constantin

    2015-01-01

    We study a highly controllable perfect plasmonic absorber -- a thin metamaterial layer which possess balanced electric and magnetic responses in some frequency range. We show that this regime is compatible with both metal-backed variant of the structure or its semitransparent variant. This regime can be implemented in a prospective thin-film photovoltaic cell with negligible parasitic losses.

  6. Thin Silicon Solar Cells: A Path to 35% Shockley-Queisser Limits

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Laura; Boccard, Mathieu; Williams, Joshua; Jeffries, April; Gangam, Srikanth; Ghosh, Kunal; Honsberg, Christiana; Bowden, Stuart; Holman, Zachary; Atwater, Harry; Buonassisi, Tonio; Bremner, Stephen; Green, Martin; Balif, Christoph; Bertoni, Mariana

    2014-06-08

    Crystalline silicon technology is expected to remain the leading photovoltaic industry workhorse for decades. We present here the objectives and workplan of a recently launched project funded by the U.S. Department of Energy through the Foundational Program to Advance Cell Efficiency II (FPACE II), which aims at leading crystalline silicon to an efficiency breakthrough. The project will tackle fundamental approach of materials design, defect engineering, device simulations and materials growth and characterization. Among the main novelties, the implementation of carrier selective contacts made of wide bandgap material or stack of materials is investigated for improved passivation, carrier extraction and carrier transport. Based on an initial selection of candidate materials, preliminary experiments are conducted to verify the suitability of their critical parameters as well as preservation of the silicon substrate surface and bulk properties. The target materials include III-V and metal-oxide materials.

  7. Plasma-induced TCO texture of ZnO:Ga back contacts on silicon thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Kuang-Chieh; Houng, Mau-Phon [Institute of Microelectronics, Department of Electrical Engineering, National Cheng Kung University, No. 1, Dasyue Rd., East District, Tainan City 701 (China); Wang, Jen-Hung; Lu, Chun-hsiung; Tsai, Fu-Ji; Yeh, Chih-Hung [NexPower Technology Corporation, Taichung County 421 (China)

    2011-02-15

    This paper considers texturing of ZnO:Ga (GZO) films used as back contacts in amorphous silicon (a-Si) thin film solar cells. GZO thin films are first prepared by conventional methods. The as-deposited GZO surface properties are modified so that their use as back contacts on a-Si solar cells is enhanced. Texturing is performed by simple dry plasma etching in a CVD process chamber,at power=100 W, substrate temperature=190 C (temperature is held at 190 C because thin film solar cells are damaged above 200 C), pressure=400 Pa and process gas H{sub 2} flow=700 sccm. Conventional a-Si solar cells are fabricated with and without GZO back contact surface treatment. Comparison of the with/without texturing GZO films shows that plasma etching increases optical scattering reflectance and reflection haze. SEM and TEM are used to evaluate the morphological treatment-induced changes in the films. Comparison of the a-Si solar cells with/without texturing shows that the plasma treatment increases both the short-circuit current density and fill factor. Consequently, a-Si solar cell efficiency is relatively improved by 4.6%. (author)

  8. Impact of ink synthesis on processing of inkjet-printed silicon nanoparticle thin films: A comparison of Rapid Thermal Annealing and photonic sintering

    Energy Technology Data Exchange (ETDEWEB)

    Drahi, E.; Blayac, S. [Centre Microélectronique de Provence/Ecole Nationale Supérieure des Mines de Saint Etienne, 880, avenue de Mimet Gardanne, 13541 (France); Borbely, A. [Science des Matériaux et des Structures/Ecole Nationale Supérieure des Mines de Saint Etienne, 158, cours Fauriel Saint Etienne Cedex 2, 42023 (France); Benaben, P. [Centre Microélectronique de Provence/Ecole Nationale Supérieure des Mines de Saint Etienne, 880, avenue de Mimet Gardanne, 13541 (France)

    2015-01-01

    Inkjet printing has a high potential for cost reduction in solar cell and thermoelectric industry. This study demonstrates that silicon thin films can be produced by inkjet-printing of silicon nanoparticles followed by subsequent drying and annealing steps. Ink formulation is crucial for the sintering of the silicon nanoparticles and control of the microstructure at low temperature. Upon heating, the microstructure is modified from porous layer made of juxtaposed silicon nanoparticles to denser layer with coarser grains. This evolution is monitored by scanning electron microscopy and by micro-Raman spectroscopy, which offer a fast and precise characterization of the microstructure and chemical composition of thin films. Above a threshold temperature of 800 °C cracks appear within thin film and substrate because of the stress induced by the oxidation of the surface. An innovative sintering method, photonic annealing, is studied in order to reduce both oxidation and stress in the thin films as well as reducing processing time. Evolution of the thermal conductivity is performed by micro-Raman spectroscopy and can be tailored in a large range between ~ 1 and ~ 100 W·m{sup −1}·K{sup −1} depending on the sintering method and atmosphere. Therefore control of the microstructure evolution with applied annealing process allows tailoring of both microstructure and thermal conductivity of the silicon thin films. - Highlights: • Impact of ink synthesis on sintering (Si nanoparticle surface chemistry) • Photonic annealing of inkjet printed Si nanoparticles • Micro-Raman spectroscopy and X-Ray Diffraction for thin film characterization.

  9. First thin AC-coupled silicon strip sensors on 8-inch wafers

    Energy Technology Data Exchange (ETDEWEB)

    Bergauer, T., E-mail: thomas.bergauer@oeaw.ac.at [Institute of High Energy Physics of the Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Wien (Vienna) (Austria); Dragicevic, M.; König, A. [Institute of High Energy Physics of the Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Wien (Vienna) (Austria); Hacker, J.; Bartl, U. [Infineon Technologies Austria AG, Siemensstrasse 2, 9500 Villach (Austria)

    2016-09-11

    The Institute of High Energy Physics (HEPHY) in Vienna and the semiconductor manufacturer Infineon Technologies Austria AG developed a production process for planar AC-coupled silicon strip sensors manufactured on 200 μm thick 8-inch p-type wafers. In late 2015, the first wafers were delivered featuring the world's largest AC-coupled silicon strip sensors. Detailed electrical measurements were carried out at HEPHY, where single strip and global parameters were measured. Mechanical studies were conducted and the long-term behavior was investigated using a climate chamber. Furthermore, the electrical properties of various test structures were investigated to validate the quality of the manufacturing process.

  10. First thin AC-coupled silicon strip sensors on 8-inch wafers

    Science.gov (United States)

    Bergauer, T.; Dragicevic, M.; König, A.; Hacker, J.; Bartl, U.

    2016-09-01

    The Institute of High Energy Physics (HEPHY) in Vienna and the semiconductor manufacturer Infineon Technologies Austria AG developed a production process for planar AC-coupled silicon strip sensors manufactured on 200 μm thick 8-inch p-type wafers. In late 2015, the first wafers were delivered featuring the world's largest AC-coupled silicon strip sensors. Detailed electrical measurements were carried out at HEPHY, where single strip and global parameters were measured. Mechanical studies were conducted and the long-term behavior was investigated using a climate chamber. Furthermore, the electrical properties of various test structures were investigated to validate the quality of the manufacturing process.

  11. Compensation of decreased ion energy by increased hydrogen dilution in plasma deposition of thin film silicon solar cells at low substrate temperatures

    NARCIS (Netherlands)

    A.D. Verkerk; M.M. de Jong; J.K. Rath; M. Brinza; R.E.I. Schropp; W.J. Goedheer; V.V. Krzhizhanovskaya; Y.E. Gorbachev; K.E. Orlov; E.M. Khilkevitch; A.S. Smirnov

    2008-01-01

    In order to deposit thin film silicon solar cells on plastics and papers, the deposition process needs to be adapted for low deposition temperatures. In a very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) process, both the gas phase and the surface processes are affected by l

  12. Technology Development for High-Efficiency Solar Cells and Modules Using Thin (<80 um) Single-Crystal Silicon Wafers Produced by Epitaxy: June 11, 2011 - April 30, 2013

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, T. S.

    2013-05-01

    Final technical progress report of Crystal Solar subcontract NEU-31-40054-01. The objective of this 18-month program was to demonstrate the viability of high-efficiency thin (less than 80 um) monocrystalline silicon (Si) solar cells and modules with a low-cost epitaxial growth process.

  13. Technology Development for High-Efficiency Solar Cells and Modules Using Thin (<80 um) Single-Crystal Silicon Wafers Produced by Epitaxy: June 11, 2011 - April 30, 2013

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, T. S.

    2013-05-01

    Final technical progress report of Crystal Solar subcontract NEU-31-40054-01. The objective of this 18-month program was to demonstrate the viability of high-efficiency thin (less than 80 um) monocrystalline silicon (Si) solar cells and modules with a low-cost epitaxial growth process.

  14. New Coefficients of the Minority Carrier Lifetime and Bandgap Narrowing Models in the Transparent Emitter of Thin Film Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    A. Zerga

    2003-01-01

    literature and in different experiments. They show us the possibility of accurately evaluating the performances for the n+p silicon solar cell. This model is then used to introduce a new concept for the thin layer emitter, called transparent emitter.

  15. Location control of crystal grains in excimer laser crystallization of silicon thin films

    Science.gov (United States)

    Kumomi, Hideya

    2003-07-01

    Location of crystal grains in polycrystalline Si thin films formed by excimer-laser crystallization is controlled by manipulating the superlateral-growth phenomenon. The superlateral growth of a single grain occurs preferentially at an artificial site where nanometer-sized crystallites are embedded in the precursory amorphous thin films. Only a part of the crystallites embedded in the site could survive the melting and grow to serve as the seed crystal in the subsequent recrystallization. Such grain-location control provides a basis for two-dimensional control of the grain-boundary location in low-temperature polycrystalline Si thin films, which is essential to the device-to-device uniformity of high-performance thin-film transistors.

  16. Mismatched front and back gratings for optimum light trapping in ultra-thin crystalline silicon solar cells

    Science.gov (United States)

    Hsu, Wei-Chun; Tong, Jonathan K.; Branham, Matthew S.; Huang, Yi; Yerci, Selçuk; Boriskina, Svetlana V.; Chen, Gang

    2016-10-01

    The implementation of a front and back grating in ultra-thin photovoltaic cells is a promising approach towards improving light trapping. A simple design rule was developed using the least common multiple (LCM) of the front and back grating periods. From this design rule, several optimal period combinations can be found, providing greater design flexibility for absorbers of indirect band gap materials. Using numerical simulations, the photo-generated current (Jph) for a 10-μm-thick crystalline silicon absorber was predicted to be as high as 38 mA/cm2, which is 11.74% higher than that of a single front grating (Jph=34 mA/cm2).

  17. Depth strain profile with sub-nm resolution in a thin silicon film using medium energy ion scattering

    Energy Technology Data Exchange (ETDEWEB)

    Jalabert, D.; Rouviere, J.L. [CEA-INAC/UJF-Grenoble 1 UMR-E, SP2M, LEMMA, MINATEC Campus, Grenoble (France); Pelloux-Gervais, D.; Canut, B. [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Beche, A. [CEA-INAC/UJF-Grenoble 1 UMR-E, SP2M, LEMMA, MINATEC Campus, Grenoble (France); FEI Company, Eindhoven (Netherlands); Hartmann, J.M.; Gergaud, P. [CEA-Leti, MINATEC, Grenoble (France)

    2012-02-15

    The depth strain profile in silicon from the Si(001) substrate to the surface of a 2 nm thick Si/12 nm thick SiGe/bulk Si heterostructure has been determined by medium energy ion scattering (MEIS). It shows with sub-nanometer resolution and high strain sensitivity that the thin Si cap presents residual compressive strain caused by Ge diffusion coming from the fully strained SiGe layer underneath. The strain state of the SiGe buffer have been checked by X-ray diffraction (XRD) and nano-beam electron diffraction (NBED) measurements. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Production and Characterisation of SLID Interconnected n-in-p Pixel Modules with 75 Micrometer Thin Silicon Sensors

    CERN Document Server

    Andricek, L; Macchiolo, A.; Moser, H.-G.; Nisius, R.; Richter, R.H.; Terzo, S.; Weigell, P.

    2014-01-01

    The performance of pixel modules built from 75 micrometer thin silicon sensors and ATLAS read-out chips employing the Solid Liquid InterDiffusion (SLID) interconnection technology is presented. This technology, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It allows for stacking of different interconnected chip and sensor layers without destroying the already formed bonds. In combination with Inter-Chip-Vias (ICVs) this paves the way for vertical integration. Both technologies are combined in a pixel module concept which is the basis for the modules discussed in this paper. Mechanical and electrical parameters of pixel modules employing both SLID interconnections and sensors of 75 micrometer thickness are covered. The mechanical features discussed include the interconnection efficiency, alignment precision and mechanical strength. The electrical properties comprise the leakage currents, tunability, charge collection, cluster sizes and hit efficiencies. Targeting at ...

  19. A Detailed Analysis of Visible Defects Formed in Commercial Silicon Thin-Film Modules During Outdoor Exposure

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Andreas; Johnston, Steve; Olivera-Pimentel, Guillermo; Siegloch, Max; Pieters, Bart; Rau, Uwe

    2016-11-21

    We analyzed defects in silicon thin-film tandem (a-Si:H/..mu..c-Si:H) modules from an outdoor installation in India. The inspection of several affected modules reveals that most of the defects -- which optically appear as bright spots -- were formed primarily nearby the separation and series connection laser lines. Cross-sectional SEM analysis reveals that the bright spots emerge due to electrical isolation, caused by a delamination of the cell from the front TCO in the affected area. In addition, the morphology of the a-Si:H top cell differs in the delaminated area compared to the surrounding unaffected area. We propose that these effects are potentially caused by an explosive and thermally triggered liberation of hydrogen from the a-Si:H layer. Electrical and thermal measurements reveal that these defects can impact the cell performance significantly.

  20. Boron- and phosphorus-doped silicon germanium alloy nanocrystals—Nonthermal plasma synthesis and gas-phase thin film deposition

    Directory of Open Access Journals (Sweden)

    David J. Rowe

    2014-02-01

    Full Text Available Alloyed silicon-germanium (SiGe nanostructures are the topic of renewed research due to applications in modern optoelectronics and high-temperature thermoelectric materials. However, common techniques for producing nanostructured SiGe focus on bulk processing; therefore little is known of the physical properties of SiGe nanocrystals (NCs synthesized from molecular precursors. In this letter, we synthesize and deposit thin films of doped SiGe NCs using a single, flow-through nonthermal plasma reactor and inertial impaction. Using x-ray and vibrational analysis, we show that the SiGe NC structure appears truly alloyed for Si1−xGex for 0.16 < x < 0.24, and quantify the atomic dopant incorporation within the SiGe NC films.

  1. Giant optical nonlinearity of silver-doped silicon thin film at low power input: laser-triggered cluster resonance

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Jingsong [Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, Shanghai (China); Zhejiang University, State Key Lab of Silicon Materials, Hangzhou (China); Liu, Jing [Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, Shanghai (China); Xiao, Mufei [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Apartado Postal 365, Ensenada, Baja California (Mexico)

    2011-09-15

    Silver-doped silicon thin films were deposited on glass substrate in a co-sputtering procedure. Silver nanoparticles were segregatedly distributed. The nonlinear properties were extracted by z-scan measurements at low laser input power. For about 50% silver density, the nonlinear absorption and refraction coefficients peaked, respectively, at -8.086 x 10{sup -2} m/W and 1.47 x 10{sup -9} m{sup 2}/W, which, with respect to the input intensity, are several orders higher than reported data. The sudden surge of nonlinear responses was explained satisfactorily based on a self-consistent microscopic model calculation for silver clusters. Resonances exist and depend apparently on the laser-modified local cluster concentration. (orig.)

  2. A New Low Temperature Polycrystalline Silicon Thin Film Transistor Pixel Circuit for Active Matrix Organic Light Emitting Diode

    Science.gov (United States)

    Fan, Ching-Lin; Lin, Yi-Yan; Chang, Jyu-Yu; Sun, Bo-Jhang; Liu, Yan-Wei

    2010-06-01

    This study presents one novel compensation pixel design and driving method for active matrix organic light-emitting diode (AMOLED) displays that use low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) with a voltage feed-back method and the simulation results are proposed and verified by SPICE simulator. The measurement and simulation of LTPS TFT characteristics demonstrate the good fitting result. The proposed circuit consists of four TFTs and two capacitors with an additional signal line. The error rates of OLED anode voltage variation are below 0.3% under the threshold voltage deviation of driving TFT (ΔVTH = ±0.33 V). The simulation results show that the pixel design can improve the display image non-uniformity by compensating the threshold voltage deviation of driving TFT and the degradation of OLED threshold voltage at the same time.

  3. Broadband and wide-angle light harvesting by ultra-thin silicon solar cells with partially embedded dielectric spheres.

    Science.gov (United States)

    Yang, Zhenhai; Shang, Aixue; Qin, Linling; Zhan, Yaohui; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

    2016-04-01

    We propose a design of crystalline silicon thin-film solar cells (c-Si TFSCs, 2 μm-thick) configured with partially embedded dielectric spheres on the light-injecting side. The intrinsic light trapping and photoconversion are simulated by the complete optoelectronic simulation. It shows that the embedding depth of the spheres provides an effective way to modulate and significantly enhance the optical absorption. Compared to the conventional planar and front sphere systems, the optimized partially embedded sphere design enables a broadband, wide-angle, and strong optical absorption and efficient carrier transportation. Optoelectronic simulation predicts that a 2 μm-thick c-Si TFSC with half-embedded spheres shows an increment of more than 10  mA/cm2 in short-circuit current density and an enhancement ratio of more than 56% in light-conversion efficiency, compared to the conventional planar counterparts.

  4. Effect of succinic anhydride as an electrolyte additive on electrochemical characteristics of silicon thin-film electrode

    Science.gov (United States)

    Han, Gi-Beom; Ryou, Myung-Hyun; Cho, Kuk Young; Lee, Yong Min; Park, Jung-Ki

    The effect of an electrolyte additive, succinic anhydride (SA), on the electrochemical performances of a silicon thin-film electrode, which is prepared by radio-frequency magnetron sputtering, is investigated. The introduction of SA into a liquid electrolyte consisting of ethylene carbonate/diethyl carbonate/1 M LiPF 6 significantly enhances the capacity retention and coulombic efficiency of the electrode. This improvement in the electrochemical performance of the electrode is attributed to modification of the solid/electrolyte interphase (SEI) layer by the introduction of SA. The differences in the characteristic properties of SEI layers, with or without SA, are explained by analysis with scanning electron microscopy, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy.

  5. Improving low pressure chemical vapor deposited zinc oxide contacts for thin film silicon solar cells by using rough glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Steinhauser, J., E-mail: jerome.steinhauser@oerlikon.com; Boucher, J.-F.; Omnes, E.; Borrello, D.; Vallat-Sauvain, E.; Monteduro, G.; Marmelo, M.; Orhan, J.-B.; Wolf, B.; Bailat, J.; Benagli, S.; Meier, J.; Kroll, U.

    2011-12-01

    Compared to zinc oxide grown (ZnO) on flat glass, rough etched glass substrates decrease the sheet resistance (R{sub sq}) of zinc oxide layers grown on it. We explain this R{sub sq} reduction from a higher thickness and an improved electron mobility for ZnO layers deposited on rough etched glass substrates. When using this etched glass substrate, we also obtain a large variety of surface texture by changing the thickness of the ZnO layer grown on it. This new combination of etched glass and ZnO layer shows improved light trapping potential compared to ZnO films grown on flat glass. With this new approach, Micromorph thin film silicon tandem solar cells with high total current densities (sum of the top and bottom cell current density) of up to 26.8 mA cm{sup -2} were fabricated.

  6. 8% Efficient thin-film polycrystalline-silicon solar cells based on aluminium-induced crystallization and thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, I.; Carnel, L.; Van Gestel, D.; Beaucarne, G.; Poortmans, J. [IMEC VZW, Leuven (Belgium)

    2006-07-01

    A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from polycrystalline-silicon (pc-Si) thin films on inexpensive substrates. We recently showed promising solar cells results using pc-Si layers obtained by aluminium-induced crystallization (AlC) of amorphous silicon in combination with thermal chemical vapor deposition (CVD). To obtain highly efficient pc-Si solar cells, however, the material quality has to be optimized and cell processes different from those applied for standard bulk-Si solar cells have to be developed. In this work, we present the different process steps that we recently developed to enhance the efficiency of pc-Si solar cells on alumina substrates made by AlC in combination with thermal CVD. Our present pc-Si solar cell process yields cells in substrate configuration with efficiencies so far of up to 8.0%. Spin-on oxides are used to smoothen the alumina substrate surface to enhance the electronic quality of the absorber layers. The cells have heterojunction emitters consisting of thin a-Si layers that yield much higher V{sub oc} values than classical diffused emitters. Base and emitter contacts are on top of the cell in interdigitated finger patterns, leading to fill factors above 70%. The front surface of the cells is plasma textured to increase the current density. Our present pc-Si solar cell efficiency of 8% together with the fast progression that we have made over the last few years indicate the large potential of pc-Si solar cells based on the AlC seed layer approach. (author)

  7. Highly transparent front electrodes with metal fingers for p-i-n thin-film silicon solar cells

    Directory of Open Access Journals (Sweden)

    Moulin Etienne

    2015-01-01

    Full Text Available The optical and electrical properties of transparent conductive oxides (TCOs, traditionally used in thin-film silicon (TF-Si solar cells as front-electrode materials, are interlinked, such that an increase in TCO transparency is generally achieved at the cost of reduced lateral conductance. Combining a highly transparent TCO front electrode of moderate conductance with metal fingers to support charge collection is a well-established technique in wafer-based technologies or for TF-Si solar cells in the substrate (n-i-p configuration. Here, we extend this concept to TF-Si solar cells in the superstrate (p-i-n configuration. The metal fingers are used in conjunction with a millimeter-scale textured foil, attached to the glass superstrate, which provides an antireflective and retroreflective effect; the latter effect mitigates the shadowing losses induced by the metal fingers. As a result, a substantial increase in power conversion efficiency, from 8.7% to 9.1%, is achieved for 1-μm-thick microcrystalline silicon solar cells deposited on a highly transparent thermally treated aluminum-doped zinc oxide layer combined with silver fingers, compared to cells deposited on a state-of-the-art zinc oxide layer.

  8. Fine Pattern Etching of Molybdenum Thin Film and Silicon Substrate by Using Atmospheric Line-Shaped Microplasma Source

    Science.gov (United States)

    Okumura, Tomohiro; Saitoh, Mitsuo; Yashiro, Yoichiro; Kimura, Tadashi

    2003-06-01

    An atmospheric line-shaped microplasma source was developed for fine pattern etching. Observation of plasma emission of the developed plasma source has revealed that the finest plasma line is formed when helium (He) gas is supplied to the inner gas feed and reaction gas to the outer gas feeds. When reaction gas is supplied to the outer gas feeds, fluorine radical (F*) emission intensity increases with the gas flow rate, eventually exceeding the maximum emission intensity obtained when a mixture of reaction gas and He gas is supplied to the inner gas feed. Fine pattern etching of molybdenum thin film and silicon substrate was experimentally carried out using microplasma sources in two different configurations: one with the copper electrode covered to protect it from plasma exposure (type 1), and the other with the aluminum electrode end knife-edged and exposed to a plasma (type 2). The experiment revealed that the type 2 source provides a higher etching rate than of the type 1 source. The type 2 source can produce a fine etched pattern with lines of several ten to several hundred μm width. The maximum etching rate of silicon substrate is 79.0 μm/min.

  9. Thin film PV standing tall side-by-side with multi-crystalline silicon: also in terms of reliability

    Science.gov (United States)

    Dhere, Neelkanth G.; Ward, Allan; Wieting, Robert; Guha, Subhendu; Dhere, Ramesh G.

    2015-09-01

    Triple junction hydrogenated amorphous silicon (a-Si:H) have shown exceptionally good reliability and durability. Cadmium telluride, CdTe PV modules have shown the lowest production cost without subsidies. Copper-indium gallium selenide sulfide (CIGS) and cadmium telluride (CdTe) cells and modules have been showing efficiencies equal or greater than those of multi-crystalline, (mx-Si), PV modules. Early generation CIGS and CdTe PV modules had a different qualification standard 61646 as compared to 61215 for crystalline silicon, (c-Si), PV modules. This, together with small vulnerability in harsh climates, was used to create doubts about their reliability. Recently CdTe and CIGS glass-to-glass modules have passed the rigorous accelerated tests, especially as long as the edge seals are not compromised. Moreover, the cumulative shipment of these modules is more than 12 GW demonstrating the customer confidence in these products. Hence it can be stated that also in terms of the reliability and durability all the thin film PV modules stand tall and compare favorably with mx-Si.

  10. Formation and dielectric properties of polyelectrolyte multilayers studied by a silicon-on-insulator based thin film resistor.

    Science.gov (United States)

    Neff, Petra A; Wunderlich, Bernhard K; Klitzing, Regine V; Bausch, Andreas R

    2007-03-27

    The formation of polyelectrolyte multilayers (PEMs) is investigated using a silicon-on-insulator based thin film resistor which is sensitive to variations of the surface potential. The buildup of the PEMs at the silicon oxide surface of the device can be observed in real time as defined potential shifts. The influence of polymer charge density is studied using the strong polyanion poly(styrene sulfonate), PSS, combined with the statistical copolymer poly(diallyl-dimethyl-ammoniumchloride-stat-N-methyl-N-vinylacetamide), P(DADMAC-stat-NMVA), at various degrees of charge (DC). The multilayer formation stops after a few deposition steps for a DC below 75%. We show that the threshold of surface charge compensation corresponds to the threshold of multilayer formation. However, no reversion of the preceding surface charge was observed. Screening of polyelectrolyte charges by mobile ions within the polymer film leads to a decrease of the potential shifts with the number of layers deposited. This decrease is much slower for PEMs consisting of P(DADMAC-stat-NMVA) and PSS as compared to PEMs consisting of poly(allylamine-hydrochloride), PAH, and PSS. From this, significant differences in the dielectric constants of the polyelectrolyte films and in the concentration of mobile ions within the films can be derived.

  11. Structural Characterization of Sputtered Silicon Thin Films after Rapid Thermal Annealing for Active-Matrix Organic Light Emitting Diode

    Science.gov (United States)

    Mugiraneza, Jean de Dieu; Miyahira, Tomoyuki; Sakamoto, Akinori; Chen, Yi; Okada, Tatsuya; Noguchi, Takashi; Itoh, Taketsugu

    2010-12-01

    The microcrystalline phase obtained by adopting a two-step rapid thermal annealing (RTA) process for rf-sputtered silicon films deposited on thermally durable glass was characterized. The optical properties, surface morphology, and internal stress of the annealed Si films are investigated. As the thermally durable glass substrate allows heating of the deposited films at high temperatures, micro-polycrystalline silicon (micro-poly-Si) films of uniform grain size with a smooth surface and a low internal stress could be obtained after annealing at 750 °C. The thermal stress in the Si films was 100 times lower than that found in the films deposited on conventional glass. Uniform grains with an average grain size of 30 nm were observed by transmission electron microscopy (TEM) in the films annealed at 800 °C. These micro-poly-Si films have potential application for fabrication of uniform and reliable thin film transistors (TFTs) for large scale active-matrix organic light emitting diode (AMOLED) displays.

  12. Arrays of ZnO nanocolumns for 3-dimensional very thin amorphous and microcrystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Neykova, Neda, E-mail: neykova@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 16253 Prague 6 (Czech Republic); Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering Trojanova 13, 120 00 Prague 2 (Czech Republic); Hruska, Karel; Holovsky, Jakub; Remes, Zdenek; Vanecek, Milan [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 16253 Prague 6 (Czech Republic)

    2013-09-30

    We report on the hydrothermal growth of high quality arrays of single crystalline zinc oxide (ZnO) nanocolumns, oriented perpendicularly to the transparent conductive oxide substrate. In order to obtain precisely defined spacing and arrangement of ZnO nanocolumns over an area up to 0.5 cm{sup 2}, we used electron beam lithography. Vertically aligned ZnO (multicrystalline or single crystals) nanocolumns were grown in an aqueous solution of zinc nitrate hexahydrate and hexamethylenetetramine at 95 °C, with a growth rate 0.5 ÷ 1 μm/h. The morphology of the nanostructures was visualized by scanning electron microscopy. Such nanostructured ZnO films were used as a substrate for the recently developed 3-dimensional thin film silicon (amorphous, microcrystalline) solar cell, with a high efficiency potential. The photoelectrical and optical properties of the ZnO nanocolumns and the silicon absorber layers of these type nanostructured solar cells were investigated in details. - Highlights: • Vertically-oriented ZnO nanocolumns were grown by hydrothermal method. • The ZnO nanocolumns were grown over an area of 0.5 cm{sup 2}. • For precise arrangement of the ZnO nanocolumns electron beam lithography was used. • We report on 3-D design of nanostructured solar cell. • Optical thickness of nanostructured cell was three times higher compared to flat cell.

  13. Improved gate oxide integrity of strained Si n-channel metal oxide silicon field effect transistors using thin virtual substrates

    Science.gov (United States)

    Yan, L.; Olsen, S. H.; Escobedo-Cousin, E.; O'Neill, A. G.

    2008-05-01

    This work presents a detailed study of ultrathin gate oxide integrity in strained Si metal oxide silicon field effect transistors (MOSFETs) fabricated on thin virtual substrates aimed at reducing device self-heating. The gate oxide quality and reliability of the devices are compared to those of simultaneously processed Si control devices and conventional thick virtual substrate devices that have the same Ge content (20%), strained Si channel thickness, and channel strain. The thin virtual substrates offer the same mobility enhancement as the thick virtual substrates (˜100% compared to universal mobility data) and are effective at reducing device self-heating. Up to 90% improvement in gate leakage current is demonstrated for the strained Si n-channel MOSFETs compared to that for the bulk Si controls. The lower leakage arises from the increased electron affinity in tensile strained Si and is significant due to the sizeable strain generated by using wafer-level stressors. The strain-induced leakage reductions also lead to major improvements in stress-induced leakage current (SILC) and oxide reliability. The lower leakage current of the thin and thick virtual substrate devices compares well to theoretical estimates based on the Wentzel-Kramers-Brillouin approximation. Breakdown characteristics also differ considerably between the devices, with the strained Si devices exhibiting a one order of magnitude increase in time to hard breakdown (THBD) compared to the Si control devices following high-field stressing at 17 MV cm-1. The strained Si devices are exempted from soft breakdown. Experimental based analytical leakage modeling has been carried out across the field range for the first time in thin oxides and demonstrates that Poole-Frenkel (PF) emissions followed by Fowler-Nordheim tunneling dominate gate leakage current at low fields in all of the devices. This contrasts to the frequently reported assumption that direct tunneling dominates gate leakage in ultrathin

  14. Tailored Voltage Waveform Deposition of Microcrystalline Silicon Thin Films from Hydrogen-Diluted Silane and Silicon Tetrafluoride: Optoelectronic Properties of Films

    Science.gov (United States)

    Johnson, Erik V.; Pouliquen, Sylvain; Delattre, Pierre-Alexandre; Booth, Jean-Paul

    2012-08-01

    The use of tailored voltage waveforms (TVW's) to excite a plasma for the deposition of thin films of hydrogenated microcrystalline silicon (µc-Si:H) has been shown to be an effective technique to decouple mean ion bombardment energy (IBE) from injected power. In this work, we examine the changes in material properties controlled by this technique through Raman scattering and spectroscopic ellipsometry for films deposited from H2-diluted SiH4, and we examine the electrical properties of such films using temperature dependent conductivity. As the laboratory-scale deposition system used had neither a load lock nor an oxygen filter in the H2 line, accidental O-doping was observed for the µc-Si:H films. We investigated suppression of this doping by adding varying amounts of SiF4, and using an SiF4/Ar pre-etch step to clean the reactor. This technique is shown to be effective in decreasing the accidental doping of the films, and intrinsic µc-Si:H films are produced with an activation energy of up to 0.55 eV. As well, an important difference in the amorphous-to-microcrystalline transition is observed once SiF4 is included in the gas mixture.

  15. Optical characterization of double-side-textured silicon wafer based on photonic nanostructures for thin-wafer crystalline silicon solar cells

    Science.gov (United States)

    Tayagaki, Takeshi; Furuta, Daichi; Aonuma, Osamu; Takahashi, Isao; Hoshi, Yusuke; Kurokawa, Yasuyoshi; Usami, Noritaka

    2017-04-01

    Crystalline silicon (c-Si) wafers have found extensive use in photovoltaic applications. In this regard, to enable advanced light manipulation in thin-wafer c-Si solar cells, we demonstrate the fabrication of double-side-textured Si wafers composed of a front-surface photonic nanotexture fabricated with quantum dot arrays and a rear-surface microtexture. The addition of the rear-surface microtexture to a Si wafer with the front-surface photonic nanotexture increases the wafer’s optical absorption in the near-infrared region, thus enabling enhanced light trapping. Excitation spectroscopy reveals that the photoluminescence intensity in the Si wafer with the double-sided texture is higher than that in the Si wafer without the rear-surface microtexture, thus indicating an increase in true optical absorption in the Si wafer with the double-sided texture. Our results indicate that the double-sided textures, i.e., the front-surface photonic nanotexture and rear-surface microtexture, can effectively reduce the surface reflection loss and provide enhanced light trapping, respectively.

  16. Modeling the Crystallization of Amorphous Silicon Thin Films Using a High Repetition Rate Scanning Laser

    Directory of Open Access Journals (Sweden)

    R. Černý

    2000-01-01

    Full Text Available An optimum design of experimental setup for the preparation of polycrystalline silicon (pc-Si films from amorphous layers applicable in the solar cell production is analyzed in the paper. In the computational simulations, the influence of basic characteristic parameters of the experimental procedure on the mechanisms of pc-Si lateral growth is studied. Among these parameters, the energy density of the applied laser and the thickness of the amorphous silicon (a-Si layer are identified as the most significant. As an optimum solution, the mechanism of pc-Si growth consisting in repeated melting of a part of already crystallized pc-Si layer by the scanning laser is proposed.

  17. Low Cost Amorphous Silicon Intrinsic Layer for Thin-Film Tandem Solar Cells

    Directory of Open Access Journals (Sweden)

    Ching-In Wu

    2013-01-01

    Full Text Available The authors propose a methodology to improve both the deposition rate and SiH4 consumption during the deposition of the amorphous silicon intrinsic layer of the a-Si/μc-Si tandem solar cells prepared on Gen 5 glass substrate. It was found that the most important issue is to find out the saturation point of deposition rate which guarantees saturated utilization of the sourcing gas. It was also found that amorphous silicon intrinsic layers with the same k value will result in the same degradation of the fabricated modules. Furthermore, it was found that we could significantly reduce the production cost of the a-Si/μc-Si tandem solar cells prepared on Gen 5 glass substrate by fine-tuning the process parameters.

  18. Significant light absorption enhancement in silicon thin film tandem solar cells with metallic nanoparticles.

    Science.gov (United States)

    Cai, Boyuan; Li, Xiangping; Zhang, Yinan; Jia, Baohua

    2016-05-13

    Enhancing the light absorption in microcrystalline silicon bottom cell of a silicon-based tandem solar cell for photocurrent matching holds the key to achieving the overall solar cell performance breakthroughs. Here, we present a concept for significantly improving the absorption of both subcells simultaneously by simply applying tailored metallic nanoparticles both on the top and at the rear surfaces of the solar cells. Significant light absorption enhancement as large as 56% has been achieved in the bottom subcells. More importantly the thickness of the microcrystalline layer can be reduced by 57% without compromising the optical performance of the tandem solar cell, providing a cost-effective strategy for high performance tandem solar cells.

  19. The establishment of a production-ready manufacturing process utilizing thin silicon substrates for solar cells

    Science.gov (United States)

    Pryor, R. A.

    1980-01-01

    Three inch diameter Czochralski silicon substrates sliced directly to 5 mil, 8 mil, and 27 mil thicknesses with wire saw techniques were procured. Processing sequences incorporating either diffusion or ion implantation technologies were employed to produce n+p or n+pp+ solar cell structures. These cells were evaluated for performance, ease of fabrication, and cost effectiveness. It was determined that the use of 7 mil or even 4 mil wafers would provide near term cost reductions for solar cell manufacturers.

  20. Investigation of the crystallization process of amorphous silicon thin films%非晶硅薄膜晶化过程的研究

    Institute of Scientific and Technical Information of China (English)

    黄木香; 杨琳; 刘玉琪; 王江涌

    2012-01-01

    Polycrystalline silicon thin film is a high quality material for micro - electronic components, thin film transistors and large flat-panel LCD displays because of its high electrical mobility and stable photoelectric properties. Moreover, it has been regarded as a candidate material for making high efficiency, lower energy consumption and optimized thin film solar cells. Therefore, how to fabricate polycrystalline silicon thin film is a very meaningful research topic. Solid phase crystallization is a usual method to fabricate polycrystalline silicon thin film, by high temperature annealing to transfer amorphous film to polycrystalline phase, In this paper, the solid phase crystallization process of amorphous silicon thin films fabricated by different techniques are studied systematically by XRD and Raman spectroscopy.%多晶硅薄膜具有较高的电迁移率和稳定的光电性能,是制备微电子器件、薄膜晶体管、大面积平板液晶显示的优质材料.多晶硅薄膜被公认为是制备高效、低耗、最理想的薄膜太阳能电池的材料.因此,如何制备多晶硅薄膜是一个非常有意义的研究课题.固相法是制备多晶硅薄膜的一种常用方法,它是在高温退火的条件下,使非晶硅薄膜通过固相相变而成为多晶硅薄膜.本文采用固相法,利用X-ray衍射及拉曼光谱,对用不同方法制备的非晶硅薄膜的晶化过程进行了系统地研究.

  1. Adhesion and Water Repellent Properties Of Nascent Dammar—Silicone Thin Film: A Bio Mimicry Approach

    Science.gov (United States)

    Zakaria, R.; Ahmad, A. H.

    2009-06-01

    Dammar, a local plant resin (Dipterocaupacea sp) has been used in coating formulation to produce dammar-modified silicone resin. Dammar and silicone were mixed in various compositions and then were coated onto Aluminum Q-panel by using spin coating method and left to dry at room temperature. Adhesion property was investigated by using impact test and pull-off test. There were no significant damage and delaminations were observed at the panel coated with 15 wt.% of dammar that has undergone the impact test. Hence, the addition of more than 15 wt.% of dammar resulted in large delaminations and cracks on the coating materials. Results from pull off test also showed that 15 wt.% of dammar organic coating has strong adhesion, 108 Psi. It made 15 wt% as optimized composition. This optimized composition was added with nanopowder as rheological modifier or additive. Again the modified samples were undergone the impact and pull off test to study the effect of adhesiveness. Contact angle measurement of wettability test was also being carried out. The surface coated with dammar-silicone resin was found to be hydrophobic where the contact angle obtained was 70° for the sample containing 10 wt% of dammar. The additional of nanopowder into optimized composition exhibited more hydrophobic phenomenon which approached towards bio-mimicry behaviour, when water droplets simply rest on the surface without actually wetting the surface to any significant extent (hydrophobic) where the angle of wetting tests more than 90° have been achieved.

  2. Absorption enhancement in amorphous silicon thin films via plasmonic resonances in nickel silicide nanoparticles

    Science.gov (United States)

    Hachtel, Jordan; Shen, Xiao; Pantelides, Sokrates; Sachan, Ritesh; Gonzalez, Carlos; Dyck, Ondrej; Fu, Shaofang; Kalnayaraman, Ramki; Rack, Phillip; Duscher, Gerd

    2013-03-01

    Silicon is a near ideal material for photovoltaics due to its low cost, abundance, and well documented optical properties. The sole detriment of Si in photovoltaics is poor absorption in the infrared. Nanoparticle surface plasmon resonances are predicted to increase absorption by scattering to angles greater than the critical angle for total internal reflection (16° for a Si/air interface), trapping the light in the film. Experiments confirm that nickel silicide nanoparticles embedded in amorphous silicon increases absorption significantly in the infrared. However, it remains to be seen if electron-hole pair generation is increased in the solar cell, or whether the light is absorbed by the nanoparticles themselves. The nature of the absorption is explored by a study of the surface plasmon resonances through electron energy loss spectrometry and scanning transmission electron microscopy experiments, as well as first principles density functional theory calculations. Initial experimental results do not show strong plasmon resonances on the nanoparticle surfaces. Calculations of the optical properties of the nickel silicide particles in amorphous silicon are performed to understand why this resonance is suppressed. Work supported by NSF EPS 1004083 (TN-SCORE).

  3. Nanomorph Silicon Thin Films Prepared by Using an HW-MWECR CVD System

    Institute of Scientific and Technical Information of China (English)

    HU Yue-Hui; MA Zhan-Jie; ZHOU Huai-En; ZHU Xiu-Hong; CHEN Guang-Hua; ZHOU Jian-Er; RONG Yan-Dong; LI Ying; SONG Xue-Mei; ZHANG Wen-Li; DING Yi; GAO Zhuo

    2005-01-01

    @@ We have prepared hydrogenated nano-amorph silicon (na-Si:H) films by using a hot-wire-assisted microwave electron-cyclotron-resonance (HW-MWECR) chemical vapour deposition (CVD) system. The films are deposited in two steps: in the first 9min, a hydrogenated amorphous silicon layer is deposited by using hydrogen-diluted silane with a concentration of SiH4/(SiH4+H2) = 20%, and then a nanocrystalline silicon (nc-Si) layer is deposited by using various highly hydrogen-diluted silane. The Raman TO-like mode peak of the films was found in the range 497-508 cm-1. When the silane concentration used for preparation of the nc-Si layer is 14.3%, the film has a large crystalline volume fraction of 65.4%, a wide optical band gap of 1.89eV and a low hydrogen content of 9.5at.%. Moreover, the na-Si:H films rather than nc-Si possess high photosensitivity of about 15.

  4. Simulation of Multilayer Silicon Thin Films Growth on Si(111) Surface

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The homoepitaxial growth of multilayer Si thin film on Si(111) surfaces was simulated by Monte Carlo (MC) method with realistic growth model and physical parameters. Special emphasis was placed on revealing the influence of the Ehrlich-Schwoebel (ES) barrier on the growth modes and morphologies. It is evident that there exists the ES barrier during multilayer Si thin film growth on Si (111) surface, which is deduced from the incomplete layer-by-layer growth process in the realistic experiments. The ES barrier EB=0.1~0.125 eV is estimated from the three-dimensional (3D) MC simulation and compared with the experimental results.

  5. Protecting the properties of monolayer MoS2 on silicon based substrates with an atomically thin buffer

    Science.gov (United States)

    Man, Michael K. L.; Deckoff-Jones, Skylar; Winchester, Andrew; Shi, Guangsha; Gupta, Gautam; Mohite, Aditya D.; Kar, Swastik; Kioupakis, Emmanouil; Talapatra, Saikat; Dani, Keshav M.

    2016-02-01

    Semiconducting 2D materials, like transition metal dichalcogenides (TMDs), have gained much attention for their potential in opto-electronic devices, valleytronic schemes, and semi-conducting to metallic phase engineering. However, like graphene and other atomically thin materials, they lose key properties when placed on a substrate like silicon, including quenching of photoluminescence, distorted crystalline structure, and rough surface morphology. The ability to protect these properties of monolayer TMDs, such as molybdenum disulfide (MoS2), on standard Si-based substrates, will enable their use in opto-electronic devices and scientific investigations. Here we show that an atomically thin buffer layer of hexagonal-boron nitride (hBN) protects the range of key opto-electronic, structural, and morphological properties of monolayer MoS2 on Si-based substrates. The hBN buffer restores sharp diffraction patterns, improves monolayer flatness by nearly two-orders of magnitude, and causes over an order of magnitude enhancement in photoluminescence, compared to bare Si and SiO2 substrates. Our demonstration provides a way of integrating MoS2 and other 2D monolayers onto standard Si-substrates, thus furthering their technological applications and scientific investigations.

  6. Dual-Layer Nanostructured Flexible Thin-Film Amorphous Silicon Solar Cells with Enhanced Light Harvesting and Photoelectric Conversion Efficiency.

    Science.gov (United States)

    Lin, Yinyue; Xu, Zhen; Yu, Dongliang; Lu, Linfeng; Yin, Min; Tavakoli, Mohammad Mahdi; Chen, Xiaoyuan; Hao, Yuying; Fan, Zhiyong; Cui, Yanxia; Li, Dongdong

    2016-05-04

    Three-dimensional (3-D) structures have triggered tremendous interest for thin-film solar cells since they can dramatically reduce the material usage and incident light reflection. However, the high aspect ratio feature of some 3-D structures leads to deterioration of internal electric field and carrier collection capability, which reduces device power conversion efficiency (PCE). Here, we report high performance flexible thin-film amorphous silicon solar cells with a unique and effective light trapping scheme. In this device structure, a polymer nanopillar membrane is attached on top of a device, which benefits broadband and omnidirectional performances, and a 3-D nanostructure with shallow dent arrays underneath serves as a back reflector on flexible titanium (Ti) foil resulting in an increased optical path length by exciting hybrid optical modes. The efficient light management results in 42.7% and 41.7% remarkable improvements of short-circuit current density and overall efficiency, respectively. Meanwhile, an excellent flexibility has been achieved as PCE remains 97.6% of the initial efficiency even after 10 000 bending cycles. This unique device structure can also be duplicated for other flexible photovoltaic devices based on different active materials such as CdTe, Cu(In,Ga)Se2 (CIGS), organohalide lead perovskites, and so forth.

  7. Structural and optical properties of thin films porous amorphous silicon carbide formed by Ag-assisted photochemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Boukezzata, A., E-mail: assiab2006@yahoo.fr [Silicon Technology Development Unit (UDTS), 02 Bd. Frantz FANON, B.P. 140 Algiers (Algeria); Keffous, A., E-mail: keffousa@yahoo.fr [Silicon Technology Development Unit (UDTS), 02 Bd. Frantz FANON, B.P. 140 Algiers (Algeria); Cheriet, A.; Belkacem, Y.; Gabouze, N.; Manseri, A. [Silicon Technology Development Unit (UDTS), 02 Bd. Frantz FANON, B.P. 140 Algiers (Algeria); Nezzal, G. [Houari Boumediene University (USTHB), Chemical Faculty, Algiers (Algeria); Kechouane, M.; Bright, A. [Houari Boumediene University, Physical Faculty, Algiers (Algeria); Guerbous, L. [Algerian Nuclear Research Center (CRNA), Algiers (Algeria); Menari, H. [Silicon Technology Development Unit (UDTS), 02 Bd. Frantz FANON, B.P. 140 Algiers (Algeria)

    2010-07-01

    In this work, we present the formation of porous layers on hydrogenated amorphous SiC (a-SiC: H) by Ag-assisted photochemical etching using HF/K{sub 2}S{sub 2}O{sub 8} solution under UV illumination at 254 nm wavelength. The amorphous films a-SiC: H were elaborated by d.c. magnetron sputtering using a hot pressed polycrystalline 6H-SiC target. Because of the high resistivity of the SiC layer, around 1.6 M{Omega} cm and in order to facilitate the chemical etching, a thin metallic film of high purity silver (Ag) has been deposited under vacuum onto the thin a-SiC: H layer. The etched surface was characterized by scanning electron microscopy, secondary ion mass spectroscopy, infrared spectroscopy and photoluminescence. The results show that the morphology of etched a-SiC: H surface evolves with etching time. For an etching time of 20 min the surface presents a hemispherical crater, indicating that the porous SiC layer is perforated. Photoluminescence characterization of etched a-SiC: H samples for 20 min shows a high and an intense blue PL, whereas it has been shown that the PL decreases for higher etching time. Finally, a dissolution mechanism of the silicon carbide in 1HF/1K{sub 2}S{sub 2}O{sub 8} solution has been proposed.

  8. Light emission in forward and reverse bias operation in OLED with amorphous silicon carbon nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, R [Facultad de Ingenieria Quimica y Textil, Universidad Nacional de Ingenieria, Av. Tupac Amaru SN, Lima (Peru); Cremona, M [Departamento de Fisica, PontifIcia Universidade Catolica de Rio de Janeiro, PUC-Rio, Cx. Postal 38071, Rio de Janeiro, RJ, CEP 22453-970 (Brazil); Achete, C A, E-mail: rreyes@uni.edu.pe [Departamento de Engenheria Metalurgica e de Materiais, Universidade Federal do Rio de Janeiro, Cx. Postal 68505, Rio de Janeiro, RJ, CEP 21945-970 (Brazil)

    2011-01-01

    Amorphous silicon carbon nitride (a-SiC:N) thin films deposited by magnetron sputtering were used in the structure of an organic light emitting diode (OLED), obtaining an OLED operating in forward and reverse bias mode. The device consist of the heterojunction structure ITO/a-SiC:N/Hole Transport Layer (HTL)/ Electron Transport Layer (ETL)/a-SiC:N/Al. As hole transporting layer was used a thin film of 1-(3-methylphenyl)-1,2,3,4 tetrahydroquinoline - 6 - carboxyaldehyde - 1,1'- diphenylhydrazone (MTCD), while the tris(8-hydroxyquinoline aluminum) (Alq{sub 3}) is used as electron transport and emitting layer. A significant increase in the voltage operation compared to the conventional ITO/MTCD/Alq{sub 3}/Al structure was observed, so the onset of electroluminescence occurs at about 22 V in the forward and reverse bias mode of operation. The electroluminescence spectra is similar in both cases, only slightly shifted 0.14 eV to lower energies in relation to the conventional device.

  9. Leakage current conduction and reliability assessment of passivating thin silicon dioxide films on n-4H-SiC

    Science.gov (United States)

    Samanta, Piyas; Mandal, Krishna C.

    2016-09-01

    We have analyzed the mechanisms of leakage current conduction in passivating silicon dioxide (SiO2) films grown on (0 0 0 1) silicon (Si) face of n-type 4H-SiC (silicon carbide). It was observed that the experimentally measured gate current density in metal-oxide-silicon carbide (MOSiC) structures under positive gate bias at an oxide field Eox above 5 MV/cm is comprised of Fowler-Nordheim (FN) tunneling of electrons from the accumulated n-4H-SiC and Poole-Frenkel (PF) emission of trapped electrons from the localized neutral traps in the SiO2 gap, IFN and IPF, respectively at temperatures between 27 and 200 °C. In MOSiC structures, PF mechanism dominates FN tunneling of electrons from the accumulation layer of n-4H-SiC due to high density (up to 1013 cm-2) of carbon-related acceptor-like traps located at about 2.5 eV below the SiO2 conduction band (CB). These current conduction mechanisms were taken into account in studying hole injection/trapping into 10 nm-thick tunnel oxide on the Si face of 4H-SiC during electron injection from n-4H-SiC under high-field electrical stress with positive bias on the heavily doped n-type polysilicon (n+-polySi) gate at a wide range of temperatures between 27 and 200 °C. Holes were generated in the n+-polySi anode material by the hot-electrons during their transport through thin oxide films at oxide electric fields Eox from 5.6 to 8.0 MV/cm (prior to the intrinsic oxide breakdown field). Time-to-breakdown tBD of the gate dielectric was found to follow reciprocal field (1/E) model irrespective of stress temperatures. Despite the significant amount of process-induced interfacial electron traps contributing to a large amount of leakage current via PF emission in thermally grown SiO2 on the Si-face of n-4H-SiC, MOSiC devices having a 10 nm-thick SiO2 film can be safely used in 5 V TTL logic circuits over a period of 10 years.

  10. Synthesis and photoluminescence property of silicon carbide nanowires thin film by HF-PECVD system

    Indian Academy of Sciences (India)

    Zhang Enlei; Wang Guosheng; Long Xiaozhu; Wang Zhumin

    2014-10-01

    A sample and scalable synthetic strategy was developed for the fabrication of nanocrystalline SiC (nc-SiC) thin film. Thin sheet of nanocrystalline diamond was deposited on Si substrate by hot filamentassisted plasma-enhanced chemical vapour deposition system (HF-PECVD). Further, the resulting carbonbased sheet was heated at 1200 °C to allow a solid state reaction between C and Si substrate to form the SiC thin films. The synthesized films mainly consist of -SiC nanowires with diameters of about 50 nm and tens of micrometers long. The nanowires axes lie along the [1 1 1] direction and possess a high density of planar defects. The -SiC nanowires thin films exhibit the strong photoluminescence (PL) peak at a wavelength of 400 nm, which is significantly shifted to the blue compared with the reported PL results of SiC materials. The blue shift may be ascribed to morphology, quantum size confinement effects of the nanomaterials and abundant structure defects that existed in the nanowires.

  11. Doping-free fabrication of silicon thin films for schottky solar cell.

    Science.gov (United States)

    Yun, Ju-Hyung; Park, Yun Chang; Yi, Junsin; Woo, Chang Su; Kim, Joondong

    2012-02-01

    Thin film Schottky solar cells were fabricated without doping processes, which may provide an alternative approach to the conventional thin film solar cells in the n-i-p configuration. A thin Co layer was coated on a substrate, which worked as a back contact metal and then Si film was grown above it. Deposition condition may modulate the Si film structure to be a fully amorphous Si (a-Si) or a mixing of microcrystalline Si (mc-Si) and a-Si. A thin Au layer was deposited above the grown Si films, which formed a Schottky junction. Two types of Schottky solar cells were prepared on a fully a-Si film and a mixing of mc-Si and a-Si film. Under one sun illumination, the mixing of mc-Si and a-Si device provided 35% and 68.4% enhancement in the open circuit voltage and fill factor compared to that of the amorphous device.

  12. Angular behavior of the absorption limit in thin film silicon solar cells

    CERN Document Server

    Naqavi, Ali; Söderström, Karin; Battaglia, Corsin; Paeder, Vincent; Scharf, Toralf; Herzig, Hans Peter; Ballif, Christophe

    2013-01-01

    We investigate the angular behavior of the upper bound of absorption provided by the guided modes in thin film solar cells. We show that the 4n^2 limit can be potentially exceeded in a wide angular and wavelength range using two-dimensional periodic thin film structures. Two models are used to estimate the absorption enhancement; in the first one, we apply the periodicity condition along the thickness of the thin film structure but in the second one, we consider imperfect confinement of the wave to the device. To extract the guided modes, we use an automatized procedure which is established in this work. Through examples, we show that from the optical point of view, thin film structures have a high potential to be improved by changing their shape. Also, we discuss the nature of different optical resonances which can be potentially used to enhance light trapping in the solar cell. We investigate the two different polarization directions for one-dimensional gratings and we show that the transverse magnetic pola...

  13. Modeling and optimization of white paint back reflectors for thin-film silicon solar cells

    NARCIS (Netherlands)

    Lipovšek, B.; Krč, J.; Isabella, O.; Zeman, M.; Topič, M.

    2010-01-01

    Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-fi

  14. Modeling and optimization of white paint back reflectors for thin-film silicon solar cells

    NARCIS (Netherlands)

    Lipovšek, B.; Krč, J.; Isabella, O.; Zeman, M.; Topič, M.

    2010-01-01

    Diffusive dielectric materials such as white paint have been demonstrated as effective back reflectors in the photovoltaic technology. In this work, a one-dimensional (1D) optical modeling approach for simulation of white paint films is developed and implemented in a 1D optical simulator for thin-fi

  15. Design of a CMOS readout circuit on ultra-thin flexible silicon chip for printed strain gauges

    Directory of Open Access Journals (Sweden)

    M. Elsobky

    2017-09-01

    Full Text Available Flexible electronics represents an emerging technology with features enabling several new applications such as wearable electronics and bendable displays. Precise and high-performance sensors readout chips are crucial for high quality flexible electronic products. In this work, the design of a CMOS readout circuit for an array of printed strain gauges is presented. The ultra-thin readout chip and the printed sensors are combined on a thin Benzocyclobutene/Polyimide (BCB/PI substrate to form a Hybrid System-in-Foil (HySiF, which is used as an electronic skin for robotic applications. Each strain gauge utilizes a Wheatstone bridge circuit, where four Aerosol Jet® printed meander-shaped resistors form a full-bridge topology. The readout chip amplifies the output voltage difference (about 5 mV full-scale swing of the strain gauge. One challenge during the sensor interface circuit design is to compensate for the relatively large dc offset (about 30 mV at 1 mA in the bridge output voltage so that the amplified signal span matches the input range of an analog-to-digital converter (ADC. The circuit design uses the 0. 5 µm mixed-signal GATEFORESTTM technology. In order to achieve the mechanical flexibility, the chip fabrication is based on either back thinned wafers or the ChipFilmTM technology, which enables the manufacturing of silicon chips with a thickness of about 20 µm. The implemented readout chip uses a supply of 5 V and includes a 5-bit digital-to-analog converter (DAC, a differential difference amplifier (DDA, and a 10-bit successive approximation register (SAR ADC. The circuit is simulated across process, supply and temperature corners and the simulation results indicate excellent performance in terms of circuit stability and linearity.

  16. Design of a CMOS readout circuit on ultra-thin flexible silicon chip for printed strain gauges

    Science.gov (United States)

    Elsobky, Mourad; Mahsereci, Yigit; Keck, Jürgen; Richter, Harald; Burghartz, Joachim N.

    2017-09-01

    Flexible electronics represents an emerging technology with features enabling several new applications such as wearable electronics and bendable displays. Precise and high-performance sensors readout chips are crucial for high quality flexible electronic products. In this work, the design of a CMOS readout circuit for an array of printed strain gauges is presented. The ultra-thin readout chip and the printed sensors are combined on a thin Benzocyclobutene/Polyimide (BCB/PI) substrate to form a Hybrid System-in-Foil (HySiF), which is used as an electronic skin for robotic applications. Each strain gauge utilizes a Wheatstone bridge circuit, where four Aerosol Jet® printed meander-shaped resistors form a full-bridge topology. The readout chip amplifies the output voltage difference (about 5 mV full-scale swing) of the strain gauge. One challenge during the sensor interface circuit design is to compensate for the relatively large dc offset (about 30 mV at 1 mA) in the bridge output voltage so that the amplified signal span matches the input range of an analog-to-digital converter (ADC). The circuit design uses the 0. 5 µm mixed-signal GATEFORESTTM technology. In order to achieve the mechanical flexibility, the chip fabrication is based on either back thinned wafers or the ChipFilmTM technology, which enables the manufacturing of silicon chips with a thickness of about 20 µm. The implemented readout chip uses a supply of 5 V and includes a 5-bit digital-to-analog converter (DAC), a differential difference amplifier (DDA), and a 10-bit successive approximation register (SAR) ADC. The circuit is simulated across process, supply and temperature corners and the simulation results indicate excellent performance in terms of circuit stability and linearity.

  17. Fabrication and Modeling of Ambipolar Hydrogenated Amorphous Silicon Thin Film Transistors.

    Science.gov (United States)

    1986-08-01

    that over 150 die can be fabricated on a single 2in Si wafer. Individual die are 4 -- ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - -- rM M- ri- PA NX RA "’K Kno ’--tx...Kusian, and B. Bullemer, "An Ambipolar Amorphous- Silicon Field-Effect Transistor," Siemens Forsch.-u. Entwickl.-Ber., vol. 14, no. 3, pp. 114-119...1985. 99. H. Pfleiderer, W. Kusian, and B. Bullemer, "An Ambipolar Field-Effect Transistor Model," Siemens Forsch.-u. Entwicki.-Ber., vol. 14, no. 2, pp

  18. High-temperature CVD for crystalline-silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Faller, F.R.; Hurrle, A.

    1999-10-01

    The fundamentals of thermal CVD for the deposition of silicon at high temperatures are briefly discussed and applied to the conditions in the CVD system that the authors have constructed and characterized. The system fulfills basic requirements to be met for solar cell application; solar cells made from epitaxial layers on various substrates were fabricated. The high-quality cells achieved 17.6% efficiency proving the excellent performance of the system, the cells on economically relevant substrates achieved 8% efficiency which still needs improvement.

  19. Heteroepitaxy of gallium-selenide on silicon(100) and (111): New silicon-compatible semiconductor thin films for nano structure formation

    Science.gov (United States)

    Ohta, Taisuke

    Silicon has been the backbone of modern electronics for decades; however, it is not readily compatible with some new types of electronics, such as optoelectronics or spintronics. We aim at overcoming this limitation by combining gallium-selenide (GaxSey) materials with silicon (Si) through heteroepitaxial growth. GaxSey materials are compatible with Si, and are optically and potentially magnetically active semiconductors. Their unusual crystal structures, layered GaSe and defected zinc-blende Ga2Se 3, may be exploited for unprecedented nanostructure formations. This dissertation demonstrates that GaxSey thin films can be grown epitaxially on Si(100) and (111) substrates into various nanostructure forms, namely 0-dimensional (0-D) "dots", 1-D "wires", 2-D "layers", and 3-D "bulk". We have found that hexagonal layered GaSe is formed on Si(111) with or without arsenic termination (Si(111):As), and defected zinc-blende Ga2Se3 is formed on arsenic terminated Si(100) (Si(100):As). The surfaces of GaSe/Si(111) and Ga 2Se3/Si(100):As are covered by triangle nanodots and oriented nanowire structures, respectively. We propose that different symmetry and bonding of the substrate surfaces induces different configurations of vacancies, resulting in the distinct surface nanostructures. We have achieved a thorough understanding for nanostructure formations of GaxSey by considering vacancies and surfaces as additional "elements" for stabilizing the structures. In contrast to layered GaSe/Si(111), we have found that Ga2Se3-GaAs alloy is formed in a zinc-blende phase at the interface of GaSe/Si(111):As. This signifies the bonding configuration of each element is responsible for determining the local composition; however, the atomic arrangement defined by the substrate symmetry plays a more decisive role in selecting GaxSey crystal structure for Ga xSey/Si heteroepitaxy. Through this study, we propose a generalized concept describing the stable structures of the selenide materials

  20. Analysis of recombination mechanisms in heterojunction silicon solar cells with rapid thermally annealed thin film emitters

    Science.gov (United States)

    Baldus-Jeursen, C.; Tarighat, R. S.; Sivoththaman, S.

    2017-05-01

    A new family of silicon (Si) wafer heterojunction solar cells fabricated by solid phase crystallization of PECVD amorphous silicon emitters by rapid thermal annealing (RTA) has been analyzed in order to understand the dominant recombination mechanisms. Solar cells fabricated with a broad RTA temperature range of 600-1000 °C were characterized through quantum efficiency, illuminated I-V, and capacitance-voltage measurements. Using the experimental data and theoretical considerations, the influence of carrier recombination in the quasi-neutral and space charge zones as well as at the heterojunction interface were studied. It is established that the carrier recombination in the quasi-neutral base region in the p-type Si substrate predominantly limits the device open circuit voltage. The analysis also showed that the interface recombination velocities at the heterojunction were less than 100 cm s-1. It is also qualitatively established that a post-fabrication forming gas anneal reduces the defect density at the hetero-interface.

  1. Silicon thin films prepared in the transition region and their use in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.; Raniero, L.; Fortunato, E.; Aguas, H.; Ferreira, I.; Martins, R. [Department of Materials Science/CENIMAT, Faculty of Sciences and Technology, New University of Lisbon and CEMOP-UNINOVA, 2829-516 Caparica (Portugal); Liao, X.; Xu, Y.; Kong, G. [State Key Laboratory for Surface Physics, Institute of Semiconductors & amp; Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100083 (China)

    2006-11-23

    Diphasic silicon films (nc-Si/a-Si:H) have been prepared by a new regime of plasma enhanced chemical vapour deposition in the region adjacent of phase transition from amorphous to microcrystalline state. Comparing to the conventional amorphous silicon (a-Si:H), the nc-Si/a-Si:H has higher photoconductivity ({sigma}{sub ph}), better stability, and a broader light spectral response range in the longer wavelength range. It can be found from Raman spectra that there is a notable improvement in the medium range order. The blue shift for the stretching mode and red shift for the wagging mode in the IR spectra also show the variation of the microstructure. By using this kind of film as intrinsic layer, a p-i-n junction solar cell was prepared with the initial efficiency of 8.51% and a stabilized efficiency of 8.01% (AM1.5, 100mw/cm{sup 2}) at room temperature. (author)

  2. Silicon template preparation for the fabrication of thin patterned gold films via template stripping

    Science.gov (United States)

    Schmidl, G.; Dellith, J.; Dellith, A.; Teller, N.; Zopf, D.; Li, G.; Dathe, A.; Mayer, G.; Hübner, U.; Zeisberger, M.; Stranik, O.; Fritzsche, W.

    2015-12-01

    Metallic nanostructures play an important role in the vast field of modern nanophotonics, which ranges from the life sciences to biomedicine and beyond. Gold is a commonly-used and attractive material for plasmonics in the visible wavelength range, most importantly due to its chemical stability. In the present work, we focused on the different methods of plasmonic nanostructure fabrication that possess the greatest potential for cost-efficient fabrication. Initially, reusable (1 0 0) silicon templates were prepared. For this purpose, three different lithography methods (i.e. e-beam, optical, and nanoparticle lithography) were used that correspond to the desired structural scales. The application of a subsequent anisotropic crystal orientation-dependent wet etching process produced well-defined pyramidal structures in a wide variety of sizes, ranging from several microns to less than 100 nm. Finally, a 200 nm-thick gold layer was deposited by means of confocal sputtering on the silicon templates and stripped in order to obtain gold films that feature a surface replica of the initial template structure. The surface roughness that was achieved on the stripped films corresponds well with the roughness of the template used. This makes it possible to prepare cost-efficient high-quality structured films in large quantities with little effort. The gold films produced were thoroughly characterized, particularly with respect to their plasmonic response.

  3. Cost reduction by using micro-fingers in thin film silicon modules

    Energy Technology Data Exchange (ETDEWEB)

    Slooff, L.H.; Bosman, J.; Loffler, J.; Budel, T. [ECN Solar Energy, Petten (Netherlands)

    2013-06-15

    A finite element electrical model is described that can be used to calculate the performance of monolithic thin film photovoltaic modules. The model is suitable for all type of thin film modules, like e.g. p-i-n a-Si:H, CIGS and polymer based modules and it includes losses due to interconnection. Using this model a parameter study is performed for a-Si:H cells with the aim to reduce metal consumption in the cell and interconnection. It is shown that a reduction in metal consumption by a factor 1.3 can be achieved with only marginal loss in performance if short cell are used with very short fingers.

  4. Electric field and temperature scaling of polarization reversal in silicon doped hafnium oxide ferroelectric thin films

    OpenAIRE

    Zhou, Dayu; Guan, Yan; Vopson, Melvin Marian; Xu, Jin; Liang, Hailong; Cao,Fei; Dong, Xianlin; Johannes, Johannes; Schenk, Tony; Schroeder, Uwe

    2015-01-01

    HfO2-based binary lead-free ferroelectrics show promising properties for non-volatile memory applications, providing that their polarization reversal behavior is fully understood. In this work, temperature-dependent polarization hysteresis measured over a wide applied field range has been investigated for Si-doped HfO2 ferroelectric thin films. Our study indicates that in the low and medium electric field regimes (E < twofold coercive field, 2Ec), the reversal process is dominated by the ther...

  5. Spectroscopy and structural properties of amorphous and nanocrystalline silicon carbide thin films

    NARCIS (Netherlands)

    Halindintwali, Sylvain; Knoesen, D.; Julies, B.A.; Arendse, C.J.; Muller, T.; Gengler, Régis Y.N.; Rudolf, P.; Loosdrecht, P.H.M. van

    2011-01-01

    Amorphous SiC:H thin films were grown by hot wire chemical vapour deposition from a SiH4/CH4/H2 mixture at a substrate temperature below 400 °C. Thermal annealing in an argon environment up to 900 °C shows that the films crystallize as μc-Si:H and SiC with a porous microstructure that favours an oxi

  6. Spectroscopy and structural properties of amorphous and nanocrystalline silicon carbide thin films

    NARCIS (Netherlands)

    Halindintwali, Sylvain; Knoesen, D.; Julies, B.A.; Arendse, C.J.; Muller, T.; Gengler, Régis Y.N.; Rudolf, P.; Loosdrecht, P.H.M. van

    2011-01-01

    Amorphous SiC:H thin films were grown by hot wire chemical vapour deposition from a SiH4/CH4/H2 mixture at a substrate temperature below 400 °C. Thermal annealing in an argon environment up to 900 °C shows that the films crystallize as μc-Si:H and SiC with a porous microstructure that favours an

  7. Iron, nitrogen and silicon doped diamond like carbon (DLC) thin films: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Sekhar C., E-mail: Raysc@unisa.ac.za [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, 1710, Science Campus, Christiaan de Wet and Pioneer Avenue, Florida Park, Johannesburg (South Africa); Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, New Taipei City, Taiwan (China); Papakonstantinou, P. [Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster, Shore Road, Newtownabbey BT37 0QB (United Kingdom)

    2016-07-01

    The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp{sup 3} network to sp{sup 2} as evidenced by an increase of the sp{sup 2} cluster and I{sub D}/I{sub G} ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp{sup 2} cluster and I{sub D}/I{sub G} ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp{sup 3}-content in DLC film structure. - Highlights: • Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively • DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films. • sp{sup 3} and sp{sup 2} contents are estimated from C K-edge XANES and VB-PES measurements.

  8. Structural and morphological study of ZnO thin films electrodeposited on n-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ait Ahmed, N., E-mail: nadiaitahmed@yahoo.fr [Laboratoire de Technologie des materiaux et Genie des Procedes : Equipe d' electrochimie - Corrosion Universite Abderrahmane Mira, Bejaia, 06000 (Algeria); Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria); Fortas, G. [Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria); Hammache, H. [Laboratoire de Technologie des materiaux et Genie des Procedes : Equipe d' electrochimie - Corrosion Universite Abderrahmane Mira, Bejaia, 06000 (Algeria); Sam, S.; Keffous, A.; Manseri, A. [Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria); Guerbous, L. [Centre de Recherche Nucleaire d' Alger (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Unite de Developpement de la Technologie du Silicium, 02 Bd Frantz Fanon, B.P. 140, Alger 7 Merveilles (Algeria)

    2010-10-01

    In this work, we report on the electrodeposition of ZnO thin films on n-Si (1 0 0) and glass substrates. The influence of the deposition time on the morphology of ZnO thin films was investigated. The ZnO thin films were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDS) and scanning electron microscopy (SEM). The results show a variation of ZnO texture from main (0 0 2) at 10 min to totally (1 0 1) at 15 min deposition time. The photoluminescence (PL) studies show that both UV ({approx}382 nm) and blue ({approx}432 nm) luminescences are the main emissions for the electrodeposited ZnO films. In addition, the film grown at 15 min indicates an evident decrease of the yellow-green ({approx}520 nm) emission band comparing with that of 10 min. Finally, transmittance spectra show a high transmission value up to 85% in the visible wavelength range. Such results would be very interesting for solar cells applications.

  9. Theory and experiments of electron-hole recombination at silicon/silicon dioxide interface traps and tunneling in thin oxide MOS transistors

    Science.gov (United States)

    Cai, Jin

    2000-10-01

    Surface recombination and channel have dominated the electrical characteristics, performance and reliability of p/n junction diodes and transistors. This dissertation uses a sensitive direct-current current voltage (DCIV) method to measure base terminal currents (IB) modulated by the gate bias (VGB) and forward p/n junction bias (VPN) in a MOS transistor (MOST). Base terminal currents originate from electron-hole recombination at Si/SiO2 interface traps. Fundamental theories which relate DCIV characteristics to device and material parameters are presented. Three theory-based applications are demonstrated on both the unstressed as well as hot-carrier-stressed MOSTs: (1) determination of interface trap density and energy levels, (2) spatial profile of interface traps in the drain/base junction-space-charge region and in the channel region, and (3) determination of gate oxide thickness and impurity doping concentrations. The results show that interface trap energy levels are discrete, which is consistent with those from silicon dangling bonds; in unstressed MOS transistors interface trap density in the channel region rises sharply toward source and drain, and after channel-hot-carrier stress, interface trap density increases mostly in the junction space-charge region. As the gate oxide thins below 3 nm, the gate oxide leakage current via quantum mechanical tunneling becomes significant. A gate oxide tunneling theory which refined the traditional WKB tunneling probability is developed for modeling tunneling currents at low electric fields through a trapezoidal SiO2 barrier. Correlation with experimental data on thin oxide MOSTs reveals two new results: (1) hole tunneling dominates over electron tunneling in p+gate p-channel MOSTs, and (2) the small gate/drain overlap region passes higher tunneling currents than the channel region under depletion to flatband gate voltages. The good theory-experimental correlation enables the extraction of impurity doping concentrations

  10. Materials and Electrical Characterization of Physical Vapor Deposited LaxLu1-xO3 Thin Films on 300 mm Silicon

    Energy Technology Data Exchange (ETDEWEB)

    L Edge; T Vo; V Paruchuri; R Iijima; J Bruley; J Jordan-Sweet; B Linder; A Kellock; T Tsunoda; S Shinde

    2011-12-31

    La{sub x}Lu{sub 1-x}O{sub 3} thin films were deposited on 300 mm silicon wafers by physical vapor deposition and fabricated into field-effect transistors using a gate-first process flow. The films were characterized using transmission electron microscopy, Rutherford backscattering spectrometry, and synchrotron x-ray diffraction. The results show the films remain amorphous even at temperatures of 1000 C. The dielectric properties of La{sub x}Lu{sub 1-x}O{sub 3} (0.125 {<=} x {<=} 0.875) thin films were evaluated as a function of film composition. The amorphous La{sub x}Lu{sub 1-x}O{sub 3} thin films have a dielectric constant (K) of 23 across the composition range. The inversion thickness (T{sub inv}) of the La{sub x}Lu{sub 1-x}O{sub 3} thin films was scaled to <1.0 nm.

  11. Effect of annealing atmosphere on secondary recrystallization in thin-gauge grain-oriented silicon steel: evolution of inhibitors

    Science.gov (United States)

    Yang, Fu-yao; He, Cheng-xu; Meng, Li; Ma, Guang; Chen, Xin; Mao, Wei-min

    2017-10-01

    Thin-gauge cold-rolled grain-oriented (TG-CRGO) silicon steels were fabricated using the acquired inhibitor method, in which the behaviors of inhibitor are strongly influenced by the final annealing atmosphere and differ from that of the TG-CRGO silicon steel. In this study, macrostructures, grain orientations, and evolution of inhibitors in two gauges of thickness (0.23 and 0.18 mm) of steels were studied and compared in five different annealing atmospheres. The second-phase particles in samples were observed by field-emission scanning electron microscopy. Distribution densities and mean diameter of particles were statistically calculated to illustrate the effect of Zener factor. Results indicated that the inhibitor behaviors in the two thickness samples are similar with the change of N2 proportion in annealing atmosphere, i.e., nitrogen loss, decomposition, coalescence, and ripening of particles would be strongly suppressed with the increase of N2 content. However, in comparison with the 0.23-mm samples, the nitride precipitation, decomposition and inhibitor coarsening of the 0.18-mm specimens are more likely to occur at a lower temperature because of the thinner thickness. Furthermore, the value of Zener factor implies that for thinner samples, more N2 should be employed when nitrides are used the main inhibitor; this condition would inhibit the development of undesirable deviated Goss grains. This study showed that the 0.23-mm sample could achieve the best magnetic properties (B8) at 1.92 T in the atmosphere containing 25% N2. The 0.18-mm sample could achieve the best magnetic properties (B8) at 1.93 T in the atmosphere containing 75% N2.

  12. Picosecond and nanosecond laser annealing and simulation of amorphous silicon thin films for solar cell applications

    Science.gov (United States)

    Theodorakos, I.; Zergioti, I.; Vamvakas, V.; Tsoukalas, D.; Raptis, Y. S.

    2014-01-01

    In this work, a picosecond diode pumped solid state laser and a nanosecond Nd:YAG laser have been used for the annealing and the partial nano-crystallization of an amorphous silicon layer. These experiments were conducted as an alternative/complementary to plasma-enhanced chemical vapor deposition method for fabrication of micromorph tandem solar cell. The laser experimental work was combined with simulations of the annealing process, in terms of temperature distribution evolution, in order to predetermine the optimum annealing conditions. The annealed material was studied, as a function of several annealing parameters (wavelength, pulse duration, fluence), as far as it concerns its structural properties, by X-ray diffraction, SEM, and micro-Raman techniques.

  13. Thin silicon strip detectors for beam monitoring in Micro-beam Radiation Therapy

    CERN Document Server

    Povoli, Marco; Bravin, Alberto; Cornelius, Iwan; Bräuer-Krisch, Elke; Fournier, Pauline; Hansen, Thor-Erik; Kok, Angela; Lerch, Michael; Monakhov, Edouard; Morse, John; Petasecca, Marco; Requardt, Herwig; Rosenfeld, Anatoly; Röhrich, Dieter; Sandaker, Heidi; Salomé, Murielle; Stugu, Bjarne

    2015-01-01

    Microbeam Radiation Therapy (MRT) is an emerging cancer treatment that is currently being developed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. This technique uses a highly collimated and fractionated X-ray beam array with extremely high dose rate and very small divergence, to benefit from the dose-volume effect, thus sparing healthy tissue. In case of any beam anomalies and system malfunctions, special safety measures must be installed, such as an emergency safety shutter that requires continuous monitoring of the beam intensity profile. Within the 3DMiMic project, a novel silicon strip detector that can tackle the special features of MRT, such as the extremely high spatial resolution and dose rate, has been developed to be part of the safety shutter system. The first prototypes have been successfully fabricated, and experiments aimed to demonstrate their suitability for this unique application have been performed. Design, fabrication and the experimental results as well as any...

  14. Modeling and simulation of boron-doped nanocrystalline silicon carbide thin film by a field theory.

    Science.gov (United States)

    Xiong, Liming; Chen, Youping; Lee, James D

    2009-02-01

    This paper presents the application of a multiscale field theory in modeling and simulation of boron-doped nanocrystalline silicon carbide (B-SiC). The multiscale field theory was briefly introduced. Based on the field theory, numerical simulations show that intergranular glassy amorphous films (IGFs) and nano-sized pores exist in triple junctions of the grains for nanocrystalline B-SiC. Residual tensile stress in the SiC grains and compressive stress on the grain boundaries (GBs) were observed. Under tensile loading, it has been found that mechanical response of 5 wt% boron-SiC exhibits five characteristic regimes. Deformation mechanism at atomic scale has been revealed. Tensile strength and Young's modulus of nanocrystalline SiC were accurately reproduced.

  15. Growth, etching, and stability of sputtered ZnO:Al for thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Jorj Ian

    2011-07-01

    Aluminum-doped zinc oxide (ZnO:Al) can fulfill many requirements in thin-film solar cells, acting as (1) a transparent contact through which the incident light is transmitted, (2) part of the back reflector, and (3) a source of light scattering. Magnetron sputtered ZnO:Al thin-films are highly transparent, conductive, and are typically texturized by post-deposition etching in a dilute hydrochloric acid (HCl) solution to achieve light scattering. The ZnO:Al thin-film electronic and optical properties, as well as the surface texture after etching, depend on the deposition conditions and the post-deposition treatments. Despite having been used in thin-film solar cells for more than a decade, many aspects regarding the growth, effects of heat treatments, environmental stability, and etching of sputtered ZnO:Al are not fully understood. This work endeavors to further the understanding of ZnO:Al for the purpose improving silicon thin-film solar cell efficiency and reducing ZnO:Al production costs. With regard to the growth of ZnO:Al, the influence of various deposition conditions on the resultant electrical and structural properties and their evolution with film thickness were studied. The surface electrical properties extracted from a multilayer model show that while carrier concentration of the surface layer saturates already at film thickness of 100 nm, the surface mobility continues to increases with film thickness, and it is concluded that electronic transport across grain boundaries limits mobility in ZnO:Al thin films. ZnO:Al deposited onto a previously etched ZnO:Al surface grows epitaxially, preserving both the original orientation and grain structure. Further, it is determined that a typical ZnO:Al used in thin-film silicon solar cells grows Zn-terminated on glass substrates. Concerning the affects of heat treatments and stability, it is demonstrated that a layer of amorphous silicon can protect ZnO:Al from degradation during annealing, and the mobility of Zn

  16. Growth, etching, and stability of sputtered ZnO:Al for thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Jorj Ian

    2011-07-01

    Aluminum-doped zinc oxide (ZnO:Al) can fulfill many requirements in thin-film solar cells, acting as (1) a transparent contact through which the incident light is transmitted, (2) part of the back reflector, and (3) a source of light scattering. Magnetron sputtered ZnO:Al thin-films are highly transparent, conductive, and are typically texturized by post-deposition etching in a dilute hydrochloric acid (HCl) solution to achieve light scattering. The ZnO:Al thin-film electronic and optical properties, as well as the surface texture after etching, depend on the deposition conditions and the post-deposition treatments. Despite having been used in thin-film solar cells for more than a decade, many aspects regarding the growth, effects of heat treatments, environmental stability, and etching of sputtered ZnO:Al are not fully understood. This work endeavors to further the understanding of ZnO:Al for the purpose improving silicon thin-film solar cell efficiency and reducing ZnO:Al production costs. With regard to the growth of ZnO:Al, the influence of various deposition conditions on the resultant electrical and structural properties and their evolution with film thickness were studied. The surface electrical properties extracted from a multilayer model show that while carrier concentration of the surface layer saturates already at film thickness of 100 nm, the surface mobility continues to increases with film thickness, and it is concluded that electronic transport across grain boundaries limits mobility in ZnO:Al thin films. ZnO:Al deposited onto a previously etched ZnO:Al surface grows epitaxially, preserving both the original orientation and grain structure. Further, it is determined that a typical ZnO:Al used in thin-film silicon solar cells grows Zn-terminated on glass substrates. Concerning the affects of heat treatments and stability, it is demonstrated that a layer of amorphous silicon can protect ZnO:Al from degradation during annealing, and the mobility of Zn

  17. Artificial neural systems using memristive synapses and nano-crystalline silicon thin-film transistors

    Science.gov (United States)

    Cantley, Kurtis D.

    Future computer systems will not rely solely on digital processing of inputs from well-defined data sets. They will also be required to perform various computational tasks using large sets of ill-defined information from the complex environment around them. The most efficient processor of this type of information known today is the human brain. Using a large number of primitive elements (˜1010 neurons in the neocortex) with high parallel connectivity (each neuron has ˜104 synapses), brains have the remarkable ability to recognize and classify patterns, predict outcomes, and learn from and adapt to incredibly diverse sets of problems. A reasonable goal in the push to increase processing power of electronic systems would thus be to implement artificial neural networks in hardware that are compatible with today's digital processors. This work focuses on the feasibility of utilizing non-crystalline silicon devices in neuromorphic electronics. Hydrogenated amorphous silicon (a-Si:H) nanowire transistors with Schottky barrier source/drain junctions, as well as a-Si:H/Ag resistive switches are fabricated and characterized. In the transistors, it is found that the on-current scales linearly with the effective width W eff of the channel nanowire array down to at least 20 nm. The solid-state electrolyte resistive switches (memristors) are shown to exhibit the proper current-voltage hysteresis. SPICE models of similar devices are subsequently developed to investigate their performance in neural circuits. The resulting SPICE simulations demonstrate spiking properties and synaptic learning rules that are incredibly similar to those in biology. Specifically, the neuron circuits can be designed to mimic the firing characteristics of real neurons, and Hebbian learning rules are investigated. Finally, some applications are presented, including associative learning analogous to the classical conditioning experiments originally performed by Pavlov, and frequency and pattern

  18. Development of Tandem Amorphous/Microcrystalline Silicon Thin-Film Large-Area See-Through Color Solar Panels with Reflective Layer and 4-Step Laser Scribing for Building-Integrated Photovoltaic Applications

    National Research Council Canada - National Science Library

    Tsai, Chin-Yi; Tsai, Chin-Yao

    2014-01-01

      In this work, tandem amorphous/microcrystalline silicon thin-film large-area see-through color solar modules were successfully designed and developed for building-integrated photovoltaic applications...

  19. Silicidation in Pd/Si thin film junction-Defect evolution and silicon surface segregation

    Energy Technology Data Exchange (ETDEWEB)

    Abhaya, S. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amarendra, G. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)], E-mail: amar@igcar.gov.in; Venugopal Rao, G.; Rajaraman, R.; Panigrahi, B.K.; Sastry, V.S. [Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2007-09-25

    Depth resolved positron annihilation studies on Pd/Si thin film system have been carried out to investigate silicide phase formation and vacancy defect production induced by thermal annealing. The evolution of defect sensitive S-parameter clearly indicates the presence of divacancy defects across the interface, due to enhanced Si diffusion beyond 870 K consequent to silicide formation. Corroborative glancing incidence X-ray diffraction (GIXRD), Auger electron spectroscopy (AES) and Rutherford backscattering spectrometry (RBS) have elucidated the aspects related to silicide phase formation and Si surface segregation.

  20. Quantum efficiency enhancement in selectively transparent silicon thin film solar cells by distributed Bragg reflectors.

    Science.gov (United States)

    Kuo, M Y; Hsing, J Y; Chiu, T T; Li, C N; Kuo, W T; Lay, T S; Shih, M H

    2012-11-05

    This work demonstrated a-Si:H thin-film solar cells with backside TiO(2) / SiO(2) distributed Bragg reflectors (DBRs) for applications involving building-integrated photovoltaics (BIPVs). Selectively transparent solar cells are formed by adjusting the positions of the DBR stop bands to allow the transmission of certain parts of light through the solar cells. Measurement and simulation results indicate that the transmission of blue light (430 ~500 nm) with the combination of three DBR mirrors has the highest increase in conversion efficiency.

  1. Growth of Hexagonal Columnar Nanograin Structured SiC Thin Films on Silicon Substrates with Graphene–Graphitic Carbon Nanoflakes Templates from Solid Carbon Sources

    Directory of Open Access Journals (Sweden)

    Wanshun Zhao

    2013-04-01

    Full Text Available We report a new method for growing hexagonal columnar nanograin structured silicon carbide (SiC thin films on silicon substrates by using graphene–graphitic carbon nanoflakes (GGNs templates from solid carbon sources. The growth was carried out in a conventional low pressure chemical vapor deposition system (LPCVD. The GGNs are small plates with lateral sizes of around 100 nm and overlap each other, and are made up of nanosized multilayer graphene and graphitic carbon matrix (GCM. Long and straight SiC nanograins with hexagonal shapes, and with lateral sizes of around 200–400 nm are synthesized on the GGNs, which form compact SiC thin films.

  2. The effect of dry shear aligning of nanotube thin films on the photovoltaic performance of carbon nanotube–silicon solar cells

    Directory of Open Access Journals (Sweden)

    Benedikt W. Stolz

    2016-10-01

    Full Text Available Recent results in the field of carbon nanotube–silicon solar cells have suggested that the best performance is obtained when the nanotube film provides good coverage of the silicon surface and when the nanotubes in the film are aligned parallel to the surface. The recently developed process of dry shear aligning – in which shear force is applied to the surface of carbon nanotube thin films in the dry state, has been shown to yield nanotube films that are very flat and in which the surface nanotubes are very well aligned in the direction of shear. It is thus reasonable to expect that nanotube films subjected to dry shear aligning should outperform otherwise identical films formed by other processes. In this work, the fabrication and characterisation of carbon nanotube–silicon solar cells using such films is reported, and the photovoltaic performance of devices produced with and without dry shear aligning is compared.

  3. Structural, morphological and optical characterizations of ZnO:Al thin films grown on silicon substrates by pulsed laser deposition

    Science.gov (United States)

    Alyamani, A.; Sayari, A.; Albadri, A.; Albrithen, H.; El Mir, L.

    2016-09-01

    The pulsed laser deposition (PLD) technique is used to grow Al-doped ZnO (AZO) thin films at 500 ° C on silicon substrates under vacuum or oxygen gas background from ablating AZO nanoparticle targets synthesized via the sol-gel process. The structural, morphological and optical properties were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and spectroscopic ellipsometry (SE) techniques. XRD and TEM images show that AZO powder has a wurtzite-type structure and is composed of small prismatic-like shape nanoparticles with an average size of 30nm. The structural properties of the AZO films grown under oxygen show no significant changes compared to those of the film grown under vacuum. However, the optical properties show a dependence on the growth conditions of the AZO films. Highly c -axis-oriented AZO thin films were obtained with grain size ˜ 15 nm. The stress in the AZO films is tensile as measured from the c -parameter. The dielectric function, the refractive index and the extinction coefficient as a function of the photon energy for the AZO films were determined by using spectroscopic ellipsometry measurements in the photon energy region from 1 to 6eV. The band gap energy was observed to slightly decrease in the presence of the O2 gas background and this may be attributed to the stress. The surface and volume energy loss functions are calculated and exhibit different behaviors in the energy range 1-6eV. Refractive indices of 1.9-2.1 in the visible region were obtained for the AZO films. Also, the electronic carrier concentration appears to be related to the presence of O2 during the growth process.

  4. n +-Microcrystalline-Silicon Tunnel Layer in Tandem Si-Based Thin Film Solar Cells

    Science.gov (United States)

    Lee, Ching-Ting; Lee, Hsin-Ying; Chen, Kuan-Hao

    2016-10-01

    In this study, the p-SiC/ i-Si/ n-Si cell and the p-SiC/ i-SiGe/ n-Si cell deposited using plasma-enhanced chemical vapor deposition were cascaded for forming the tandem Si-based thin film solar cells to absorb the wide solar spectrum. To further improve the performances of the tandem Si-based thin film solar cells, a 5-nm-thick n +-microcrystalline-Si ( n +-μc-Si) tunnel layer deposited using the laser-assisted plasma-enhanced chemical vapor deposition was inserted between the p-SiC/ i-Si/ n-Si cell and the p-SiC/ i-SiGe/ n-Si cell. Since both the plasma and the CO2 laser were simultaneously utilized to efficiently decompose the reactant and doping gases, the carrier concentration and the carrier mobility of the n +-μc-Si tunnel layer were significantly improved. The ohmic contact formed between the p-SiC layer and the n +-μc-Si tunnel layer with low resistance was beneficial to the generated current transportation and the carrier recombination rate. Therefore, the conversion efficiency of the tandem solar cells was promoted from 8.57% and 8.82% to 9.91% compared to that without tunnel layer and with 5-nm-thick n +-amorphous-Si tunnel layer.

  5. Al-doped and in-doped ZnO thin films in heterojunctions with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chabane, L.; Zebbar, N.; Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32-16111, Algiers (Algeria); Aida, M.S. [LCMet Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32-16111 Algiers (Algeria)

    2016-04-30

    The undoped, Al-doped and In-doped ZnO thin films were deposited by ultrasonic spray pyrolysis technique, onto glass and p-Si substrates and the physical properties of the films were investigated. The X-ray diffraction, optical analysis and electrical characterisations, indicate that the films were polycrystalline with hexagonal würtzite type structure and revealed that the aluminium doping deteriorates the crystalline and optical properties and enhances the electrical conductivity whereas indium doping improves all properties. The transport mechanism controlling the conduction through the heterojunctions was studied. For the heterostructures, the temperature dependent current–voltage characteristics showed rectifying behaviour in the dark, but current transport mechanism is not the same for all heterojunctions. Therefore, the presence of the interface states and volume defects are identified as limiting factors for obtaining a high quality heterojunction interface. - Highlights: • Al-doped and In-doped ZnO thin films have been deposited onto Si. • In-doped ZnO/p-Si heterojunction showed poor rectifying behaviour. • Al-doped ZnO/p-Si heterojunction showed a good rectifying at room temperature. • The carriers transport mechanisms was controlled by interfacial and volume defects.

  6. Preparation of coarse grained polycrystalline thin films for silicon solar cells. Final report; Praeparation von grobkoernig-polykristallinen Duennschichten fuer Solarzellen aus Silizium. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Andrae, G.; Bergmann, J.; Falk, F.; Ose, E.

    1999-06-01

    The project was to test methods for preparation of large-crystallite silicon thin films on glass by laser crystallization of amorphous silicon. Further, the properties of those thin films were examined for their suitability of use in solar cells. As the film thickness of some 10{mu}m, required for light absorption by crystalline silicon (unless light traps are used), cannot be achieved in one step via laser crystallization, a multi-step technique was proposed, the first step consisting of a conventional PECVD process for deposition of amorphous silicon films of some nm in thickness. This process was optimized, achieving the thin film properties required for subsequent laser crystallization, including resolution of some other problems involved, primarily those of reliable adhesive strength of the thin films, and their hydrogen content. As a second step, various techniques for laser crystallization of the amorphous thin films were tested and optimized. The objective was to prepare crystalline silicon thin films with a thickness of some hundred nm, consisting of crystallites as large as possible. The targeted size of crystallites was a lateral size of 100 {mu}m. (orig./CB) [German] In dem hier beschriebenen Projekt sollten Laserverfahren erprobt werden, um auf Glas moeglichst grosse Siliciumkristallite durch Kristallisation aus amorphem Siliciumschichten herzustellen. Weiterhin sollten die Eigenschaften dieser kristallinen Schichten mit Hinblick auf ihre Eignung fuer Solarzellen untersucht werden. Da die fuer die Lichtabsorption in kristallinem Silicum erforderliche Schichtdicke von einigen 10 {mu}m (wenn keine Lichtfallen eingesetzt werden) nicht in einem einzigen Schritt mit dem Laser kristallisiert werden kann, wurde ein Mehrschrittverfahren vorgeschlagen. In einem ersten Schritt sollte amorphes Silicium mit einer Schichtdicke von einigen hundert nm Dicke durch einen konventionellen PECVD-Prozess abgeschieden werden. Das Abscheideverfahren sollte so optimiert

  7. A Comparison of Photo-Induced Hysteresis Between Hydrogenated Amorphous Silicon and Amorphous IGZO Thin-Film Transistors.

    Science.gov (United States)

    Ha, Tae-Jun; Cho, Won-Ju; Chung, Hong-Bay; Koo, Sang-Mo

    2015-09-01

    We investigate photo-induced instability in thin-film transistors (TFTs) consisting of amorphous indium-gallium-zinc-oxide (a-IGZO) as active semiconducting layers by comparing with hydrogenated amorphous silicon (a-Si:H). An a-IGZO TFT exhibits a large hysteresis window in the illuminated measuring condition but no hysteresis window in the dark condition. On the contrary, a large hysteresis window measured in the dark condition in a-Si:H was not observed in the illuminated condition. Even though such materials possess the structure of amorphous phase, optical responses or photo instability in TFTs looks different from each other. Photo-induced hysteresis results from initially trapped charges at the interface between semiconductor and dielectric films or in the gate dielectric which possess absorption energy to interact with deep trap-states and affect the movement of Fermi energy level. In order to support our claim, we also perform CV characteristics in photo-induced hysteresis and demonstrate thermal-activated hysteresis. We believe that this work can provide important information to understand different material systems for optical engineering which includes charge transport and band transition.

  8. Microspot-based ELISA in microfluidics: chemiluminescence and colorimetry detection using integrated thin-film hydrogenated amorphous silicon photodiodes.

    Science.gov (United States)

    Novo, Pedro; Prazeres, Duarte Miguel França; Chu, Virginia; Conde, João Pedro

    2011-12-07

    Microfluidic technology has the potential to decrease the time of analysis and the quantity of sample and reactants required in immunoassays, together with the potential of achieving high sensitivity, multiplexing, and portability. A lab-on-a-chip system was developed and optimized using optical and fluorescence microscopy. Primary antibodies are adsorbed onto the walls of a PDMS-based microchannel via microspotting. This probe antibody is then recognised using secondary FITC or HRP labelled antibodies responsible for providing fluorescence or chemiluminescent and colorimetric signals, respectively. The system incorporated a micron-sized thin-film hydrogenated amorphous silicon photodiode microfabricated on a glass substrate. The primary antibody spots in the PDMS-based microfluidic were precisely aligned with the photodiodes for the direct detection of the antibody-antigen molecular recognition reactions using chemiluminescence and colorimetry. The immunoassay takes ~30 min from assay to the integrated detection. The conditions for probe antibody microspotting and for the flow-through ELISA analysis in the microfluidic format with integrated detection were defined using antibody solutions with concentrations in the nM-μM range. Sequential colorimetric or chemiluminescence detection of specific antibody-antigen molecular recognition was quantitatively detected using the photodiode. Primary antibody surface densities down to 0.182 pmol cm(-2) were detected. Multiplex detection using different microspotted primary antibodies was demonstrated.

  9. Production and characterisation of SLID interconnected n-in-p pixel modules with 75 μm thin silicon sensors

    Energy Technology Data Exchange (ETDEWEB)

    Andricek, L. [Halbleiterlabor der Max-Planck-Gesellschaft, Otto Hahn Ring 6, D-81739 München (Germany); Beimforde, M.; Macchiolo, A.; Moser, H.-G. [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805 München (Germany); Nisius, R., E-mail: Richard.Nisius@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805 München (Germany); Richter, R.H. [Halbleiterlabor der Max-Planck-Gesellschaft, Otto Hahn Ring 6, D-81739 München (Germany); Terzo, S.; Weigell, P. [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, D-80805 München (Germany)

    2014-09-11

    The performance of pixel modules built from 75 μm thin silicon sensors and ATLAS read-out chips employing the Solid Liquid InterDiffusion (SLID) interconnection technology is presented. This technology, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It allows for stacking of different interconnected chip and sensor layers without destroying the already formed bonds. In combination with Inter-Chip-Vias (ICVs) this paves the way for vertical integration. Both technologies are combined in a pixel module concept which is the basis for the modules discussed in this paper. Mechanical and electrical parameters of pixel modules employing both SLID interconnections and sensors of 75 μm thickness are covered. The mechanical features discussed include the interconnection efficiency, alignment precision and mechanical strength. The electrical properties comprise the leakage currents, tuning characteristics, charge collection, cluster sizes and hit efficiencies. Targeting at a usage at the high luminosity upgrade of the LHC accelerator called HL-LHC, the results were obtained before and after irradiation up to fluences of 10{sup 16}n{sub eq}/cm{sup 2}.

  10. Scattering effect of the high-index dielectric nanospheres for high performance hydrogenated amorphous silicon thin-film solar cells

    Science.gov (United States)

    Yang, Zhenhai; Gao, Pingqi; Zhang, Cheng; Li, Xiaofeng; Ye, Jichun

    2016-07-01

    Dielectric nanosphere arrays are considered as promising light-trapping designs with the capability of transforming the freely propagated sunlight into guided modes. This kinds of designs are especially beneficial to the ultrathin hydrogenated amorphous silicon (a-Si:H) solar cells due to the advantages of using lossless material and easily scalable assembly. In this paper, we demonstrate numerically that the front-sided integration of high-index subwavelength titanium dioxide (TiO2) nanosphere arrays can significantly enhance the light absorption in 100 nm-thick a-Si:H thin films and thus the power conversion efficiencies (PCEs) of related solar cells. The main reason behind is firmly attributed to the strong scattering effect excited by TiO2 nanospheres in the whole waveband, which contributes to coupling the light into a-Si:H layer via two typical ways: 1) in the short-waveband, the forward scattering of TiO2 nanospheres excite the Mie resonance, which focuses the light into the surface of the a-Si:H layer and thus provides a leaky channel; 2) in the long-waveband, the transverse waveguided modes caused by powerful scattering effectively couple the light into almost the whole active layer. Moreover, the finite-element simulations demonstrate that photocurrent density (Jph) can be up to 15.01 mA/cm2, which is 48.76% higher than that of flat system.

  11. Surface modification of ZnO-Films as transparent conductive oxide layer for silicon thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Luekermann, Florian; Moenkemoeller, Viola; Brechling, Armin; Sacher, Marc; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Kurz, Henning; Hamelmann, Frank; Stiebig, Helmut [Malibu GmbH, Bielefeld (Germany)

    2009-07-01

    Transparent conductive oxides are used as front electrode in thin film solar cells. Especially ZnO deposited by Low Pressure Chemical Vapor Deposition provides useful features for solar cells. On the one hand ZnO shows a good conductivity and on the other hand a rough surface consisting of pyramidal grains which possess a good light scattering capability. To influence this light scattering, two different kinds of treatments have been applied on the ZnO surface: etching with diluted HCl and Reactive Ion Etching with Ar and O{sub 2}. The main interest is focused on the change of surface morphology and the resulting changes in light scattering and transmission. HCl etching leads to an increasing surface roughness as well as diffuse transmittance. Ar/O{sub 2} bombardment decreases the roughness and thus the scattering. The lowered roughness enhances the growth of the a-Si absorber layer and reduces the formation of pinholes. Finally the properties of amorphous silicon solar cells deposited on treated ZnO-films are compared with those deposited on untreated films.

  12. Optimized absorption of solar radiations in nano-structured thin films of crystalline silicon via a genetic algorithm

    Science.gov (United States)

    Mayer, Alexandre; Muller, Jérôme; Herman, Aline; Deparis, Olivier

    2015-08-01

    We developed a genetic algorithm to achieve optimal absorption of solar radiation in nano-structured thin films of crystalline silicon (c-Si) for applications in photovoltaics. The device includes on the front side a periodic array of inverted pyramids, with conformal passivation layer (a-Si:H or AlOx) and anti-reflection coating (SiNx). The device also includes on the back side a passivation layer (a-Si:H) and a flat reflector (ITO and Ag). The geometrical parameters of the inverted pyramids as well as the thickness of the different layers must be adjusted in order to maximize the absorption of solar radiations in the c-Si. The genetic algorithm enables the determination of optimal solutions that lead to high performances by evaluating only a reduced number of parameter combinations. The results achieved by the genetic algorithm for a 40μm thick c-Si lead to short-circuit currents of 37 mA/cm2 when a-Si:H is used for the front-side passivation and 39.1 mA/cm2 when transparent AlOx is used instead.

  13. Label-free electrical determination of trypsin activity by a silicon-on-insulator based thin film resistor.

    Science.gov (United States)

    Neff, Petra A; Serr, Andreas; Wunderlich, Bernhard K; Bausch, Andreas R

    2007-10-08

    A silicon-on-insulator (SOI) based thin film resistor is employed for the label-free determination of enzymatic activity. We demonstrate that enzymes, which cleave biological polyelectrolyte substrates, can be detected by the sensor. As an application, we consider the serine endopeptidase trypsin, which cleaves poly-L-lysine (PLL). We show that PLL adsorbs quasi-irreversibly to the sensor and is digested by trypsin directly at the sensor surface. The created PLL fragments are released into the bulk solution due to kinetic reasons. This results in a measurable change of the surface potential allowing for the determination of trypsin concentrations down to 50 ng mL(-1). Chymotrypsin is a similar endopeptidase with a different specificity, which cleaves PLL with a lower efficiency as compared to trypsin. The activity of trypsin is analyzed quantitatively employing a kinetic model for enzyme-catalyzed surface reactions. Moreover, we have demonstrated the specific inactivation of trypsin by a serine protease inhibitor, which covalently binds to the active site of the enzyme.

  14. Neutron measurements with ultra-thin 3D silicon sensors in a radiotherapy treatment room using a Siemens PRIMUS linac

    Science.gov (United States)

    Guardiola, C.; Gómez, F.; Fleta, C.; Rodríguez, J.; Quirion, D.; Pellegrini, G.; Lousa, A.; Martínez-de-Olcoz, L.; Pombar, M.; Lozano, M.

    2013-05-01

    The accurate detection and dosimetry of neutrons in mixed and pulsed radiation fields is a demanding instrumental issue with great interest both for the industrial and medical communities. In recent studies of neutron contamination around medical linacs, there is a growing concern about the secondary cancer risk for radiotherapy patients undergoing treatment in photon modalities at energies greater than 6 MV. In this work we present a promising alternative to standard detectors with an active method to measure neutrons around a medical linac using a novel ultra-thin silicon detector with 3D electrodes adapted for neutron detection. The active volume of this planar device is only 10 µm thick, allowing a high gamma rejection, which is necessary to discriminate the neutron signal in the radiotherapy peripheral radiation field with a high gamma background. Different tests have been performed in a clinical facility using a Siemens PRIMUS linac at 6 and 15 MV. The results show a good thermal neutron detection efficiency around 2% and a high gamma rejection factor.

  15. Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

    Directory of Open Access Journals (Sweden)

    Mason L. Terry

    2007-01-01

    Full Text Available The changes in open-circuit voltage (Voc, short-circuit current density (Jsc, and internal quantum efficiency (IQE of aLuminum induced crystallization, ion-assisted deposition (ALICIA polycrystalline silicon thin-film solar cells on low-temperature glass substrates due to rapid thermal anneal (RTA treatment and subsequent remote microwave hydrogen plasma passivation (hydrogenation are examined. Voc improvements from 130 mV to 430 mV, Jsc improvements from 1.2 mA/cm2 to 11.3 mA/cm2, and peak IQE improvements from 16% to > 70% are achieved. A 1-second RTA plateau at 1000°C followed by hydrogenation increases the Jsc by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion length of at least 1 μm due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and Voc due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance.

  16. Integration of a 2D Periodic Nanopattern Into Thin Film Polycrystalline Silicon Solar Cells by Nanoimprint Lithography

    CERN Document Server

    Abdo, Islam; Deckers, Jan; Depauw, Valérie; Tous, Loic; Van Gestel, Dries; Guindi, Rafik; Gordon, Ivan; Daif, Ounsi El

    2015-01-01

    The integration of two-dimensional (2D) periodic nanopattern defined by nanoimprint lithography and dry etching into aluminum induced crystallization (AIC) based polycrystalline silicon (Poly-Si) thin film solar cells is investigated experimentally. Compared to the unpatterned cell an increase of 6% in the light absorption has been achieved thanks to the nanopattern which, in turn, increased the short circuit current from 20.6 mA/cm2 to 23.8 mA/cm2. The efficiency, on the other hand, has limitedly increased from 6.4% to 6.7%. We show using the transfer length method (TLM) that the surface topography modification caused by the nanopattern has increased the sheet resistance of the antireflection coating (ARC) layer as well as the contact resistance between the ARC layer and the emitter front contacts. This, in turn, resulted in increased series resistance of the nanopatterned cell which has translated into a decreased fill factor, explaining the limited increase in efficiency.

  17. The Effect of High Temperature Annealing on the Grain Characteristics of a Thin Chemical Vapor Deposition Silicon Carbide Layer.

    Energy Technology Data Exchange (ETDEWEB)

    Isabella J van Rooyen; Philippus M van Rooyen; Mary Lou Dunzik-Gougar

    2013-08-01

    The unique combination of thermo-mechanical and physiochemical properties of silicon carbide (SiC) provides interest and opportunity for its use in nuclear applications. One of the applications of SiC is as a very thin layer in the TRi-ISOtropic (TRISO) coated fuel particles for high temperature gas reactors (HTGRs). This SiC layer, produced by chemical vapor deposition (CVD), is designed to withstand the pressures of fission and transmutation product gases in a high temperature, radiation environment. Various researchers have demonstrated that macroscopic properties can be affected by changes in the distribution of grain boundary plane orientations and misorientations [1 - 3]. Additionally, various researchers have attributed the release behavior of Ag through the SiC layer as a grain boundary diffusion phenomenon [4 - 6]; further highlighting the importance of understanding the actual grain characteristics of the SiC layer. Both historic HTGR fission product release studies and recent experiments at Idaho National Laboratory (INL) [7] have shown that the release of Ag-110m is strongly temperature dependent. Although the maximum normal operating fuel temperature of a HTGR design is in the range of 1000-1250°C, the temperature may reach 1600°C under postulated accident conditions. The aim of this specific study is therefore to determine the magnitude of temperature dependence on SiC grain characteristics, expanding upon initial studies by Van Rooyen et al, [8; 9].

  18. Investigation of the adhesion mechanisms of silicon alloy thin films on polymer substrates by IR ellipsometry. [Si

    Energy Technology Data Exchange (ETDEWEB)

    Drevillon, B. (LPICM, Ecole Polytechnique, 91 Palaiseau (France)); Rostaing, J.C. (L' Air Liquide CRCD, 78 Les Loges en Josas (France)); Vallon, S. (LPICM, Ecole Polytechnique, 91 Palaiseau (France))

    1993-12-15

    The adhesion mechanisms of plasma-deposited silicon alloys on polymer substrates (polycarbonate) were studied by a new double-modulated IR ellipsometer. This ellipsometer combines the low frequencies typical of Fourier transform spectroscopy with the high frequency (37 kHz) of the phase modulation provided by a photoelastic device. The film adhesion is characterized by the evolution of the vibrational properties of the polymer surface during the early stages of the film preparation. The influence of preliminary plasma treatments on the polymer surface is emphasized. Successive exposure of polycarbonate to Ar and (NH[sub 3], Ar) plasmas induces a substrate activation characterized by the formation of CN bonds at the surface. Then it is shown that the SiH[sub 4] plasma treatment leads to the formation of a very thin SiO[sub x] layer at the substrate surface. The enhancement of the film adhesion appears to be correlated to the presence of a vibration located at 1030 cm[sup -1]. (orig.)

  19. The 30-band k ⋅ p theory of valley splitting in silicon thin layers.

    Science.gov (United States)

    Čukarić, Nemanja A; Partoens, Bart; Tadić, Milan Ž; Arsoski, Vladimir V; Peeters, F M

    2016-05-18

    The valley splitting of the conduction-band states in a thin silicon-on-insulator layer is investigated using the 30-band k ⋅ p theory. The system composed of a few nm thick [Formula: see text] layer embedded within thick SiO2 layers is analyzed. The valley split states are found to cross periodically with increasing quantum well width, and therefore the energy splitting is an oscillatory function of the quantum well width, with period determined by the wave vector K 0 of the conduction band minimum. Because the valley split states are classified by parity, the optical transition between the ground hole state and one of those valley split conduction band states is forbidden. The oscillations in the valley splitting energy decrease with electric field and with smoothing of the composition profile between the well and the barrier by diffusion of oxygen from the SiO2 layers to the Si quantum well. Such a smoothing also leads to a decrease of the interband transition matrix elements. The obtained results are well parametrized by the effective two-valley model, but are found to disagree from previous 30-band calculations. This discrepancy could be traced back to the fact that the basis for the numerical solution of the eigenproblem must be restricted to the first Brillouin zone in order to obtain quantitatively correct results for the valley splitting.

  20. Off-current in polycrystalline silicon thin film transistors: An analysis of the thermally generated component

    Science.gov (United States)

    Pecora, A.; Schillizzi, M.; Tallarida, G.; Fortunato, G.; Reita, C.; Migliorato, P.

    1995-04-01

    The thermal generation component of polycrystalline silicon TFTs off-current is analysed experimentally and theoretically. In order to minimize the field-enhanced component of the leakage current, hot-hole injection, obtained by stressing the device at negative gate voltage and high source-drain voltage, has been used to reduce the electric field at the drain junction. After stress, the electrical characteristics in the off-regime are channel length independent and do not depend on gate voltage. This behaviour has been associated with the thermal generation-recombination processes occurring at the drain junction. Two-dimensional numerical simulations have been carried out with the program HFIELD, which has been modified to take into account the presence of gap states in polysilicon, and to incorporate the thermal generation-recombination processes by using the Shockley-Read-Hall statistics. Numerical simulations confirm that the generation occurs in the depletion region of the drain junction. The experimental Id- Vds characteristics measured at negative gate voltage have been compared with the calculated characteristics. The best fit with the experimental data was obtained only by using a rather short carrier lifetime (10 -12 s). The simulations indicate that a decrease of the density of states produces a lower off-current owing to a longer carrier lifetime and to a reduction of the drain junction depletion layer.

  1. Dispersion engineering and frequency comb generation in thin silicon nitride concentric microresonators.

    Science.gov (United States)

    Kim, Sangsik; Han, Kyunghun; Wang, Cong; Jaramillo-Villegas, Jose A; Xue, Xiaoxiao; Bao, Chengying; Xuan, Yi; Leaird, Daniel E; Weiner, Andrew M; Qi, Minghao

    2017-08-29

    Kerr nonlinearity-based frequency combs and solitons have been generated from on-chip microresonators. The initiation of the combs requires global or local anomalous dispersion which leads to many limitations, such as material choice, film thickness, and spectral ranges where combs can be generated, as well as fabrication challenges. Using a concentric racetrack-shaped resonator, we show that such constraints can be lifted and resonator dispersion can be engineered to be anomalous over moderately broad bandwidth. We demonstrate anomalous dispersion in a 300 nm thick silicon nitride film, suitable for semiconductor manufacturing but previously thought to result in waveguides with high normal dispersion. Together with a mode-selective, tapered coupling scheme, we generate coherent mode-locked frequency combs. Our method can realize anomalous dispersion for resonators at almost any wavelength and simultaneously achieve material and process compatibility with semiconductor manufacturing.Kerr frequency comb generation from microresonators requires anomalous dispersion, imposing restrictions on materials and resonator design. Here, Kim et al. propose a concentric racetrack-resonator design where the dispersion can be engineered to be anomalous via resonant mode coupling.

  2. Thin silicon strip detectors for beam monitoring in Micro-beam Radiation Therapy

    Science.gov (United States)

    Povoli, M.; Alagoz, E.; Bravin, A.; Cornelius, I.; Bräuer-Krisch, E.; Fournier, P.; Hansen, T. E.; Kok, A.; Lerch, M.; Monakhov, E.; Morse, J.; Petasecca, M.; Requardt, H.; Rosenfeld, A. B.; Röhrich, D.; Sandaker, H.; Salomé, M.; Stugu, B.

    2015-11-01

    Microbeam Radiation Therapy (MRT) is an emerging cancer treatment that is currently being developed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. This technique uses a highly collimated and fractionated X-ray beam array with extremely high dose rate and very small divergence, to benefit from the dose-volume effect, thus sparing healthy tissue. In case of any beam anomalies and system malfunctions, special safety measures must be installed, such as an emergency safety shutter that requires continuous monitoring of the beam intensity profile. Within the 3DMiMic project, a novel silicon strip detector that can tackle the special features of MRT, such as the extremely high spatial resolution and dose rate, has been developed to be part of the safety shutter system. The first prototypes have been successfully fabricated, and experiments aimed to demonstrate their suitability for this unique application have been performed. Design, fabrication and the experimental results as well as any identified inadequacies for future optimisation are reported and discussed in this paper.

  3. Hydrogenated Nanocrystalline Silicon Thin Films Prepared by Hot-Wire Method with Varied Process Pressure

    Directory of Open Access Journals (Sweden)

    V. S. Waman

    2011-01-01

    Full Text Available Hydrogenated nanocrystalline silicon films were prepared by hot-wire method at low substrate temperature (200∘C without hydrogen dilution of silane (SiH4. A variety of techniques, including Raman spectroscopy, low angle X-ray diffraction (XRD, Fourier transform infrared (FTIR spectroscopy, atomic force microscopy (AFM, and UV-visible (UV-Vis spectroscopy, were used to characterize these films for structural and optical properties. Films are grown at reasonably high deposition rates (>15 Å/s, which are very much appreciated for the fabrication of cost effective devices. Different crystalline fractions (from 2.5% to 63% and crystallite size (3.6–6.0 nm can be achieved by controlling the process pressure. It is observed that with increase in process pressure, the hydrogen bonding in the films shifts from Si–H to Si–H2 and (Si–H2n complexes. The band gaps of the films are found in the range 1.83–2.11 eV, whereas the hydrogen content remains <9 at.% over the entire range of process pressure studied. The ease of depositing films with tunable band gap is useful for fabrication of tandem solar cells. A correlation between structural and optical properties has been found and discussed in detail.

  4. Amorphous Silicon Single-Junction Thin-Film Solar Cell Exceeding 10% Efficiency by Design Optimization

    Directory of Open Access Journals (Sweden)

    Mohammed Ikbal Kabir

    2012-01-01

    Full Text Available The conversion efficiency of a solar cell can substantially be increased by improved material properties and associated designs. At first, this study has adopted AMPS-1D (analysis of microelectronic and photonic structures simulation technique to design and optimize the cell parameters prior to fabrication, where the optimum design parameters can be validated. Solar cells of single junction based on hydrogenated amorphous silicon (a-Si:H have been analyzed by using AMPS-1D simulator. The investigation has been made based on important model parameters such as thickness, doping concentrations, bandgap, and operating temperature and so forth. The efficiency of single junction a-Si:H can be achieved as high as over 19% after parametric optimization in the simulation, which might seem unrealistic with presently available technologies. Therefore, the numerically designed and optimized a-SiC:H/a-SiC:H-buffer/a-Si:H/a-Si:H solar cells have been fabricated by using PECVD (plasma-enhanced chemical vapor deposition, where the best initial conversion efficiency of 10.02% has been achieved ( V,  mA/cm2 and for a small area cell (0.086 cm2. The quantum efficiency (QE characteristic shows the cell’s better spectral response in the wavelength range of 400 nm–650 nm, which proves it to be a potential candidate as the middle cell in a-Si-based multijunction structures.

  5. Matching of Silicon Thin-Film Tandem Solar Cells for Maximum Power Output

    Directory of Open Access Journals (Sweden)

    C. Ulbrich

    2013-01-01

    Full Text Available We present a meaningful characterization method for tandem solar cells. The experimental method allows for optimizing the output power instead of the current. Furthermore, it enables the extraction of the approximate AM1.5g efficiency when working with noncalibrated spectra. Current matching of tandem solar cells under short-circuit condition maximizes the output current but is disadvantageous for the overall fill factor and as a consequence does not imply an optimization of the output power of the device. We apply the matching condition to the maximum power output; that is, a stack of solar cells is power matched if the power output of each subcell is maximal at equal subcell currents. The new measurement procedure uses additional light-emitting diodes as bias light in the JV characterization of tandem solar cells. Using a characterized reference tandem solar cell, such as a hydrogenated amorphous/microcrystalline silicon tandem, it is possible to extract the AM1.5g efficiency from tandems of the same technology also under noncalibrated spectra.

  6. Influence of laser annealing on hydrogen bonding in compensated polycrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, R. [Jurusan Fisika, Fakultas MIPA, Universitas Indonesia, 16424 Depok (Indonesia)]. E-mail: rosarisaleh@research-ui.org; Nickel, N.H. [Hahn-Meitner-Institut Berlin, Kekulestr.5, 12489 Berlin (Germany); Maydell, K.V. [Hahn-Meitner-Institut Berlin, Kekulestr.5, 12489 Berlin (Germany)

    2005-09-01

    Compensated hydrogenated amorphous silicon films were crystallized using a step-by-step laser dehydrogenation and crystallization procedure. The influence of laser crystallization on hydrogen bonding is investigated employing Raman spectroscopy and hydrogen effusion measurements. In P-doped samples a considerable amount of hydrogen is accommodated in the clustered phase, while for B-doped samples most of the H atoms are accommodated in isolated Si-H bonds. In specimens where the boron and phosphorous doping is at equal levels, the hydrogen bonding configuration is close to that found for singly P-doped samples. From hydrogen effusion measurements, the hydrogen density-of-states distribution in fully crystallized poly-Si is derived. For the compensated poly-Si films four peaks arise in the H density-of-states distribution that are located at 2.0, 2.2, 2.5 and 2.8 eV below the hydrogen transport states. The peak observed at 2.8 eV below the hydrogen transport states is not observed in singly B-doped samples.

  7. Uniform dehydrogenation of amorphous silicon thin films using a wide thermal annealing system

    Science.gov (United States)

    Jung, Yong Chan; Seong, Sejong; Lee, Taehoon; Ahn, Jinho; Kim, Tae Hyun; Yeo, Won-Jae; Park, In-Sung

    2017-02-01

    To prevent ablation caused by sudden hydrogen eruption during crystallization of hydrogenated amorphous Si (a-Si:H) thin films, a wide dehydrogenation thermal annealing (wDTA) system was developed to reduce hydrogen content in a-Si:H film prior to its crystallization process. The annealed a-Si:H films were fully dehydrogenated and nanocrystallized by the wDTA system. Raman scattering measurement revealed that the dehydrogenation process lowers the hydrogen content through disappearance of the peak intensity at 2000 cm-1. The a-Si:H film was transformed into nanocrystallized Si with lower residual stress. The major advantage of this wDTA was the large area uniformity of the thermal and the resulting material properties for 8 generation display. The uniform material characteristics of the hydrogen content, thickness, energy bandgap, and transmittance of the annealed Si films in the overall area was confirmed by Raman spectroscopy, spectroscopic ellipsometry, and UV-vis spectrometer measurement.

  8. Bismuth Oxide Thin Films Deposited on Silicon Through Pulsed Laser Ablation, for Infrared Detectors

    Science.gov (United States)

    Condurache-Bota, Simona; Constantinescu, Catalin; Tigau, Nicolae; Praisler, Mirela

    2016-12-01

    Infrared detectors are used in many human activities, from industry to military, telecommunications, environmental studies and even medicine. Bismuth oxide thin films have proved their potential for optoelectronic applications, but their uses as infrared sensors have not been thoroughly studied so far. In this paper, pulsed laser ablation of pure bismuth targets within a controlled oxygen atmosphere is proposed for the deposition of bismuth oxide films on Si (100) substrates. Crystalline films were obtained, whose uniformity depends on the deposition conditions (number of laser pulses and the use of a radio-frequency (RF) discharge of the oxygen inside the deposition chamber). The optical analysis proved that the refractive index of the films is higher than 3 and that their optical bandgap is around 1eV, recommending them for infrared applications.

  9. Reduction of bacterial adhesion on dental composite resins by silicon-oxygen thin film coatings.

    Science.gov (United States)

    Mandracci, Pietro; Mussano, Federico; Ceruti, Paola; Pirri, Candido F; Carossa, Stefano

    2015-01-29

    Adhesion of bacteria on dental materials can be reduced by modifying the physical and chemical characteristics of their surfaces, either through the application of specific surface treatments or by the deposition of thin film coatings. Since this approach does not rely on the use of drugs or antimicrobial agents embedded in the materials, its duration is not limited by their possible depletion. Moreover it avoids the risks related to possible cytotoxic effects elicited by antibacterial substances released from the surface and diffused in the surrounding tissues. In this work, the adhesion of Streptococcus mutans and Streptococcus mitis was studied on four composite resins, commonly used for manufacturing dental prostheses. The surfaces of dental materials were modified through the deposition of a-SiO(x) thin films by plasma enhanced chemical vapor deposition. The chemical bonding structure of the coatings was analyzed by Fourier-transform infrared spectroscopy. The morphology of the dental materials before and after the coating deposition was assessed by means of optical microscopy and high-resolution mechanical profilometry, while their wettability was investigated by contact angle measurements. The sample roughness was not altered after coating deposition, while a noticeable increase of wettability was detected for all the samples. Also, the adhesion of S. mitis decreased in a statistically significant way on the coated samples, when compared to the uncoated ones, which did not occur for S. mutans. Within the limitations of this study, a-SiO(x) coatings may affect the adhesion of bacteria such as S. mitis, possibly by changing the wettability of the composite resins investigated.

  10. Thin film polycrystalline silicon solar cells. Quarterly report No. 1, January 1, 1979-March 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, A.K.; Feng, T.; Maruska, H.P.; Fishman, C.

    1979-01-01

    A theory capable of predicting the performance of polycrystalline silicon solar cells is formulated. It relates grain size to mobility, lifetime, diffusion length, reverse saturation current, open circuit photovoltage and fill factor. Only the diffusion lengths measured by the surface photovoltage technique for grains less than or equal to 5 ..mu..m do not agree with our theory. The reason for this discrepancy is presently being investigated. We conclude that grains greater than or equal to 100 ..mu..m are necessary to achieve efficiencies greater than or equal to 10 percent at AM1 irradiance. The calculations were performed for the case of no grain boundary passivation. At present we are investigating the improvements to be expected from grain boundary passivation. We have determined that the parameters that best fit the available data are as follows: (1) Number of surface states at grain boundaries acting as recombination centers - 1.6 x 10/sup 13//cm/sup 2/. (2) Capture cross section - 2 x 10/sup -16/ cm/sup 2/. (3) Surface recombination velocity at grain boundary - 3.2 x 10/sup 4/ cm/sec. The following types of solar cells are considered in the model: SnO/sub 2//Si Heterostructure, MIS, and p/n junction. In all types of solar cells considered, grain boundary recombination plays a dominant role, especially for small grains. Though the calculations were originally expected to yield only order of magnitude results, they have proven to be accurate for most parameters within 10 percent.

  11. Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, Minden 11800 Penang (Malaysia)

    2015-04-24

    One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as an absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.

  12. A bow-tie photoconductive antenna using a low-temperature-grown GaAs thin-film on a silicon substrate for terahertz wave generation and detection

    Science.gov (United States)

    Darío Velásquez Ríos, Rubén; Bikorimana, Siméon; Ummy, Muhammad Ali; Dorsinville, Roger; Seo, Sang-Woo

    2015-12-01

    This paper presents heterogeneously integrated bow-tie emitter-detector photoconductive antennas (PCAs) based on low-temperature grown-gallium arsenide (LTG-GaAs) thin-film devices on silicon-dioxide/silicon (SiO2/Si) host substrates for integrated terahertz (THz) systems. The LTG-GaAs thin-film devices are fabricated with standard photolithography and thermal evaporation of metal-contact layers of chromium (Cr), nickel (Ni) and gold (Au). They are etched selectively and separated from their growth GaAs substrate. The LTG-GaAs thin-film devices are then heterogeneously integrated on bow-tie antenna electrodes patterned on the surface of a SiO2/Si host substrate for THz emitters and THz detectors. Cost-effective and selective integration of LTG-GaAs thin-film devices on a Si platform is demonstrated. THz radiation from the fabricated THz PCAs is successfully measured using a pump-probe THz time-domain configuration. The THz temporal duration was measured at full width half maximum of 0.36 ps. Its frequency spectrum exhibits a broadband response with a peak resonant frequency of about 0.31 THz. The demonstration illustrates the feasibility of creating heterogeneously integrated THz systems using separately optimized LTG-GaAs devices and Si based electronics.

  13. Formaldehyde gas sensor based on TiO2 thin membrane integrated with nano silicon structure

    Science.gov (United States)

    Zheng, Xuan; Ming, An-jie; Ye, Li; Chen, Feng-hua; Sun, Xi-long; Liu, Wei-bing; Li, Chao-bo; Ou, Wen; Wang, Wei-bing; Chen, Da-peng

    2016-07-01

    An innovative formaldehyde gas sensor based on thin membrane type metal oxide of TiO2 layer was designed and fabricated. This sensor under ultraviolet (UV) light emitting diode (LED) illumination exhibits a higher response to formaldehyde than that without UV illumination at low temperature. The sensitivities of the sensor under steady working condition were calculated for different gas concentrations. The sensitivity to formaldehyde of 7.14 mg/m3 is about 15.91 under UV illumination with response time of 580 s and recovery time of 500 s. The device was fabricated through micro-electro-mechanical system (MEMS) processing technology. First, plasma immersion ion implantation (PIII) was adopted to form black polysilicon, then a nanoscale TiO2 membrane with thickness of 53 nm was deposited by DC