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Sample records for p-type crystalline si

  1. Boric acid solution concentration influencing p-type emitter formation in n-type crystalline Si solar cells

    Science.gov (United States)

    Singha, Bandana; Singh Solanki, Chetan

    2016-09-01

    Boric acid (BA) is a spin on dopant (BSoD) source which is used to form p+ emitters in n-type c-Si solar cells. High purity boric acid powder (99.99% pure) when mixed with deionized (DI) water can result in high quality p-type emitter with less amount of surface defects. In this work, we have used different concentrations of boric acid solution concentrations to fabricate p-type emitters with sheet resistance values < 90 Ω/□. The corresponding junction depths for the same are less than 500 nm as measured by SIMS analysis. Boron rich layer (BRL), which is considered as detrimental in emitter performance is found to be minimal for BA solution concentration less than 2% and hence useful for p-type emitter formation.

  2. Efficiency Improvement of HIT Solar Cells on p-Type Si Wafers

    Directory of Open Access Journals (Sweden)

    Chun-You Wei

    2013-11-01

    Full Text Available Single crystal silicon solar cells are still predominant in the market due to the abundance of silicon on earth and their acceptable efficiency. Different solar-cell structures of single crystalline Si have been investigated to boost efficiency; the heterojunction with intrinsic thin layer (HIT structure is currently the leading technology. The record efficiency values of state-of-the art HIT solar cells have always been based on n-type single-crystalline Si wafers. Improving the efficiency of cells based on p-type single-crystalline Si wafers could provide broader options for the development of HIT solar cells. In this study, we varied the thickness of intrinsic hydrogenated amorphous Si layer to improve the efficiency of HIT solar cells on p-type Si wafers.

  3. Recycling of p-type mc-si Top Cuts into p-type mono c-Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bronsveld, P.C.P.; Manshanden, P.; Lenzmann, F.O. [ECN Solar Energy, Westerduinweg 3, P.O. Box 1, NL-1755 ZG Petten (Netherlands); Gjerstad, O. [Si Pro Holding AS, Ornesveien 3, P.O. Box 37, 8161, Glomfjord (Norway); Oevrelid, E.J. [SINTEF, Alfred Getz Vei 2, 7465, Trondheim (Norway)

    2013-07-01

    Solar cell results and material analysis are presented of 2 p-type Czochralski (Cz) ingots pulled from a charge consisting of 100% and 50% recycled multicrystalline silicon top cuts. The top cuts were pre-cleaned with a dedicated low energy consuming technology. No structure loss was observed in the bodies of the ingots. The performance of solar cells made from the 100% recycled Si ingot decreases towards the seed end of the ingot, which could be related to a non-optimal pulling process. Solar cells from the tail end of this ingot and from the 50% recycled Si ingot demonstrated an average solar cell efficiency of 18.6%. This is only 0.1% absolute lower than the efficiency of higher resistivity reference solar cells from commercially available wafers that were co-processed.

  4. Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jie, E-mail: j.cui@unsw.edu.au [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia); Grant, Nicholas [Centre for Sustainable Energy Systems, Australian National University, Canberra, A.C.T. 0200 (Australia); Lennon, Alison [School of Photovoltaic and Renewable Energy Engineering, The University of New South Wales, Sydney 2052 (Australia)

    2014-12-30

    Highlights: • The surface passivation by anodic SiO{sub 2} formed by light-induced anodisation is investigated. • The anodic SiO{sub 2} grows lower temperatures with shorter growth times. After annealing in oxygen and then forming gas the effective minority carrier lifetime is increased to 150 μs. • It shows a very low positive Q{sub eff} of 3.4 × 10{sup 11} cm{sup −2}, a moderate D{sub it} of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. • It has a very low leakage current density suggesting its application in solar cell as a functional dielectric. - Abstract: Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO{sub 2}) was investigated. The anodic SiO{sub 2} was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 °C for 30 min, the effective minority carrier lifetime of 3–5 Ω cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 Ω/□ emitter and a LIA anodic SiO{sub 2} formed on the p-type surface was increased by two orders of magnitude to 150 μs. Capacitance–voltage measurements demonstrated a very low positive charge density of 3.4 × 10{sup 11} cm{sup −2} and a moderate density of interface states of 6 × 10{sup 11} eV{sup −1} cm{sup −2}. This corresponded to a silicon surface recombination velocity of 62 cm s{sup −1}, which is comparable with values reported for other anodic SiO{sub 2} films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 × 10{sup −10} and 1.6 × 10{sup −9} A cm{sup −2} at 1 and −1 V, respectively, was measured for LIA SiO{sub 2} suggesting its potential application as insulation layer in

  5. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating.

    Science.gov (United States)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-28

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  6. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating

    Science.gov (United States)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-01

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  7. Optical and Electrical Effects of p-type μc-SiOx:H in Thin-Film Silicon Solar Cells on Various Front Textures

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2014-01-01

    Full Text Available p-type hydrogenated microcrystalline silicon oxide (µc-SiOx:H was developed and implemented as a contact layer in hydrogenated amorphous silicon (a-Si:H single junction solar cells. Higher transparency, sufficient electrical conductivity, low ohmic contact to sputtered ZnO:Al, and tunable refractive index make p-type µc-SiOx:H a promising alternative to the commonly used p-type hydrogenated microcrystalline silicon (µc-Si:H contact layers. In this work, p-type µc-SiOx:H layers were fabricated with a conductivity of up to 10−2 S/cm and a Raman crystallinity of above 60%. Furthermore, we present p-type µc-SiOx:H films with a broad range of optical properties (2.1 eV < band gap E04<2.8 eV and 1.6 < refractive index n<2.6. These properties can be tuned by adapting deposition parameters, for example, the CO2/SiH4 deposition gas ratio. A conversion efficiency improvement of a-Si:H solar cells is achieved by applying p-type µc-SiOx:H contact layer compared to the standard p-type µc-Si:H contact layer. As another aspect, the influence of the front side texture on a-Si:H p-i-n solar cells with different p-type contact layers, µc-Si:H and µc-SiOx:H, is investigated. Furthermore, we discuss the correlation between the decrease of Voc and the cell surface area derived from AFM measurements.

  8. Light and current induced degradation in p-type multi-crystalline cells and development of an inspection method and a stabilization method

    Energy Technology Data Exchange (ETDEWEB)

    Broek, K.M.; Bennett, I.J.; Jansen, M.J.; Borg, Van der N.J.C.M.; Eerenstein, W. [ECN Solar Energy, Petten (Netherlands)

    2012-09-15

    Stable solar cells are needed for durability testing of different combinations of module materials. In such a test, significant power losses in full-size modules with multi-crystalline cells after thermal cycling have been observed. This has been related to degradation of the solar cells used and it appeared that this was caused by current induced degradation. This phenomenon is not limited to boron doped Cz-Si, but can also occur in p-type multi-crystalline silicon. Work was done to develop an incoming inspection method for new batches of cells. Also, stabilisation procedures for modules containing cells that are sensitive to degradation have been determined.

  9. Efficiency Improvement of HIT Solar Cells on p-Type Si Wafers

    OpenAIRE

    Chun-You Wei; Chu-Hsuan Lin; Hao-Tse Hsiao; Po-Chuan Yang; Chih-Ming Wang; Yen-Chih Pan

    2013-01-01

    Single crystal silicon solar cells are still predominant in the market due to the abundance of silicon on earth and their acceptable efficiency. Different solar-cell structures of single crystalline Si have been investigated to boost efficiency; the heterojunction with intrinsic thin layer (HIT) structure is currently the leading technology. The record efficiency values of state-of-the art HIT solar cells have always been based on n-type single-crystalline Si wafers. Improving the efficiency ...

  10. Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Vidya, E-mail: vj1510@yahoo.com

    2015-09-01

    Surface modifications caused by a swift heavy ion irradiation on crystalline p-type gallium antimonide crystal have been reported. Single crystal, 1 0 0〉 orientations and ∼500 μm thick p-type GaSb samples with carrier concentration of 3.30 × 10{sup 17} cm{sup −3} were irradiated at 100 MeV Fe{sup 7+} ions. We have used 15UD Pelletron facilities at IUAC with varying fluences of 5 × 10{sup 10}–1 × 10{sup 14} ions cm{sup −2}. The effects of irradiation on these samples have been investigated using, spectroscopic ellipsometry, atomic force microscopy and ultraviolet–visible–NIR spectroscopy techniques. Ellipsometry parameters, psi (Ψ) and delta (Δ) for the unirradiated sample and samples irradiated with different fluences were recorded. The data were fit to a three phase model to determine the refractive index and extinction coefficient. The refractive index and extinction coefficient for various fluences in ultraviolet, visible, and infrared, regimes were evaluated. Atomic force microscopy has been used to study these surface modifications. In order to have more statistical information about the surface, we have plotted the height structure histogram for all the samples. For unirradiated sample, we observed the Gaussian fitting. This result indicates the more ordered height structure symmetry. Whereas for the sample irradiated with the fluence of 1 × 10{sup 13}, 5 × 10{sup 13} and 1 × 10{sup 14} ions cm{sup −2}, we observed the scattered data. The width of the histogram for samples irradiated up to the fluence of 1 × 10{sup 13} ion cm{sup −2} was found to be almost same however it decreased at higher fluence. UV reflectance spectra of the sample irradiated with increasing fluences exhibit three peaks at 292, 500 and 617 nm represent the high energy GaSb; E{sub 1}, E{sub 1} + Δ and E{sub 2} band gaps in all irradiated samples.

  11. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  12. a-Si:H/c-Si heterojunction front- and back contacts for silicon solar cells with p-type base

    Energy Technology Data Exchange (ETDEWEB)

    Rostan, Philipp Johannes

    2010-07-01

    This thesis reports on low temperature amorphous silicon back and front contacts for high-efficiency crystalline silicon solar cells with a p-type base. The back contact uses a sequence of intrinsic amorphous (i-a-Si:H) and boron doped microcrystalline (p-{mu}c-Si:H) silicon layers fabricated by Plasma Enhanced Chemical Vapor Deposition (PECVD) and a magnetron sputtered ZnO:Al layer. The back contact is finished by evaporating Al onto the ZnO:Al and altogether prepared at a maximum temperature of 220 C. Analysis of the electronic transport of mobile charge carriers at the back contact shows that the two high-efficiency requirements low back contact series resistance and high quality c-Si surface passivation are in strong contradiction to each other, thus difficult to achieve at the same time. The preparation of resistance- and effective lifetime samples allows one to investigate both requirements independently. Analysis of the majority charge carrier transport on complete Al/ZnO:Al/a-Si:H/c-Si back contact structures derives the resistive properties. Measurements of the effective minority carrier lifetime on a-Si:H coated wafers determines the back contact surface passivation quality. Both high-efficiency solar cell requirements together are analyzed in complete photovoltaic devices where the back contact series resistance mainly affects the fill factor and the back contact passivation quality mainly affects the open circuit voltage. The best cell equipped with a diffused emitter with random texture and a full-area a-Si:H/c-Si back contact has an independently confirmed efficiency {eta} = 21.0 % with an open circuit voltage V{sub oc} = 681 mV and a fill factor FF = 78.7 % on an area of 1 cm{sup 2}. An alternative concept that uses a simplified a-Si:H layer sequence combined with Al-point contacts yields a confirmed efficiency {eta} = 19.3 % with an open circuit voltage V{sub oc} = 655 mV and a fill factor FF = 79.5 % on an area of 2 cm{sup 2}. Analysis of the

  13. Correlation Between the Raman Crystallinity of p-Type Micro-Crystalline Silicon Layer and Open Circuit Voltage of n-i-p Solar Cells.

    Science.gov (United States)

    Jung, Junhee; Kim, Sunbo; Park, Jinjoo; Shin, Chonghoon; Pham, Duy Phong; Kim, Jiwoong; Chung, Sungyoun; Lee, Youngseok; Yi, Junsin

    2015-10-01

    This article mainly discusses the difference between p-i-n and n-i-p type solar cells. Their structural difference has an effect on cell performance, such as open circuit voltage and fill factor. Although the deposition conditions are the same for both p-i-n and n-i-p cases, the substrate layers for depositing p-type microcrystalline silicon layers differ. In n-i-p cells, the substrate layer is p-type amorphous silicon oxide layer; whereas, in p-i-n cells, the substrate layer is ZnO:Al. The interfacial change leads to a 12% difference in the crystallinity of the p-type microcrystalline silicon layers. When the p-type microcrystalline silicon layer's crystallinity was not sufficient to activate an internal electric field, the open circuit voltage and fill factor decreased 0.075 V and 7.36%, respectively. We analyzed this problem by comparing the Raman spectra, electrical conductivity, activation energy and solar cell performance. By adjusting the thickness of the p-type microcrystalline silicon layer, we increased the open circuit voltage of the n-i-p cell from 0.835 to 0.91 V.

  14. p+-n--n+-type power diode with crystalline/nanocrystalline Si mosaic electrodes

    Science.gov (United States)

    Wensheng, Wei; Chunxi, Zhang

    2016-06-01

    Using p+-type crystalline Si with n+-type nanocrystalline Si (nc-Si) and n+-type crystalline Si with p+-type nc-Si mosaic structures as electrodes, a type of power diode was prepared with epitaxial technique and plasma-enhanced chemical vapor deposition (PECVD) method. Firstly, the basic p+-n--n+-type Si diode was fabricated by epitaxially growing p+- and n+-type layers on two sides of a lightly doped n--type Si wafer respectively. Secondly, heavily phosphorus-doped Si film was deposited with PECVD on the lithography mask etched p+-type Si side of the basic device to form a component with mosaic anode. Thirdly, heavily boron-doped Si film was deposited on the etched n+-type Si side of the second device to form a diode with mosaic anode and mosaic cathode. The images of high resolution transmission electronic microscope and patterns of X-ray diffraction reveal nanocrystallization in the phosphorus- and boron-deposited films. Electrical measurements such as capacitance-voltage relation, current-voltage feature and reverse recovery waveform were carried out to clarify the performance of prepared devices. The important roles of (n-)Si/(p+)nc-Si and (n-)Si/(n+)nc-Si junctions in the static and dynamic conduction processes in operating diodes were investigated. The performance of mosaic devices was compared to that of a basic one. Project supported by the National Natural Science Foundation of China (No. 61274006).

  15. Fabrication and simulation of single crystal p-type Si nanowire using SOI technology

    Energy Technology Data Exchange (ETDEWEB)

    Dehzangi, Arash, E-mail: arashd53@hotmail.com [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Larki, Farhad [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Naseri, Mahmud G. [Department of Physics, Faculty of Science, Malayer University, Malayer, Hamedan (Iran, Islamic Republic of); Navasery, Manizheh [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Majlis, Burhanuddin Y.; Razip Wee, Mohd F. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Halimah, M.K. [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Islam, Md. Shabiul; Md Ali, Sawal H. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Saion, Elias [Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2015-04-15

    Highlights: • Single crystal silicon nanowire is fabricated on Si on insulator substrate, using atomic force microscope (AFM) nanolithography and KOH + IPA chemical wet etching. • Some of major parameters in fabrication process, such as writing speed and applied voltage along with KOH etching depth are investigated, and then the I–V characteristic of Si nanowires is measured. • For better understanding of the charge transmission through the nanowire, 3D-TCAD simulation is performed to simulate the Si nanowires with the same size of the fabricated ones, and variation of majority and minority carriers, hole quasi-Fermi level and generation/recombination rate are investigated. - Abstract: Si nanowires (SiNWs) as building blocks for nanostructured materials and nanoelectronics have attracted much attention due to their major role in device fabrication. In the present work a top-down fabrication approach as atomic force microscope (AFM) nanolithography was performed on Si on insulator (SOI) substrate to fabricate a single crystal p-type SiNW. To draw oxide patterns on top of the SOI substrate local anodic oxidation was carried out by AFM in contact mode. After the oxidation procedure, an optimized solution of 30 wt.% KOH with 10 vol.% IPA for wet etching at 63 °C was applied to extract the nanostructure. The fabricated SiNW had 70–85 nm full width at half maximum width, 90 nm thickness and 4 μm length. The SiNW was simulated using Sentaurus 3D software with the exact same size of the fabricated device. I–V characterization of the SiNW was measured and compared with simulation results. Using simulation results variation of carrier's concentrations, valence band edge energy and recombination generation rate for different applied voltage were investigated.

  16. Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2009-04-01

    Full Text Available In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors.

  17. Phonon bottleneck in p-type Ge/Si quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yakimov, A. I., E-mail: yakimov@isp.nsc.ru [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Tomsk State University, 634050 Tomsk (Russian Federation); Kirienko, V. V.; Armbrister, V. A. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Bloshkin, A. A.; Dvurechenskii, A. V. [Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2015-11-23

    We study the effect of quantum dot size on the mid-infrared photo- and dark current, photoconductive gain, and hole capture probability in ten-period p-type Ge/Si quantum dot heterostructures. The dot dimensions are varied by changing the Ge coverage and the growth temperature during molecular beam epitaxy of Ge/Si(001) system in the Stranski-Krastanov growth mode. In all samples, we observed the general tendency: with decreasing the size of the dots, the dark current and hole capture probability are reduced, while the photoconductive gain and photoresponse are enhanced. Suppression of the hole capture probability in small-sized quantum dots is attributed to a quenched electron-phonon scattering due to phonon bottleneck.

  18. Low cost sol–gel derived SiC–SiO{sub 2} nanocomposite as anti reflection layer for enhanced performance of crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jannat, Azmira [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Solar Energy Engineering, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Lee, Woojin [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Akhtar, M. Shaheer, E-mail: shaheerakhtar@jbnu.ac.kr [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); New & Renewable Energy Materials Development Center (NewREC), Chonbuk National University, Jeonbuk (Korea, Republic of); Li, Zhen Yu [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); Yang, O.-Bong, E-mail: obyang@jbnu.ac.kr [School of Semiconductor and Chemical Engineering, Solar Energy Research Center, Chonbuk National University, Jeonju, Jeonbuk 54896 (Korea, Republic of); New & Renewable Energy Materials Development Center (NewREC), Chonbuk National University, Jeonbuk (Korea, Republic of)

    2016-04-30

    Graphical abstract: - Highlights: • Sol–gel derived SiC–SiO{sub 2} nanocomposite was prepared. • It effectively coated as AR layer on p-type Si-wafer. • SiC–SiO{sub 2} layer on Si solar cells exhibited relatively low reflectance of 7.08%. • Fabricated Si solar cell attained highly comparable performance of 16.99% to commercial device. - Abstract: This paper describes the preparation, characterizations and the antireflection (AR) coating application in crystalline silicon solar cells of sol–gel derived SiC–SiO{sub 2} nanocomposite. The prepared SiC–SiO{sub 2} nanocomposite was effectively applied as AR layer on p-type Si-wafer via two step processes, where the sol–gel of precursor solution was first coated on p-type Si-wafer using spin coating at 2000 rpm and then subjected to annealing at 450 °C for 1 h. The crystalline, and structural observations revealed the existence of SiC and SiO{sub 2} phases, which noticeably confirmed the formation of SiC–SiO{sub 2} nanocomposite. The SiC–SiO{sub 2} layer on Si solar cells was found to be an excellent AR coating, exhibiting the low reflectance of 7.08% at wavelengths ranging from 400 to 1000 nm. The fabricated crystalline Si solar cell with SiC–SiO{sub 2} nanocomposite AR coating showed comparable power conversion efficiency of 16.99% to the conventional Si{sub x}N{sub x} AR coated Si solar cell. New and effective sol–gel derived SiC–SiO{sub 2} AR layer would offer a promising technique to produce high performance Si solar cells with low-cost.

  19. Valence band states in Si-based p-type delta-doped field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Orozco, J C; Vlaev, Stoyan J, E-mail: jcmover@correo.unam.m [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad esquina con Paseo la Bufa S/N, C.P. 98060, Zacatecas, Zac. (Mexico)

    2009-05-01

    We present tight-binding calculations of the hole level structure of delta-doped Field Effect Transistor in a Si matrix within the first neighbors sp{sup 3}s* semi-empirical tight-binding model including spin. We employ analytical expressions for Schottky barrier potential and the p-type delta-doped well based on a Thomas-Fermi approximation, we consider these potentials as external ones, so in the computations they are added to the diagonal terms of the tight-binding Hamiltonian, by this way we have the possibility to study the energy levels behavior as we vary the backbone parameters in the system: the two-dimensional impurity density (p{sub 2d}) of the p-type delta-doped well and the contact voltage (V{sub c}). The aim of this calculation is to demonstrate that the tight-binding approximation is suitable for device characterization that permits us to propose optimal values for the input parameters involved in the device design.

  20. A porous Si-emitter crystalline-Si solar cell with 18.97% efficiency.

    Science.gov (United States)

    Wang, Liang-Xing; Zhou, Zhi-Quan; Hao, Hong-Chen; Lu, Ming

    2016-10-21

    A p-n junction was made on p-type Si〈100〉 wafer (15 × 15 × 0.2 mm(3) in size) via phosphorous diffusion at 900 °C. Porous Si (PSi) with ultralow reflectivity (Si emitter in a solution of HF, H2O2 and H2O. The PSi was found to mainly consist of Si nanocrystallites with bandgap widths larger than that of bulk Si. Compared to other micro- or nanostructured Si-based crystalline-Si solar cells found in the literature, this PSi one possessed the feature of a graded band gap, which helped to suppress the surface recombination. In addition, the preparation method was readily applicable on large-scale-sized Si wafers. Also, the PSi acted as a down-shifter that absorbed the ultraviolet/violet light to which the Si solar cell responded poorly, and emitted a red one to which the cell responded well. Front and rear surface passivations were conducted by using SiO2 and Al2O3, respectively, to suppress the surface recombination and to facilitate the charge transfer. Indium-tin-oxide was used as the front electrode that was in good contact with the PSi, and Al was used as the rear one. For such a PSi-emitter crystalline-Si solar cell, enhancements of the photovoltaic responses from the ultraviolet to near-infrared regimes were observed; the open-circuit voltage was 606.8 mV, the short-circuit current density was 40.13 mA cm(-2), the fill factor was 0.779 and the conversion efficiency was 18.97%.

  1. TSC measurements on proton-irradiated p-type Si-sensors

    Energy Technology Data Exchange (ETDEWEB)

    Donegani, Elena; Fretwurst, Eckhart; Garutti, Erika; Junkes, Alexandra [University of Hamburg (Germany)

    2016-07-01

    Thin n{sup +}p Si sensors are potential candidates for coping with neutron equivalent fluences up to 2.10{sup 16} n{sub eq}/cm{sup 2} and an ionizing dose in the order of a few MGy, which are expected e.g. for the HL-LHC upgrade. The aim of the present work is to provide experimental data on radiation-induced defects in order to: firstly, get a deeper understanding of the properties of hadron induced defects, and secondly develop a radiation damage model based on microscopic measurements. Therefore, the outcomes of Thermally Stimulated Current measurements on 200 μm thick Float-Zone (FZ) and Magnetic Czochralski (MCz) diodes will be shown, as a results of irradiation with 23 MeV protons and isothermal annealing. The samples were irradiated in the fluence range (0.3-1).10{sup 14} n{sub eq}/cm{sup 2}, so that the maximal temperature at which the TSC signal is still sharply distinguishable from the dark current is 200 K. In particular, special focus will be given to the defect introduction rate and to the issue of boron removal in p-type silicon. Annealing studies allow to distinguish which defects mainly contribute to the leakage current and which to the space charge, and thus correlate microscopic defects properties with macroscopic sensor properties.

  2. A porous Si-emitter crystalline-Si solar cell with 18.97% efficiency

    Science.gov (United States)

    Wang, Liang-Xing; Zhou, Zhi-Quan; Hao, Hong-Chen; Lu, Ming

    2016-10-01

    A p-n junction was made on p-type Si wafer (15 × 15 × 0.2 mm3 in size) via phosphorous diffusion at 900 °C. Porous Si (PSi) with ultralow reflectivity (cells found in the literature, this PSi one possessed the feature of a graded band gap, which helped to suppress the surface recombination. In addition, the preparation method was readily applicable on large-scale-sized Si wafers. Also, the PSi acted as a down-shifter that absorbed the ultraviolet/violet light to which the Si solar cell responded poorly, and emitted a red one to which the cell responded well. Front and rear surface passivations were conducted by using SiO2 and Al2O3, respectively, to suppress the surface recombination and to facilitate the charge transfer. Indium-tin-oxide was used as the front electrode that was in good contact with the PSi, and Al was used as the rear one. For such a PSi-emitter crystalline-Si solar cell, enhancements of the photovoltaic responses from the ultraviolet to near-infrared regimes were observed; the open-circuit voltage was 606.8 mV, the short-circuit current density was 40.13 mA cm-2, the fill factor was 0.779 and the conversion efficiency was 18.97%.

  3. Lifetime and DLTS studies of interstitial Fe in p-type Si

    Energy Technology Data Exchange (ETDEWEB)

    Syre, M.; Holt, A. [Institute for Energy Technology (IFE), Solar Energy Department, P.O. Box 40, 2027 Kjeller (Norway); Monakov, E. [University of Oslo (UiO), Department of Physics, Blindern P.O. Box 1048, 0316 Oslo (Norway); Institute for Energy Technology (IFE), Solar Energy Department, P.O. Box 40, 2027 Kjeller (Norway); Svensson, B.G. [University of Oslo (UiO), Department of Physics, Blindern P.O. Box 1048, 0316 Oslo (Norway)

    2011-03-15

    Fe is one of the most prominent metallic impurities in solar-grade Si. In this work we have investigated the kinetics of in-diffusion and formation of the interstitial fraction (Fe{sub i}). P-type Cz-Si with a resistivity of 10 {omega}-cm has been intentionally contaminated with Fe by in-diffusion from a surface layer of FeCl{sub 3} at 700 C followed by cooling with a rate of {proportional_to} 3.3 K/s. The concentration of Fe{sub i} has been measured both by microwave photo conductance decay ({mu}-PCD) and deep level transient spectroscopy (DLTS). In the {mu}-PCD measurements, the Fe{sub i} concentration has been determined using the ef- fect of light-induced splitting of the iron-boron pairs (FeB), while in the DLTS measurements Fe{sub i} has been monitored by the donor electronic state at 0.43 eV above the valence band. We have observed a linear dependence between the minority carrier lifetime ({tau}) and the inverse Fe{sub i} concentration. This confirms Fe{sub i} as the dominating recombination centre. In the present investigations we use a material relevant for solar cells with a resistivity of 10 {omega}-cm. We have found that the concentration of interstitial iron decreases with increasing time for in-diffusion of Fe, provided identical cooling condition. This decreasing con- centration of Fe{sub i} is believed to be due to formation of more iron precipitates that serve as sinks for fast diffusing Fe{sub i}. A high temperature anneal at 1000 C for 1 minute followed by fast cooling ({proportional_to} 33 K/s) results in dissolution of the precipitates and freezing Fe into interstitial positions, where the concentration of Fe{sub i} increases with increasing in-diffusion time. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. CVD-Based Valence-Mending Passivation for Crystalline-Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Meng [Arizona State Univ., Mesa, AZ (United States)

    2015-03-01

    The objective of this project is to investigate a new surface passivation technique, valence-mending passivation, for its applications in crystalline-Si solar cells to achieve significant efficiency improvement and cost reduction. As the enabling technique, the project includes the development of chemical vapor deposition recipes to passivate textured Si(100) and multicrystalline-Si surfaces by sulfur and the characterization of the passivated Si surfaces, including thermal stability, Schottky barrier height, contact resistance and surface recombination. One important application is to replace the Ag finger electrode in Si cells with Al to reduce cost, by ~$0.1/Wp, and allow terawatt-scale deployment of crystalline-Si solar cells. These all-Al Si cells require a low-temperature metallization process for the Al electrode, to be compatible with valence-mending passivation and to prevent Al diffusion into n-type Si. Another application is to explore valence-mending passivation of grain boundaries in multicrystalline Si by diffusing sulfur into grain boundaries, to reduce the efficiency gas between monocrystalline-Si solar cells and multicrystalline-Si cells. The major accomplishments of this project include: 1) Demonstration of chemical vapor deposition processes for valence-mending passivation of both monocrystalline Si(100) and multicrystalline Si surfaces. Record Schottky barriers have been demonstrated, with the new record-low barrier of less than 0.08 eV between Al and sulfur-passivated n-type Si(100) and the new record-high barrier of 1.14 eV between Al and sulfur-passivated p-type Si(100). On the textured p-type monocrystalline Si(100) surface, the highest barrier with Al is 0.85 eV by valence-mending passivation. 2) Demonstration of a low-temperature metallization process for Al in crystalline-Si solar cells. The new metallization process is based on electroplating of Al in a room-temperature ionic liquid. The resistivity of the electroplated Al is ~7×10–6

  5. Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures

    Directory of Open Access Journals (Sweden)

    Rafal Pietruszka

    2014-02-01

    Full Text Available Selected properties of photovoltaic (PV structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100 are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%.

  6. DLTS of p-type Czochralski Si wafers containing processing-induced macropores

    Science.gov (United States)

    Simoen, E.; Depauw, V.; Gordon, I.; Poortmans, J.

    2012-01-01

    The deep levels present in p-type Czochralski silicon with processing-induced macropores in the depletion region have been studied by the deep-level transient (DLT) spectroscopy technique. It is shown that a broad band is present for a bias pulse close to the interface with the Al Schottky contact, which exhibits anomalously slow hole capture and is ascribed to the internal interface states of the macropores. For depths beyond the pore region, other deep levels, associated with point defects—possibly metal contamination during the high-temperature annealing step under H2 ambient--have been observed. The impact of the observed defects on the lifetime of thin-film solar cells, fabricated using macropore-based layer transfer is discussed. Finally, it is shown that the presence of pores in the depletion region, which also affects the DLT-spectrum, alters the capacitance-voltage characteristics.

  7. Ag Nanodots Emitters Embedded in a Nanocrystalline Thin Film Deposited on Crystalline Si Solar Cells.

    Science.gov (United States)

    Park, Seungil; Ryu, Sel Gi; Ji, HyungYong; Kim, Myeong Jun; Peck, Jong Hyeon; Kim, Keunjoo

    2016-06-01

    We fabricated crystalline Si solar cells with the inclusion of various Ag nanodots into the additional emitters of nanocrystallite Si thin films. The fabricated process was carried out on the emitter surface of p-n junction for the textured p-type wafer. The Ag thin films were deposited on emitter surfaces and annealed at various temperatures. The amorphous Si layers were also deposited on the Ag annealed surfaces by hot-wire chemical vapor deposition and then the deposited layers were doped by the second n-type doping process to form an additional emitter. From the characterization, both the Ag nanodots and the deposited amorphous Si thin films strongly reduce photo-reflectances in a spectral region between 200-400 nm. After embedding Ag nanodots in nanocrystallite Si thin films, a conversion efficiency of the sample with added emitter was achieved to 15.1%, which is higher than the 14.1% of the reference sample and the 14.7% of the de-posited sample with a-Si:H thin film after the Ag annealing process. The additional nanocrystallite emitter on crystalline Si with Ag nanodots enhances cell properties.

  8. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  9. Emitter formation using laser doping technique on n- and p-type c-Si substrates

    Science.gov (United States)

    López, G.; Ortega, P.; Colina, M.; Voz, C.; Martín, I.; Morales-Vilches, A.; Orpella, A.; Alcubilla, R.

    2015-05-01

    In this work laser doping technique is used to create highly-doped regions defined in a point-like structure to form n+/p and p+/n junctions applying a pulsed Nd-YAG 1064 nm laser in the nanosecond regime. In particular, phosphorous-doped silicon carbide stacks (a-SiCx/a-Si:H (n-type)) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and aluminum oxide (Al2O3) layers deposited by atomic layer deposition (ALD) on 2 ± 0.5 Ω cm p- and n-type FZ c-Si substrates respectively are used as dopant sources. Laser power and number of pulses per spot are explored to obtain the optimal electrical behavior of the formed junctions. To assess the quality of the p+ and n+ regions, the junctions are electrically contacted and characterized by means of dark J-V measurements. Additionally, a diluted HF treatment previous to front metallization has been explored in order to know its impact on the junction quality. The results show that fine tuning of the energy pulse is critical while the number of pulses has minor effect. In general the different HF treatments have no impact in the diode electrical behavior except for an increase of the leakage current in n+/p junctions. The high electrical quality of the junctions makes laser doping, using dielectric layers as dopant source, suitable for solar cell applications. Particularly, a potential open circuit voltage of 0.64 V (1 sun) is expected for a finished solar cell.

  10. Emitter formation using laser doping technique on n- and p-type c-Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    López, G., E-mail: gema.lopez@upc.edu; Ortega, P.; Colina, M.; Voz, C.; Martín, I.; Morales-Vilches, A.; Orpella, A.; Alcubilla, R.

    2015-05-01

    Highlights: • We use laser doping technique to create highly-doped regions. • Dielectric layers are used as both passivating layer and dopant source. • The high quality of the junctions makes laser doping technique using dielectric layers as dopant source suitable for solar cells applications. - Abstract: In this work laser doping technique is used to create highly-doped regions defined in a point-like structure to form n+/p and p+/n junctions applying a pulsed Nd-YAG 1064 nm laser in the nanosecond regime. In particular, phosphorous-doped silicon carbide stacks (a-SiC{sub x}/a-Si:H (n-type)) deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) and aluminum oxide (Al{sub 2}O{sub 3}) layers deposited by atomic layer deposition (ALD) on 2 ± 0.5 Ω cm p- and n-type FZ c-Si substrates respectively are used as dopant sources. Laser power and number of pulses per spot are explored to obtain the optimal electrical behavior of the formed junctions. To assess the quality of the p+ and n+ regions, the junctions are electrically contacted and characterized by means of dark J–V measurements. Additionally, a diluted HF treatment previous to front metallization has been explored in order to know its impact on the junction quality. The results show that fine tuning of the energy pulse is critical while the number of pulses has minor effect. In general the different HF treatments have no impact in the diode electrical behavior except for an increase of the leakage current in n+/p junctions. The high electrical quality of the junctions makes laser doping, using dielectric layers as dopant source, suitable for solar cell applications. Particularly, a potential open circuit voltage of 0.64 V (1 sun) is expected for a finished solar cell.

  11. Thermal stability of Ni/Ti/Al ohmic contacts to p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hailong; Shen, Huajun, E-mail: shenhuajun@ime.ac.cn; Tang, Yidan; Bai, Yun; Liu, Xinyu [Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029 (China); Zhang, Xufang [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wu, Yudong; Liu, Kean [Zhuzhou CSR Times Electric Co., Ltd, ZhuZhou 412001 (China)

    2015-01-14

    Low resistivity Ni/Ti/Al ohmic contacts on p-type 4H-SiC epilayer were developed, and their thermal stabilities were also experimentally investigated through high temperature storage at 600 °C for 100 h. The contact resistance of the Al/Ti/Ni/SiC contacts degraded in different degrees, and the contact morphology deteriorated with the increases of the average surface roughness and interface voids. X-ray spectra showed that Ni{sub 2}Si and Ti{sub 3}SiC{sub 2}, which were formed during ohmic contact annealing and contributed to low contact resistivity, were stable under high temperature storage. The existence of the TiAl{sub 3} and NiAl{sub 3} intermetallic phases was helpful to prevent Al agglomeration on the interface and make the contacts thermally stable. Auger electron spectroscopy indicated that the incorporation of oxygen at the surface and interface led to the oxidation of Al or Ti resulting in increased contact resistance. Also, the formation of these oxides roughened the surface and interface. The temperature-dependence of the specific contact resistance indicated that a thermionic field emission mechanism dominates the current transport for contacts before and after the thermal treatment. It suggests that the Ni/Ti/Al composite ohmic contacts are promising for SiC devices to be used in high temperature applications.

  12. Energy band design for p-type tensile strained Si/SiGe multi-quantum well infrared photodetector

    Institute of Scientific and Technical Information of China (English)

    LI Jin-tao; CHEN Song-yan; QI Dong-feng; HUANG Wei; LI Cheng; LAI Hong-kai

    2011-01-01

    The band structure of the confined states is calculated for Si/SiGe multi-quantum well infrared photodetector (M-QWIP). The influence of the Ge component in pseudosubstrate on the energy band structure of Si/Si0.54Ce0.46 multi-quantum wells (MQWs) is investigated. It is found that the high energy levels in the MQWs move up while the low energy levels move down as the Ge component in psendosubstrate increases. The influence of the barrier width on the energy band structure of MQWs is also studied based on the 6 × 6 k-p method. The results show that the Si barrier between 5 nm and 10 nm is optimized to enhance the intersubband absorption in the MQWs.

  13. Study of an Amorphous Silicon Oxide Buffer Layer for p-Type Microcrystalline Silicon Oxide/n-Type Crystalline Silicon Heterojunction Solar Cells and Their Temperature Dependence

    Directory of Open Access Journals (Sweden)

    Taweewat Krajangsang

    2014-01-01

    Full Text Available Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the front and rear buffer layers in c-Si-HJ solar cells was investigated. The front i-a-SiO:H buffer layer thickness and the CO2/SiH4 ratio influenced the open-circuit voltage (Voc, fill factor (FF, and temperature coefficient (TC of the c-Si-HJ solar cells. The highest total area efficiency obtained was 18.5% (Voc=700 mV, Jsc=33.5 mA/cm2, and FF=0.79. The TC normalized for this c-Si-HJ solar cell efficiency was −0.301%/°C.

  14. Reduction of deep levels generated by ion implantation into n- and p-type 4H-SiC

    Science.gov (United States)

    Kawahara, Koutarou; Suda, Jun; Pensl, Gerhard; Kimoto, Tsunenobu

    2010-08-01

    The authors have investigated effects of thermal oxidation on deep levels in the whole energy range of the band gap of 4H-SiC by deep level transient spectroscopy. The deep levels are generated by ion implantation. The dominant defects in n-type samples after ion implantation and high-temperature annealing at 1700 °C are IN3 (Z1/2: EC-0.63 eV) and IN9 (EH6/7: EC-1.5 eV) in low-dose-implanted samples, and IN8 (EC-1.2 eV) in high-dose-implanted samples. These defects can remarkably be reduced by thermal oxidation at 1150 °C. In p-type samples, however, IP8 (HK4: EV+1.4 eV) survives and additional defects such as IP4 (HK0: EV+0.72 eV) appear after thermal oxidation in low-dose-implanted samples. In high-dose-implanted p-type samples, three dominant levels, IP5 (HK2: EV+0.85 eV), IP6 (EV+1.0 eV), and IP7 (HK3: EV+1.3 eV), are remarkably reduced by oxidation at 1150 °C. The dominant defect IP4 observed in p-type 4H-SiC after thermal oxidation can be reduced by subsequent annealing in Ar at 1400 °C. These phenomena are explained by a model that excess interstitials are generated at the oxidizing interface, which diffuse into the bulk region.

  15. Thomas-Fermi approximation in two p-type delta-doped quantum wells in GaAs an Si

    Energy Technology Data Exchange (ETDEWEB)

    Gaggero-Sager, L. M. [Universidad Autonoma de Zacatecas, Zacatecas (Mexico); M' Peko, J. C.; Perez Alvarez, R. [Universidad de La Habana, Ciudad Habana (Cuba)

    2001-04-01

    Thomas-Fermi calculations of the hole subband structure in two coupled p-type d-doped GaAs and Si quantum wells are carried out as a function of the impurity concentration and the distance l between them. A simple formula is obtained for the potential as a function of these two magnitudes by both types of systems. The numerical results for a double Be-{delta}-doped GaAs (double B-{delta}-doped Si) quantum well show that the energy levels degenerate for l{>=}300 A(l{>=}200 A) for an impurity concentration of 1 x 10{sup 1}3 cm{sup -2}. [Spanish] Presentamos calculos de la estructura de subbandas de huecos, utilizando la aproximacion de Thomas-Fermi para dos pozos cuanticos d-dopados tipo p en GaAs y Si, como funcion de la concentracion de impurezas y de la distancia l entre ambos para los dos tipos de sistemas. Los resultados numericos muestran que para un pozo doble de B-{delta}-dopado GaAs (pozo doble de B-{delta}-dopado Si) con una concentracion de 1 x 10{sup 1}3 cm{sup -2} los niveles estan degenerados para l{>=}300 A(l{>=}200 A).

  16. Low specific contact resistance on epitaxial p-type 4H-SiC with a step-bunching surface

    Institute of Scientific and Technical Information of China (English)

    韩超; 张玉明; 宋庆文; 汤晓燕; 张义门; 郭辉; 王悦湖

    2015-01-01

    This paper reports the performances of Ti/Al based ohmic contacts fabricated on highly doped p-type 4H-SiC epitaxial layer which has a severe step-bunching surface. Different contact schemes are investigated based on the Al:Ti composition with no more than 50 at.%Al. The specific contact resistance (SCR) is obtained to be as low as 2.6 × 10−6Ω·cm2 for the bilayered Ti(100 nm)/Al(100 nm) contact treated with 3 min rapid thermal annealing (RTA) at 1000◦C. The microstructure analyses examined by physical and chemical characterization techniques reveal an alloy-assisted ohmic contact formation mechanism, i.e., a high degree of alloying plays a decisive role in forming the interfacial ternary Ti3SiC2 dominating the ohmic behavior of the Ti/Al based contact. Furthermore, a globally covered Ti3SiC2 layer with (0001)-oriented texture can be formed, regardless of the surface step bunching as well as its structural evolution during the metallization annealing.

  17. Carrier mediated reduction of stiffness in nanoindented crystalline Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Kataria, S., E-mail: s-kataria2k2@yahoo.co.in; Dhara, Sandip, E-mail: dhara@igcar.gov.in; Dash, S.; Tyagi, A. K. [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2015-07-21

    We report the observation of carrier mediated decrease in the stiffness of crystalline (c)-Si(100) under nanoindentation. The apparent elastic moduli of heavily doped (∼1 × 10{sup 21} cm{sup −3}) p- and n-type c-Si are observed to be lower by 5.3%–7.5% than the estimated value for intrinsic (∼1 × 10{sup 14} cm{sup −3}) c-Si. The deviation observed with respect to elastic modulus remarkably matches with the estimated value while considering the electronic elastic strain effect on carrier concentration as an influence of negative pressure coefficient of band gap for Si (Γ-X). The value is predominantly higher than the reported value of a decrease of 1%–3% in stiffness as an effect of impurity in c-Si.

  18. Diffusion thermopower of a p-type Si/Si{sub 1-x}Ge{sub x} heterostructure at zero magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Huan, Tran Doan [Institute of Engineering Physics, Hanoi University of Technology, 1 Dai Co Viet Rd., Hanoi (Viet Nam); Hai, Nguyen Phuc [Faculty of Engineering, Katholieke University of Leuven, Kasteelpark Arenberg 44, 3001 Heverlee (Leuven) (Belgium)

    2007-06-15

    We calculate the diffusion thermopower of the degenerate two-dimensional hole gas in a p-type Si/Si{sub 1-x}Ge{sub x} lattice mismatched heterostructure at low temperatures and zero magnetic field. The effects of possible scatterings, e.g. remote impurity, alloy disorder, interface roughness, deformation potential, and random piezoelectric on the hole mobility and the diffusion thermopower are examined. Calculated results are well fitted to the experimental data recently reported. In addition, we predict a possibility for the diffusion thermopower to change its sign as the SiGe layer thickness changes, the effect has not been discussed yet. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Effect of germanium fraction on the effective minority carrier lifetime in thin film amorphous-Si/crystalline-Si1xGex/crystalline-Si heterojunction solar cells

    Directory of Open Access Journals (Sweden)

    Sabina Abdul Hadi

    2013-05-01

    Full Text Available The effect of germanium fraction on the effective minority carrier lifetime (τeff for epitaxial Si1-xGex layers is extracted using measurements on amorphous(a Si(n+/crystalline(c-Si1-xGex(p/crystalline(c-Si(p+ heterojunction solar cells with x = 0.25, 0.41 and 0.56. The τeff extracted for Si0.75Ge0.25 is ∼1 μs, decreasing to ∼ 40 ns for Si0.44Ge0.56. In addition, the band-gap voltage offset (Woc increases from 0.5 eV for Si to 0.65 eV for 56% Ge indicating an increase in non-radiative recombination consistent with the reduction in effective lifetime.

  20. Low specific contact resistance on epitaxial p-type 4H-SiC with a step-bunching surface

    Science.gov (United States)

    Han, Chao; Zhang, Yu-Ming; Song, Qing-Wen; Tang, Xiao-Yan; Zhang, Yi-Men; Guo, Hui; Wang, Yue-Hu

    2015-11-01

    This paper reports the performances of Ti/Al based ohmic contacts fabricated on highly doped p-type 4H-SiC epitaxial layer which has a severe step-bunching surface. Different contact schemes are investigated based on the Al:Ti composition with no more than 50 at.% Al. The specific contact resistance (SCR) is obtained to be as low as 2.6 × 10-6 Ω·cm2 for the bilayered Ti(100 nm)/Al(100 nm) contact treated with 3 min rapid thermal annealing (RTA) at 1000 °C. The microstructure analyses examined by physical and chemical characterization techniques reveal an alloy-assisted ohmic contact formation mechanism, i.e., a high degree of alloying plays a decisive role in forming the interfacial ternary Ti3SiC2 dominating the ohmic behavior of the Ti/Al based contact. Furthermore, a globally covered Ti3SiC2 layer with (0001)-oriented texture can be formed, regardless of the surface step bunching as well as its structural evolution during the metallization annealing. Project supported by the Key Specific Projects of Ministry of Education of China (Grant No. 625010101), the National Natural Science Foundation of China (Grant No. 61234006), the Natural Science Foundation of ShaanXi Province, China (Grant No. 2013JQ8012), the Doctoral Fund of Ministry of Education of China (Grant No. 20130203120017), and the Specific Project of the Core Devices, China (Grant No. 2013ZX0100100-004).

  1. Electroless deposition of NiWB alloy on p-type Si(1 0 0) for NiSi contact metallization

    Energy Technology Data Exchange (ETDEWEB)

    Duhin, A. [Department of Physical Electronics, Engineer Faculty, Tel-Aviv University, Ramat-Aviv 69978 (Israel)], E-mail: alla.douhin@gmail.com; Sverdlov, Y. [Department of Physical Electronics, Engineer Faculty, Tel-Aviv University, Ramat-Aviv 69978 (Israel); Feldman, Y. [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel); Shacham-Diamand, Y. [Department of Physical Electronics, Engineer Faculty, Tel-Aviv University, Ramat-Aviv 69978 (Israel)

    2009-10-30

    Recently, we have proposed a novel method to form NiSi contacts using electroless plating of Ni-alloys (NiP, NiWP, NiWB) on p-type Si(1 0 0) modified by aminopropyltriethoxysilane (APTS) activated with Pd-citrate [A. Duhin, Y. Sverdlov, Yishay Feldman, Y. Shacham-Diamand, Microelectron. Eng. 84 (2007) 2506]. In this work we focus on NiWB thin films that were formed by this method. Alkali metal free electroless plating was developed using dimethylamine-borane (DMAB) and tungstatic acid (H{sub 2}WO{sub 4}) as a reducing agent and a source of tungsten ions, respectively. Using this method we succeeded to receive relatively high tungsten concentration (maximum value of 19-21 at%) in the electroless deposited NiWB films with good adhesion to the Si-substrate. In this paper, the advantages of using the APTS activated with Pd-citrate for NiWB alloy deposition on the Si substrate is discussed. The chemically deposited NiWB samples were annealed for 1-2 h in vacuum (<10{sup -6} Torr) forming the silicide layer. The annealing temperatures were 650 deg. C for NiWB alloys. X-ray diffraction (XRD) measurement confirmed the presence of NiSi phase after annealing. In addition the WSi{sub 2} phase was formed. The results are reported and summarized.

  2. In situ monitoring of stacking fault formation and its carrier lifetime mediation in p-type 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin, E-mail: chenbinmse@gmail.com; Chen, Jun; Yao, Yuanzhao; Sekiguchi, Takashi [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Matsuhata, Hirofumi; Okumura, Hajime [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)

    2014-07-28

    Using the fine control of an electron beam (e-beam) in scanning electron microscopy with the capabilities of both electrical and optical imaging, the stacking fault (SF) formation together with its tuning of carrier lifetime was in situ monitored and investigated in p-type 4H-SiC homoepitaxial films. The SFs were formed through engineering basal plane dislocations with the energy supplied by the e-beam. The e-beam intensity required for the SF formation in the p-type films was ∼100 times higher than that in the n-type ones. The SFs reduced the minority-carrier lifetime in the p-type films, which was opposite to that observed in the n-type case. The reason for the peculiar SF behavior in the p-type 4H-SiC is discussed with the cathodoluminescence results.

  3. Extended point defects in crystalline materials: Ge and Si.

    Science.gov (United States)

    Cowern, N E B; Simdyankin, S; Ahn, C; Bennett, N S; Goss, J P; Hartmann, J-M; Pakfar, A; Hamm, S; Valentin, J; Napolitani, E; De Salvador, D; Bruno, E; Mirabella, S

    2013-04-12

    B diffusion measurements are used to probe the basic nature of self-interstitial point defects in Ge. We find two distinct self-interstitial forms--a simple one with low entropy and a complex one with entropy ∼30  k at the migration saddle point. The latter dominates diffusion at high temperature. We propose that its structure is similar to that of an amorphous pocket--we name it a morph. Computational modeling suggests that morphs exist in both self-interstitial and vacancylike forms, and are crucial for diffusion and defect dynamics in Ge, Si, and probably many other crystalline solids.

  4. Flexible Solar Cells Using Doped Crystalline Si Film Prepared by Self-Biased Sputtering Solid Doping Source in SiCl4/H2 Microwave Plasma.

    Science.gov (United States)

    Hsieh, Ping-Yen; Lee, Chi-Young; Tai, Nyan-Hwa

    2016-02-01

    We developed an innovative approach of self-biased sputtering solid doping source process to synthesize doped crystalline Si film on flexible polyimide (PI) substrate via microwave-plasma-enhanced chemical vapor deposition (MWPECVD) using SiCl4/H2 mixture. In this process, P dopants or B dopants were introduced by sputtering the solid doping target through charged-ion bombardment in situ during high-density microwave plasma deposition. A strong correlation between the number of solid doping targets and the characteristics of doped Si films was investigated in detail. The results show that both P- and B-doped crystalline Si films possessed a dense columnar structure, and the crystallinity of these structures decreased with increasing the number of solid doping targets. The films also exhibited a high growth rate (>4.0 nm/s). Under optimal conditions, the maximum conductivity and corresponding carrier concentration were, respectively, 9.48 S/cm and 1.2 × 10(20) cm(-3) for P-doped Si film and 7.83 S/cm and 1.5 × 10(20) cm(-3) for B-doped Si film. Such high values indicate that the incorporation of dopant with high doping efficiency (around 40%) into the Si films was achieved regardless of solid doping sources used. Furthermore, a flexible crystalline Si film solar cell with substrate configuration was fabricated by using the structure of PI/Mo film/n-type Si film/i-type Si film/p-type Si film/ITO film/Al grid film. The best solar cell performance was obtained with an open-circuit voltage of 0.54 V, short-circuit current density of 19.18 mA/cm(2), fill factor of 0.65, and high energy conversion of 6.75%. According to the results of bending tests, the critical radius of curvature (RC) was 12.4 mm, and the loss of efficiency was less than 1% after the cyclic bending test for 100 cycles at RC, indicating superior flexibility and bending durability. These results represent important steps toward a low-cost approach to high-performance flexible crystalline Si film

  5. Impact of common metallurgical impurities on ms-Si solar cell efficiency. P-type versus n-type doped ingots

    Energy Technology Data Exchange (ETDEWEB)

    Geerligs, L.J.; Manshanden, P. [ECN Solar Energy, Petten (Netherlands); Solheim, I.; Ovrelid, E.J.; Waernes, A.N. [Sintef materials technology, Trondheim (Norway)

    2006-09-15

    Silicon solar cells based on n-type silicon wafers are less sensitive to carrier lifetime degradation due to several common metal impurities than p-base cells. The theoretical and experimental indications for this have recently received considerable attention. This paper compares p-type and n-type cells purposely contaminated with relatively high levels of impurities, processed by industrial techniques. The impurities considered are Al, Ti, and Fe, which are the dominant impurities in metallurgical silicon and natural quartz. The work also preliminary addresses the question whether the optimal wafer resistivity is the same for n-type as for p-type base mc-Si cells.

  6. Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB2

    Science.gov (United States)

    Ahmad, Sajid; Dubey, K.; Bhattacharya, Shovit; Basu, Ranita; Bhatt, Ranu; Bohra, A. K.; Singh, Ajay; Aswal, D. K.; Gupta, S. K.

    2016-05-01

    Nearly 60% of the world's useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research[1]. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel[2]. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe and p-type SiGe-x wt.%TiB2 (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α2/ρ) of SiGe alloy on addition of TiB2 upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.

  7. Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Sajid, E-mail: sajidahmadiitkgp@gmail.com [Nuclear Research Laboratory, Astrophysical Sciences Division, B.A.R.C., Zakura, Srinagar, Kashmir-190024 (India); Dubey, K. [Barkatullah University, Bhopal–462026 (India); Bhattacharya, Shovit; Basu, Ranita; Bhatt, Ranu; Bohra, A. K.; Singh, Ajay; Aswal, D. K.; Gupta, S. K. [Technical Physics Division, B.A.R.C., Trombay, Mumbai – 400085 (India)

    2016-05-23

    Nearly 60% of the world’s useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research{sup [1]}. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel{sup [2]}. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe and p-type SiGe-x wt.%TiB{sub 2} (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α{sup 2}/ρ) of SiGe alloy on addition of TiB{sub 2} upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.

  8. Origin of Photovoltage Enhancement via Interfacial Modification with Silver Nanoparticles Embedded in an a-SiC:H p-Type Layer in a-Si:H Solar Cells.

    Science.gov (United States)

    Li, Tiantian; Zhang, Qixing; Ni, Jian; Huang, Qian; Zhang, Dekun; Li, Baozhang; Wei, Changchun; Yan, Baojie; Zhao, Ying; Zhang, Xiaodan

    2017-03-17

    We used silver nanoparticles (Ag-NPs) embedded in the p-type semiconductor layer of hydrogenated amorphous silicon (a-Si:H) solar cells in the Schottky barrier contact design to modify the interface between aluminum-doped ZnO (ZnO:Al, AZO) and p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) without plasmonic absorption. The high work function of the Ag-NPs provided a good channel for the transport of photogenerated holes. A p-type nanocrystalline SiC:H layer was used to compensate for the real surface defects and voids on the surface of Ag-NPs to reduce recombination at the AZO/p-type layer interface, which then enhanced the photovoltage of single-junction a-Si:H solar cells to values as high as 1.01 V. The Ag-NPs were around 10 nm in diameter and thermally stable in the p-type a-SiC:H film at the solar-cell process temperature. We will also show that a wide range of photovoltages between 1.01 and 2.89 V could be obtained with single-, double-, and triple-junction solar cells based on the single-junction a-Si:H solar cells with tunable high photovoltage. These solar cells are suitable photocathodes for solar water-splitting applications.

  9. Interface modification effect between p-type a-SiC:H and ZnO:Al in p-i-n amorphous silicon solar cells.

    Science.gov (United States)

    Baek, Seungsin; Lee, Jeong Chul; Lee, Youn-Jung; Iftiquar, Sk Md; Kim, Youngkuk; Park, Jinjoo; Yi, Junsin

    2012-01-18

    Aluminum-doped zinc oxide (ZnO:Al) [AZO] is a good candidate to be used as a transparent conducting oxide [TCO]. For solar cells having a hydrogenated amorphous silicon carbide [a-SiC:H] or hydrogenated amorphous silicon [a-Si:H] window layer, the use of the AZO as TCO results in a deterioration of fill factor [FF], so fluorine-doped tin oxide (Sn02:F) [FTO] is usually preferred as a TCO. In this study, interface engineering is carried out at the AZO and p-type a-SiC:H interface to obtain a better solar cell performance without loss in the FF. The abrupt potential barrier at the interface of AZO and p-type a-SiC:H is made gradual by inserting a buffer layer. A few-nanometer-thick nanocrystalline silicon buffer layer between the AZO and a-SiC:H enhances the FF from 67% to 73% and the efficiency from 7.30% to 8.18%. Further improvements in the solar cell performance are expected through optimization of cell structures and doping levels.

  10. Fabrication and electrical characterization of Al/DNA-CTMA/ p-type a-Si:H photodiode based on DNA-CTMA biomaterial

    Science.gov (United States)

    Siva Pratap Reddy, M.; Puneetha, Peddathimula; Lee, Young-Woong; Jeong, Seong-Hoon; Park, Chinho

    2017-01-01

    In this work, a deoxyribonucleic acid-cetyltrimethylammonium chloride (DNA-CTMA) biomaterial based p-type hydrogenated amorphous silicon ( a-Si:H) photodiode (PD) is fabricated and its electrical characteristics are investigated. The Al/DNA-CTMA/ p-type a-Si:H PD parameters are studied using current-voltage ( I-V), capacitancevoltage-frequency ( C-V-f) and conductance-voltage-frequency ( G/ω-V-f) measurements. The barrier height and the ideality factor of the diode are found to be 0.78 eV and 1.9, respectively. The electrical and photoconductivity properties of the diode are analyzed by using dark I-V and transient photocurrent techniques. The C-V-f and G/ω-V-f measurements indicate that the capacitance and conductance of the diode depend on the voltage and frequency, respectively. The experimental results reveal that the decreases in capacitance and the increases in conductance with an increase in frequency can be explained on the basis of interface states ( N SS ). Series resistance ( R S ) measurements are performed on the diode and discussed here. The obtained electrical parameters confirm that the Al/DNA-CTMA/ p-type a-Si:H PD can be used as an optical sensor for the development of commercial applications that are environmentally benign. [Figure not available: see fulltext.

  11. Optical properties of ZnO nanowire arrays electrodeposited on n- and p-type Si(1 1 1): Effects of thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Lupan, O., E-mail: oleg-lupan@chimie-paristech.fr [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie (LECIME), UMR 7575 CNRS, Chimie ParisTech, 11 rue P. et M. Curie, 75231 Paris (France); Pauporte, Th., E-mail: thierry-pauporte@chimie-paristech.fr [Laboratoire d' Electrochimie, Chimie des Interfaces et Modelisation pour l' Energie (LECIME), UMR 7575 CNRS, Chimie ParisTech, 11 rue P. et M. Curie, 75231 Paris (France); Tiginyanu, I.M.; Ursaki, V.V. [Institute of Electronic Engineering and Nanotechnologies, Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau MD-2028 (Moldova, Republic of); Heinrich, H.; Chow, L. [Department of Physics, University of Central Florida, PO Box 162385 Orlando, FL 32816-2385 (United States)

    2011-09-25

    Highlights: > A new template-free electrochemical deposition method for the synthesis of ZnO nanorods/nanowires directly on n- and p-type silicon (Si) substrates. > Improved structural, electrical and optical properties of the ZnO nanowires/p-Si (1 1 1) heterojunction have been demonstrated. > Photodetectors have been fabricated based on the n-ZnO nanowires/p-Si heterojunction obtained by electrodeposition. - Abstract: Electrodeposition is a low temperature and low cost growth method of high quality nanostructured active materials for optoelectronic devices. We report the electrochemical preparation of ZnO nanorod/nanowire arrays on n-Si(1 1 1) and p-Si(1 1 1). The effects of thermal annealing and type of substrates on the optical properties of ZnO nanowires electroplated on silicon (1 1 1) substrate are reported. We fabricated ZnO nanowires/p-Si structure that exhibits a strong UV photoluminescence emission and a negligible visible emission. This UV photoluminescence emission proves to be strongly influenced by the thermal annealing at 150-800 deg. C. Photo-detectors have been fabricated based on the ZnO nanowires/p-Si heterojunction.

  12. Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS)x:(ZnS)1-x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells.

    Science.gov (United States)

    Xu, Xiaojie; Bullock, James; Schelhas, Laura T; Stutz, Elias Z; Fonseca, Jose J; Hettick, Mark; Pool, Vanessa L; Tai, Kong Fai; Toney, Michael F; Fang, Xiaosheng; Javey, Ali; Wong, Lydia Helena; Ager, Joel W

    2016-03-09

    P-type transparent conducting films of nanocrystalline (CuS)x:(ZnS)1-x were synthesized by facile and low-cost chemical bath deposition. Wide angle X-ray scattering (WAXS) and high resolution transmission electron microscopy (HRTEM) were used to evaluate the nanocomposite structure, which consists of sub-5 nm crystallites of sphalerite ZnS and covellite CuS. Film transparency can be controlled by tuning the size of the nanocrystallites, which is achieved by adjusting the concentration of the complexing agent during growth; optimal films have optical transmission above 70% in the visible range of the spectrum. The hole conductivity increases with the fraction of the covellite phase and can be as high as 1000 S cm(-1), which is higher than most reported p-type transparent materials and approaches that of n-type transparent materials such as indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) synthesized at a similar temperature. Heterojunction p-(CuS)x:(ZnS)1-x/n-Si solar cells were fabricated with the nanocomposite film serving as a hole-selective contact. Under 1 sun illumination, an open circuit voltage of 535 mV was observed. This value compares favorably to other emerging heterojunction Si solar cells which use a low temperature process to fabricate the contact, such as single-walled carbon nanotube/Si (370-530 mV) and graphene/Si (360-552 mV).

  13. Influence of annealing in H atmosphere on the electrical properties of Al2O3 layers grown on p-type Si by the atomic layer deposition technique

    Science.gov (United States)

    Kolkovsky, Vl.; Stübner, R.; Langa, S.; Wende, U.; Kaiser, B.; Conrad, H.; Schenk, H.

    2016-09-01

    In the present study the electrical properties of 100 nm and 400 nm alumina films grown by the atomic layer deposition technique on p-type Si before and after a post-deposition annealing at 440 °C and after a dc H plasma treatment at different temperatures are investigated. We show that the density of interface states is below 2 × 1010 cm-2 in these samples and this value is significantly lower compared to that reported previously in thinner alumina layers (below 50 nm). The effective minority carrier lifetime τg,eff and the effective surface recombination velocity seff in untreated p-type Si samples with 100 nm and 400 nm aluminum oxide is comparable with those obtained after thermal oxidation of 90 nm SiO2. Both, a post-deposition annealing in forming gas (nitrogen/hydrogen) at elevated temperatures and a dc H-plasma treatment at temperatures close to room temperature lead to the introduction of negatively charged defects in alumina films. The results obtained in samples annealed in different atmospheres at different temperatures or subjected to a dc H plasma treatment allow us to correlate these centers with H-related defects. By comparing with theory we tentatively assign them to negatively charged interstitial H atoms.

  14. Evidences of the existence of SiTe2 crystalline phase and a proposed new Si-Te phase diagram

    Science.gov (United States)

    Mishra, R.; Mishra, P. K.; Phapale, S.; Babu, P. D.; Sastry, P. U.; Ravikumar, G.; Yadav, A. K.

    2016-05-01

    The existence of two distinct crystalline phases viz., Si2Te3 and SiTe2, in the Si-Te system is established from differential thermal analysis (DTA) studies. Thermo-gravimetric (TG) data on SiTe2 indicate that the compound decomposes to Si in multiple steps via intermediate Si2Te3 phase. X-ray diffraction (XRD) reveals that SiTe2 crystallizes in P 3 ̅m1 space group with CdI2 trigonal structure, whereas Si2Te3 crystallizes in trigonal structure with space group P 3 ̅1c with varying occupation of octahedral voids. Single Si atoms fill only 1/2 of the octahedral voids in SiTe2 structure whereas in Si2Te3, Si atoms are arranged in pairs occupying 2/3 of the octahedral voids in alternating planes along c-axis. Further, X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) confirm the distinctness of the chemical environment in the two crystalline structures confirming the uniqueness of both the phases. DTA results on the two compounds indicate the presence of one crystallographic phase-transition in each of the compound with transition temperatures at 441 °C for Si2Te3 and 392 °C for SiTe2. At the same time both Si2Te3 and SiTe2 undergo peritectic decomposition at 683 °C and 432 °C forming [Si(s)+Te(liq)] and [α-Si2Te3(s)+Te(liq)], respectively. The system revealed eutectic reaction between β-SiTe2 and Te at 398 °C [L=Te+SiTe2]. Consequently, the phase diagram in the Si-Te system has been delineated.

  15. Origin of the n -type and p -type conductivity of MoS 2 monolayers on a SiO 2 substrate

    KAUST Repository

    Dolui, Kapildeb

    2013-04-02

    Ab initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over a SiO 2 substrate in the presence of interface impurities and defects. When MoS2 is placed on a defect-free substrate, the oxide plays an insignificant role since the conduction band top and the valence band minimum of MoS2 are located approximately in the middle of the SiO2 band gap. However, if Na impurities and O dangling bonds are introduced at the SiO2 surface, these lead to localized states, which modulate the conductivity of the MoS2 monolayer from n- to p-type. Our results show that the conductive properties of MoS2 deposited on SiO 2 are mainly determined by the detailed structure of the MoS 2/SiO2 interface, and suggest that doping the substrate can represent a viable strategy for engineering MoS2-based devices. © 2013 American Physical Society.

  16. Three Crystalline Polymorphs of KFeSi04, Potassium Ferrisilicate

    DEFF Research Database (Denmark)

    Bentzen, Janet Jonna

    1983-01-01

    Orthorhombic α-KFeSi04 ( a =0.5478, b =0.9192, c =0.8580 nm), hexagonal β-KFeSiO4 (a =0.5309, c =0.8873 nm), and hexagonal γ-KFeSi04 (a =0.5319, c =0.8815 nm) were synthesized by devitrification of KFeSiO4 glass. Powder X-ray diffraction data are given for all three polymorphs. Alpha KFeSiO4, the...

  17. Study of the electrical, thermal and chemical properties of Pd ohmic contacts to p-type 4H-SiC: dependence on annealing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kassamakova, L.; Kakanakov, R. [Inst. of Appl. Phys., Plovdiv (Bulgaria). BAS; Nordell, N.; Savage, S. [Industrial Microelectronics Center, Kista (Sweden); Kakanakova-Georgieva, A.; Marinova, Ts. [Inst. of General and Inorganic Chemistry, BAS, Sofia (Bulgaria)

    1999-07-30

    The electrical and chemical properties of Pd ohmic contacts to p-type 4H-SiC, together with their thermal stability, have been studied in the annealing temperature range 600 - 700 C. The ohmic behaviour of as-deposited and annealed contacts has been checked from I - V characteristics and the contact resistivity has been determined by the linear TLM method in order to determine the electrical properties and the thermal stability. An ohmic behaviour was established after annealing at 600 C, while the lowest contact resistivity 5.5 x 10{sup -5} {omega}cm{sup 2} was obtained at 700 C. The contact structure, before and after annealing, was investigated using X-ray photoelectron spectroscopy depth analysis. As-deposited Pd films form an abrupt and chemically inert Pd/SiC interface. Annealing causes the formation of palladium silicide. After formation at 600 C the contact structure consists of unreacted Pd and Pd{sub 3}Si. During annealing at 700 C. Pd and SiC react completely and a mixture of Pd{sub 3}Si, Pd{sub 2}Si and C in a graphite state is found in the contact layer. The examination of the thermal stability shows that after a 100 h heating at 500 C, only the contacts annealed at 700 C did not suffer from a change in resistivity. This can be explained by a more complete reaction between the Pd contact layer and the SiC substrate at this higher annealing temperature. (orig.)

  18. Three Crystalline Polymorphs of KFeSi04, Potassium Ferrisilicate

    DEFF Research Database (Denmark)

    Bentzen, Janet Jonna

    1983-01-01

    Orthorhombic α-KFeSi04 ( a =0.5478, b =0.9192, c =0.8580 nm), hexagonal β-KFeSiO4 (a =0.5309, c =0.8873 nm), and hexagonal γ-KFeSi04 (a =0.5319, c =0.8815 nm) were synthesized by devitrification of KFeSiO4 glass. Powder X-ray diffraction data are given for all three polymorphs. Alpha KFeSiO4, the......, and synthetic kaliophilite, KAISiO4, respectively, and it is proposed that β- and λ-KFeSiO4 are linked by Si-Fe order-disorder. Beta KFeSiO4 transforms slowly into α-KFeSi04 above 910°C but the transformation was not shown to be reversible in the present dry-heating experiments....

  19. Non-linear optical functions of crystalline-Si resulting from nanoscale layered systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuznicki, Z.T. [Laboratoire PHASE, CNRS UPR 292, 23 rue du Loess, F-67037 Strasbourg cedex 2 (France)]. E-mail: kuznicki@phase.c-strasbourg.fr; Ley, M. [Laboratoire PHASE, CNRS UPR 292, 23 rue du Loess, F-67037 Strasbourg cedex 2 (France); Lezec, H.J. [ISIS, ULP, 8 allee Gaspard Monge, F-67083 Strasbourg cedex (France); Sarrabayrouse, G. [LAAS-CNRS, 7 av. du colonel Roche, 31077 Toulouse cedex 4 (France); Rousset, B. [LAAS-CNRS, 7 av. du colonel Roche, 31077 Toulouse cedex 4 (France); Rossel, F. [LAAS-CNRS, 7 av. du colonel Roche, 31077 Toulouse cedex 4 (France); Migeon, H. [LAM, Centre de Recherche Public - Gabriel Lippmann, 162a, av. de la Faiaencerie, L-1511 Luxembourg (Luxembourg); Wirtz, T. [LAM, Centre de Recherche Public - Gabriel Lippmann, 162a, av. de la Faiaencerie, L-1511 Luxembourg (Luxembourg)

    2006-07-15

    New non-linear optoelectronic and photovoltaic behavior of crystalline silicon (c-Si) has been obtained with a strained nanoscale Si-layered system. We have found c-Si absorptances that even exceed values of amorphous silicon (a-Si) thin films. The present investigation exploits charge carrier and photon flux transformations at the so-called carrier collection limit. A correlation between free carrier density and the absorption coefficient could be established by combining reflectivity and transmissivity measurements on samples having different surface free carrier reservoirs. In summary, Si modifications implemented on the nanoscale lead to new effects that can widen applications of conventional Si devices.

  20. Chemical etching investigation of polycrystalline p-type 6H-SiC in HF/Na{sub 2}O{sub 2} solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gabouze, Noureddine [Silicon Technology Development Unit (UDTS), 2 Bd Frantz Fanon, B.P. 140, Algiers (Algeria); Keffous, Aissa, E-mail: ngabouze@yahoo.fr [Silicon Technology Development Unit (UDTS), 2 Bd Frantz Fanon, B.P. 140, Algiers (Algeria); Kerdja, Tahar; Belaroussi, Yasmine [Advanced Techniques Development Center (CDTA), Haouch Loukil, Baba Hassen, Algiers (Algeria)

    2009-05-15

    In this work, an experimental study on the chemical etching reaction of polycrystalline p-type 6H-SiC was carried out in HF/Na{sub 2}O{sub 2} solutions. The morphology of the etched surface was examined with varying Na{sub 2}O{sub 2} concentration, etching time, agitation speed and temperature. The surfaces of the etched samples were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) Fourier transform infrared spectroscopy (FT-IR) and photoluminescence. The surface morphology of samples etched in HF/Na{sub 2}O{sub 2} is shown to depend on the solution composition and bath temperature. The investigation of the HF/Na{sub 2}O{sub 2} solutions on 6H-SiC surface shows that as Na{sub 2}O{sub 2} concentration increases, the etch rate increases to reach a maximum value at about 0.5 M and then decreases. A similar behaviour has been observed when temperature of the solution is increased. The maximum etch rate is found for 80 deg. C. In addition, a new polishing etching solution of 6H-SiC has been developed. This result is very interesting since to date no chemical polishing solution has been developed on the material.

  1. Calibration on wide-ranging aluminum doping concentrations by photoluminescence in high-quality uncompensated p-type 4H-SiC

    Science.gov (United States)

    Asada, Satoshi; Kimoto, Tsunenobu; Ivanov, Ivan G.

    2017-08-01

    Previous work has shown that the concentration of shallow dopants in a semiconductor can be estimated from the photoluminescence (PL) spectrum by comparing the intensity of the bound-to-the-dopant exciton emission to that of the free exciton. In this work, we study the low-temperature PL of high-quality uncompensated Al-doped p-type 4H-SiC and propose algorithms for determining the Al-doping concentration using the ratio of the Al-bound to free-exciton emission. We use three different cryogenic temperatures (2, 41, and 79 K) in order to cover the Al-doping range from mid 1014 cm-3 up to 1018 cm-3. The Al-bound exciton no-phonon lines and the strongest free-exciton replica are used as a measure of the bound- and free-exciton emissions at a given temperature, and clear linear relationships are obtained between their ratio and the Al-concentration at 2, 41, and 79 K. Since nitrogen is a common unintentional donor dopant in SiC, we also discuss the criteria allowing one to determine from the PL spectra whether a sample can be considered as uncompensated or not. Thus, the low-temperature PL provides a convenient non-destructive tool for the evaluation of the Al concentration in 4H-SiC, which probes the concentration locally and, therefore, can also be used for mapping the doping homogeneity.

  2. Synthesis of crystalline Si-based nanosheets by extraction of Ca from CaSi2 in inositol hexakisphosphate solution

    Science.gov (United States)

    Meng, Xiang; Sasaki, Kenta; Sano, Koki; Yuan, Peiling; Tatsuoka, Hirokazu

    2017-05-01

    Crystalline Si-based nanosheets were successfully synthesized from CaSi2 by a simple soft chemical synthetic method in solution. By immersing CaSi2 powder or CaSi2/Si substrates in an inositol hexakisphosphate (IP6) solution, Ca atoms were extracted from the CaSi2 particles, then Si-based nanosheets were formed. The morphological, structural and optical properties of the Si-based nanosheets were investigated. It is noted that the thin Si-based nanosheets stacked with a void space formed bundle structures, and the nanosheets were easily exfoliated from the bundles to expose the surfaces corresponding to the Si{111} planes. Meanwhile, the surface of the Si nanosheets might be terminated by O, H, or OH bonds. The Si-based nanosheet bundles were then formed and directly rooted to the Si(111) substrates, and had a remarkably highly symmetrical morphology. This study demonstrated a simple method for preparing Si-based nanosheets, and electro- and photo-chemical applications would possibly be expected, such as in lithium ion batteries.

  3. Hydrogen plasma treatment of very thin p-type nanocrystalline Si films grown by RF-PECVD in the presence of B(CH33

    Directory of Open Access Journals (Sweden)

    Sergej Alexandrovich Filonovich, Hugo Águas, Tito Busani, António Vicente, Andreia Araújo, Diana Gaspar, Marcia Vilarigues, Joaquim Leitão, Elvira Fortunato and Rodrigo Martins

    2012-01-01

    Full Text Available We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (~20 nm films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film.

  4. The novel transparent sputtered p-type CuO thin films and Ag/p-CuO/n-Si Schottky diode applications

    Directory of Open Access Journals (Sweden)

    A. Tombak

    2015-01-01

    Full Text Available In the current paper, the physical properties and microelectronic parameters of direct current (DC sputtered p-type CuO film and diode have been investigated. The film of CuO as oxide and p-type semiconductor is grown onto glass and n-Si substrates by reactive DC sputtering at 250 °C. After deposition, a post-annealing procedure is applied at various temperatures in ambient. Through this research, several parameters are determined such structural, optical and electrical magnitudes. The thickness of CuO thin films goes from 122 to 254 nm. A (111-oriented cubic crystal structure is revealed by X-ray analysis. The grain size is roughly depending on the post-annealing temperature, it increases with temperature within the 144–285 nm range. The transmittance reaches 80% simultaneously in visible and infrared bands. The optical band gap is varied between 1.99 and 2.52 eV as a result of annealing temperature while the resistivity and the charge carrier mobility decrease with an increase in temperature from 135 to 14 Ω cm and 0.92 to 0.06 cm2/Vs, respectively. The surface of samples is homogenous, bright dots are visible when temperature reaches the highest value. As a diode, Ag/CuO/n-Si exhibits a non-ideal behavior and the ideality factor is about 3.5. By Norde method, the barrier height and the series resistance are extracted and found to be 0.96 V and 86.6 Ω respectively.

  5. Defects left after regrowth of amorphous silicon on crystalline Si : C (V) and DLTS studies

    OpenAIRE

    Castaing, J.; Cass, T.

    1985-01-01

    n and p-type silicon have been self-ion implanted at 77 K with multi-energetic beams. This process was used to amorphize a 0.4 μm layer with a minimum amount of damage in the underlying crystal. After regrowth by a 550 °C anneal, the remaining defects were assessed by capacitance-voltage (C(V )) measurements and deep level transient spectroscopy (DLTS). In n-type Si, a buried layer of deep donors in large concentration was found, whereas in p-type Si, their concentration was small. These trap...

  6. THERMOELECTRIC PROPERTIES OF HOT-PRESSED p-TYPE Mg2Si0.3Sn0.7 SOLID SOLUTION

    Directory of Open Access Journals (Sweden)

    G. N. Isachenko

    2014-05-01

    Full Text Available It is shown that thermoelectric energy conversion which gives the possibility for utilizing a low potential heat is one of the ways for adoption of energy-saving technologies; and semiconductor materials with p-type and n-type conductivities having high thermoelectric figure of merit are necessary for operation of thermoelectric generators. The paper deals with possibility of usage of the p-Mg2Si0.3Sn0.7 solid solution (with a nanostructured modification as a couple for the well studied thermoelectric material based on n-Mg2Si-Mg2Sn. A technological scheme for fabrication of heavily doped Mg2Si0.3Sn0.7 solid solution of p-type by hot pressing from nanopowder is developed. The given technology has made it possible to reduce duration of a homogeneous material fabrication and has improved its physical and chemical properties. The samples were made by three ways: direct fusion for polycrystals fabrication; hot pressing from microparticles; nanostructuring, i.e. hot pressing from nanoparticles. By X-ray diffraction it is shown that sizes of structural elements in the fabricated samples are about 40 nm. The probe technique is used for measurement of electric conductivity and Seebeck coefficient. The stationary absolute method is used for measurement of thermal conductivity. Thermoelectric figure of merit is defined by measured values of kinetic coefficients in the temperatures range of 77 – 800 K. It was demonstrated, that electric conductivity, Seebeck coefficient and the power factor do not depend practically on a way of solid solution preparation. Thermal conductivity of samples pressed from nanoparticles has appeared to be higher, than of samples, obtained by direct fusion; i.e. in this case nanostructuring has not led to increase of thermoelectric figure of merit. The conclusion is drawn, that polycrystalline semiconductor Mg2Si0.3Sn0.7 can be used as a p-branch for a thermoelectric generator though nanostructuring has not led to the figure of

  7. Spectroscopic characterization of a single dangling bond on a bare Si(100)- c ( 4 × 2 ) surface for n - and p -type doping

    KAUST Repository

    Mantega, M.

    2012-07-19

    We investigate the charging state of an isolated single dangling bond formed on an unpassivated Si(100) surface with c(4×2) reconstruction, by comparing scanning tunneling microscopy and spectroscopy analysis with density functional theory calculations. The dangling bond is created by placing a single hydrogen atom on the bare surface with the tip of a scanning tunneling microscope. The H atom passivates one of the dimer dangling bonds responsible for the surface one-dimensional electronic structure. This leaves a second dangling at the reacted surface dimer which breaks the surface periodicity. We consider two possible H adsorption configurations for both the neutral and the doped situation (n- and p-type). In the case of n-doping we find that the single dangling bond state is doubly occupied and the most stable configuration is that with H bonded to the bottom Si atom of the surface dimer. In the case of p-doping the dangling bond is instead empty and the configuration with the H attached to the top atom of the dimer is the most stable. Importantly the two configurations have different scattering properties and phase shift fingerprints. This might open up interesting perspectives for fabricating a switching device by tuning the doping level or by locally charging the single dangling bond state. © 2012 American Physical Society.

  8. Microstructural characterization and current conduction mechanisms of front-side contact of n-type crystalline Si solar cells with Ag/Al pastes

    Science.gov (United States)

    Liang, L.; Li, Z. G.; Cheng, L. K.; Takeda, N.; Carroll, A. F.

    2015-06-01

    Recently, high efficiency n-type crystalline Si cells made with the screen printed Ag/Al metallization have received considerable attention. We report here our microstructural investigations of the critical interfacial region between the front-side contact and the Si wafer of n-type cells fired under progressively higher temperatures. Our study revealed that the key characteristic microstructures of the interfacial region changed from one with a large fraction of residual SiNx, to one consisting of a thin glass layer with nano-Ag colloids, and finally to one decorated with Ag and Ag/Al crystallites attached to the emitter surface for cells with under-, optimally-, and over-fired conditions, respectively. We did not find any Al-Si eutectic layer on the emitter surface that would support a silicon dissolution and re-growth mechanism, which is operative in the back surface field formation process for the Al back contact of p-type industrial solar cells. The presence of the SiNx antireflection coating has likely altered the chemistry between Si and Al significantly. The observed microstructures lead us to conclude that the main current conduction mechanism in optimally-fired n-type cells is tunneling through those areas of thin interfacial glass containing nano-Ag colloids. This mechanism is similar to the current conduction model we have proposed previously for optimally-fired p-type crystalline Si solar cells. We believe that the intrusion of Ag/Al (and/or Ag) crystallites into the p+-Si emitter in over-fired cells is one of the major sources of metallization-induced recombination losses, which degrades cell performance.

  9. High-Quality Single Crystalline Ge(111) Growth on Si(111) Substrates by Solid Phase Epitaxy

    Institute of Scientific and Technical Information of China (English)

    SUN Bing; CHANG Hu-Dong; LU Li; LIU Hong-Gang; WU De-Xin

    2012-01-01

    Heterogeneous integration of crystalline Ge layers on cleaned and H-terminated Si(111) substrates are demonstrated by employing a combination of e-beam evaporation and solid phase epitaxy techniques. High-quality single crystalline Ge(111) layers on Si(111) substrates with a smooth Ge surface and an abrupt interface between Ge and Si are obtained.An XRD rocking curve scan of the Ge(111) diffraction peak shovs a FWHM of only 260 arcsec for a 50-nm-thick Ge layer annealed at 600℃ with a ramp-up rate of 20℃/s and a holding time of 1 min. The AFM images exhibit that the rms surface roughness of all the crystalline Ge layers are less than 2.1 nm.

  10. Combustion synthesis of Si-related crystalline nanostructures

    Science.gov (United States)

    Soszyński, Michał; Łabędź, Olga; Huczko, Andrzej

    2014-09-01

    The unique self propagated high temperature synthesis (SHS technique) allows for an effective, energetically autothermal formation of different novel materials, including nanostructural, non-stoichiometric and bearing new phases, this all during fast reaction in a mixture strong oxidant/strong reducer. This all results from specific characteristics of the process: high temperatures/pressures, short reaction times and very fast quenching of gaseous reaction products during their expansion from combustion zone towards cooling zone. Silicon carbide as so-called refractory special ceramics possesses very special physical and chemical properties, especially in case of its nanostructural morphology this including 1-D (nanofibres). The results of the exploratory runs regarding the application of SiCNFs as polymer modifier, super-hard ceramic composites (SiCNFs/nano-SiC mixtures) or electron emitter are very encouraging indeed. The results will provide the information regarding the possible reaction channels. The fundamental parametric studies concentrate on the relationship between many process variables and SiCNFs formation efficiency. Relatively costly commercial reactants (Aldrich) were previously used which are now replaced by waste Tarflen (as oxidant). Their cost is a few orders of magnitude (!) lower. It will drastically reduce the costs of SiCNFs production since the operational costs of energetically autogenic SSW technique are obviously very low.

  11. Si-C Linked Organic Monolayers on Crystalline Silicon Surfaces as Alternative Gate Insulators

    NARCIS (Netherlands)

    Faber, Erik J.; Smet, de Louis C.P.M.; Olthuis, Wouter; Zuilhof, Han; Sudhölter, Ernst J.R.; Bergveld, Piet; Berg, van den Albert

    2005-01-01

    Herein, the influence of silicon surface modification via Si-CnH2n+1 (n=10,12,16,22) monolayer-based devices on p-type (100) and n-type (100) silicon is studied by forming MIS (metal–insulator–semiconductor) diodes using a mercury probe. From current density–voltage (J–V) and capacitance–voltage (C–

  12. Crystalline silicon photovoltaics via low-temperature TiO 2/Si and PEDOT/Si heterojunctions

    Science.gov (United States)

    Nagamatsu, Ken Alfred

    The most important goals in developing solar cell technology are to achieve high power conversion efficiencies and lower costs of manufacturing. Solar cells based on crystalline silicon currently dominate the market because they can achieve high efficiency. However, conventional p-n junction solar cells require high-temperature diffusions of dopants, and conventional heterojunction cells based on amorphous silicon require plasma-enhanced deposition, both of which can add manufacturing costs. This dissertation investigates an alternative approach, which is to form crystalline-silicon-based solar cells using heterojunctions with materials that are easily deposited at low temperatures and without plasma enhancement, such as organic semiconductors and metal oxides. We demonstrate a heterojunction between the organic polymer, poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT), and crystalline silicon, which acts as a hole-selective contact and an alternative to a diffused p-n junction. We also present the use of a heterojunction between titanium dioxide and crystalline silicon as a passivating electron-selective contact. The Si/TiO2 heterojunction is demonstrated for the first time as a back-surface field in a crystalline silicon solar cell, and is incorporated into a PEDOT/Si device. The resulting PEDOT/Si/TiO2 solar cell represents an alternative to conventional silicon solar cells that rely on thermally-diffused junctions or plasma-deposited heterojunctions. Finally, we investigate the merits of using conductive networks of silver nanowires to enhance the photovoltaic performance of PEDOT/Si solar cells. The investigation of these materials and devices contributes to the growing body of work regarding crystalline silicon solar cells made with selective contacts.

  13. Irradiation induced improvement in crystallinity of epitaxially grown Ag thin films on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Takahiro, Katsumi; Nagata, Shinji; Yamaguchi, Sadae [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    1997-03-01

    We report the improvement in crystallinity of epitaxially grown Ag films on Si(100) substrates with ion irradiation. The irradiation of 0.5 MeV Si ions to 2x10{sup 16}/cm{sup 2} at 200degC, for example, reduces the channeling minimum yield from 60% to 6% at Ag surface. The improvement originates from the decrease of mosaic spread in the Ag thin film. In our experiments, ion energy, ion species and irradiation temperature have been varied. The better crystallinity is obtained as the higher concentration of defect is generated. The mechanism involved in the irradiation induced improvement is discussed. (author)

  14. Crystalline SiCO: Implication on structure and thermochemistry of ternary silicon oxycarbide ceramics

    Science.gov (United States)

    Bodiford, Nelli

    The need for innovative refractory materials---materials that can sustain extreme temperatures---has been constantly growing within the modern industries. Basic requirements for usage at ultra-high-temperatures have been considered such as high melting point, high structural strength, exceptional resistance to oxidation, zero or almost zero creep. Monolithic ceramics alone cannot provide these properties, therefore, composite materials are sought to fulfill the demand. For example, silicon nitride and silicon carbide based ceramics have long been leading contenders for structural use in gas turbine engines. In the course of this work we are investigating amorphous SiCO formed via polymer-to-ceramic route. Previously a considerable amount of work has been done on structures of stoichiometric amorphous SiCO and a "perfect" random network was obtained (experimentally as well as supported by computational work) up to the phase content of 33 mol-% SiC. By "perfect" one assumes to have four fold coordinated Si atoms bonded to C and O; C atoms bond to Si atoms only and O is two fold connected to Si. Beyond 33 mol-% SiC within SiCO phase the structural imperfections and defects start to develop. Aside from the stoichiometric form of SiCO, the polymer-to-ceramic route allows for the incorporation of high molar amounts of carbon to create SiCO ceramic with excess carbon. The incorporation of carbon into silica glass improves high-temperature mechanical properties and increases resistance to crystallization of the amorphous material. The amount of 'free carbon' can be controlled through the choice of precursors used during synthesis. There were no ternary crystalline phases of SiCO observed. However, in systems such as MgO-SiO2, Na2O-Al2O 3-SiO2 there are ternary crystalline compounds (MgSiO 3, Mg2SiO4, NaAlSiO4, NaAlSi3 O8) that are of a greater energetic stability than glasses of the same composition. What makes the SiCO system different? In the approach proposed in this

  15. Thermoluminescent analysis of amorphous and crystalline SiO{sub 2} exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Villa S, G.; Mendoza A, D.; Gonzalez, P.R.; Espinosa P, M.E. [ININ, 52750 Ocoyoacac, EStado de Mexico (Mexico)

    2006-07-01

    Silicon oxide (SiO{sub 2}) has been used in electroluminescence and thermoluminescence (TL) devices. However, its emission mechanism have not been yet clearly explained. The crystalline and amorphous SiO{sub 2} luminescent analyses are important to compare their behaviour in order to understand the emission mechanism. For this reason, the present work has the goal to show and compare the thermoluminescent analysis of obsidian and quartz: amorphous and crystalline SiO{sub 2}, respectively. According to the results, quartz shows two TL peaks located at 145 and 215 C, while obsidian shows three TL peaks at 125, 195 and 298 C. Moreover, TL intensity was higher for quartz than obsidian samples. Nonetheless, both signals shown a linear correlation in the interval of radiation dose from 50 to 400 Gy. These facts suggest that the atomic array plays a very important role in the thermoluminescent behaviour of the SiO{sub 2} materials. (Author)

  16. Determination of bandgap states in p-type In0.49Ga0.51P grown on SiGe/Si and GaAs by deep level optical spectroscopy and deep level transient spectroscopy

    Science.gov (United States)

    González, M.; Carlin, A. M.; Dohrman, C. L.; Fitzgerald, E. A.; Ringel, S. A.

    2011-03-01

    The presence and properties of traps in p-type In0.49Ga0.51P grown on low dislocation density, metamorphic Ge/SiGe/Si substrates and GaAs substrates were determined using deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS) leading to the quantification of trap behavior throughout the entire 1.9 eV bandgap of the In0.49Ga0.51P material as a function of substrate. Thermal emission-based DLTS revealed a single hole trap at Ev + 0.71 eV for growth on both lattice matched and mismatched substrates with similar concentrations. Complementary, optical emission-based DLOS measurements detected bandgap states at Ev + 1.18 eV, Ev + 1.36 eV, and Ev + 1.78 eV for p-type In0.49Ga0.51P grown on both substrate types. The total concentration of the DLOS-detected states was found to comprise approximately 80% of the entire trap concentration in p-type In0.49Ga0.51P bandgap. This relatively high concentration of above midgap levels may be of great significance for minority carrier devices that utilize p-type In0.49Ga0.51P (such as high efficiency III-V multijunction solar cells) since their position in the bandgap and high concentrations suggest that strong minority carrier electron trapping behavior can be expected. The primary effect of substituting the GaAs substrate by Ge/SiGe/Si is to increase the concentration of these states by a factor of 2-3, with no additional levels detected due to the replacement by the Si-based substrates, indicating that all detected traps are native to the epitaxial In0.49Ga0.51P material (regardless of the substrate), but whose concentrations appear to be influenced by dislocation density.

  17. Fabrication of p-type CuO thin films using chemical bath deposition technique and their solar cell applications with Si nanowires

    Science.gov (United States)

    Akgul, Funda Aksoy; Akgul, Guvenc

    2017-02-01

    Recently, CuO has attracted much interest owing to its suitable material properties, inexpensive fabrication cost and potential applications for optoelectronic devices. In this study, CuO thin films were deposited on glass substrates using chemical bath deposition technique and post-deposition annealing effect on the properties of the prepared samples were investigated. p-n heterojunction solar cells were then constructed by coating of p-type CuO films onto the vertically well-aligned n-type Si nanowires synthesized through MACE method. Photovoltaic performance of the fabricated devices were determined with current-voltage (I-V) measurements under AM 1.5 G illumination. The optimal short-circuit current density, open-circuit voltage, fill factor and power conversion efficiency were found to be 3.2 mA/cm-2, 337 mV, 37.9 and 0.45%, respectively. The observed performance clearly indicates that the investigated device structure could be a promising candidate for high-performance low-cost new-generation photovoltaic diodes.

  18. Eu3+ DOPED SILICA FILM AS LUMINESCENT DOWN-SHIFTING LAYER FOR CRYSTALLINE Si SOLAR CELLS

    OpenAIRE

    ZUJUN CHENG; LIKUN PAN; FENFANG SU; MEILING CAO; ZHUO SUN

    2009-01-01

    Eu3+ doped silica films have been prepared by sol–gel method and employed as luminescent down-shifting layer on the front side of a crystalline Si solar cell to improve their conversion efficiency. Measurements under standard test conditions (AM1.5, 100 mW/cm2) show the conversion efficiency of Si solar cell with silica film containing Eu3+ is improved 9.5% maximally as compared to the Si solar cell with pure silica film. However, high Eu3+ concentration is not encouraged because concentratio...

  19. Semiconducting graphene nanoribbon retains band gap on amorphous or crystalline SiO_2

    OpenAIRE

    Hossain, M. Zubaer

    2011-01-01

    Electronic properties of a semiconducting armchair graphene nanoribbon on SiO_2 are examined using first-principles calculations and taking into account the van der Waals interaction. Unlike semiconducting carbon nanotubes, which exhibit variations in band gap on SiO_2, the nanoribbon is found to retain its band gap on SiO_2, regardless of the separation distance or the dielectric’s surface type—crystalline or amorphous. The interfacial interaction leads to electron-transfer from the nanor...

  20. Computation of Heterojunction Parameters at Low Temperatures in Heterojunctions Comprised of n-Type β-FeSi2 Thin Films and p-Type Si(111 Substrates Grown by Radio Frequency Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Phongsaphak Sittimart

    2017-01-01

    Full Text Available In this study, n-type β-FeSi2/p-type Si heterojunctions, inside which n-type β-FeSi2 films were epitaxially grown on p-type Si(111 substrates, were created using radio frequency magnetron sputtering at a substrate temperature of 560°C and Ar pressure of 2.66×10-1 Pa. The heterojunctions were measured for forward and reverse dark current density-voltage curves as a function of temperature ranging from 300 down to 20 K for computation of heterojunction parameters using the thermionic emission (TE theory and Cheung’s and Norde’s methods. Computation using the TE theory showed that the values of ideality factor (n were 1.71 at 300 K and 16.83 at 20 K, while the barrier height (ϕb values were 0.59 eV at 300 K and 0.06 eV at 20 K. Both of the n and ϕb values computed using the TE theory were in agreement with those computed using Cheung’s and Norde’s methods. The values of series resistance (Rs computed at 300 K and 20 K by Norde’s method were 10.93 Ω and 0.15 MΩ, respectively, which agreed with the Rs values found through computation by Cheung’s method. The dramatic increment of Rs value at low temperatures was likely attributable to the increment of n value at low temperatures.

  1. Large-scale synthesis of ultralong single-crystalline SiC nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jianjun [Center of Materials Engineering, Zhejiang Sci-Tech University, Xiasha College Park, 310018 Hangzhou (China); The Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Zhejiang Sci-Tech University, Ministry of Education, 310018 Hangzhou (China); Shi, Qiang [The Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Zhejiang Sci-Tech University, Ministry of Education, 310018 Hangzhou (China); Gao, Linhui; Zhu, Hongliang [Center of Materials Engineering, Zhejiang Sci-Tech University, Xiasha College Park, 310018 Hangzhou (China)

    2010-11-15

    A large number of cotton-like ultralong {beta}-SiC nanowires (NWs) were successfully synthesized via a simple catalyst-free carbothermal reduction approach using a carbonaceous silica xerogel as raw materials. The length of the NWs is in the millimeter range and the diameter of the NWs is about 130 nm. The ultralong NWs are bamboo-like single-crystalline {beta}-SiC NWs. A vapor-solid mechanism was proposed to elucidate the growth process of the NWs, and the large length and high-yield of the SiC NWs may be ascribed to the stable release of SiO and CO gases form the carbonaceous silica xerogel. The simple method provides a promising candidate for industrial fabrication of {beta}-SiC NWs. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Fourier transform infrared spectroscopic estimation of crystallinity in SiO2 based rocks

    Indian Academy of Sciences (India)

    Bhaskar J Saikia; G Parthasarathy; N C Sarmah

    2008-10-01

    We present here optical properties and crystallinity index of quartz (SiO2) in natural rocks samples from the Mikir and Khasi hills, Assam, India. Infrared spectroscopy has been used to study the structure of quartz in rock samples and estimate the mining quality of quartz mineral, which is substantiated by calculating the crystallinity index. Systematic investigations of structure have been carried out in between 10 m (1000 cm–1) and 20 m (500 cm–1) bands of silicates. Investigation is based on the assignment of infrared bands to certain structural groups of SiO4 tetrahedra. The crystallinity of samples has been ascertained by comparing the ratio of intensity of the characteristic peak at 778 and 695 cm–1 with the corresponding ratio for a standard sample. The crystallinity parameter is calculated by using a standard procedure which can be used to estimate the distribution of quartz in various rocks for mining purpose. The infrared spectroscopic investigation is found to be an ideal tool for structure elucidation and for estimating quartz crystallinity of the natural samples.

  3. Si-C linked organic monolayers on crystalline silicon surfaces as alternative gate insulators

    NARCIS (Netherlands)

    Faber, E.J.; Smet, de L.C.P.M.; Olthuis, W.; Zuilhof, H.; Sudhölter, E.J.R.; Bergveld, P.; Berg, van den A.

    2005-01-01

    Herein, the influence of silicon surface modification via SiCnH2n+1 (n=10,12,16,22) monolayer-based devices on p-type 100 and n-type 100 silicon is studied by forming MIS (metal-insulator-semiconductor) diodes using a mercury probe. From current density-voltage (J-V) and capacitance-voltage (C-V) me

  4. Si-C linked organic monolayers on crystalline silicon surfaces as alternative gate insulators

    NARCIS (Netherlands)

    Faber, E.J.; Smet, de L.C.P.M.; Olthuis, W.; Zuilhof, H.; Sudhölter, E.J.R.; Bergveld, P.; Berg, van den A.

    2005-01-01

    Herein, the influence of silicon surface modification via SiCnH2n+1 (n=10,12,16,22) monolayer-based devices on p-type 100 and n-type 100 silicon is studied by forming MIS (metal-insulator-semiconductor) diodes using a mercury probe. From current density-voltage (J-V) and capacitance-voltage (C-V)

  5. Random Si nanopillars for broadband antireflection in crystalline silicon solar cells

    Science.gov (United States)

    Choi, Junhee; Lee, Taek Sung; Jeong, Doo Seok; Lee, Wook Seong; Kim, Won Mok; Lee, Kyeong-Seok; Kim, Donghwan; Kim, Inho

    2016-09-01

    We demonstrate the fabrication of shallow Si nanopillar structures at a submicron scale which provides broadband antireflection for crystalline Si (c-Si) solar cells in the wavelength range of 350 nm-1100 nm. The Si random nanopillars were made by reactive ion etch (RIE) processing with thermally dewetted Sn metals as an etch mask. The diameters and coverages of the Si nanopillars were adjusted in a wide range of the nanoscale to microscale by varying the nominal thickness of the Sn metals and subsequent annealing temperatures. The height of the nanopillars was controlled by the RIE process time. The optimal size of the nanopillars, which are 340 nm in diameter and 150 nm in height, leads to the lowest average reflectance of 3.6%. We showed that the power conversion efficiency of the c-Si solar cells could be enhanced with the incorporation of optimally designed Si random nanopillars from 13.3% to 14.0%. The fabrication scheme of the Si nanostructures we propose in this study would be a cost-effective and promising light trapping technique for efficient c-Si solar cells.

  6. Characterisation of Si-crystalline PV modules by artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Almonacid, F.; Rus, C.; Hontoria, L.; Fuentes, M.; Nofuentes, G. [Grupo Investigacion y Desarrollo en Energia Solar y Automatica, Dpto. de Ingenieria Electronica y Automatica, E.P.S. Jaen, Universidad de Jaen, Despacho B-110-AB, C vertical stroke Alfoso X El Sabio n 28, 23071 Linares (Jaen) (Spain)

    2009-04-15

    In the photovoltaic field, manufacturers provide ratings for PV modules for conditions referred to as standard test conditions (STC). However, these conditions rarely occur outdoors, so the usefulness and applicability of the indoors' characterisation in standard test conditions of PV modules are a controversial issue. Therefore, to carry out photovoltaic engineering well, a suitable characterisation of PV module electrical behaviour (V-I curves) is necessary. The IDEA Research Group from Jaen University has developed a method based on artificial neural networks (ANNs) to electrical characterisation of PV modules. An ANN has been developed which is able to generate V-I curves of Si-crystalline PV modules for any irradiance and module cell temperature. The results show that the proposed ANN introduces a good accurate prediction for Si-crystalline PV modules' performance when compared with the measured values. (author)

  7. AN ABNORMAL BEHAVIOR OF NANO—CRYSTALLINE IN SiO2 SUBSTRATE

    Institute of Scientific and Technical Information of China (English)

    张桂林; 刘文宏; 等

    1994-01-01

    Temperature dependence of the hyperfine field of Fe nonocrystalline in SiO2 matrix prepared by using an ion implantation and subsequent heat treatment can not be described by a formula for the isolated Fe nanocrystalline.The large stresses or chemical bond force to which interface atoms may be subjected lead to increase effective anisotropic constant.In addition a little concentration of oxygen atoms contained in the crystalline might enhance the byperfine field.

  8. Advanced fabrication of single-crystalline silver nanopillar on SiO{sub 2} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Tomohiro, E-mail: tomohiro-mori@wakayama-kg.jp, E-mail: kenzo@eng.kagawa-u.ac.jp [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, Hayashicho 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Industrial Technology Center of Wakayama Prefecture, Ogura 60, Wakayama 649-6261 (Japan); Tanaka, Yasuhiro; Suzaki, Yoshifumi; Yamaguchi, Kenzo, E-mail: tomohiro-mori@wakayama-kg.jp, E-mail: kenzo@eng.kagawa-u.ac.jp [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, Hayashicho 2217-20, Takamatsu, Kagawa 761-0396 (Japan)

    2016-01-25

    Nanoscale crystallographic textures have received very little attention in research on surface plasmons using metallic nanostructures. A single-crystalline metallic nanostructure with a controlled crystallographic texture is expected to reduce optical losses. We elucidated the grain growth mechanism in silver thin films deposited on a highly transparent SiO{sub 2} substrate by electron backscatter diffraction methods with nanoscale resolution. At higher substrate temperatures, the grain growth was facilitated but the preferred orientation was not achieved. Moreover, we fabricated a single-crystalline silver nanopillar in a (111)-oriented large growing grain, which was controlled by varying the substrate temperature during film deposition by focused ion-beam milling. Furthermore, the light intensity of the scattering spectrum was measured for a single-crystalline silver nanopillar (undersurface diameter: 200 nm) for which surface plasmon resonance was observed. The single-crystalline silver nanopillar exhibits a stronger and sharper spectrum than the polycrystalline silver nanopillar. These results can be applied to the direct fabrication of a single-crystalline silver nanopillar using only physical processing.

  9. Heterojunction Diodes and Solar Cells Fabricated by Sputtering of GaAs on Single Crystalline Si

    Directory of Open Access Journals (Sweden)

    Santiago Silvestre

    2015-04-01

    Full Text Available This work reports fabrication details of heterojunction diodes and solar cells obtained by sputter deposition of amorphous GaAs on p-doped single crystalline Si. The effects of two additional process steps were investigated: A hydrofluoric acid (HF etching treatment of the Si substrate prior to the GaAs sputter deposition and a subsequent annealing treatment of the complete layered system. A transmission electron microscopy (TEM exploration of the interface reveals the formation of a few nanometer thick SiO2 interface layer and some crystallinity degree of the GaAs layer close to the interface. It was shown that an additional HF etching treatment of the Si substrate improves the short circuit current and degrades the open circuit voltage of the solar cells. Furthermore, an additional thermal annealing step was performed on some selected samples before and after the deposition of an indium tin oxide (ITO film on top of the a-GaAs layer. It was found that the occurrence of surface related defects is reduced in case of a heat treatment performed after the deposition of the ITO layer, which also results in a reduction of the dark saturation current density and resistive losses.

  10. Butterfly-shaped distribution of SiNx precipitates in multi-crystalline Si for solar cells

    Science.gov (United States)

    Li, Jianyong; Prakash, Ronit Roneel; Jiptner, Karolin; Chen, Jun; Miyamura, Yoshiji; Harada, Hirofumi; Kakimoto, Koichi; Ogura, Atsushi; Sekiguchi, Takashi

    2013-08-01

    This paper concerns the precipitation mechanism of SiNx impurities in multi-crystalline silicon grown with a directional solidification system. A butterfly-shaped precipitate region was found across the middle part of ingot. These precipitates showed filament-like and fiber-like shapes of several micrometers in diameter and up to several millimeters in length. These two types of precipitates exist in different areas, forming three distribution zones in the butterfly region. The precipitate growth periodically stopped at the last stage of the butterfly formation. A non-uniform convection flow model was proposed to explain the precipitation behavior at the butterfly.

  11. Very low surface recombination velocity on p-type c-Si by high-rate plasma-deposited aluminum oxide

    Science.gov (United States)

    Saint-Cast, Pierre; Kania, Daniel; Hofmann, Marc; Benick, Jan; Rentsch, Jochen; Preu, Ralf

    2009-10-01

    Aluminum oxide layers can provide excellent passivation for lowly and highly doped p-type silicon surfaces. Fixed negative charges induce an accumulation layer at the p-type silicon interface, resulting in very effective field-effect passivation. This paper presents highly negatively charged (Qox=-2.1×1012 cm-2) aluminum oxide layers produced using an inline plasma-enhanced chemical vapor deposition system, leading to very low effective recombination velocities (˜10 cm s-1) on low-resistivity p-type substrates. A minimum static deposition rate (100 nm min-1) at least one order of magnitude higher than atomic layer deposition was achieved on a large carrier surfaces (˜1 m2) without significantly reducing the resultant passivation quality.

  12. Crystallization-mediated amorphous CuxO (x = 1, 2)/crystalline CuI p-p type heterojunctions with visible light enhanced and ultraviolet light restrained photocatalytic dye degradation performance

    Science.gov (United States)

    Wang, Hongli; Cai, Yun; Zhou, Jian; Fang, Jun; Yang, Yang

    2017-04-01

    We report simple and cost-effective fabrication of amorphous CuxO (x = 1, 2)/crystalline CuI p-p type heterojunctions based on crystallization-mediated approaches including antisolvent crystallization and crystal reconstruction. Starting from CuI acetonitrile solution, large crystals in commercial CuI can be easily converted to aggregates consisting of small particles by the crystallization processes while the spontaneous oxidation of CuI by atmospheric/dissolved oxygen can induce the formation of trace CuxO on CuI surface. As a proof of concept, the as-fabricated CuxO/CuI heterojunctions exhibit effective photocatalytic activity towards the degradation of methyl blue and other organic pollutants under visible light irradiation, although the wide band-gap semiconductor CuI is insensible to visible light. Unexpectedly, the CuxO/CuI heterojunctions exhibit restrained photocatalytic activity when ultraviolet light is applied in addition to the visible. It is suggested that the CuxO/CuI interface can enhance the spatial separation of the electron-hole pairs with the excitation of CuxO under visible light and prolong the lifetime of photogenerated charges with high redox ability. The present work represents a critically important step in advancing the crystallization technique for potential mass production of semiconductor heterojunctions in a mild manner.

  13. Crystalline and liquid Si3 N4 characterization by first-principles molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Castellani Niccoló

    2011-05-01

    Full Text Available Silicon nitride (Si3 N4 has a wide range of engineering applications where its mechanical and electronic properties can be effectively exploited. In particular, in the microelectronics field, the amorphous silicon nitride films are widely used as charge storage layer in metal-alumina-nitrideoxide nonvolatile memory devices. Atomic structure of amorphous silicon nitride is characterized by an high concentration of traps that control the electric behavior of the final device by the trappingde-trapping mechanism of the electrical charge occurring in its traps. In order to have a deep understanding of the material properties and, in particular, the nature of the electrical active traps a detailed numerical characterization of the crystalline and liquid phases is mandatory. For these reasons first-principles molecular dynamics simulations are extensively employed to simulate the crystalline Si3 N4 in its crystalline and liquid phases. Good agreement with experimental results is obtained in terms of density and formation entalpy. Detailed characterization of c-Si3 N4 electronic properties is performed in terms of band structure and band gap. Then constant temperature and constant volume first-principles molecular dynamics is used to disorder a stoichiometric sample of Si3 N4 . Extensive molecular dynamics simulations are performed to obtain a reliable liquid sample whose atomic structure does not depend on the starting atomic configuration. Detailed characterization of the atomic structure is achieved in terms of radial distribution functions and total structure factor.

  14. Piezoresistance in p-type silicon revisited

    DEFF Research Database (Denmark)

    Richter, Jacob; Pedersen, Jesper; Brandbyge, Mads;

    2008-01-01

    We calculate the shear piezocoefficient pi44 in p-type Si with a 6×6 k·p Hamiltonian model using the Boltzmann transport equation in the relaxation-time approximation. Furthermore, we fabricate and characterize p-type silicon piezoresistors embedded in a (001) silicon substrate. We find that the ...

  15. Effect on thickness of Al layer in poly-crystalline Si thin films using aluminum(Al) induced crystallization method.

    Science.gov (United States)

    Jeong, Chaehwan; Na, Hyeon Sik; Lee, Suk Ho

    2011-02-01

    The polycrystalline silicon (poly-Si) thin films were prepared by aluminum induced crystallization. Aluminum (Al) and amorphous silicon (a-Si) layers were deposited using DC sputtering and plasma enhanced chemical vapor deposition method, respectively. For the whole process Al properties of bi-layers can be one of the important factors. In this paper we investigated the structural and electrical properties of poly-crystalline Si thin films with a variation of Al thickness through simple annealing process. All samples showed the polycrystalline phase corresponding to (111), (311) and (400) orientation. Process time, defined as the time required to reach 95% of crystalline fraction, was within 60 min and Al(200 nm)/a-Si(400 nm) structure of bi-layer showed the fast response for the poly-Si films. The conditions with a variation of Al thickness were executed in preparing the continuous poly-Si films for solar cell application.

  16. Crystalline structures and misfit strain inside Er silicide nanocrystals self-assembled on Si(001) substrates.

    Science.gov (United States)

    Ding, Tao; Wu, Yueqin; Song, Junqiang; Li, Juan; Huang, Han; Zou, Jin; Cai, Qun

    2011-06-17

    The morphology and crystalline structure of Er silicide nanocrystals self-assembled on the Si(001) substrate were investigated using scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). It was found that the nanowires and nanorods formed at 630 °C has dominant hexagonal AlB(2)-type structure, while inside the nanoislands self-organized at 800 °C the tetragonal ThSi(2)-type structure is prevalent. The lattice analysis via cross-sectional high-resolution TEM demonstrated that internal misfit strain plays an important role in controlling the growth of nanocrystals. With the relaxation of strain, the nanoislands could evolve from a pyramid-like shape into a truncated-hut-like shape.

  17. Effects of damage build-up in range profiles in crystalline Si; Molecular dynamics simulations

    CERN Document Server

    Peltola, J; Keinonen, J

    2002-01-01

    Molecular dynamics (MD) has been successful in predicting range profiles for ions implanted into crystalline materials in the fluence regime where it can be approximated that changes in the sample structure do not affect the profiles. Many experimental distributions are, however, strongly fluence-dependent due to the amorphization of the crystalline material. This has so far been taken into account only in some binary-collision-approximation calculations with a damage build-up model that depends on the probability of amorphization occurring at a certain depth. We present here a fast MD model for predicting range profiles of ions in crystalline Si. The model includes cumulative damage build-up, where the amorphization states of the material are taken from MD simulations of cascade damage. The method can be used to predict profiles for any material. We used silicon because of the large amount of experimental data available. No free parameters were used. Comparison of results with the results of a wide range of ...

  18. Modal Contributions to Heat Conduction across Crystalline and Amorphous Si/Ge Interfaces

    Science.gov (United States)

    Gordiz, Kiarash; Henry, Asegun

    Until now, our entire understanding of interfacial heat transfer has been based on the phonon gas model and Landauer formalism. Based on this framework, it is difficult to offer any intuition on heat transfer between two solid materials if one side of the interface is an amorphous structure. Here, using the interface conductance modal analysis (ICMA) method, we investigate the modal contributions to thermal interface conductance (TIC) through crystalline (c) and amorphous (a) Si/Ge interfaces. It is revealed that around 15% of the conductance through the cSi/cGe interface arises from less than 0.1% of the modes of vibration in the structure that exist between 12-13THz and because of their large eigenvectors around the interface are classified as interfacial modes. Correlation maps show that these interfacial modes exhibit strong correlations with all the other modes. The physics behind this strong coupling ability is studied by calculating the mode-level harmonic and anharmonic energy distribution among all the atoms in the system. It is found that these interfacial modes are enabled by the large degree of anharmonicity near the interface, which is higher than the bulk and ultimately allows this small group of modes to couple to other modes of vibration. In addition, unlike the cSi/cGe, correlation maps for aSi/cGe, cSi/aGe, and aSi/aGe interfaces show that the majority of contributions to TIC arise from auto-correlations instead of cross-correlations. The provided analysis sheds light on the nature of localized vibrations at interfaces and can be enlightening for other investigations of localization.

  19. Iron-Treated NiO as a Highly Transparent p-Type Protection Layer for Efficient Si-Based Photoanodes

    DEFF Research Database (Denmark)

    Mei, Bastian Timo; Permyakova, Anastasia Aleksandrovna; Frydendal, Rasmus;

    2014-01-01

    Sputter deposition of 50 nm thick NiO films on p+–n-Si and subsequent treatment in an Fe-containing electrolyte yielded highly transparent photoanodes capable of water oxidation (OER) in alkaline media (1 M KOH) with high efficiency and stability. The Fe treatment of NiO thin films enabled Si...... stability for more than 2000 days of continuous operation. Therefore, protection by Fe-treated NiO films is a promising strategy to achieve highly efficient and stable photoanodes....

  20. Wetting and reaction characteristics of crystalline and amorphous SiO2 derived rice-husk ash and SiO2/SiC substrates with Al-Si-Mg alloys

    Science.gov (United States)

    Bahrami, A.; Pech-Canul, M. I.; Gutiérrez, C. A.; Soltani, N.

    2015-12-01

    A study of the wetting behavior of three substrate types (SiC, SiO2-derived RHA and SiC/SiO2-derived RHA) by two Al-Si-Mg alloys using the sessile drop method has been conducted, using amorphous and crystalline SiO2 in the experiment. Mostly, there is a transition from non-wetting to wetting contact angles, being the lowest θ values achieved with the alloy of high Mg content in contact with amorphous SiO2. The observed wetting behavior is attributed to the deposited Mg on the substrates. A strong diffusion of Si from the SiC/Amorphous RHA substrate into the metal drop explains the free Si segregated at the drop/substrate interface and drop surface. Although incorporation of both SiO2-derived RHA structures into the SiC powder compact substrates increases the contact angles in comparison with the SiC substrate alone, the still observed acute contact angles in RHA/SiC substrates make them promising for fabrication of composites with high volume fraction of reinforcement by the pressureless infiltration technique. The observed wetting characteristics, with decrease in surface tension and contact angles is explained by surface related phenomena. Based on contact angle changes, drop dimensions and surface tension values, as well as on the interfacial elemental mapping, and XRD analysis of substrates, some wetting and reaction pathways are proposed and discussed.

  1. Improving Crystalline Silicon Solar Cell Efficiency Using Graded-Refractive-Index SiON/ZnO Nanostructures

    OpenAIRE

    Yung-Chun Tu; Shui-Jinn Wang; Chien-Hung Wu; Kow-Ming Chang; Tseng-Hsing Lin; Chien-Hsiung Hung; Jhen-Siang Wu

    2015-01-01

    The fabrication of silicon oxynitride (SiON)/ZnO nanotube (NT) arrays and their application in improving the energy conversion efficiency (η) of crystalline Si-based solar cells (SCs) are reported. The SiON/ZnO NT arrays have a graded-refractive-index that varies from 3.5 (Si) to 1.9~2.0 (Si3N4 and ZnO) to 1.72~1.75 (SiON) to 1 (air). Experimental results show that the use of 0.4 μm long ZnO NT arrays coated with a 150 nm thick SiON film increases Δη/η by 39.2% under AM 1.5 G (100 mW/cm2) ill...

  2. Photocatalytic performance of the SiO2 sphere/ n-type TiO2/ p-type CuBiS2 composite catalysts coated with different contents of Ag nanoparticles under ultraviolet and visible light irradiations

    Science.gov (United States)

    Abdullah, Hairus; Kuo, Dong-Hau

    2016-08-01

    Photocatalytic performance of the SiO2 sphere/ n-type TiO2/ p-type CuBiS2 composite catalysts with different contents of silver nanoparticles (abbreviated as SiO2/ n-TiO2/ p-CuBiS2/Ag) toward the photodegradation of Acid Black 1 ( AB 1) dye under ultraviolet (UV) and visible light was investigated. The composite catalyst spheres were analyzed their crystal structure, microstructure, optical absorbance capabilities, and photodegradation capabilities of AB 1 dye. The best photodegradation performances of the 20 mg composite powder with only ~5 mg photoactive catalysts showed the degradation of AB 1 dye in 5 min under UV and 60 min under visible light irradiations. The concept of composite catalyst with numerous nano p- n diodes and its photodegradation mechanism were proposed.

  3. Temperature dependence of pin solar cell parameters with intrinsic layers made of pm-Si:H and low crystalline volume fraction {mu}c-Si:H

    Energy Technology Data Exchange (ETDEWEB)

    Hamadeh, H. [AECS, Physics Department, P.O. Box 6091, Damascus (Syria)

    2010-07-15

    A comparison of the temperature dependence of the IV characteristics parameters of hydrogenated silicon pin solar cells with intrinsic layers made of polymorphous silicon (pm-Si:H) and of {mu}c-Si:H with low crystalline volume fraction has been performed. When using pm-Si:H, higher efficiency and higher filling factors are achieved over a wide temperature range. Diode quality factors of both types of cells show similar temperature dependence. Recombination processes over the whole intrinsic layer dominates the forward current. A change of the cell parameters under illumination is also observed. The transport mechanism of both cells is similar in the temperature range that is important for most applications. Due to its optical and transport properties, pm-Si:H poses a very interesting alternative to {mu}c-Si:H and a-Si:H in the temperature range of normal terrestrial applications. (author)

  4. Study on the SiN_x/Al rear reflectance performance of crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The performance of internal rear surface reflectance of crystalline silicon solar cells is becoming more and more important with the decrease of thickness of the silicon wafers. In this paper PC1D was used to simulate the correlations between the rear surface reflectance and the electrical as well as optical properties of the solar cells. The results showed that the short circuit current, open circuit voltage and quantum efficiency were all enhanced with the increase of the rear reflectance. When the rear reflectance increased from 60% to 100%, the short circuit current, open circuit voltage and maximum output power were improved by about 0.128 A, 0.007 V, and 0.066 W, respectively. The internal quantum efficiency was improved by 39.9%, the external quantum increased by 17.4%, and the efficiency of the solar cells was enhanced by 0.4% at 1100 nm wavelength. The screen-printing was selected to prepare SiNx/Al reflector, and experimental results showed that the SiNx/Al reflector has desired characteristic of internal rear reflectance, with the reflectivity of 15% higher than that of conventional aluminum BSF at 1100 nm wavelength.

  5. Variation in the Optical Properties of the SiC-SiO2 Composite Antireflection Layer in Crystalline Silicon Solar Cells by Annealing

    Science.gov (United States)

    Jannat, Azmira; Li, Zhen Yu; Akhter, M. Shaheer; Yang, O.-Bong

    2017-07-01

    This study showed the effects of annealing on a sol-gel-derived SiC-SiO2 composite antireflection (AR) layer and investigated the optical and photovoltaic properties of crystalline silicon (Si) solar cells. The SiC-SiO2 composite AR coating showed a considerable decrease in reflectance from 7.18% to 3.23% at varying annealing temperatures of 450-800°C. The refractive indices of the SiC-SiO2 composite AR layer were tuned from 2.06 to 2.45 with the increase in annealing temperature. The analysis of the current density-voltage characteristics indicated that the energy conversion efficiencies of the fabricated Si solar cells gradually increased from 16.99% to 17.73% with increasing annealing temperatures of 450-800°C. The annealing of the SiC-SiO2 composite AR layer in Si solar cells was crucial to improving the optical, morphological, and photovoltaic properties.

  6. Transformation from amorphous to nano-crystalline SiC thin films prepared by HWCVD technique without hydrogen dilution

    Indian Academy of Sciences (India)

    F Shariatmadar Tehrani

    2015-09-01

    Silicon carbide (SiC) thin films were deposited on Si(111) by the hot wire chemical vapour deposition (HWCVD) technique using silane (SiH4) and methane (CH4) gases without hydrogen dilution. The effects of SiH4 to CH4 gas flow ratio (R) on the structural properties, chemical composition and photoluminescence (PL) properties of the films deposited at the different gas flow ratios were investigated and compared. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra revealed a structural transition from amorphous SiC to cubic nano-crystalline SiC films with the increase in the gas flow ratio. Raman scattering confirmed the multi-phased nature of the films. Auger electron spectroscopy showed that the carbon incorporation in the film structure was strongly dependent on the gas flow ratio. A similar broad visible room-temperature PL with two peaks was observed for all SiC films. The main PL emission was correlated to the band to band transition in uniform a-SiC phase and the other lower energy emission was related to the confined a-Si : H clusters in a-SiC matrix. SiC nano-crystallites exhibit no significant contribution to the radiative recombination.

  7. Field-Induced Crystalline-to-Amorphous Phase Transformation on the Si Nano-Apex and the Achieving of Highly Reliable Si Nano-Cathodes

    Science.gov (United States)

    Huang, Yifeng; Deng, Zexiang; Wang, Weiliang; Liang, Chaolun; She, Juncong; Deng, Shaozhi; Xu, Ningsheng

    2015-05-01

    Nano-scale vacuum channel transistors possess merits of higher cutoff frequency and greater gain power as compared with the conventional solid-state transistors. The improvement in cathode reliability is one of the major challenges to obtain high performance vacuum channel transistors. We report the experimental findings and the physical insight into the field induced crystalline-to-amorphous phase transformation on the surface of the Si nano-cathode. The crystalline Si tip apex deformed to amorphous structure at a low macroscopic field (0.6~1.65 V/nm) with an ultra-low emission current (1~10 pA). First-principle calculation suggests that the strong electrostatic force exerting on the electrons in the surface lattices would take the account for the field-induced atomic migration that result in an amorphization. The arsenic-dopant in the Si surface lattice would increase the inner stress as well as the electron density, leading to a lower amorphization field. Highly reliable Si nano-cathodes were obtained by employing diamond like carbon coating to enhance the electron emission and thus decrease the surface charge accumulation. The findings are crucial for developing highly reliable Si-based nano-scale vacuum channel transistors and have the significance for future Si nano-electronic devices with narrow separation.

  8. Room temperature deposition of amorphous p-type CuFeO$_2$ and fabrication of CuFeO$_2$/n-Si heterojunction by RF sputtering method

    Indian Academy of Sciences (India)

    TAO ZHU; ZANHONG DENG; XIAODONG FANG; WEIWEI DONG; JINGZHEN SHAO; RUHUA TAO; SHIMAO WANG

    2016-06-01

    Transparent conducting amorphous p-type CuFeO$_2$ (CFO) thin film was prepared by radio-frequency (RF) magnetron sputtering method at room temperature using polycrystalline CuFeO$_2$ target. Amorphous structureof as-deposited film was confirmed by XRD. XPS analysis convinced that the chemical state of Cu$^{+}$ and Fe$^{3+}$ in the film, and the chemical composition of the thin films is close to the stoichiometry of CuFeO$^2$. Surface morphology of the film was analysed by SEM studies. p-type nature and concentration of carriers was investigated by Hall effect measurement. The p–n heterojunction in the structure of Al/n-Si/p-CuFeO$_2$/Al showed good rectifying behaviour with a forward and reverse currents ratio of 555 at 2 V. The turn-on voltage and reverse leakage current values were found to be 0.9 V and 4 $\\mu$A at $−$2 V. Further, the conduction mechanism of forward bias voltage was controlled by thermionic emission (TE) and trap-space charge limited current (TCLC) mechanisms.

  9. Improving Crystalline Silicon Solar Cell Efficiency Using Graded-Refractive-Index SiON/ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    Yung-Chun Tu

    2015-01-01

    Full Text Available The fabrication of silicon oxynitride (SiON/ZnO nanotube (NT arrays and their application in improving the energy conversion efficiency (η of crystalline Si-based solar cells (SCs are reported. The SiON/ZnO NT arrays have a graded-refractive-index that varies from 3.5 (Si to 1.9~2.0 (Si3N4 and ZnO to 1.72~1.75 (SiON to 1 (air. Experimental results show that the use of 0.4 μm long ZnO NT arrays coated with a 150 nm thick SiON film increases Δη/η by 39.2% under AM 1.5 G (100 mW/cm2 illumination as compared to that of regular SCs with a Si3N4/micropyramid surface. This enhancement can be attributed to SiON/ZnO NT arrays effectively releasing surface reflection and minimizing Fresnel loss.

  10. Characteristics and optimization of 4H-SiC MESFET with a novel p-type spacer layer incorporated with a field-plate structure based on improved trap models

    Institute of Scientific and Technical Information of China (English)

    Song Kun; Chai Changchun; Yang Yintang; Jia Hujun; Zhang Xianjun; Chen Bin

    2011-01-01

    A novel structure of 4H-SiC MESFETs is proposed that focuses on surface trap suppression.Characteristics of the device have been investigated based on physical models for material properties and improved trap models.By comparing with the performance of the well-utilized buried-gate incorporated with a field-plate (BG-FP) structure,it is shown that the proposed structure improves device properties in comprehensive aspects.A p-type spacer layer introduced in the channel layer suppresses the surface trap effect and reduces the gate-drain capacitance (Cgd) under a large drain voltage.A p-type spacer layer incorporated with a field-plate improves the electric field distribution on the gate edge while the spacer layer induces less Cgd than a conventional FP.For microwave applications,4H-SiC MESFET for the proposed structure has a larger gate-lag ratio in the saturation region due to better surface trap isolation from the conductive channel.For high power applications,the proposed structure is able to endure higher operating voltage as well.The maximum saturation current density of 460 mA/mm is yielded.Also,the gate-lag ratio under a drain voltage of 20 V is close to 90%.In addition,5% and 17.8% improvements in fT and fmax are obtained compared with a BG-FP MESFET in AC simulation,respectively.Parameters and dimensions of the proposed structure are optimized to make the best of the device for microwave applications and to provide a reference for device design.

  11. Characteristics and optimization of 4H-SiC MESFET with a novel p-type spacer layer incorporated with a field-plate structure based on improved trap models

    Energy Technology Data Exchange (ETDEWEB)

    Song Kun; Chai Changchun; Yang Yintang; Jia Hujun; Zhang Xianjun; Chen Bin, E-mail: sk88205853@sina.com [Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of the Ministry of Education, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2011-07-15

    A novel structure of 4H-SiC MESFETs is proposed that focuses on surface trap suppression. Characteristics of the device have been investigated based on physical models for material properties and improved trap models. By comparing with the performance of the well-utilized buried-gate incorporated with a field-plate (BG-FP) structure, it is shown that the proposed structure improves device properties in comprehensive aspects. A p-type spacer layer introduced in the channel layer suppresses the surface trap effect and reduces the gate-drain capacitance (C{sub gd}) under a large drain voltage. A p-type spacer layer incorporated with a field-plate improves the electric field distribution on the gate edge while the spacer layer induces less C{sub gd} than a conventional FP. For microwave applications, 4H-SiC MESFET for the proposed structure has a larger gate-lag ratio in the saturation region due to better surface trap isolation from the conductive channel. For high power applications, the proposed structure is able to endure higher operating voltage as well. The maximum saturation current density of 460 mA/mm is yielded. Also, the gate-lag ratio under a drain voltage of 20 V is close to 90%. In addition, 5% and 17.8% improvements in f{sub T} and f{sub max} are obtained compared with a BG-FP MESFET in AC simulation, respectively. Parameters and dimensions of the proposed structure are optimized to make the best of the device for microwave applications and to provide a reference for device design. (semiconductor devices)

  12. Scanning transmission electron microscope analysis of amorphous-Si insertion layers prepared by catalytic chemical vapor deposition, causing low surface recombination velocities on crystalline silicon wafers

    OpenAIRE

    2012-01-01

    Microstructures of stacked silicon-nitride/amorphous-silicon/crystalline-silicon (SiN_x/a-Si/c-Si) layers prepared by catalytic chemical vapor deposition were investigated with scanning transmission electron microscopy to clarify the origin of the sensitive dependence of surface recombination velocities (SRVs) of the stacked structure on the thickness of the a-Si layer. Stacked structures with a-Si layers with thicknesses greater than 10 nm exhibit long effective carrier lifetimes, while thos...

  13. Characterization of carrier transport properties in strained crystalline Si wall-like structures in the quasi-quantum regime

    Energy Technology Data Exchange (ETDEWEB)

    Mayberry, C. S.; Huang, Danhong, E-mail: danhong.huang@us.af.mil; Kouhestani, C. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Balakrishnan, G. [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Islam, N. [Department of Electrical and Computer Engineering, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Brueck, S. R. J. [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87106 (United States); Sharma, A. K. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States)

    2015-10-07

    We report the transport characteristics of both electrons and holes through narrow constricted crystalline Si “wall-like” long-channels that were surrounded by a thermally grown SiO{sub 2} layer. The strained buffering depth inside the Si region (due to Si/SiO{sub 2} interfacial lattice mismatch) is where scattering is seen to enhance some modes of the carrier-lattice interaction, while suppressing others, thereby changing the relative value of the effective masses of both electrons and holes, as compared to bulk Si. In the narrowest wall devices, a considerable increase in conductivity was observed as a result of higher carrier mobilities due to lateral constriction and strain. The strain effects, which include the reversal splitting of light- and heavy-hole bands as well as the decrease of conduction-band effective mass by reduced Si bandgap energy, are formulated in our microscopic model for explaining the experimentally observed enhancements in both conduction- and valence-band mobilities with reduced Si wall thickness. Also, the enhancements of the valence-band and conduction-band mobilities are found to be associated with different aspects of theoretical model.

  14. Nanoscopic oxidation of p-type and un-doped Si (100) surfaces using un-externally biased atomic force microscope tips (AFM) in the presence of selected organic solvents

    Science.gov (United States)

    McCausland, Jeffrey; Withanage, Sajeevi; Mallik, Robert; Lyuksyutov, Sergei

    A conductive un-biased AFM tip oscillating above p-type or un-doped Si (100) treated with toluene, butan-2-ol, and propan-2-ol creates nanostructures ranging in height from 1-100 nm. The tip was oscillated in ambient conditions (30-70% Rel. Humidity) at frequencies in the 102 kHz range. It was repeatable with various concentrations of solvent in aqueous solution. It is suggested that mechanical oscillations of the AFM tip polarizes the solvent molecules deposited on the surface resulting in electron transfer from the tip to the surface followed by feature formation. This process effectively creates an electrochemical cell at the microscopic level and the miscibility of the solvents is the key to enabling the process. Species which ionize during the process may be consumed in irreversible reactions whereas the alcohols act as catalysts and are not consumed. The influence of boron defects in the Si substrates is also discussed. It appears that the observed oxidation is different from all other similar reported phenomena including local anodic oxidation, and chemo-mechanical lithographic techniques utilizing AFM.

  15. Tight-binding study of the hole subband structure properties of p-type delta-doped quantum wells in Si by using a Thomas-Fermi-Dirac potential

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Vargas, I; Madrigal-Melchor, J; Vlaev, S J, E-mail: isaac@planck.reduaz.m [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, ZAC. (Mexico)

    2009-05-01

    We present the hole subband structure of p-type delta-doped single, double, multiple and superlattice quantum wells in Si. We use the first neighbors sp{sup 3}s' tight-binding approximation including spin for the hole level structure analysis. The parameters of the tight-binding hamiltonian were taken from Klimeck et al. [Klimeck G, Bowen R C, Boykin T B, Salazar-Lazaro C, Cwik T A and Stoica A 2000 Superlattice. Microst. 27 77], first neighbors parameters that give realiable results for the valence band of Si. The calculations are based on a scheme previously proposed and applied to delta-doped quantum well systems [Vlaev S J and Gaggero-Sager L M 1998 Phys. Rev. B 58 1142]. The scheme relies on the incorporation of the delta-doped quantum well potential in the diagonal terms of the tight-binding hamiltonian. We give a detail description of the delta-doped quantum well structures, this is, we study the hole subband structure behavior as a function of the impurity density, the interwell distance of the doped planes and the superlattice period. We also compare our results with the available theoretical and experimental data, obtaining a reasonable agreement.

  16. Lowest surface recombination velocity on n-type crystalline silicon using PECVD a-Si:H/SiNx bi-layer passivation

    Science.gov (United States)

    Stepanov, Dmitri S.; Chowdhury, Zahidur R.; Kherani, Nazir P.

    2011-08-01

    Energy conversion efficiency of crystalline silicon (c-Si) solar cells manufactured on thin substrates is strongly influenced by the recombination losses of photo-generated charge carriers at the surface and in its proximity. Intrinsic hydrogenated amorphous silicon (i-a-Si:H) deposited using DC saddle-field plasma enhanced chemical vapour deposition (PECVD) at a low temperature of ~200°C reduces recombination losses of photo-generated carriers through passivation of defects at the surface. This study reports on high quality surface passivation achieved using a dual layer approach wherein a 70nm amorphous silicon nitride (SiNx) capping layer is deposited on a less than 10nm thin i-a-Si:H layer. While the a-Si:H layer is effective in passivating the interface recombination sites, SiNx is deemed to incorporate field-effect passivation, thus providing a minority carrier mirror. Additionally, SiNx layer acts as an anti-reflection coating with a low absorption coefficient in the optical frequency range of interest. The SiNx deposition conditions, known to strongly influence the passivating quality of the dual layer structure, were systematically investigated using the response surface methodology (RSM). The optimal deposition parameters obtained from the RSM study were experimentally verified to yield the lowest surface recombination velocity of 3.5 cm/s on 1-2 Ω-cm n-type FZ c-Si using a PECVD a-Si:H/SiNx bi-layer passivation stack.

  17. Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes

    Science.gov (United States)

    Espíndola-Gonzalez, A.; Martínez-Hernández, A. L.; Angeles-Chávez, C.; Castaño, V. M.; Velasco-Santos, C.

    2010-09-01

    The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids ( Eisenia foetida) is reported. The product ( humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransformation allows creating specific crystalline phases, since equivalent particles synthesized without biotransformation are bigger and with different crystalline structure.

  18. Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes

    Directory of Open Access Journals (Sweden)

    Angeles-Chávez C

    2010-01-01

    Full Text Available Abstract The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids (Eisenia foetida is reported. The product (humus is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD, transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM and dynamic light scattering (DLS show that the biotransformation allows creating specific crystalline phases, since equivalent particles synthesized without biotransformation are bigger and with different crystalline structure.

  19. Elasticity and structure of the compounds in the wollastonite (CaSiO3)-Na 2SiO 3 system: from amorphous to crystalline state.

    Science.gov (United States)

    Lin, Chung-Cherng; Leung, Kak Si; Shen, Pouyan; Chen, Shih-Fan

    2015-01-01

    The elastic properties and structure of four potential bioactive compounds in the CaSiO3-Na2SiO3 system were characterized by Raman and Brillouin spectroscopy at ambient conditions. The increase of Na2O content in the Na2O-CaO-SiO2 glass with the same silica content and hence polymerization was found to lower the elastic moduli with accompanied decrease of Q(0) and Q(2) species, increase of Q(1) species and negligible change of Q(3) species, corresponding to a lower and higher equilibrium constant for the disproportional reactions [Formula: see text] and [Formula: see text] (without balance), respectively. The composition-dependent variation in the shear modulus (G) of the Na2O-CaO-SiO2 glass can be attributed to the concentration change of Q(2) and probably Q(4) species; while bulk modulus (K) ascribed to the cohesion factor. The elastic moduli of the corresponding crystalline phases in this system also lower with the increase of Na2O content following two general criteria as a function of Na2O/CaO molar ratio: (1) K decreases faster than G for both the amorphous and crystalline phases and (2) both K and G decreases faster for the crystals than the glasses.

  20. Effect of the CO2/SiH4 Ratio in the p-[mu]c-SiO:H Emitter Layer on the Performance of Crystalline Silicon Heterojunction Solar Cells

    National Research Council Canada - National Science Library

    Jaran Sritharathikhun; Taweewat Krajangsang; Apichan Moollakorn; Sorapong Inthisang; Amornrat Limmanee; Aswin Hongsingtong; Nattaphong Boriraksantikul; Tianchai Taratiwat; Nirod Akarapanjavit; Kobsak Sriprapha

    2014-01-01

    .... The reported work focused on the effects of the CO2/SiH4 ratio on the properties of p-μ c-SiO:H films and the effectiveness of the films as an emitter layer of crystalline silicon heterojunction (c-Si-HJ) solar cells. A p-μ c...

  1. pH sensitivity of Si-C linked organic monolayers on crystalline silicon surfaces

    NARCIS (Netherlands)

    Faber, Erik Jouwert; Sparreboom, Wouter; Groeneveld, Wilrike; de Smet, Louis C.P.M.; Bomer, Johan G.; Olthuis, Wouter; Zuilhof, Han; Sudholter, Ernst; Sudhölter, Ernst J.R.; Bergveld, Piet; van den Berg, Albert

    2007-01-01

    The electrochemical behaviour of Si-C linked organic monolayers is studied in electrolyte-insulator-Si devices, under conditions normally encountered in potentiomeric biosensors, to gain fundamental knowledge on the behaviour of such Si electrodes under practical conditions. This is done via

  2. Si1-yGey or Ge1-zSnz Source/Drain Stressors on Strained Si1-xGex-Channel P-Type Field-Effect Transistors: A Technology Computer-Aided Design Study

    Science.gov (United States)

    Eneman, Geert; De Keersgieter, An; Witters, Liesbeth; Mitard, Jerome; Vincent, Benjamin; Hikavyy, Andriy; Loo, Roger; Horiguchi, Naoto; Collaert, Nadine; Thean, Aaron

    2013-04-01

    The interaction between two stress techniques, strain-relaxed buffers (SRBs) and epitaxial source/drain stressors, is studied on short, Si1-xGex- and Ge-channel planar transistors. This work focuses on the longitudinal channel stress generated by these two techniques. Unlike for unstrained silicon-channel transistors, for strained channels on top of a strain-relaxed buffer a source/drain stressor without recess generates similar longitudinal channel stress than source/drain stressors with a deep recess. The least efficient stress transfer is obtained for source/drain stressors with a small recess that removes only the strained channel, not the substrate underneath. These trends are explained by a trade-off between elastic relaxation of the strained-channel during source/drain recess and the increased stress generation of thicker source/drain stressors. For Ge-channel pFETs, GeSn source/drains and Si1-xGex strain-relaxed buffers are efficient stressors for mobility enhancement. The former is more efficient for gate-last schemes than for gate-first, while the stress generated by the SRB is found to be independent of the gate-scheme.

  3. Topological Crystalline Insulator SnTe/Si Vertical Heterostructure Photodetectors for High-Performance Near-Infrared Detection.

    Science.gov (United States)

    Zhang, Hongbin; Man, Baoyuan; Zhang, Qi

    2017-04-26

    Due to the gapless surface state and narrow bulk band gap, the light absorption of topological crystalline insulators covers a broad spectrum ranging from terahertz to infrared, revealing promising applications in new generation optoelectronic devices. To date, the photodetectors based on topological insulators generally suffer from a large dark current and a weaker photocurrent especially under the near-infrared lights, which severely limits the practical application of devices. Owing to the lower excitation energy of infrared lights, the photodetection application of topological crystalline insulators in the near-infrared region relies critically on understanding the preparation and properties of their heterostructures. Herein, we fabricate the high-quality topological crystalline insulator SnTe film/Si vertical heterostructure by a simple physical vapor deposition process. The resultant heterostructure exhibits an excellent diode characteristic, enabling the construction of high-performance near-infrared photodetectors. The built-in electric field at SnTe/Si interface enhances the absorption efficiency of near-infrared lights and greatly facilitates the separation of photogenerated carriers, making the device capable of operating as a self-driven photodetector. The as-grown SnTe film acts as the hole transport layer in heterostructure photodetectors, promoting the transport of holes to electrode and reducing electron-hole recombination effectively. These merits enable the SnTe/Si heterostructure photodetector to have a high responsivity of 2.36 AW(-1), a high detectivity of 1.54 × 10(14) Jones, and a large bandwidth of 10(4) Hz in the near-infrared wavelength, which makes the detector have a promising market in novel device applications.

  4. Insulin adsorption on crystalline SiO2: Comparison between polar and nonpolar surfaces using accelerated molecular-dynamics simulations

    Science.gov (United States)

    Nejad, Marjan A.; Mücksch, Christian; Urbassek, Herbert M.

    2017-02-01

    Adsorption of insulin on polar and nonpolar surfaces of crystalline SiO2 (cristobalite and α -quartz) is studied using molecular dynamics simulation. Acceleration techniques are used in order to sample adsorption phase space efficiently and to identify realistic adsorption conformations. We find major differences between the polar and nonpolar surfaces. Electrostatic interactions govern the adsorption on polar surfaces and can be described by the alignment of the protein dipole with the surface dipole; hence spreading of the protein on the surface is irrelevant. On nonpolar surfaces, on the other hand, van-der-Waals interaction dominates, inducing surface spreading of the protein.

  5. Channeling and Radiation of Electrons in Silicon Single Crystals and Si1−xGex Crystalline Undulators

    DEFF Research Database (Denmark)

    Backe, H.; Krambrich, D.; Lauth, W.

    2013-01-01

    potential of the silicon single crystals. Radiation from a crystalline undulator, produced at the Aarhus University (UAAR), has been investigated at the Mainz Microtron electron accelerator facility MAMI. The 4-period epitaxially grown strained layer Si1−xGex undulator had a period length λu = 9.9 μm....... At a beam energy of 375 MeV a broad excess yield around the theoretically expected photon energy of 0.132 MeV has been observed. Model calculations on the basis of synchrotron-like radiation emission suggest that evidence for a weak undulator effect has been observed....

  6. Influence of SiO{sub 2} buffer layer on the crystalline quality and photoluminescence of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, L H; Chen, Y L; Xu, F [College of Math and Physics, Nanjing University of Information Science and Technology, Nanjing, 210044 (China); Li, X Y [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China); Hua, S, E-mail: congyu3256@sina.com [Institute of Electronic Engineering and Photoelectric Technology, Nanjing University of Science and Technology, Nanjing, 210094 (China)

    2011-02-01

    In this work, a SiO{sub 2} buffer layer was first grown on Si substrate by thermal oxidation, and then ZnO thin films were deposited on SiO{sub 2} buffer layer and Si substrate by electron beam evaporation and sol-gel method. The influence of SiO{sub 2} buffer layer on the crystalline quality and photoluminescence of the films was investigated. The analyses of X-ray diffraction (XRD) showed that all the ZnO thin films had a hexagonal wurtzite structure and were preferentially oriented along the c-axis perpendicular to the substrate surface. The SiO{sub 2} buffer layer improved the crystalline quality and decreased the stress in ZnO thin films. The surface morphology analyses of the samples indicated that ZnO thin films deposited on SiO{sub 2} buffer layers had densely packed grains which obviously increased compared with those grown on bare Si substrate. The photoluminescence spectra of the samples showed that the ZnO thin films deposited on SiO{sub 2} buffer layers had stronger ultraviolet emission performance. The results suggest that SiO{sub 2} buffer layer can improve the crystalline quality and ultraviolet emission of ZnO thin films.

  7. Stability of SiNX/SiNX double stack antireflection coating for single crystalline silicon solar cells

    Science.gov (United States)

    Lee, Youngseok; Gong, Daeyeong; Balaji, Nagarajan; Lee, Youn-Jung; Yi, Junsin

    2012-01-01

    Double stack antireflection coatings have significant advantages over single-layer antireflection coatings due to their broad-range coverage of the solar spectrum. A solar cell with 60-nm/20-nm SiNX:H double stack coatings has 17.8% efficiency, while that with a 80-nm SiNX:H single coating has 17.2% efficiency. The improvement of the efficiency is due to the effect of better passivation and better antireflection of the double stack antireflection coating. It is important that SiNX:H films have strong resistance against stress factors since they are used as antireflective coating for solar cells. However, the tolerance of SiNX:H films to external stresses has never been studied. In this paper, the stability of SiNX:H films prepared by a plasma-enhanced chemical vapor deposition system is studied. The stability tests are conducted using various forms of stress, such as prolonged thermal cycle, humidity, and UV exposure. The heat and damp test was conducted for 100 h, maintaining humidity at 85% and applying thermal cycles of rapidly changing temperatures from -20°C to 85°C over 5 h. UV exposure was conducted for 50 h using a 180-W UV lamp. This confirmed that the double stack antireflection coating is stable against external stress.

  8. The modulation of surface texture for single-crystalline Si solar cells using calibrated silver nanoparticles as a catalyst

    Science.gov (United States)

    Gu, Xin; Yu, Xuegong; Liu, Tao; Li, Dongsheng; Yang, Deren

    2011-01-01

    We have employed Ag nanoparticles with calibrated size as catalysts to modulate the surface texture of single-crystalline Si surfaces for reducing sunlight reflectivity. Both experiments and theoretical analysis have proved that a well-organized microporous structure on the pyramids can be obtained by optimizing the size of Ag nanoparticles and the texturing time, and the Si wafer with such structures can effectively reduce the reflectivity of sunlight. However, based on the conventional cell fabrication process, the performance of silicon solar cells with such microporous structures gets degraded. It is closely associated with the strong surface recombination and the high phosphorus diffusion barrier induced by the microporous textures. These results are interesting for us to understand the application of nanotechnology on the silicon solar cell.

  9. Si and Ge nanostructures epitaxy on a crystalline insulating LaAlO{sub 3}(001) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, Jean-Luc; Mortada, Hussein; Dentel, Didier; Derivaz, Mickael [Institut de Science des Materiaux de Mulhouse (IS2M), LRC 7228 CNRS-UHA, Universite de Haute Alsace, Mulhouse (France); Ben Azzouz, Chiraz; Akremi, Abdelwahab; Chefi, Chaabanne [Equipe Surface et Interface (ESI) - Faculte des Sciences, Bizerte (Tunisia); Morales, Francisco Miguel; Herrera, Miriam; Manuel, Jose Manuel; Garcia, Rafael [Department of Materials Science, Metallurgical Engineering and Inorganic Chemistry, Cadiz University (Spain); Diani, Mustapha [Equipe de Recherche en Mecanique, Materiaux et Metallurgie, FST, Tanger (Morocco)

    2012-04-15

    We present a comparative structural study of the growth of Si and Ge deposited by molecular beam epitaxy (MBE) on a c(2 x 2) reconstructed LaAlO{sub 3}(001) substrate. Our findings are based on complementary experimental techniques such as in situ X-ray photoelectron spectroscopy (XPS), reflection high-energy electron diffraction (RHEED), low energy electron diffraction (LEED) and ex situ atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). While the layers are amorphous and wet uniformly the substrate in a low deposition temperature range, above 500 C both Si and Ge growths proceed in a Volmer-Weber (VW) mode leading to the formation of nanocrystals (NCs). The islands are found to be composed of pure Si and Ge and to have abrupt interfaces with the substrate. Both semiconductors (SCs) crystallize in their own diamond structure leading to relaxed NCs. No facets could be observed on the crystalline islands. An epitaxial relationship is established for which the (001) planes of Si and Ge are parallel to the LaAlO{sub 3}(001) surface but are rotated by 45 around the [001] growth axis. The Ge lattice undergoes a second rotation of 6 with respect to the (001) growth axis. This 6 tilt is an original mechanism to partially compensate the strain in the Ge islands induced by the large misfit. Whereas a unique epitaxial relationship is pointed out for Si NCs, many Ge NCs are randomly orientated on the surface. This is interpreted by the fact that the Ge islands are less anchored to the substrate due to a large misfit and to the fact that the Ge-O bonds are weaker than the Si-O ones. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Creep deformation of grain boundary in a highly crystalline SiC fibre.

    Science.gov (United States)

    Shibayama, Tamaki; Yoshida, Yutaka; Yano, Yasuhide; Takahashi, Heishichiro

    2003-01-01

    Silicon carbide (SiC) matrix composites reinforced by SiC fibres (SiC/SiC composites) are currently being considered as alternative materials in high Ni alloys for high-temperature applications, such as aerospace components, gas-turbine energy-conversion systems and nuclear fusion reactors, because of their high specific strength and fracture toughness at elevated temperatures compared with monolithic SiC ceramics. It is important to evaluate the creep properties of SiC fibres under tensile loading in order to determine their usefulness as structural components. However, it would be hard to evaluate creep properties by monoaxial tensile properties when we have little knowledge on the microstructure of crept specimens, especially at the grain boundary. Recently, a simple fibre bend stress relaxation (BSR) test was introduced by Morscher and DiCarlo to address this problem. Interpretation of the fracture mechanism at the grain boundary is also essential to allow improvement of the mechanical properties. In this paper, effects of stress applied by BSR test on microstructural evolution in advanced SiC fibres, such as Tyranno-SA including small amounts of Al, are described and discussed along with the results of microstructure analysis on an atomic scale by using advanced microscopy.

  11. O-vacancies in (i) nano-crystalline HfO2 and (i) non-crystalline SiO2 and Si3N4 studied by X-ray absorption spectroscopy.

    Science.gov (United States)

    Lucovsky, Gerald; Miotti, Leonardo; Bastos, Karen Paz

    2012-06-01

    Performance and reliability in semiconductor devices are limited by electronically active defects, primarily O-atom and N-atom vacancies. Synchrotron X-ray spectroscopy results, interpreted in the context of two-electron multiplet theories, have been used to analyze conduction band edge, and O-vacancy defect states in nano-crystalline transition metal oxides, e.g., HfO2, and the noncrystalline dielectrics, SiO2, Si3N4 and Si-oxynitride alloys. Two-electron multiplet theory been used to develop a high-spin state equivalent d2 model for O-vacancy allowed transitions and negative ion states as detected by X-ray absorption spectroscopy in the O K pre-edge regime. Comparisons between theory and experiment have used Tanabe-Sugano energy level diagrams for determining the symmetries and relative energies of intra-d-state transitions for an equivalent d2 ground state occupancy. Trap-assisted-tunneling, Poole-Frenkel hopping transport, and the negative bias temperature instability have been explained in terms of injection and/or trapping into O-atom and N-atom vacancy sites, and applied to gate dielectric, and metal-insulator-metal structures.

  12. Gettering effects in Si{sub x}Ge{sub 1-x} single crystalline wafers

    Energy Technology Data Exchange (ETDEWEB)

    Wollweber, J.; Schulz, D.; Schroeder, W. [Institut fuer Kristallzuechtung, Berlin (Germany)] [and others

    1995-08-01

    The new interest in single crystal growth of SiGe solid solutions is caused by the development of advanced electronics. The SiGe alloys are mostly used in the form of Si/Si{sub x}Ge{sub 1-x} epitaxial layers in heterostructures, the perfect bulk crystals are required to study fundamental properties. Furthermore, Si{sub x}Ge{sub 1-x} crystals can be used as a substrate material instead of Silicon in order to avoid the buffer layers between the Silicon substrate and strained Si{sub x}Ge{sub 1-x}. Monocrystalline SiGe alloys may be a potential candidate as a base material for infrared solar cells too because of an enhanced IR-sensitivity. In this paper we report a new approach to the growth of Si{sub x}Ge{sub 1-x} single crystals (up to 2{double_prime} in diameter) using the crucible free rf-heated float zone technique as well as the Czochralski-technique for solar cells. The goal is to produce solar cells with an increased photo current in comparison to Silicon cells. based on the lower bandgap of the alloyed crystal. In order to be able to use the Si cells technology (a matter still pending to be proven), low contents of Ge are intended, desirably in the range of about x=0.2. It is worth to mention, that in the conventional Silicon cell processes which give efficiencies up to 18-19%, this efficiency is not limited by the bulk base recombination in the lifetime is above 200 {mu}s there. We can conclude, that there is no basic limitation did prevents Si{sub x}Ge{sub 1-x} wafers to present high lifetimes, above 200{mu}s, at least if the Ge content is below 5%. We can also conclude that the phosphorous gettering from a POCl{sub 3} source, used in silicon, can be successfully used to enhance lifetimes in Si{sub x}Ge{sub 1-x}, at least for the Ge concentration used here.

  13. First-order ferromagnetic transition in single-crystalline (Mn,Fe)(2)( P,Si)

    NARCIS (Netherlands)

    Yibole, H.; Guillou, F.; Huang, Y. K.; Blake, G. R.; Lefering, A. J. E.; van Dijk, N. H.; Bruck, E.

    2015-01-01

    (Mn,Fe)(2)(P, Si) single crystals have been grown by flux method. Single crystal X-ray diffraction demonstrates that Mn0.83Fe1.17P0.72Si0.28 crystallizes in a hexagonal Fe2P crystal structure (space group P (6) over bar 2m) at both 100 and 280 K, in the ferromagnetic and paramagnetic states,

  14. Mechanisms of pit formation at strained crystalline Si(111)/Si3N4(0001) interfaces: Molecular-dynamics simulations

    Science.gov (United States)

    Bachlechner, Martina E.; Srivastava, Deepak; Owens, Eli T.; Schiffbauer, Jarrod; Anderson, Jonas T.; Burky, Melissa R.; Ducatman, Samuel C.; Gripper, Adam M.; Guffey, Eric J.; Ramos, Fernando Serrano

    2006-08-01

    Molecular-dynamics simulations of the crystalline silicon-silicon nitride interfaces are performed to investigate the mechanical failure mechanisms at the interfaces under external strain. At 8% applied tensile strain, parallel to the interface, regular crack initiation and propagation in silicon nitride and dislocation emission and propagation in silicon are observed. At larger 16% strain, however, the formation of a pit similar to that in experiments with lattice-mismatched systems is observed. The simulation results suggest the primary mechanism of pit formation is interaction of a local compressional pinch of the film at the interface with the close proximity to the arrival of a dislocation at the interface in the highly strained silicon.

  15. Influence of thermal annealing on the memory effect in MIS structures containing crystalline Si nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Sebastian; Brueggemann, R. [Institut fuer Physik, Carl von Ossietzky Universitaet Oldenburg, 26111 Oldenburg (Germany); Kirilov, Kiril [Department of Solid State Physics and Microelectronics, Sofia Univ. (Bulgaria); Levi, Zelma; Manolov, E. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Nedev, N. [Instituto de Ingenieria Universidad Autonoma de Baja California, Benito Juarez Blvd., s/n, C.P. 21280, Mexicali, Baja California, Mexico (Mexico)

    2007-07-01

    Silicon nanocrystals embedded in a SiO{sub 2} matrix are fabricated by thermal annealing of Metal/SiO{sub 2}/SiO{sub x}/c-Si structures (x=1.15) at 1000 C in N{sub 2} atmosphere for 30 or 60 min. High frequency C-V measurements demonstrate that both types of sample can be charged negatively or positively by applying a positive or negative bias voltage to the gate. The clockwise hysteresis windows of 30 and 60 min annealed samples are about 7 and 5.5 V for the {+-}12 V scanning range (E{sub ox}={+-}2.4 MV/cm), respectively. Although the samples annealed for 60 min have a smaller hysteresis window, they have two important advantages compared to the 30 min annealed ones: a lower defect density at the c-Si wafer/SiO{sub 2} interface and a smaller value of the fixed oxide charge close to this interface.

  16. Confocal Raman studies in determining crystalline nature of PECVD grown Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nafis; Bhargav, P. Balaji; Ramasamy, P. [SSN Research Centre, Kalavakkam-603110, Tamilnadu (India); Department of Physics, SSN College of Engineering, Kalavakkam-603110, Tamilnadu (India); Sivadasan, A. K.; Tyagi, A. K.; Dhara, S., E-mail: dhara@igcar.gov.in [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amirthapandian, S.; Panigrahi, B. K. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Bhattacharya, S. [SSN Research Centre, Kalavakkam-603110, Tamilnadu (India)

    2015-06-24

    Silicon nanowires of diameter ∼200 nm and length of 2-4 µm are grown in the plasma enhanced chemical vapour deposition technique using nanoclustered Au catalyst assisted vapour-liquid-solid process. The crystallinity in the as-grown and annealed samples is studied using confocal Raman spectroscopic studies. Amorphous phase is formed in the as-grown samples. Structural studies using high resolution transmission electron microscopy confirm the polycrystalline nature in the annealed sample.

  17. The difference of energies of Si atoms with single-crystalline, amorphous, free and nanoparticle configurations

    Science.gov (United States)

    Wang, Y. L.; Deng, Z. C.; Chu, L. Z.; Fu, G. S.; Peng, Y. C.

    2009-04-01

    Nanocrystalline silicon (nc-Si) films were systematically prepared via three ways: a) laser anneal or b) thermal anneal of the amorphous silicon (α-Si) films deposited by pulsed-laser ablation (PLA) in base vacuum, c) direct PLA in high-purity Ar gas with pressure of 10 Pa. The anneal-laser fluence, thermal-anneal temperature and ablation-laser fluence thresholds corresponding to the beginning of nanoparticles formation were respectively determined by using scanning electron microscopy (SEM), Raman and X-ray diffraction (XRD) techniques. Incorporated with crystallization mechanism, energies compensated for the formation of one Si nanoparticle in the three ways were calculated approximately. The result shows that for different crystallization ways, the potential barriers during the formation of one ~16 nm nanoparticle are on the order of 10-9 mJ.

  18. FTIR studies of BPO 4·2SiO 2, BPO 4·SiO 2 and 2BPO 4·SiO 2 joints in amorphous and crystalline forms

    Science.gov (United States)

    Adamczyk, A.; Handke, M.; Mozgawa, W.

    1999-11-01

    The MIR spectra of glasses and devitrificates of BPO 4·2SiO 2, BPO 4 SiO 2 and 2BPO 4·SiO 2 compositions have been shown. The bands arising from the Si-O, B-O and P-O bonds vibrations can be assigned in the spectra of the above samples. All bands appear almost at the same wavenumber range: what causes their coincidence? Therefore, all spectra of crystalline and amorphous materials were decomposed into component bands. The decomposed MIR spectra of these samples, as well as the tetragonal boron orthophosphate BPO 4 and the low temperature crystobalite spectra, were then compared. Therefore, one can estimate the probability of the existence of any compounds within the BPO 4-SiO 2 (P 2O 5-B 2O 3-SiO 2) system. The presence of BPO 4·2SiO 2 was reported in a few papers. The results obtained in this work can be treated as an attempt to verify the above hypothesis verifying because of the opposed information existing on this subject in literature.

  19. Crystalline Structure of the Pb/Si(111)7x7 Stable Wetting Layer

    Science.gov (United States)

    Gramlich, M.; Hayden, S. T.; Chen, Yiyao; Kim, C.; Tringides, M. C.; Miceli, P. F.

    2012-02-01

    The wetting layer formation in the Pb/Si(111)7x7 system has attracted extensive interest because of anomalously fast kinetics, which enables the formation of quantum size effect (QSE) nanoislands [Jeffrey et al. PRL 96, 106105 (2006)]. However, previous studies of the wetting layer by x-ray diffraction and scanning-probes have led to inconsistent structural models; thus, the structure of this wetting layer has been unsolved. Furthermore, a recent investigation has revealed that the wetting layer is out-of-equilibrium over a surprisingly broad temperature range [Gramlich et al., PRB 84, 075433 (2011)]. Using in situ x-ray scattering methods, we have solved the stable, low temperature annealed structure of the wetting layer. It exhibits a strained atomic layer where Pb atoms are in transition, from Si-7x7 sites towards 8x8-sites, with some Pb-atoms vertically closer to the Si-7x7. Interestingly, the Si adatoms shift to the edges of the unit cell. Funding is acknowledged from NSF DMR-0706278 (PFM, MWG, STH, YC, and the Ministry of Knowledge Economy of Korea 2009-F014-01 (CK). The experiments were performed on the 6IDC beam line, supported by the US-DOE (through Ames Lab, W-7405-Eng-82), at the Advanced Photon Source (US-DOE, W-31-109-Eng-38) located at Argonne National Laboratory.

  20. Synthesis of crystalline Ge nanoclusters in PE-CVD-deposited SiO2 films

    DEFF Research Database (Denmark)

    Leervad Pedersen, T.P.; Skov Jensen, J.; Chevallier, J.

    2005-01-01

    The synthesis of evenly distributed Ge nanoclusters in plasma-enhanced chemical-vapour-deposited (PE-CVD) SiO2 thin films containing 8 at. % Ge is reported. This is of importance for the application of nanoclusters in semiconductor technology. The average diameter of the Ge nanoclusters can...

  1. Magnetization reversal process in Fe/Si (001) single-crystalline film investigated by planar Hall effect

    Institute of Scientific and Technical Information of China (English)

    叶军; 何为; 胡泊; 汤进; 张永圣; 张向群; 陈子瑜; 成昭华

    2015-01-01

    Planar Hall effect (PHE) is introduced to investigate the magnetization reversal process in single-crystalline iron film grown on Si (001) substrate. Owing to the domain structure of iron film and the characteristics of PHE, the magnetization switches sharply in an angular range of the external field for two steps of 90◦ domain wall displacement and one step of 180◦domain wall displacement near the easy axis, respectively. However, the magnetization reversal process near hard axis is completed by only one step of 90◦ domain wall displacement and then rotates coherently. The magnetization reversal process mechanism near the hard axis seems to be a combination of coherent rotation and domain wall displacement. Furthermore, the domain wall pinning energy and uniaxial magnetic anisotropy energy can also be derived from the PHE measurement.

  2. Integration of crystalline orientated γ-Al2O3 films and complementary metal-oxide-semiconductor circuits on Si(1 0 0) substrate

    Science.gov (United States)

    Oishi, Koji; Akai, Daisuke; Ishida, Makoto

    2015-01-01

    In this paper, integration of crystalline orientated γ-Al2O3 films and complementary metal-oxide-semiconductor (CMOS) circuits on Si(1 0 0) substrate was reported. In this integration processes, crystalline γ-Al2O3 films need to be preserved their crystallinity during high temperature annealing processes of CMOS fabrication in order to prevent surface condition changes. The γ-Al2O3 films grown on Si substrates are annealed in the CMOS fabrication process conditions, drive-in annealing at 1150 °C in O2 atmosphere and wet annealing 1000 °C in H2O vapor atmosphere. Reflection high energy electron diffraction (RHEED) and x-ray diffraction (XRD) were used to characterize the crystallinity of γ-Al2O3 films after the annealing processes. Surface conditions of the films are analyzed and observed with X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). As a result, RHEED patterns of the γ-Al2O3 films indicated that wet oxidation annealing was a critical process severally inferior surface condition of crystalline γ-Al2O3 films. XRD, XPS, and SEM investigation unveiled further details of the crystallinity changes on γ-Al2O3 films for each process. These results indicated passivation films were required to integrate γ-Al2O3 films with CMOS fabrication process. Therefore we proposed and introduced Si3N4/TEOS passivation films on γ-Al2O3 films in CMOS fabrication processes. At last, MOSFETs on γ-Al2O3 integrated Si(1 0 0) substrate were fabricated and characterized. The designed characteristics of MOSFETs were obtained on γ-Al2O3 integrated Si substrate.

  3. Defect-Band Emission Photoluminescence Imaging on Multi-Crystalline Si Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Yan, F.; Johnston, S.; Zaunbrecher, K.; Al-Jassim, M.; Sidelkheir, O.; Blosse, A.

    2011-07-01

    Defect-band photoluminescence (PL) imaging with an InGaAs camera was applied to multicrystalline silicon (mc-Si) wafers, which were taken from different heights of different Si bricks. Neighboring wafers were picked at six different processing steps, from as-cut to post-metallization. By using different cut-off filters, we were able to separate the band-to-band emission images from the defect-band emission images. On the defect-band emission images, the bright regions that originate from the grain boundaries and defect clusters were extracted from the PL images. The area fraction percentage of these regions at various processing stages shows a correlation with the final cell electrical parameters.

  4. Laser recrystallization and inscription of compositional microstructures in crystalline SiGe-core fibres

    Science.gov (United States)

    Coucheron, David A.; Fokine, Michael; Patil, Nilesh; Breiby, Dag Werner; Buset, Ole Tore; Healy, Noel; Peacock, Anna C.; Hawkins, Thomas; Jones, Max; Ballato, John; Gibson, Ursula J.

    2016-10-01

    Glass fibres with silicon cores have emerged as a versatile platform for all-optical processing, sensing and microscale optoelectronic devices. Using SiGe in the core extends the accessible wavelength range and potential optical functionality because the bandgap and optical properties can be tuned by changing the composition. However, silicon and germanium segregate unevenly during non-equilibrium solidification, presenting new fabrication challenges, and requiring detailed studies of the alloy crystallization dynamics in the fibre geometry. We report the fabrication of SiGe-core optical fibres, and the use of CO2 laser irradiation to heat the glass cladding and recrystallize the core, improving optical transmission. We observe the ramifications of the classic models of solidification at the microscale, and demonstrate suppression of constitutional undercooling at high solidification velocities. Tailoring the recrystallization conditions allows formation of long single crystals with uniform composition, as well as fabrication of compositional microstructures, such as gratings, within the fibre core.

  5. Observation of sub-GeV electrons mirrored by ultrathin crystalline Si

    Energy Technology Data Exchange (ETDEWEB)

    Takabayashi, Y., E-mail: takabayashi@saga-ls.jp [SAGA Light Source, 8-7 Yayoigaoka, Tosu, Saga 841-0005 (Japan); Pivovarov, Yu.L.; Tukhfatullin, T.A. [National Research Tomsk Polytechnic University, Tomsk (Russian Federation)

    2015-12-17

    Detailed experimental studies are performed on the mirroring effect for 255-MeV electrons channeled through a 0.74-μm-thick Si crystal at the injector linac of the SAGA-LS facility. For the planar channeling alignment, deflection of the beam by 0.45 mrad is observed with 29% efficiency. The effect is explained by computer simulations as a sequence of trajectories of planar-channeled relativistic electrons in an attractive one-dimensional periodic potential of crystallographic planes. Possible applications as a beam splitter are proposed.

  6. Non-equilibrium crystalline superconductors in Zr-Si binary alloys rapidly quenched from melts

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, A.; Takahashi, Y.; Toyota, N.; Fukase, T.; Masumoto, T. (Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals)

    1982-08-01

    The new non-equilibrium superconductor with a bcc structure has been found in rapidly quenched Zr-Si alloys. The silicon content in the bcc alloys was limited to the narrow range between 8 and 11 at%. The bcc alloys showed a superconducting transition whose temperature increased from 3.20 to 3.84 K with decreasing silicon content. The upper critical magnetic field and the critical current density for Zr/sub 92/Si/sub 8/ alloy were of the order of 3.58 x 10/sup 6/ Am/sup -1/ at 2.0 K and 3.3 x 10/sup 6/ Am/sup -2/ at 2.42 K in the absence of an applied field. The upper critical field gradient at the transition temperature and the electrical resistivity at 4.2 K were about -1.82 x 10/sup 6/ Am/sup -1/ K/sup -1/ and about 150 ..mu cap omega.. cm. The Ginzburg-Landau parameter and coherence length were estimated to be about 65 and 6.3 nm, respectively, from these experimental values by using the Ginzburg-Landau-Abrikosov-Gorkov theory and hence it is concluded that the present bcc alloys are extremely 'soft' type-II superconductors with a high degree of dirtiness.

  7. Negative effects of crystalline-SiC doping on the critical current density in Ti-sheathed MgB{sub 2}(SiC){sub y} superconducting wires

    Energy Technology Data Exchange (ETDEWEB)

    Liang, G [Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States); Fang, H [Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States); Luo, Z P [Microscopy and Imaging Center, Biological Sciences Building West, Texas A and M University, College Station, TX 77843-2257 (United States); Hoyt, C [Department of Physics, Sam Houston State University, Huntsville, TX 77341 (United States); Yen, F [Texas Center for Superconductivity, University of Houston, Houston, TX 77204-4006 (United States); Guchhait, S [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States); Lv, B [Department of Chemistry, University of Houston, Houston, TX 77204-5003 (United States); Markert, J T [Department of Physics, University of Texas at Austin, Austin, TX 78712 (United States)

    2007-07-15

    Ti-sheathed MgB{sub 2} wires doped with nanosize crystalline-SiC up to a concentration of 15 wt% SiC have been fabricated, and the effects of the SiC doping on the critical current density (J{sub c}) and other superconducting properties studied. In contrast with the previously reported results that nano-SiC doping with a doping range below 16 wt% usually enhances J{sub c}, particularly at higher fields, our measurements show that SiC doping decreases J{sub c} over almost the whole field range from 0 to 7.3 T at all temperatures. Furthermore, it is found that the degradation of J{sub c} becomes stronger at higher SiC doping levels, which is also in sharp contrast with the reported results that J{sub c} is usually optimized at doping levels near 10 wt% SiC. Our results indicate that these negative effects on J{sub c} could be attributed to the absence of significant effective pinning centres (mainly Mg{sub 2}Si) due to the high chemical stability of the crystalline-SiC particles.

  8. Gas doping ratio effects on p-type hydrogenated nanocrystalline silicon thin films grown by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, P.Q. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: robt@sjtu.edu.cn; Zhou, Z.B. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)], E-mail: zbzhou@sjtu.edu.cn; Chan, K.Y. [Thin Film Laboratory, Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya 63100, Selangor (Malaysia); Tang, D.Y.; Cui, R.Q.; Dou, X.M. [Solar Energy Institute, Department of Physics, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2008-12-30

    Hydrogenated nanocrystalline silicon (nc-Si:H) grown by hot-wire chemical vapor deposition (HWCVD) has recently drawn significant attention in the area of thin-film large area optoelectronics due to possibility of high deposition rate. We report on the effects of diborane (B{sub 2}H{sub 6}) doping ratio on the microstructural and optoelectrical properties of the p-type nc-Si:H thin films grown by HWCVD at low substrate temperature of 200 deg. C and with high hydrogen dilution ratio of 98.8%. An attempt has been made to elucidate the boron doping mechanism of the p-type nc-Si:H thin films deposited by HWCVD and the correlation between the B{sub 2}H{sub 6} doping ratio, crystalline volume fraction, optical band gap and dark conductivity.

  9. Nano-regime Length Scales Extracted from the First Sharp Diffraction Peak in Non-crystalline SiO2 and Related Materials: Device Applications

    Directory of Open Access Journals (Sweden)

    Phillips James

    2010-01-01

    Full Text Available Abstract This paper distinguishes between two different scales of medium range order, MRO, in non-crystalline SiO2: (1 the first is ~0.4 to 0.5 nm and is obtained from the position of the first sharp diffraction peak, FSDP, in the X-ray diffraction structure factor, S(Q, and (2 the second is ~1 nm and is calculated from the FSDP full-width-at-half-maximum FWHM. Many-electron calculations yield Si–O third- and O–O fourth-nearest-neighbor bonding distances in the same 0.4–0.5 nm MRO regime. These derive from the availability of empty Si dπ orbitals for back-donation from occupied O pπ orbitals yielding narrow symmetry determined distributions of third neighbor Si–O, and fourth neighbor O–O distances. These are segments of six member rings contributing to connected six-member rings with ~1 nm length scale within the MRO regime. The unique properties of non-crystalline SiO2 are explained by the encapsulation of six-member ring clusters by five- and seven-member rings on average in a compliant hard-soft nano-scaled inhomogeneous network. This network structure minimizes macroscopic strain, reducing intrinsic bonding defects as well as defect precursors. This inhomogeneous CRN is enabling for applications including thermally grown ~1.5 nm SiO2 layers for Si field effect transistor devices to optical components with centimeter dimensions. There are qualitatively similar length scales in nano-crystalline HfO2 and phase separated Hf silicates based on the primitive unit cell, rather than a ring structure. Hf oxide dielectrics have recently been used as replacement dielectrics for a new generation of Si and Si/Ge devices heralding a transition into nano-scale circuits and systems on a Si chip.

  10. The crystallization of (NiCu)ZrTiAlSi glass/crystalline composite

    Energy Technology Data Exchange (ETDEWEB)

    Czeppe, T.; Sypien, A. [Institute of Metallurgy and Materials Science PAS, 25 Reymonta St, 30-059 Krakow (Poland); Ochin, P. [Centre d' Etudes de Chimie Metallurgique, UPR 2801, 15, Rue G. Urbain, 94407 Vitry-sur-Seine, Cedex (France); Anastassova, S. [University of Sofia, Faculty of Chemistry, 1, J. Bourchier Blvd., Sofia 1164 (Bulgaria)

    2007-06-15

    Alloys of composition (Ni{sub 1-x}Cu{sub x}){sub 60}Zr{sub 18}Ti{sub 13}A1{sub 5}Si{sub 4} were investigated in the form of ribbons and massive samples. The microstructure of the massive samples consists of dendritic crystals in the amorphous or nanocrystalline matrix. The amount of the amorphous phase is the lowest in the sample with the highest Cu content. The segregation in the liquid phase, leading to the local differences in density and the composition of the crystallizing dendrites in the samples crystallized in the copper mould was shown. The typical compositions of the multi-component crystals could be distinguished; one with the increased content of aluminum, the second with the high content of silicon and third, with the high content of (NiCu) and (ZrTi). The cubic phase Ni(Cu)Ti(Zr) with Cu and Zr dissolved could be identified. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  11. Sintered powder cores of high Bs and low coreloss Fe84.3Si4B8P3Cu0.7 nano-crystalline alloy

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2013-06-01

    Full Text Available Nano-crystalline Fe-rich Fe84.3Si4B8P3Cu0.7 alloy ribbon with saturation magnetic flux density (Bs close to Si-steel exhibits much lower core loss (Wt than Si-Steels. Low glass forming ability of this alloy limits fabrication of magnetic cores only to stack/wound types. Here, we report on fabrication, structural, thermal and magnetic properties of bulk Fe84.3Si4B8P3Cu0.7 cores. Partially crystallized ribbons (obtained after salt-bath annealing treatment were crushed into powdered form (by ball milling, and were compacted to high-density (∼88% bulk cores by spark plasma sintering (SPS. Nano-crystalline structure (consisting of α-Fe grain in remaining amorphous matrix similar to wound ribbon cores is preserved in the compacted cores. At 50 Hz, cores sintered at Ts = 680 K show Wt 1 kHz. A trade-off between porosity and electrical resistivity is necessary to get low Wt at higher f. In the f range of ∼1 to 100 kHz, we have shown that the cores mixed with SiO2 exhibit much lower Wt than Fe-powder cores, non-oriented Si-steel sheets and commercially available sintered cores. We believe our core material is very promising to make power electronics/electrical devices much more energy-efficient.

  12. Photo-induced density-of-states variation measured by DLTS method in intrinsic micro-crystalline silicon (i-μc-Si:H) films

    Science.gov (United States)

    Wang, J.; Sun, Q. S.; Liu, H. N.; He, Y. L.

    1987-06-01

    This paper advances a measurement and two calculations of a high-frequency DLTS method for the density-of-states g(E) of intrinsic micro-crystalline and amorphous silicon film. The method surmounts the difficulties of DLTS measurement of i-a-Si:H or i-μc-Si:H samples and applies the common high-frequency DLTS to it, while the temperature of measurement is extended below 77K. Following the method, we successfully observed the obvious increase of density-of-states produced by illumination.

  13. In-situ optical emission spectroscopy diagnostic of plasma ignition impact on crystalline silicon passivation by a-Si:H films

    Science.gov (United States)

    Meddeb, Hosny; Bearda, Twan; Abdulraheem, Yaser; Dimassi, Wissem; Ezzaouia, Hatem; Gordon, Ivan; Szlufcik, Jozef; Poortmans, Jef

    2016-08-01

    The influence of the plasma ignition condition during PECVD deposition from a silane/hydrogen mixture on the amorphous silicon passivation of crystalline silicon surface is investigated. The changes in this process step mainly consist in varying the power density for very brief durations in between 1 s and 3 s. We find that the ignition phase contributes significantly in the film growth, especially in the a-Si:H/c-Si interface formation. In particular, the deposition rate increases with ignition power density. TEM cross-section inspection presents a rougher a-Si:H/c-Si interface with higher plasma power and thus, a tendency for nano-clusters formation caused by the crystalline nature of the substrate. In-situ plasma diagnostics reveal the gradual raise up of IHa*/ISiH* with the power density leading to worse SiH* abstraction to the surface. Whereas, time-resolved optical emission spectroscopy explains the possible recombination mechanism in the plasma due to higher-silane related reactive species (HSRS) formation via polymerization reactions. Our results point out that the ignition conditions with a rather low power for longer time give the best passivation, resulting an effective lifetime up to 9 ms.

  14. Structural investigation of the amorphous/crystalline interface by means of quantitative high-resolution transmission electron microscopy on the systems a-Si/c-Si and a-Ge/c-Si; Strukturelle Untersuchung der amorph/kristallinen Grenzflaeche mittels quantitativer hochaufloesender Transmissionselektronenmikroskopie an den Systemen a-Si/c-Si und a-Ge/c-Si

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, K.

    2006-11-02

    In this Thesis the interfaces between covalently bonded crystalline and amorphous materials were studied with regard to the induced ordering in the amorphous material in the interfacial region by means of high-resolution transmission electron microscopy (HREM). The interface between amorphous germanium and crystalline silicon and the interface between amorphous and crystalline silicon served as material system. In order to quantify the influence of the crystalline order on the amorphous material, the HREM images were periodically averaged along the interface. The intensity components, which are correlated with the period of the lattice image, could thus be separated from the statistical intensity fluctuations, which are characteristic for images of amorphous materials. Since amorphous materials can only be described meaningful by statistical distribution functions, for the induced order a three-dimensional distribution function {rho}{sub 3D}(r) was taken as a basis, which describes the probability to find an atom in the amorphous material, if r=0 is the position of an atom in the crystal. Its two-dimensional projection, {rho}, can be determined using iterative image matching techniques on averaged experimental and simulated interface images. For the analyzed material systems {rho} exhibits lateral ordering as well as a pronounced layering in the vicinity of the interface. In the case of the a-Si/c-Si sample the mean orientation of bonds was 70.5 , as is in the case of the undistorted diamond lattice, while for the a-Ge/c-Si sample 65 resulted. The standard deviation for the distribution of the deviations from the mean bond angle yields for the a-Ge/c-Si sample in the first atomic layer a value of 11.3 and for the a-Si/c-Si sample 1.9 . These results suggest the conclusion, that the differences in these values are to be interpreted as the reaction of the amorphous material to the volume misfit. Although for both material systems 1.4 nm was calculated for the width

  15. Evolution of enhanced crystallinity and mechanical property of nanocomposite Ti-Si-N thin films using magnetron reactive co-sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Chung, C.K., E-mail: ckchung@mail.ncku.edu.tw [Department of Mechanical Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China); Chang, H.C.; Chang, S.C.; Liao, M.W. [Department of Mechanical Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China)

    2012-10-05

    Highlights: Black-Right-Pointing-Pointer The TiN-related hard coatings encounter poor high-temperature oxidation resistance problem. Black-Right-Pointing-Pointer The transition metal-Si-N nanocomposites have used for enhancing hard coating applications. Black-Right-Pointing-Pointer The effect of process parameters on Ti-Si-N microstructure and property was studied. Black-Right-Pointing-Pointer The orientation model for texture development of TiSiN is used for deeper discussing. Black-Right-Pointing-Pointer Both Ti-Si-N microstructure and texture are crucial factors for hardness enhancement. - Abstract: Nanocomposite Ti-Si-N thin films (nc-TiN/a-SiN{sub x} or nc-TiN/a-TiSi{sub x}N{sub y}) were deposited on Si(1 0 0) substrates from pure Ti and Si targets by magnetron reactive co-sputtering with a negative bias of -150 V. The effects of N{sub 2} flow ratio (FN{sub 2}% = FN{sub 2}/(FAr + FN{sub 2}) Multiplication-Sign 100%) and Ti power on the evolution of enhanced crystallinity and mechanical properties of Ti-Si-N have been investigated. The crystallinity, morphology, microstructure, elemental composition and mechanical properties of films were characterized by grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy, energy dispersive spectroscopy and nanoindentation, respectively. When both Ti and Si target powers were fixed at 100 W, the GIXRD pattern of Ti-Si-N at 3 FN{sub 2}% exhibited a broad peak corresponding to quasi-amorphous microstructure with nanocrystalline grains embedded in an amorphous matrix. Then Ti-Si-N films showed high amount of crystallization with multiple diffraction peaks at 5 FN{sub 2}%, but the reduced peak intensity formed at 7 FN{sub 2}% and even to be amorphous films without any peak at high 10-20 FN{sub 2}%. The measured mean hardnesses of Ti-Si-N films formed at 3, 5, 7, 10 and 20 FN{sub 2}% were 18.1, 21.5, 20.4, 17.8 and 15.7 GPa, respectively. Based on the high-hardness Ti-Si-N at constant 5 FN{sub 2}%, changing Ti

  16. The Synthesis and Structural Properties of Crystalline Silicon Quantum Dots upon Thermal Annealing of Hydrogenated Amorphous Si-Rich Silicon Carbide Films

    Science.gov (United States)

    Wen, Guozhi; Zeng, Xiangbin; Li, Xianghu

    2016-08-01

    Silicon quantum dots (QDs) embedded in non-stoichiometric hydrogenated silicon carbide (SiC:H) thin films have been successfully synthesized by plasma-enhanced chemical vapor deposition and post-annealing. The chemical composition analyses have been carried out by x-ray photoelectron spectroscopy (XPS). The bonding configurations have been deduced from Fourier transform infrared absorption measurements (FTIR). The evolution of microstructure with temperature has been characterized by glancing incident x-ray diffraction (XRD) and Raman diffraction spectroscopy. XPS and FTIR show that it is in Si-rich feature and there are a few hydrogenated silicon clusters in the as-grown sample. XRD and Raman diffraction spectroscopy show that it is in amorphous for the as-grown sample, while crystalline silicon QDs have been synthesized in the 900°C annealed sample. Silicon atoms precipitation from the SiC matrix or silicon phase transition from amorphous SiC is enhanced with annealing temperature increase. The average sizes of silicon QDs are about 5.1 nm and 5.6 nm, the number densities are as high as 1.7 × 1012 cm-2 and 3.2 × 1012 cm-2, and the crystalline volume fractions are about 58.3% and 61.3% for the 900°C and 1050°C annealed samples, respectively. These structural properties analyses provide an understanding about the synthesis of silicon QDs upon thermal annealing for applications in next generation optoelectronic and photovoltaic devices.

  17. Silicon Diphosphide: A Si-Based Three-Dimensional Crystalline Framework as a High-Performance Li-Ion Battery Anode.

    Science.gov (United States)

    Kwon, Hyuk-Tae; Lee, Churl Kyoung; Jeon, Ki-Joon; Park, Cheol-Min

    2016-06-28

    The development of an electrode material for rechargeable Li-ion batteries (LIBs) and the understanding of its reaction mechanism play key roles in enhancing the electrochemical characteristics of LIBs for use in various portable electronics and electric vehicles. Here, we report a three-dimensional (3D) crystalline-framework-structured silicon diphosphide (SiP2) and its interesting electrochemical behaviors for superior LIBs. During Li insertion in the SiP2, a three-step electrochemical reaction mechanism, sequentially comprised of a topotactic transition (0.55-2 V), an amorphization (0.25-2 V), and a conversion (0-2 V), was thoroughly analyzed. On the basis of the three-step electrochemical reaction mechanism, excellent electrochemical properties, such as high initial capacities, high initial Coulombic efficiencies, stable cycle behaviors, and fast-rate capabilities, were attained from the preparation of a nanostructured SiP2/C composite. This 3D crystalline-framework-structured SiP2 compound will be a promising alternative anode material in the realization and mass production of excellent, rechargeable LIBs.

  18. Degree of crystallinity and strain in B{sub 4}C and SiC thin films as a function of processing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hershberger, J.; Yalisove, S.M.; Bilello, J.C. [Univ. of Michigan, Ann Arbor, MI (United States); Rek, Z.U. [Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.; Kustas, F. [Technology Assessment and Transfer, Annapolis, MD (United States)

    1998-12-31

    Amorphous and crystalline content in sputtered B{sub 4}C and SiC thin films has been analyzed by synchrotron grazing incidence x-ray scattering (GIXS). GIXS provided quantitative information on the average structure while TEM was used to find inhomogeneities such as small volume fraction phases. GIXS results were compared to simulations to determine average particle size or bond length for crystalline or amorphous phases respectively. In this work, the authors compared results from films deposited with, and without, an RF bias applied to the substrate during deposition. Results indicated that SiC can be described as strained polycrystalline material with particle size of approximately 13 {angstrom} for biased samples and 9 {angstrom} for unbiased samples. Boron carbide deposited without bias was completely crystalline with a particle size of approximately 30 {angstrom}, while the data suggested that B{sub 4}C deposited with bias is amorphous. The scattering from the biased materials was fourier transformed to yield radial distribution functions (RDF). This provided nearest neighbor distances, and it was demonstrated that the technique can be used to determine full three-dimensional strain tensors in amorphous thin films.

  19. An in situ gelling liquid crystalline system based on monoglycerides and polyethylenimine for local delivery of siRNAs

    NARCIS (Netherlands)

    Borgheti-Cardoso, Lívia Neves; Depieri, Lívia Vieira; Kooijmans, Sander A A; Diniz, Henrique; Calzzani, Ricardo Alexandre Junqueira; De Carvalho Vicentini, Fabiana Testa Moura; Van Der Meel, Roy; De Abreu Fantini, Márcia Carvalho; Iyomasa, Mamie Mizusaki; Schiffelers, Raymond M.; Bentley, Maria Vitória Lopes Badra; Schiffelers, Raymond

    2015-01-01

    The development of delivery systems able to complex and release siRNA into the cytosol is essential for therapeutic use of siRNA. Among the delivery systems, local delivery has advantages over systemic administration. In this study, we developed and characterized non-viral carriers to deliver siRNA

  20. An in situ gelling liquid crystalline system based on monoglycerides and polyethylenimine for local delivery of siRNAs

    NARCIS (Netherlands)

    Borgheti-Cardoso, Lívia Neves; Depieri, Lívia Vieira; Kooijmans, Sander; Diniz, Henrique; Calzzani, Ricardo Alexandre Junqueira; De Carvalho Vicentini, Fabiana Testa Moura; van der Meel, Roy; De Abreu Fantini, Márcia Carvalho; Iyomasa, Mamie Mizusaki; Schiffelers, Raymond; Bentley, Maria Vitória Lopes Badra

    2015-01-01

    The development of delivery systems able to complex and release siRNA into the cytosol is essential for therapeutic use of siRNA. Among the delivery systems, local delivery has advantages over systemic administration. In this study, we developed and characterized non-viral carriers to deliver siRNA

  1. Enhanced conversion efficiency and surface hydrophobicity of nano-roughened Teflon-like film coated poly-crystalline Si solar cells.

    Science.gov (United States)

    Lin, Gong-Ru; Meng, Fan-Shuen; Pai, Yi-Hao; Lin, Yung-Hsiang

    2012-03-21

    Nano-roughened Teflon-like film coated poly-crystalline Si photovoltaic solar cells (PVSCs) with enhanced surface hydrophobicity and conversion efficiency (η) are characterized and compared with those coated by a Si nanorod array or a standard SiN anti-reflection layer. The Teflon-like film coated PVSC surface reveals a water contact angle increasing from 89.3° to 96.2° as its thickness enlarges from 22 to 640 nm, which is much larger than those of the standard and Si nanorod array coated PVSC surfaces (with angles of 55.6° and 32.8°, respectively). After nano-roughened Teflon-like film passivation, the PVSC shows a comparable η(10.89%) with the standard SiN coated PVSC (η = 11.39%), while the short-circuit current (I(SC)) is slightly reduced by 2% owing to the slightly decreased UV transmittance and unchanged diode performance. In contrast, the Si nanorod array may offer an improved surface anti-reflection with surface reflectance decreasing from 30% to 5% at a cost of optical scattering and randomized deflection, which simultaneously decrease the optical transmittance from 15% to 3% in the visible region without improving hydrophobicity and conversion efficiency. The Si nanorod array covered PVSC with numerous surface dangling bonds induced by 1 min wet-etching, which greatly reduces the open-circuit voltage (V(OC)) by 10-15% and I(SC) by 30% due to the reduced shunt resistance from 3 to 0.24 kΩ. The nano-scale roughened Teflon-like film coated on PVSC has provided better hydrophobicity and conversion efficiency than the Si nanorod array covered PVSC, which exhibits superior water repellant performance and comparable conversion efficiency to be one alternative approach for self-cleaning PVSC applications.

  2. Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes

    OpenAIRE

    Angeles-Chávez C; Martínez-Hernández AL; Velasco-Santos C.; Espíndola-Gonzalez A; Castaño VM

    2010-01-01

    Abstract The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids (Eisenia foetida) is reported. The product (humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransformation allows creating specific crystalline phase...

  3. Formation and annihilation of intrinsic defects induced by electronic excitation in high-purity crystalline SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kajihara, Koichi [Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji 192-0397 (Japan); Skuja, Linards [Institute of Solid State Physics, University of Latvia, Kengaraga iela 8, LV1063 Riga (Latvia); Hosono, Hideo [Materials and Structures Laboratory and Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2013-04-14

    Formation and thermal annihilation of intrinsic defects in {alpha}-quartz were examined using high-purity samples, while minimizing the contributions of reactions involving metallic impurities. Electronic excitation with {sup 60}Co {gamma}-rays was employed to avoid radiation-induced amorphization. The results clearly show that formation of oxygen vacancies (Si-Si bonds) as a result of decomposition of regular Si-O-Si bonds (Frenkel process) is the dominant intrinsic defect process. Compared with amorphous SiO{sub 2}, in {alpha}-quartz, the formation yield of Si-Si bonds is an order of magnitude smaller, the 7.6 eV optical absorption band is less broadened, and their thermal annihilation is complete at a lower temperature, around the {alpha}-{beta} quartz transition. In contrast, radiation-induced interstitial oxygen atoms practically do not form interstitial oxygen molecules.

  4. Electrical Properties of Photodiode Ba0.25Sr0.75TiO3 (BST Thin Film Doped with Ferric Oxide on p-type Si (100 Substrate using Chemical Solution Deposition Method

    Directory of Open Access Journals (Sweden)

    Irzaman

    2011-12-01

    Full Text Available In this paper we have grown pure Ba0.25Sr0.75TiO3 (BST and BST doped by Ferric Oxide Fe2O3 (BFST with doping variations of 5%, 10%, and 15% above type-p Silicon (100 substrate using the chemical solution deposition (CSD method with spin coating technique at rotation speed of 3000 rpm, for 30 seconds. BST thin film are made with a concentration of 1 M 2-methoxyethanol and annealing temperature of 850OC for the Si (100 substrate. Characterization of the thin film is performed for the electrical properties such as the current-voltage (I-V curve using Keithley model 2400 as well as dielectric constant, time constant, pyroelectric characteristics, and depth measurement. The results show that the thin film depth increases if the concentration of the Ferric Oxide doping increases. The I-V characterization shows that the BST and BFST thin film has photodiode properties. The dielectric constant increases with the addition of doping. The maximum dielectric constant value is obtained for 15 % doping concentration namely 83.1 for pure BST and 6.89, 11.1, 41.63 and 83.1, respectively for the Ferric Oxide doping based BST with concentration of 5%, 10%, and 15%. XRD spectra of 15 % of ferric oxide doped BST thin film tetragonal phase, we carried out the lattice constant were a = b = 4.203 Å; c = 4.214 Å; c/a ratio = 1.003

  5. Characteristics of poly- and mono-crystalline BeO and SiO{sub 2} as thermal and cold neutron filters

    Energy Technology Data Exchange (ETDEWEB)

    Adib, M.; Habib, N. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Bashter, I.I. [Physics Department, Faculty of Science, Zagazig University (Egypt); Morcos, H.N.; El-Mesiry, M.S. [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt); Mansy, M.S., E-mail: drmohamedmansy88@hotmail.com [Reactor Physics Department, NRC, Atomic Energy Authority, Cairo (Egypt)

    2015-09-01

    Highlights: • Neutron filtering features of BeO and SiO{sub 2} poly- and mono-crystals. • Calculations of the cold and thermal neutron cross sections and transmission with the code “HEXA-FILTERS”. • Optimal mosaic spread, thicknesses and cutting planes for BeO and SiO{sub 2} mono-crystals. - Abstract: A simple model along with a computer code “HEXA-FILTERS” is used to carry out the calculation of the total cross-sections of BeO and SiO{sub 2} having poly or mono-crystalline form as a function of neutron wavelength at room (R.T.) and liquid nitrogen (L.N.) temperatures. An overall agreement is indicated between the calculated neutron cross-sections and experimental data. Calculation shows that 25 cm thick of polycrystalline BeO cooled at liquid nitrogen temperature was found to be a good filter for neutron wavelengths longer than 0.46 nm. While, 50 cm of SiO{sub 2}, with much less transmission, for neutrons with wavelengths longer than 0.85 nm. It was also found that 10 cm of BeO and 15 cm SiO{sub 2} thick mono-crystals cut along their (0 0 2) plane, with 0.5° FWHM on mosaic spread and cooled at L.N., are a good thermal neutron filter, with high effect-to-noise ratio.

  6. One-step synthesis route of the aligned and non-aligned single crystalline α-Si3N4 nanowires

    Institute of Scientific and Technical Information of China (English)

    shkoor; AHMAD

    2009-01-01

    This paper reports the bulk synthesis route of the aligned and non-aligned high-quality α-Si3N4 nanowires (NWS) which were grown directly from the Si substrate by vapor phase deposition at 1050℃. The as-grown products were characterized by employing XRD, SEM, HRTEM and photoluminescence. The microscopic results revealed that the products consist of single crystalline aligned and nonaligned α-Si3N4 NWs having a same diameter range of 30-100 nm and different lengths of about hundreds of microns. The XRD observation revealed that the products consist of α-phase Si3N4 NWs. The room temperature PL spectra indicated that the NWs have good emission property. The non-aligned NWs were formed at lower temperature as compared with aligned NWs. Our method is a simple and one-step procedure to synthesize the bulk-quantity and high-purity aligned and non-aligned α-Si3N4 NWs at a relatively low temperature. The possible growth mechanism was also briefly discussed.

  7. One-step synthesis route of the aligned and non-aligned single crystalline α-Si3N4 nanowires

    Institute of Scientific and Technical Information of China (English)

    Mashkoor AHMAD; ZHAO Jiong; ZHANG Fan; PAN CaoFeng; ZHU Jing

    2009-01-01

    This paper reports the bulk synthesis route of the aligned and non-aligned high-quality α-Si3N4 nanowires (NWS) which were grown directly from the Si substrate by vapor phase deposition at 1050℃. The as-grown products were characterized by employing XRD, SEM, HRTEM and photoluminescence. The microscopic results revealed that the products consist of single crystalline aligned and non-aligned α-Si3N4 NWs having a same diameter range of 30-100 nm and different lengths of about hun-dreds of microns. The XRD observation revealed that the products consist of co-phase Si3N4 NWs. The room temperature PL spectra indicated that the NWs have good emission property. The non-aligned NWs were formed at lower temperature as compared with aligned NWs. Our method is a simple and one-step procedure to synthesize the bulk-quantity and high-purity aligned and non-aligned α-Si3N4NWs at s relatively low temperature. The possible growth mechanism was also briefly discussed.

  8. Magnetotransport, structural and optical characterization of p-type modulation doped heterostructures with high Ge content Si sub 1 sub - sub x Ge sub x channel grown by SS-MBE on Si sub 1 sub - sub y Ge sub y /Si(001) virtual substrates

    CERN Document Server

    Myronov, M

    2001-01-01

    sub 4 Ge sub 0 sub . sub 6 linearly graded VS and corresponds to 14855cm sup 2 centre dot V sup - sup 1 centre dot s sup - sup 1 (2.87 centre dot 10 sup 1 sup 2 cm sup - sup 2). The highest Hall mobility (at sheet carrier density) measured at 293K was observed for Si sub 0 sub . sub 2 Ge sub 0 sub . sub 8 /Si sub 0 sub . sub 6 sub 5 Ge sub 0 sub . sub 3 sub 5 heterostructure after FTA at 750C for 30min and corresponds to 1776cm sup 2 centre dot V sup - sup 1 centre dot s sup - sup 1 (2.37 centre dot 10 sup 1 sup 3 cm sup - sup 2). To extract the drift mobility and sheet carrier density of 2DHG at temperatures up to 300K, magnetotransport measurements in magnetic fields up to 11T were performed on several heterostructures. The data were analyzed by technique of Maximum-Entropy Mobility Spectrum Analysis. The highest drift mobility (at sheet carrier density) of 2DHG at 290K was obtained for the Si sub 0 sub . sub 2 Ge sub 0 sub . sub 8 /Si sub 0 sub . sub 6 sub 5 Ge sub 0 sub . sub 3 sub 5 heterostructure after...

  9. Plasma etching on large-area mono-, multi- and quasi-mono crystalline silicon

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Schmidt, Michael Stenbæk; Boisen, Anja

    2013-01-01

    We use plasma etched Black Si (BS)[1][2] nanostructures to achieve low reflectance due to the resulting graded refractive index at the Si-air interface. The goal of this investigation is to develop a suitable texturing method for Si solar cells. Branz et al. [3]report below 3% average reflectance...... advantages such as; (i) excellent light trapping, (ii) dry, single-sided and scalable process method and (iii) etch independence on crystallinity of Si, RIE-texturing has so far not been proven superior to standard wet texturing, primarily as a result of lower power conversion efficiency due to increased...... using maskless RIE in a O2 and SF6 plasma, and the surface topology was optimized for solar cell applications by varying gas flows, pressure, power and process time. The starting substrates were 156x156 mm p-type, CZ mono-, multi- and quasi-mono crystalline Si wafers, respectively, with a thickness...

  10. Ultraviolet responses of a heterojunction Si quantum dot solar cell.

    Science.gov (United States)

    Lee, Seong Hyun; Kwak, Gyea Young; Hong, Songwoung; Kim, Chanhong; Kim, Sung; Kim, Ansoon; Kim, Kyung Joong

    2017-01-20

    We investigated the ultraviolet (UV) responses of a heterojunction Si quantum dot (QD) solar cell consisting of p-type Si-QDs fabricated on a n-type crystalline Si (p-Si-QD/n-c-Si HJSC). The UV responses were compared with a conventional n-type crystalline Si solar cell (n-c-Si SC). The external and internal quantum efficiency results of the p-Si-QD/n-c-Si HJSC exhibited a clear enhancement in the UV responses (300-400 nm), which was not observed in the n-c-Si SC. Based on the results of the cell reflectance and bias-dependent responses, we expect that almost all UV responses occur in the p-Si-QD layer, and the generated carriers can be transported via the Si-QD layer due to the formation of a sufficient electric filed. As a result, a high power conversion efficiency of 14.5% was achieved from the p-Si-QD/n-c-Si HJSC. By reducing the thickness of the n-Si substrate from 650 μm to 300 μm, more enhanced power conversion efficiency of 14.8% was obtained which is the highest value among the reported Si-QD based solar cells to date.

  11. Ultraviolet responses of a heterojunction Si quantum dot solar cell

    Science.gov (United States)

    Lee, Seong Hyun; Kwak, Gyea Young; Hong, Songwoung; Kim, Chanhong; Kim, Sung; Kim, Ansoon; Kim, Kyung Joong

    2017-01-01

    We investigated the ultraviolet (UV) responses of a heterojunction Si quantum dot (QD) solar cell consisting of p-type Si-QDs fabricated on a n-type crystalline Si (p-Si-QD/n-c-Si HJSC). The UV responses were compared with a conventional n-type crystalline Si solar cell (n-c-Si SC). The external and internal quantum efficiency results of the p-Si-QD/n-c-Si HJSC exhibited a clear enhancement in the UV responses (300–400 nm), which was not observed in the n-c-Si SC. Based on the results of the cell reflectance and bias-dependent responses, we expect that almost all UV responses occur in the p-Si-QD layer, and the generated carriers can be transported via the Si-QD layer due to the formation of a sufficient electric filed. As a result, a high power conversion efficiency of 14.5% was achieved from the p-Si-QD/n-c-Si HJSC. By reducing the thickness of the n-Si substrate from 650 μm to 300 μm, more enhanced power conversion efficiency of 14.8% was obtained which is the highest value among the reported Si-QD based solar cells to date.

  12. Decoupling crystalline volume fraction and V{sub OC} in microcrystalline silicon pin solar cells by using a {mu}c-Si:F:H intrinsic layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q.; Johnson, E.V.; Djeridane, Y.; Abramov, A.; Roca i Cabarrocas, P. [LPICM-CNRS, Ecole Polytechnique, Palaiseau (France)

    2008-08-15

    Microcrystalline silicon thin film pin solar cells with a highly crystallized intrinsic {mu}c-Si:F:H absorber were prepared by RF-plasma enhanced chemical vapour deposition using SiF{sub 4} as the gas precursor. The cells were produced with a vacuum break between the doped layer and intrinsic layer depositions, and the effect of different subsequent interface treatment processes was studied. The use of an intrinsic {mu}c-Si:H p/i buffer layer before the first air break increased the short circuit current density from 22.3 mA/cm{sup 2} to 24.7 mA/cm{sup 2}. However, the use of a hydrogen-plasma treatment after both air breaks without an interface buffer layer improved both the open circuit voltage and the fill factor. Although the material used for the absorber layer showed a very high crystalline fraction and thus an increased spectral response at long wavelengths, an open-circuit voltage (V{sub OC}) of 0.523 V was nevertheless observed. Such a value of V{sub OC} is higher than is typically obtained in devices that employ a highly crystallized absorber as reported in the literature (see abstract figure). Using a hydrogen-plasma treatment, a single junction {mu}c-Si:F:H pin solar cell with an efficiency of 8.3% was achieved. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Impact of LT-GaAs layers on crystalline properties of the epitaxial GaAs films grown by MBE on Si substrates

    Science.gov (United States)

    Petrushkov, M. O.; Putyato, M. A.; Gutakovsky, A. K.; Preobrazhenskii, V. V.; Loshkarev, I. D.; Emelyanov, E. A.; Semyagin, B. R.; Vasev, A. V.

    2016-08-01

    GaAs films with low-temperature GaAs (LT-GaAs) layers were grown by molecular beam epitaxy (MBE) method on vicinal (001) Si substrates oriented 6° off towards [110]. The grown structures were different with the thickness of LT-GaAs layers and its arrangement in the film. The processes of epitaxial layers nucleation and growth were controlled by reflection high energy electron diffraction (RHEED) method. Investigations of crystalline properties of the grown structures were carried out by the methods of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The crystalline perfection of the GaAs films with LT-GaAs layers and the GaAs films without ones was comparable. It was found that in the LT- GaAs/Si layers the arsenic clusters are formed, as it occurs in the LT-GaAs/GaAs system without dislocation. It is shown that large clusters are formed mainly on the dislocations. However, the clusters have practically no effect on the density and the propagation path of threading dislocations. With increasing thickness of LT-GaAs layer the dislocations are partly bent along the LT-GaAs/GaAs interface due to the presence of stresses.

  14. Luminescent and scintillation properties of Bi{sup 3+} doped Y{sub 2}SiO{sub 5} and Lu{sub 2}SiO{sub 5} single crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu., E-mail: zorenko@ukw.edu.pl [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Gorbenko, V.; Zorenko, T. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Laboratory for Optoelectronic Materials (LOM), Department of Electronics of Ivan Franko National University of Lviv, 79017 Lviv (Ukraine); Malinowski, P. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Jary, V.; Kucerkova, R.; Beitlerova, A.; Mares, J.A.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Fedorov, A. [Institute for Single Crystals NAS of Ukraine, 60 Lenin ave., 61001 Kharkiv (Ukraine)

    2014-10-15

    In this paper we report our follow-up research on the Bi{sup 3+} luminescence in orthosilicate compounds, focusing on absorption, luminescent and scintillation properties of YSO:Bi and LSO:Bi SCFs with the Bi concentration ranging from 0.05 to 0.18 at%. For purpose of this research, single crystalline films (SCF) of Y{sub 2}SiO{sub 5}:Bi and Lu{sub 2}SiO{sub 5}:Bi have been grown by the LPE method onto YSO and LSO substrates from the melt-solution based on Bi{sub 2}O{sub 3} flux. - Highlights: • YSO:Bi and LSO:Bi films have been grown by liquid phase epitaxy. • Bi{sup 3+} absorption and luminescence depends on Bi concentration. • Scintillation properties of YSO:Bi and LSO:Bi films have been studied.

  15. Raman scattering study of ro-vibrational modes of interstitial H{sub 2} in crystalline Si

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Sandro; Lavrov, Edward; Weber, Joerg [Technische Universitaet Dresden, 01062 Dresden (Germany)

    2011-07-01

    Raman scattering studies of Si samples hydrogenated in a rf plasma have been performed. Ro-vibrational Q(J) transitions for rotational quantum number J=0,1,2, and 3 have been investigated in the temperature range from 90 to 388 K. We demonstrate that the Q(2) transition appears in the Raman spectra above 200 K as suggested by Hiller et al. Additionally, the Q(3) transition is detected at 388 K. From the temperature dependence of the phonon spectrum of the Si host, we can show that the coupling between rotational states of H{sub 2} depends on the temperature.

  16. Fabrication and characterization of Al2O3 /Si composite nanodome structures for high efficiency crystalline Si thin film solar cells

    Science.gov (United States)

    Zhang, Ruiying; Zhu, Jian; Zhang, Zhen; Wang, Yanyan; Qiu, Bocang; Liu, Xuehua; Zhang, Jinping; Zhang, Yi; Fang, Qi; Ren, Zhong; Bai, Yu

    2015-12-01

    We report on our fabrication and characterization of Al2O3/Si composite nanodome (CND) structures, which is composed of Si nanodome structures with a conformal cladding Al2O3 layer to evaluate its optical and electrical performance when it is applied to thin film solar cells. It has been observed that by application of Al2O3thin film coating using atomic layer deposition (ALD) to the Si nanodome structures, both optical and electrical performances are greatly improved. The reflectivity of less than 3% over the wavelength range of from 200 nm to 2000 nm at an incident angle from 0° to 45° is achieved when the Al2O3 film is 90 nm thick. The ultimate efficiency of around 27% is obtained on the CND textured 2 μm-thick Si solar cells, which is compared to the efficiency of around 25.75% and 15% for the 2 μm-thick Si nanodome surface-decorated and planar samples respectively. Electrical characterization was made by using CND-decorated MOS devices to measure device's leakage current and capacitance dispersion. It is found the electrical performance is sensitive to the thickness of the Al2O3 film, and the performance is remarkably improved when the dielectric layer thickness is 90 nm thick. The leakage current, which is less than 4x10-9 A/cm2 over voltage range of from -3 V to 3 V, is reduced by several orders of magnitude. C-V measurements also shows as small as 0.3% of variation in the capacitance over the frequency range from 10 kHz to 500 kHz, which is a strong indication of surface states being fully passivated. TEM examination of CND-decorated samples also reveals the occurrence of SiOx layer formed between the interface of Si and the Al2O3 film, which is thin enough that ensures the presence of field-effect passivation, From our theoretical and experimental study, we believe Al2O3 coated CND structures is a truly viable approach to achieving higher device efficiency.

  17. Fabrication and characterization of Al{sub 2}O{sub 3} /Si composite nanodome structures for high efficiency crystalline Si thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ruiying, E-mail: ryzhang2008@sinano.ac.cn [Key lab of nanodevices and applications, Chinese Academy of Sciences, Division of nano-devices and related materials, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, 215123 (China); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050 China (China); Zhu, Jian; Zhang, Zhen; Wang, Yanyan; Qiu, Bocang [Key lab of nanodevices and applications, Chinese Academy of Sciences, Division of nano-devices and related materials, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, 215123 (China); Liu, Xuehua; Zhang, Jinping; Zhang, Yi [Platform for Characterization & Test, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou, 215123 (China); Fang, Qi; Ren, Zhong [Oxford Instruments Plasma Technology, Yatton, Bristol, BS49 4AP (United Kingdom); Bai, Yu [School of Nano-Science and Nano-Engineering, Xi’an Jiaotong University, Suzhou, 215123 (China)

    2015-12-15

    We report on our fabrication and characterization of Al{sub 2}O{sub 3}/Si composite nanodome (CND) structures, which is composed of Si nanodome structures with a conformal cladding Al{sub 2}O{sub 3} layer to evaluate its optical and electrical performance when it is applied to thin film solar cells. It has been observed that by application of Al{sub 2}O{sub 3}thin film coating using atomic layer deposition (ALD) to the Si nanodome structures, both optical and electrical performances are greatly improved. The reflectivity of less than 3% over the wavelength range of from 200 nm to 2000 nm at an incident angle from 0° to 45° is achieved when the Al{sub 2}O{sub 3} film is 90 nm thick. The ultimate efficiency of around 27% is obtained on the CND textured 2 μm-thick Si solar cells, which is compared to the efficiency of around 25.75% and 15% for the 2 μm-thick Si nanodome surface-decorated and planar samples respectively. Electrical characterization was made by using CND-decorated MOS devices to measure device’s leakage current and capacitance dispersion. It is found the electrical performance is sensitive to the thickness of the Al{sub 2}O{sub 3} film, and the performance is remarkably improved when the dielectric layer thickness is 90 nm thick. The leakage current, which is less than 4x10{sup −9} A/cm{sup 2} over voltage range of from -3 V to 3 V, is reduced by several orders of magnitude. C-V measurements also shows as small as 0.3% of variation in the capacitance over the frequency range from 10 kHz to 500 kHz, which is a strong indication of surface states being fully passivated. TEM examination of CND-decorated samples also reveals the occurrence of SiO{sub x} layer formed between the interface of Si and the Al{sub 2}O{sub 3} film, which is thin enough that ensures the presence of field-effect passivation, From our theoretical and experimental study, we believe Al{sub 2}O{sub 3} coated CND structures is a truly viable approach to achieving higher device

  18. Fabrication and characterization of Al2O3 /Si composite nanodome structures for high efficiency crystalline Si thin film solar cells

    Directory of Open Access Journals (Sweden)

    Ruiying Zhang

    2015-12-01

    Full Text Available We report on our fabrication and characterization of Al2O3/Si composite nanodome (CND structures, which is composed of Si nanodome structures with a conformal cladding Al2O3 layer to evaluate its optical and electrical performance when it is applied to thin film solar cells. It has been observed that by application of Al2O3thin film coating using atomic layer deposition (ALD to the Si nanodome structures, both optical and electrical performances are greatly improved. The reflectivity of less than 3% over the wavelength range of from 200 nm to 2000 nm at an incident angle from 0° to 45° is achieved when the Al2O3 film is 90 nm thick. The ultimate efficiency of around 27% is obtained on the CND textured 2 μm-thick Si solar cells, which is compared to the efficiency of around 25.75% and 15% for the 2 μm-thick Si nanodome surface-decorated and planar samples respectively. Electrical characterization was made by using CND-decorated MOS devices to measure device’s leakage current and capacitance dispersion. It is found the electrical performance is sensitive to the thickness of the Al2O3 film, and the performance is remarkably improved when the dielectric layer thickness is 90 nm thick. The leakage current, which is less than 4x10−9 A/cm2 over voltage range of from -3 V to 3 V, is reduced by several orders of magnitude. C-V measurements also shows as small as 0.3% of variation in the capacitance over the frequency range from 10 kHz to 500 kHz, which is a strong indication of surface states being fully passivated. TEM examination of CND-decorated samples also reveals the occurrence of SiOx layer formed between the interface of Si and the Al2O3 film, which is thin enough that ensures the presence of field-effect passivation, From our theoretical and experimental study, we believe Al2O3 coated CND structures is a truly viable approach to achieving higher device efficiency.

  19. Ni/Cu/Ag plated contacts: A study of resistivity and contact adhesion for crystalline-Si solar cells

    Science.gov (United States)

    ur Rehman, Atteq; Lee, Sang Hee; Bhopal, Muhammad Fahad; Lee, Soo Hong

    2016-07-01

    Ni/Cu/Ag plated contacts were examined as an alternate to Ag screen printed contacts for silicon (Si) solar cell metallization. To realize a reliable contact for industrial applications, the contact resistance and its adhesion to Si substrates were evaluated. Si surface roughness by picosecond (ps) laser ablation of silicon-nitride (SiNx) antireflection coating (ARC) was done in order to prepare the patterns. The sintering process after Ni/Cu/Ag full metallization in the form of the post-annealing process was applied to investigate the contact resistivity and adhesion. A very low contact resistivity of approximately 0.5 mΩcm2 has been achieved with measurements made by the transfer length method (TLM). Thin finger lines of about 26 μm wide and a line resistance of 0.51 Ω/cm have been realized by plating technology. Improved contact adhesion by combining the ps-laser-ablation and post-annealing process has been achieved. We have shown the peel-off strengths >1 N/mm with a higher average adhesion of 1.9 N/mm. Our pull-tab adhesion tests demonstrate excellent strength well above the wafer breakage force. [Figure not available: see fulltext.

  20. Crystalline Fraction and Doping Concentration Effect on Heterojunction Solar Cells n-Doped µc-Si:H Back Surface Field Layer.

    Science.gov (United States)

    Kim, Sangho; Shin, Chonghoon; Balaji, Nagarajan; Yi, Junsin

    2015-03-01

    The back surface field (BSF) plays a vital role for high efficiency in the Heterojunction Intrinsic Thin (HIT) film solar cell. This paper investigated the effect of crystalline volume fraction (Xc) and 1% hydrogen diluted phosphine (PH3) gas doping concentration of the n-type µc-Si:H back surface file (BSF) layer. Initially, the thickness of the n-type µc-Si:H BSF layer was optimized. With increase in Xc from 6% to 59%, the open circuit voltage (Voc) increased from 573 mV to 696 mV, and the fill factor (FF) also increased from 59% to 71%. In the long wavelengths region (≥ 950 nm), the QE of the solar cells decreased over the optimized Xc of the n-doped micro BSF layer, due to the defects of a film. In the second part of this paper, the effect of high conductivity n-type µc-Si:H BSF layer with optimized thickness on the performance of HIT solar cells was investigated, by doping gas ratio variation. Even though Xc decreased, conductivity was increased, with increasing PH3 doping concentration. Under the optimized condition, a n-µc-Si:H BSF layer has a dark conductivity of 2.59 S/cm, activation energy of 0.0519 eV, and X, of 52%. The conversion efficiency of 18.9% was achieved with a Voc of 706 mV, fill factor of 72%, and short circuit current density of 37.1 mW·cm(-2).

  1. Evolution of plant P-type ATPases

    Directory of Open Access Journals (Sweden)

    Christian N.S. Pedersen

    2012-02-01

    Full Text Available Five organisms having completely sequenced genomes and belonging to all major branches of green plants (Viridiplantae were analyzed with respect to their content of P-type ATPases encoding genes. These were the chlorophytes Ostreococcus tauria and Chlamydomonas reinhardtii, and the streptophytes Physcomitrella patens (a moss, Selaginella moellendorffii (a primitive vascular plant, and Arabidopsis thaliana (a model flowering plant. Each organism contained sequences for all five subfamilies of P-type ATPases. Our analysis demonstrates when specific subgroups of P-type ATPases disappeared in the evolution of Angiosperms. Na/K-pump related P2C ATPases were lost with the evolution of streptophytes whereas Na+ or K+ pumping P2D ATPases and secretory pathway Ca2+-ATPases remained until mosses. An N-terminally located calmodulin binding domain in P2B ATPases can only be detected in pumps from Streptophytae, whereas, like in animals, a C-terminally localized calmodulin binding domain might be present in chlorophyte P2B Ca2+-ATPases. Chlorophyte genomes encode P3A ATPases resembling protist plasma membrane H+-ATPases and a C-terminal regulatory domain is missing. The complete inventory of P-type ATPases in the major branches of Viridiplantae is an important starting point for elucidating the evolution in plants of these important pumps.

  2. Behind the Nature of Titanium Oxide Excellent Surface Passivation and Carrier Selectivity of c-Si

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Crovetto, Andrea; Hansen, Ole

    We present an expanded study of the passivation properties of titanium dioxide (TiO2) on p-type crystalline silicon (c-Si). We report a low surface recombination velocity (16 cm/s) for TiO2 passivation layers with a thin tunnelling oxide interlayer (SiO2 or Al2O3) on p-type crystalline silicon (c......-Si). The TiO2 films were deposited by thermal atomic layer deposition (ALD) at temperatures in the range of 80-300  ̊C using titanium tetrachloride (TiCl4) as Ti precursor and water as the oxidant. The influence of TiO2 thickness (5, 10, 20 nm), presence of additional tunneling interlayer (SiO2 or Al2O3...

  3. Dual ohmic contact to N- and P-type silicon carbide

    Science.gov (United States)

    Okojie, Robert S. (Inventor)

    2013-01-01

    Simultaneous formation of electrical ohmic contacts to silicon carbide (SiC) semiconductor having donor and acceptor impurities (n- and p-type doping, respectively) is disclosed. The innovation provides for ohmic contacts formed on SiC layers having n- and p-doping at one process step during the fabrication of the semiconductor device. Further, the innovation provides a non-discriminatory, universal ohmic contact to both n- and p-type SiC, enhancing reliability of the specific contact resistivity when operated at temperatures in excess of 600.degree. C.

  4. Fabrication of c-Si:H(p)/c-Si(n) Heterojunction Solar Cells with Microcrystalline Emitters

    Institute of Scientific and Technical Information of China (English)

    ZHOU Bing-Qing; LIU Feng-Zhen; ZHANG Qun-Fang; XU Ying; ZHOU Yu-Qin; LIU Jin-Long; ZHU Mei-Fang

    2006-01-01

    The p-type microcrystalline silicon (fj,c-Si) on n-type crystalline silicon (c-Si) heterojunction solar cells is fabricated by radio-frequency plasma enhanced chemical vapour deposition (rf-PECVD). The effect of the pc-Si:H p-layers on the performance of the heterojunction solar cells is investigated. Optimum μcSi:H p-layer is obtained with hydrogen dilution ratio of 99.65%, rf-power of 0.08 W/cm2, gas phase doping ratio of 0.125%, and the p-layer thickness of 15 nm. We fabricate μc-Si:H(p)/c-Si(n) heterojunction solar cells without texturing and obtained an efficiency of 13.4%. The comparisons of the solar-cell performances using different surface passivation techniques are discussed.

  5. Micropower thermoelectric generator from thin Si membranes

    OpenAIRE

    2014-01-01

    We report the development of a Si-based micro thermogenerator build from silicon-on-insulator by using standard CMOS processing. Ultrathin single-crystalline Si membranes, 100 nm in thickness, with embedded n and p-type doped regions electrically connected in series and thermally in parallel, are active elements of the thermoelectric device that generate thermopower under various thermal gradients. This proof-of-concept device produces an output power density of 4.5 µW/cm2, under a temperatur...

  6. Optical and structural properties of InAs nanoclusters in crystalline Si obtained through sequential ion implantation and RTA

    Energy Technology Data Exchange (ETDEWEB)

    Sortica, Mauricio A.; Canut, Bruno; Chauvin, Nicolas [Institut des Nanotechnologies de Lyon INL-UMR5270, INSA - Lyon, CNRS, 7 av. Jean Capelle, 69621, Villeurbanne (France); Hatori, Masahiro; Dias, Johnny F. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul IF-UFRGS, av. Bento Goncalves 9500, 91501-970, Porto Alegre - RS (Brazil); Marty, Olivier [Institut des Nanotechnologies de Lyon INL-UMR5270, Universite Claude Bernard Lyon 1, 8 rue Andre-Marie Ampere, 69622, Villeurbanne (France)

    2015-12-15

    Si (100) wafers were implanted at 500 C with 250 keV As ions and 350 keV In ions in this order. The implantations were carried out with three different fluences, namely 1 x 10{sup 16}, 2 x 10{sup 16}, and 5 x 10{sup 16} cm{sup -2}. The samples were annealed with rapid thermal annealing (RTA) for 30 s at temperatures ranging from 800 up to 1000 C. Different techniques like photoluminescence (PL) and Rutherford backscattering spectrometry (RBS) were employed to characterize the samples. Finally, scanning and transmission electron microscopy (SEM and TEM, respectively) provided further structural information of the InAs nanoclusters. The results indicate that InAs nanoprecipitates are formed after RTA treatment. Moreover, a broad photoluminescence peak was observed in all samples submitted to RTA. RBS results reveal that losses of implanted ions due to diffusion processes can be minimized through the use of RTA, depending of the fluence of ion implantation. Finally, the present results suggest that the photoluminescence yield depends on the degree of the radiation damage induced in the Si matrix during the implantation process. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. PEALD-Grown Crystalline AlN Films on Si (100) with Sharp Interface and Good Uniformity

    Science.gov (United States)

    Liu, Sanjie; Peng, Mingzeng; Hou, Caixia; He, Yingfeng; Li, Meiling; Zheng, Xinhe

    2017-04-01

    Aluminum nitride (AlN) thin films were deposited on Si (100) substrates by using plasma-enhanced atomic layer deposition method (PEALD). Optimal PEALD parameters for AlN deposition were investigated. Under saturated deposition conditions, the clearly resolved fringes are observed from X-ray reflectivity (XRR) measurements, showing the perfectly smooth interface between the AlN film and Si (100). It is consistent with high-resolution image of the sharp interface analyzed by transmission electron microscope (TEM). The highly uniform thickness throughout the 2-inch size AlN film with blue covered surface was determined by spectroscopic ellipsometry (SE). Grazing incident X-ray diffraction (GIXRD) patterns indicate that the AlN films are polycrystalline with wurtzite structure and have a tendency to form (002) preferential orientation with increasing of the thickness. The obtained AlN films could open up a new approach of research in the use of AlN as the template to support gallium nitride (GaN) growth on silicon substrates.

  8. Effects of post-deposition annealing on crystalline state of GeSn thin films sputtered on Si substrate and its application to MSM photodetector

    Science.gov (United States)

    Mahmodi, H.; Hashim, M. R.

    2016-10-01

    Ge1-x Sn x alloy thin films were prepared by co-sputtering from Ge and Sn targets on a Si (100) substrate at room temperature, and were then heated at temperature ranging from 200 {}\\circ {{C}} to 500 {}\\circ {{C}} in N2 ambient to reduce the disorder and defects and increase the crystalline quality of the films. Images obtained by field emission scanning electron microscopy revealed that the as-grown and all annealed samples displayed a densely packed morphology. The atomic percent composition of Sn in the as-grown Ge1-x Sn x film is 5.7 at % . Energy-dispersive x-ray spectroscopy results showed Sn surface segregation after heat treatment, as the Sn composition is reduced to 3.3 at % for the film annealed at 500 {}\\circ C. The Raman analysis showed that the only observed phonon mode is attributed to Ge-Ge vibrations. The Raman spectra of as-sputtered and annealed films revealed their nanocrystalline-amorphous nature. The samples annealed at lower temperature exhibited higher phonon intensity, indicating the improvement of crystallinity of the film. The optoelectronic characteristics of fabricated metal-semiconductor-metal photodetectors on the annealed sample at 200 {}\\circ {{C}} and the as-sputtered sample were studied in the dark and under illumination. Compared with the as-sputtered one, the annealed sample showed lower dark current and higher current gain of 209. The results showed the potentiality of using the sputtering technique to produce GeSn layer for optoelectronics application.

  9. Fabrication and electrical characteristics of Si nanocrystal/c-Si heterojunctions

    Science.gov (United States)

    Song, Dengyuan; Cho, Eun-Chel; Conibeer, Gavin; Huang, Yidan; Green, Martin A.

    2007-09-01

    Heterojunctions (HJs) were fabricated from p-type Si nanocrystals (Si NCs) embedded in a SiC matrix on an n-type crystalline Si substrate. Transmission electron microscopy revealed that Si NCs are clearly established, with sizes in the range of 3-5nm. The HJ diodes showed a good rectification ratio of 1.0×104 at ±1.0V at 298K. The ideality factor, junction built-in potential, and open-circuit voltage are ˜1.24, 0.72V, and 0.48V, respectively. Measurement of temperature-dependent I-V curves in forward conduction suggests that, in the medium voltage range, junction interface recombination can be described as the dominant current transport mechanism.

  10. Stabilisation of a thin crystalline Si wafer solar cell using glass substrate; Duenne kristalline Silizium Wafer-Solarzelle mit Glastraeger stabilisiert

    Energy Technology Data Exchange (ETDEWEB)

    Muehlbauer, Maria

    2009-07-01

    An attempt was made to stabilise ultrathin crystalline silicon wafers (< 100 {mu}m) by a support material (BOROFLOAT33 by Schott Glas). It was found that the total serial resistance results mainly from the specific resistance of the back contact, and that especially the ultrathin solar cells have high recombination in the back. The ultrathin Si wafers also are slightly corrugated, which results in uneven joining of the Si wafer with the glass support. For optimisation, the solar cells of this specific types, with different thicknesses, were modelled in the one-dimensional simulation code PC1D, including all material-specific and electric properties. It was found that a slight reduction of the serial resistance will be enough for a significant improvement of the efficiency of the stabilized solar cell. With this knowledge, selective optimisation of the stabilised solar cells was possible, with the following results: 1. The improved temperature-time profile of the RTP step will improve the solar cell parameters for all Si thicknesses, which is assumed to be the result of better quality of the Al/Si back contact. 2. Thicker aluminium layers improved passivation on the back of solar cells with a thickness of 300 {mu}m and 120 {mu}m. In thinner stabilised solar cells, this measure resulted in enhanced formation of shunts and did not reduce the recombination rate on the back of the solar cell. 3. An additional optimisation step was the introduction of the so-called 'combined method' in which part of the aluminium layer is replaced by silkscreen paste. This combination, with adequate preparation, ensures uniform joining of the ultrathin silicon to the glass carrier. The resulting intermediate layers are highly homogeneous and have good fill factors and current densities for thin solar cells with a si thickness of 60 {mu}m. A decisive argument for the combined method is its near-100% reproducibility. [German] Ziel dieser Arbeit ist es sehr duenne kristalline

  11. P-type transparent conducting oxides

    Science.gov (United States)

    Zhang, Kelvin H. L.; Xi, Kai; Blamire, Mark G.; Egdell, Russell G.

    2016-09-01

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of ‘chemical modulation of the valence band’ to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d 10 orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu+-based delafossites, layered oxychalcogenides, nd 6 spinel oxides, Cr3+-based oxides (3d 3) and post-transition metal oxides with lone pair state (ns 2). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p-n junctions will also be briefly discussed.

  12. Boron-doped hydrogenated microcrystalline silicon oxide (μc-SiOx:H) for application in thin-film silicon solar cells

    NARCIS (Netherlands)

    Lambertz, A.; Finger, F.; Holländer, B.; Rath, J.K.; Schropp, R.E.I.

    2011-01-01

    We report on the development of p-type μc-SiOx:H material, in particular the relationship between the deposition parameters and the material properties like band gap, electrical conductivity, and crystalline volume fraction. The material was deposited from gas mixtures of silane, carbon dioxide and

  13. p-Type Transparent Conducting Oxide/n-Type Semiconductor Heterojunctions for Efficient and Stable Solar Water Oxidation.

    Science.gov (United States)

    Chen, Le; Yang, Jinhui; Klaus, Shannon; Lee, Lyman J; Woods-Robinson, Rachel; Ma, Jie; Lum, Yanwei; Cooper, Jason K; Toma, Francesca M; Wang, Lin-Wang; Sharp, Ian D; Bell, Alexis T; Ager, Joel W

    2015-08-05

    Achieving stable operation of photoanodes used as components of solar water splitting devices is critical to realizing the promise of this renewable energy technology. It is shown that p-type transparent conducting oxides (p-TCOs) can function both as a selective hole contact and corrosion protection layer for photoanodes used in light-driven water oxidation. Using NiCo2O4 as the p-TCO and n-type Si as a prototypical light absorber, a rectifying heterojunction capable of light driven water oxidation was created. By placing the charge separating junction in the Si using a np(+) structure and by incorporating a highly active heterogeneous Ni-Fe oxygen evolution catalyst, efficient light-driven water oxidation can be achieved. In this structure, oxygen evolution under AM1.5G illumination occurs at 0.95 V vs RHE, and the current density at the reversible potential for water oxidation (1.23 V vs RHE) is >25 mA cm(-2). Stable operation was confirmed by observing a constant current density over 72 h and by sensitive measurements of corrosion products in the electrolyte. In situ Raman spectroscopy was employed to investigate structural transformation of NiCo2O4 during electrochemical oxidation. The interface between the light absorber and p-TCO is crucial to produce selective hole conduction to the surface under illumination. For example, annealing to produce more crystalline NiCo2O4 produces only small changes in its hole conductivity, while a thicker SiOx layer is formed at the n-Si/p-NiCo2O4 interface, greatly reducing the PEC performance. The generality of the p-TCO protection approach is demonstrated by multihour, stable, water oxidation with n-InP/p-NiCo2O4 heterojunction photoanodes.

  14. Influences of preparation conditions on the crystalline structure of CuO/SiO2%制备条件对CuO/SiO2催化剂铜晶相的影响

    Institute of Scientific and Technical Information of China (English)

    王仁国; 童冬梅; 谢正强; 胡常伟; 田安民

    2001-01-01

    采用醇盐法制备了一系列不同铜负载量及含不同助剂的SiO2负载的铜基催化剂。考察了不同制备条件对催化剂制备过程中硅酸凝胶生成速度的影响,发现在其它条件相同的情况下,正硅酸乙酯与乙二醇的体积比起主要作用,与金属铜盐的浓度基本无关。用XRD测试表明,本实验方法所制备的催化剂中的CuO是高度分散的非晶相状态,极易还原。高铜负载量的催化剂在500℃,空气气氛中焙烧4h后有Cu的晶相产生,其中含Fe、Ni助剂的有助于铜盐在分解过程中被还原为晶相铜,而Zn、V助剂的存在却抑制了铜物种的还原。%A series of CuO/SiO2 catalysts with different copper loading and containing various promoters (Fe,Ni,Zn,V) were prepared by alkoxide method.The crystalline structures were investigated by XRD.The results show that when the temperature,the mole ratio between water and ethyl silicate,and acidity in the solution keep constant,the rate of the gel formation depends only on the volume ratio between ethyl silicate and ethylene glyol,which is assumed to be related to the size of SiO2 particle.In CuO/SiO2 catalysts,the copper species exhibited as amorphorious or microcrystallite phase.XRD could not detect the Fe,Ni,Zn,V species after calcination.It shows that they were highly dispersed on the catalysts.It was found that in the catalysts promoted by Fe or Ni promoters the copper species were reduced to copper crystallite by ethylene glyol after calcination,and in the catalysts promoted by Ni the copper species were reduced much easier.However,the copper species in the catalysts promoted by Zn or V were not reduced and CuO formed after calcination at the same experimental conditions.

  15. Using the hydrothermal method to grow p-type ZnO nanowires on Al-doped ZnO thin film to fabricate a homojunction diode.

    Science.gov (United States)

    Tseng, Yung-Kuan; Hung, Meng-Chun; Su, Shun-Lung; Li, Sheng-Kai

    2014-10-01

    In this study, the hydrothermal method is used to grow phosphorus-doped ZnO nanowires on Si/SiO2 substrates deposited with Al-doped ZnO thin film. This structure forms a homogeneous p-n junction. In this study, we are the pioneers to use ammonium hypophosphite (NH4H2PO2) as a source of phosphorus to prepare the precursor solution. Ammonium hypophosphite of different concentration levels is used to observe its effects on the growth of nanowires. The results show that the precursor solution prepared from ammonium hypophosphite can produce good crystalline ZnO nanowires while there is no linear relationship between the amounts and concentration levels of phosphorus doped into the nanowires. Whether the phosphorus-doped ZnO nanowires have the characteristics of a p-type semiconductor is indirectly verified by measuring whether the p-n junction made up of Al-doped ZnO thin film and phosphorus-doped ZnO nanowires shows rectifying behavior. I-V measurements are made on the specimens. The results show good rectifying behavior, proving that the phosphorus-doped ZnO nanowires and Al-doped AZO films have p-type and n-type semiconductor properties, constituting a good p-n junction. This result also proves that ammonium hypophosphite is a better source of phosphorus in the hydrothermal method to synthesize phosphorus-doped ZnO nanowires.

  16. Improvement of minority carrier life time in N-type monocrystalline Si by the Czochralski method

    Science.gov (United States)

    Baik, Sungsun; Pang, Ilsun; Kim, Jaemin; Kim, Kwanghun

    2016-07-01

    The installation amount of solar power plants increases every year. Multi-crystalline Si solar cells comprise a large share of the market of solar power plants. Multi-crystalline and single-crystalline Si solar cells are competing against one another in the market. Many single-crystalline companies are trying to develop and produce n-type solar cells with higher cell efficiency than that of p-type. In n-type wafers with high cell efficiency, wafer quality has become increasingly important. In order to make ingots with higher MCLT, the effects of both poly types related to metal impurities and pull speeds related to vacancy concentration on minority carrier life time were studied. In the final part of ingots, poly types related to the metal impurities are a dominant factor on MCLT. In the initial part of ingots, pull speeds related to vacancy concentration are a dominant factor on MCLT. [Figure not available: see fulltext.

  17. Impact of microcrystalline silicon carbide growth using hot-wire chemical vapor deposition on crystalline silicon surface passivation

    Energy Technology Data Exchange (ETDEWEB)

    Pomaska, M., E-mail: m.pomaksa@fz-juelich.de [Forschungszentrum Jülich, IEK5-Photovoltaics, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); Beyer, W. [Helmholtz-Zentrum Berlin für Materialien und Energie, Silicon Photovoltaics, Kekuléstrasse 5, 12489 Berlin (Germany); Neumann, E. [Forschungszentrum Jülich, PGI-8-PT, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany); Finger, F.; Ding, K. [Forschungszentrum Jülich, IEK5-Photovoltaics, Wilhelm-Johnen-Strasse, 52425 Jülich (Germany)

    2015-11-30

    Highly crystalline microcrystalline silicon carbide (μc-SiC:H) with excellent optoelectronic material properties is a promising candidate as highly transparent doped layer in silicon heterojunction (SHJ) solar cells. These high quality materials are usually produced using hot wire chemical vapor deposition under aggressive growth conditions giving rise to the removal of the underlying passivation layer and thus the deterioration of the crystalline silicon (c-Si) surface passivation. In this work, we introduced the n-type μc-SiC:H/n-type μc-SiO{sub x}:H/intrinsic a-SiO{sub x}:H stack as a front layer configuration for p-type SHJ solar cells with the μc-SiO{sub x}:H layer acting as an etch-resistant layer against the reactive deposition conditions during the μc-SiC:H growth. We observed that the unfavorable expansion of micro-voids at the c-Si interface due to the in-diffusion of hydrogen atoms through the layer stack might be responsible for the deterioration of surface passivation. Excellent lifetime values were achieved under deposition conditions which are needed to grow high quality μc-SiC:H layers for SHJ solar cells. - Highlights: • High surface passivation quality was preserved after μc-SiC:H deposition. • μc-SiC:H/μc-SiO{sub x}:H/a-SiO{sub x}:H stack a promising front layer configuration • Void expansion at a-SiO{sub x}:H/c-Si interface for deteriorated surface passivation • μc-SiC:H provides a high transparency and electrical conductivity.

  18. Scanning tunneling microscopic and spectroscopic studies on a crystalline silica monolayer epitaxially formed on hexagonal SiC(0001¯) surfaces

    Science.gov (United States)

    Tochihara, Hiroshi; Shirasawa, Tetsuroh; Suzuki, Takayuki; Miyamachi, Toshio; Kajiwara, Takashi; Yagyu, Kazuma; Yoshizawa, Shunsuke; Takahashi, Toshio; Tanaka, Satoru; Komori, Fumio

    2014-02-01

    An epitaxial silicon-oxide monolayer of chemical composition of Si2O3 (the Si2O3 layer) formed on hexagonal SiC(0001¯) surfaces has been observed by scanning tunneling microscopy (STM). Filled- and empty-state STM images with atomic resolution support the previously reported model. Typical structural defects in the Si2O3 layer are found to be missing SiOn (n = 1, 2, 3) molecules. The band gap of the Si2O3 layer obtained by point tunneling spectroscopy is 5.5±0.5 eV, exhibiting considerable narrowing from that of bulk SiO2, 8.9 eV. It is proposed that the Si2O3 layer is suitable as a relevant interface material for formation of SiC-based metal-oxide-semiconductor devices.

  19. Novel chemical cleaning of textured crystalline silicon for realizing surface recombination velocity <0.2 cm/s using passivation catalytic CVD SiN x /amorphous silicon stacked layers

    Science.gov (United States)

    Thanh Nguyen, Cong; Koyama, Koichi; Higashimine, Koichi; Terashima, Shigeki; Okamoto, Chikao; Sugiyama, Shuichiro; Ohdaira, Keisuke; Matsumura, Hideki

    2017-05-01

    In this study, the development of a novel chemical cleaning method suitable for textured surfaces of crystalline silicon (c-Si) used for solar cells is demonstrated. To remove contaminants from such textured structures, chemicals have to penetrate into their complicated fine structures. Thus, the viscosity, reaction activity, and surface tension of the chemicals are adjusted by increasing the reaction temperature or introducing a surfactant. Actually, the use of concentrated (conc.) sulfuric acid (H2SO4) of 140 °C and the introduction of methanol (CH3OH) to other chemicals contribute to the improvement of the cleaning ability in textured structures. The present cleaning method in conjunction with plasma-damage-less catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD passivation with silicon-nitride (SiN x )/amorphous silicon (a-Si) stacked layers, also contributes to the decrease in the surface recombination velocity (SRV) of c-Si. The maximum estimated SRV (SRVmax), evaluated under the assumed absence of recombination in bulk c-Si, is less than 1.1 cm/s for textured surfaces, and the real SRV, evaluated by changing the c-Si substrate thickness, is less than 0.2 cm/s.

  20. pH Sensitivity of Si-C Linked Organic Monolayers on Crystalline Silicon Surfaces: Titration Experiments, Mott Schottky Analysis and Site-Binding Modeling

    NARCIS (Netherlands)

    Faber, E.J.; Sparreboom, W.; Groeneveld, W.; Smet, de L.C.P.M.; Bomer, J.; Olthuis, W.; Zuilhof, H.; Sudhölter, E.J.R.; Bergveld, P.; Berg, van den A.

    2007-01-01

    The electrochemical behavior of SiC linked organic monolayers is studied in electrolyte-insulator-Si devices, under conditions normally encountered in potentiometric biosensors, to gain fundamental knowledge on the behavior of such Si electrodes under practical conditions. This is done via titration

  1. 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.

  2. P type porous silicon resistivity and carrier transport

    Energy Technology Data Exchange (ETDEWEB)

    Ménard, S., E-mail: samuel.menard@st.com [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Fèvre, A. [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France); Billoué, J.; Gautier, G. [Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France)

    2015-09-14

    The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P{sub %}) was found to be the major contributor to the PS resistivity (ρ{sub PS}). ρ{sub PS} increases exponentially with P{sub %}. Values of ρ{sub PS} as high as 1 × 10{sup 9} Ω cm at room temperature were obtained once P{sub %} exceeds 60%. ρ{sub PS} was found to be thermally activated, in particular, when the temperature increases from 30 to 200 °C, a decrease of three decades is observed on ρ{sub PS}. Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P{sub %} lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P{sub %} overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power electronic devices.

  3. Single-Crystalline 3C-SiC anodically Bonded onto Glass: An Excellent Platform for High-Temperature Electronics and Bioapplications.

    Science.gov (United States)

    Phan, Hoang-Phuong; Cheng, Han-Hao; Dinh, Toan; Wood, Barry; Nguyen, Tuan-Khoa; Mu, Fengwen; Kamble, Harshad; Vadivelu, Raja; Walker, Glenn; Hold, Leonie; Iacopi, Alan; Haylock, Ben; Dao, Dzung Viet; Lobino, Mirko; Suga, Tadatomo; Nguyen, Nam-Trung

    2017-08-23

    Single-crystal cubic silicon carbide has attracted great attention for MEMS and electronic devices. However, current leakage at the SiC/Si junction at high temperatures and visible-light absorption of the Si substrate are main obstacles hindering the use of the platform in a broad range of applications. To solve these bottlenecks, we present a new platform of single crystal SiC on an electrically insulating and transparent substrate using an anodic bonding process. The SiC thin film was prepared on a 150 mm Si with a surface roughness of 7 nm using LPCVD. The SiC/Si wafer was bonded to a glass substrate and then the Si layer was completely removed through wafer polishing and wet etching. The bonded SiC/glass samples show a sharp bonding interface of less than 15 nm characterized using deep profile X-ray photoelectron spectroscopy, a strong bonding strength of approximately 20 MPa measured from the pulling test, and relatively high optical transparency in the visible range. The transferred SiC film also exhibited good conductivity and a relatively high temperature coefficient of resistance varying from -12 000 to -20 000 ppm/K, which is desirable for thermal sensors. The biocompatibility of SiC/glass was also confirmed through mouse 3T3 fibroblasts cell-culturing experiments. Taking advantage of the superior electrical properties and biocompatibility of SiC, the developed SiC-on-glass platform offers unprecedented potentials for high-temperature electronics as well as bioapplications.

  4. Amorphous-crystalline dual-layer structures resulting from metastable liquid phase separation in (Fe50Co25B15Si10)8oCu20 melt-spun ribbons

    Institute of Scientific and Technical Information of China (English)

    Cao Chong-De; Gong Su-Lian; Guo Jin-Bo; Song Rui-Bo; Sun Zhan-Bo; Yang Sen; Wang Wei-Min

    2012-01-01

    (Fe50Co25B15Si10)80Cu20 ribbons are prepared by using the single-roller melt-spinning method.A dual-layer structure consisting of a (Fe,Co)-rich amorphous phase and a Cu-rich crystalline phase forms due to metastable liquid phase separation before solidification.The magnetic hysteresis loops of the as-quenched and annealed samples are measured at room temperature.It is indicated that the coercivity of the ribbon is almost zero in the as-quenched state.The crystallization leads to the increase of coercivity and decrease of saturation magnetization.

  5. Effect of wet-chemical substrate pretreatment on electronic interface properties and recombination losses of a -Si:H/c -Si and a -SiN{sub x}:H/c -Si hetero-interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Angermann, Heike; Conrad, Erhard; Korte, Lars; Schmidt, Manfred [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institut fuer Silizium-Photovoltaik, Berlin (Germany); Wuensch, Frank; Kunst, Marinus [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institut Solare Brennstoffe und Energiespeichermaterialien, Berlin (Germany); Laades, Abdelazize; Stuerzebecher, Uta [CiS Institut fuer Mikrosensorik GmbH, SolarZentrum Erfurt (Germany)

    2011-03-15

    Surface charge, surface state density and interface recombination behavior on polished float zone (FZ) solar cell substrates were investigated after various wet-chemical pre-cleaning procedures and deposition of amorphous silicon (a-Si:H) or silicon nitride (a-SiNx:H). Applying surface photo voltage (SPV), microwave detected photo conductance decay ({mu}W-PCD) and transient microwave conduction (TRMC) measurements, electronic interface properties were monitored repeatedly during the preparation processes. As shown for an inverted a-Si:H/c-Si hetero-junction structure, with front side passivation by a-SiN{sub x}:H and a p-type a-Si:H emitter on the rear side, the effect of optimised wet-chemical pre-treatment can be preserved during the subsequent soft plasma enhanced chemical vapour deposition of a-Si:H or a-SiN{sub x}:H. This leads to hetero-interfaces with low interface recombination velocities. These results were compared to previously reported findings, obtained on textured Czochralski (CZ) single crystalline substrates. a-SiN{sub x}:H is known to result in a field effect passivation. Nevertheless a strong influence of wet-chemical treatments on surface charge and recombination losses was observed on both flat and textured a-SiN{sub x}:H/c-Si interfaces. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Scanning tunneling microscopic and spectroscopic studies on a crystalline silica monolayer epitaxially formed on hexagonal SiC(0001{sup ¯}) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tochihara, Hiroshi, E-mail: tochihara@fukuoka-u.ac.jp, E-mail: tochihara.hiroshi.146@m.kyushu-u.ac.jp; Suzuki, Takayuki; Yagyu, Kazuma [Department of Electronics Engineering and Computer Science, Fukuoka University, Fukuoka 814-0180 (Japan); Shirasawa, Tetsuroh; Takahashi, Toshio [Laser and Synchrotron Research Center, Institute for Solid State Physics, University of Tokyo, Chiba 277-8581 (Japan); Miyamachi, Toshio; Yoshizawa, Shunsuke; Komori, Fumio [Nanoscale Science Division, Institute for Solid State Physics, University of Tokyo, Chiba 277-8581 (Japan); Kajiwara, Takashi; Tanaka, Satoru [Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395 (Japan)

    2014-02-03

    An epitaxial silicon-oxide monolayer of chemical composition of Si{sub 2}O{sub 3} (the Si{sub 2}O{sub 3} layer) formed on hexagonal SiC(0001{sup ¯}) surfaces has been observed by scanning tunneling microscopy (STM). Filled- and empty-state STM images with atomic resolution support the previously reported model. Typical structural defects in the Si{sub 2}O{sub 3} layer are found to be missing SiO{sub n} (n = 1, 2, 3) molecules. The band gap of the Si{sub 2}O{sub 3} layer obtained by point tunneling spectroscopy is 5.5±0.5 eV, exhibiting considerable narrowing from that of bulk SiO{sub 2}, 8.9 eV. It is proposed that the Si{sub 2}O{sub 3} layer is suitable as a relevant interface material for formation of SiC-based metal-oxide-semiconductor devices.

  7. Photocatalytic activity of magnetically anatase TiO2 with high crystallinity and stability for dyes degradation: Insights into the dual roles of SiO2 interlayer between TiO2 and CoFe2O4

    Science.gov (United States)

    Yang, Zewei; Shi, Yingying; Wang, Bing

    2017-03-01

    A novel magnetically separable photocatalyst comprising hollow TiO2-SiO2-CoFe2O4 (TSC) was prepared. In the TSC photocatalyst, an SiO2 interlayer between CoFe2O4 core and TiO2 shell is used to both weaken adverse influence of the magnetic core on photocatalysis and increase the temperature of the transition from anatase to rutile phase TiO2, thus increasing the anatase TiO2 crystallinity. Such an interlayer promotes photocatalytic activity by changing the competition between the injecting process and reacting process of the photogenerated carriers. The photocatalytic activity of TSC was determined for degradation of dye molecules in water under either UV or visible light. The photocatalytic reaction of cationic dyes was governed by rad OH radicals, while O2rad - was the main active species in the initial photoreaction of anionic dyes.

  8. Nafion-Modified PEDOT:PSS as a Transparent Hole-Transporting Layer for High-Performance Crystalline-Si/Organic Heterojunction Solar Cells with Improved Light Soaking Stability.

    Science.gov (United States)

    Hossain, Jaker; Liu, Qiming; Miura, Takuya; Kasahara, Koji; Harada, Daisuke; Ishikawa, Ryo; Ueno, Keiji; Shirai, Hajime

    2016-11-23

    We demonstrate the chemistry of amphiphilic perfluorosulfonic copolymer Nafion-coated conductive poly(3,4-ethyelenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and its effect on the photovoltaic performance of PEDOT:PSS/crystalline Si (c-Si) heterojunction solar cells. The highly hydrophilic sulfonate group of insulating, chemically stable Nafion interacts with PSS in PEDOT:PSS, which reduce the Coulombic interaction between PEDOT and PSS. The highly hydrophobic fluorocarbon backbone of Nafion favorably interacts with hydrophobic PEDOT of PEDOT:PSS. These factors give rise to the extension of π-conjugation of PEDOT chains. Silver paste used as a top grid electrode diffused into the Nafion layer and contacted with underneath Nafion-modified PEDOT:PSS layer. As a consequent, solution-processed Nafion-coated PEDOT:PSS/c-Si heterojunction solar cells exhibited a higher power conversion efficiency of 14.0% with better stability for light soaking rather than that of the pristine PEDOT:PSS/c-Si device by adjusting the layer thickness of Nafion. These findings originate from the chemical stability of hydrophobic fluorocarbon backbone of Nafion, diffusivity of silver paste into Nafion and contact with PEDOT:PSS, and Nafion as an antireflection layer.

  9. Optical and electrical characterization of crystalline silicon films formed by rapid thermal annealing of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Baldus-Jeursen, Christopher, E-mail: cjbaldus@uwaterloo.ca; Tarighat, Roohollah Samadzadeh, E-mail: rsamadza@uwaterloo.ca; Sivoththaman, Siva, E-mail: sivoththaman@uwaterloo.ca

    2016-03-31

    The effect of rapid thermal annealing (RTA) on n-type hydrogenated amorphous silicon (a-Si:H) films deposited on single-crystal silicon (c-Si) wafers was studied by electrical and optical methods. Deposition of a-Si:H films by plasma-enhanced chemical vapor deposition (PECVD) was optimized for high deposition rate and maximum film uniformity. RTA processed films were characterized by spreading resistance profiling (SRP), Hall effect, spectroscopic ellipsometry, defect etching, and transmission electron microscopy (TEM). It was found that the films processed between 600 °C and 1000 °C were highly crystalline and that the defect density in the films diminished with increasing thermal budget. Junctions formed by the RTA processed n-type a-Si:H films on p-type c-Si wafers were tested for device applicability. It was established that these films can be used as the emitter layer in n{sup +}p photovoltaic (PV) devices with over 14% conversion efficiency. - Highlights: • Rapid thermal annealing of doped amorphous silicon deposited on single-crystal silicon (c-Si) wafers resulted in highly crystalline films for photovoltaic devices. • As the annealing temperature increased, the electrical and optical properties of the films became increasingly similar to single-crystal silicon. • Annealing temperatures between 500-1000 oC were investigated. Solar cell devices fabricated after annealing at 750 oC were found to be the most suitable compromise between good quality crystalline films and minimal dopant diffusion into the c-Si wafer. • Annealed films were highly conductive without the need for a transparent conducting oxide.

  10. A facile and environmentally friendly NaCl nonaqueous ionic liquid route to prepare crystalline β-CaSiO3 nanowires.

    Science.gov (United States)

    Wang, Wenzhong; Zhang, Suyun; Wang, Lijuan; Shi, Honglong

    2013-05-01

    We described an environmentally friendly and facile NaCl nonaqueous ionic liquid route for the first time to synthesize β-CaSiO3 nanowires. β-CaSiO3 nanowires were prepared by annealing precursor calcium silicate hydrate (CSH) nanostructures in NaCl nonaqueous ionic liquid, in which the precursor CSH nanostructures were first prepared by a facile one-step, solid state reaction, ground with both NaCl and surfactant nonyl phenyl ether (9) (NP-9), and heated at 850 °C for 2 h. β-CaSiO3 nanowires were characterized by XRD, TEM and HRTEM. The comparative experiments have been conducted systemically to investigate the growth mechanism of β-CaSiO3 nanowires, and the roles of salt NaCl nonaqueous ionic liquid and NP-9 on the formation of β-CaSiO3 nanowires. The results demonstrated that both salt NaCl nonaqueous ionic liquid and surfactant NP-9 played key roles on the formation of β-CaSiO3 nanowires. A rational growth mechanism of β-CaSiO3 nanowires has been proposed on the basis of experimental results. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Radicals and ions controlling by adjusting the antenna-substrate distance in a-Si:H deposition using a planar ICP for c-Si surface passivation

    Science.gov (United States)

    Zhou, H. P.; Xu, S.; Xu, M.; Xu, L. X.; Wei, D. Y.; Xiang, Y.; Xiao, S. Q.

    2017-02-01

    Being a key issue in the research and fabrication of silicon heterojunction (SHJ) solar cells, crystalline silicon (c-Si) surface passivation is theoretically and technologically intricate due to its complicate dependence on plasma characteristics, material properties, and plasma-material interactions. Here amorphous silicon (a-Si:H) grown by a planar inductively coupled plasma (ICP) reactor working under different antenna-substrate distances of d was used for the surface passivation of low-resistivity p-type c-Si. It is found that the microstructures (i.e., the crystallinity, Si-H bonding configuration etc.) and passivation function on c-Si of the deposited a-Si:H were profoundly influenced by the parameter of d, which primarily determines the types of growing precursors of SiHn/H contributing to the film growth and the interaction between the plasma and growing surface. c-Si surface passivation is analyzed in terms of the d-dependent a-Si:H properties and plasma characteristics. The controlling of radical types and ion bombardment on the growing surface through adjusting parameter d is emphasized.

  12. Optimization of Al2O3/SiNx stacked antireflection structures for N-type surfacepassivated crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    Wu Dawei; Jia Rui; Ding Wuchang; Chen Chen; Wu Deqi; Chen Wei; Li Haofeng; Yue Huihui; Liu Xinyu

    2011-01-01

    In the case of N-type solar cells,the anti-reflection property,as one of the important factors to further improve the energy-conversion efficiency,has been optimized using a stacked Al2O3/SiNx layer.The effect of SiNx layer thickness on the surface reflection property was systematically studied in terms of both experimental and theoretical measurement.In the stacked Al2O3/SiNx layers,results demonstrated that the surface reflection property can be effectively optimized by adding a SiNx layer,leading to the improvement in the final photovoltaic characteristic of the N-type solar cells.

  13. P-Type Doping of GaN by Mg+ Implantation

    Institute of Scientific and Technical Information of China (English)

    YAO Shu-De; ZHAO Qiang; ZHOU Sheng-Qiang; YANG Zi-Jian; LU Yi-Hong; SUN Chang-Chun; SUN Chang; ZHANG Guo-Yi; VANTOMME Andre; PIPELEERS Bert

    2003-01-01

    Mg+ and Mg++P+ were introduced into GaN by ion implantation. The structure and crystalline quality of the GaN samples were analysed by Rutherford backscattering and channelling spectrometry before (xmin = 1.6%) and after implantation (Xmin = 4.1%). X-ray diffraction reveals the existence of implantation-induced damage in the case of post-implantation followed by rapid thermal annealing. The resistivity, average factor, carrier concentration and carrier mobility were measured by the Hall effect. The transformation from n-type to p-type for GaN was observed.

  14. DEFORMATION INVESTIGATION ON iPP/SiO2 COMPOSITES: INFLUENCE OF STRETCHING TEMPERATURE AND PARTICLE SIZE ON MORPHOLOGY EVOLUTION AND CRYSTALLINE STRUCTURE OF THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    Xiu-qin Zhang; Qian Xing; Rong-bo Li; Rui Wang; Du-jin Wang

    2013-01-01

    In the present work,structure changes during stretching of isotactic polypropylene (iPP) and iPP/silicon dioxide (SiO2) composites have been investigated systematically.The α-form crystal structure of both iPP and iPP/SiO2 composites is destroyed and transforms into the mesophase as the samples are stretched at a low temperature (35℃),while stretching at high temperatures (90℃ and 120℃) can restrain the appearance of defects and keep the perfection of crystal structure.FTIR results reveal that the stretching temperatures show no obvious difference of the effect on the orientation of pure iPP,however,the orientation of iPP/SiO2 composites is greatly changed by the tensile temperature.In the case of micron-sized SiO2 particles (average particle diameter d > 1 μm),the orientation of the composites is lower than that of pure iPP at all stretching temperatures.The above results suggest that the stretching temperature and the SiO2 particle size have great influence on the structure variation and orientation behavior of iPP/SiO2 composites.

  15. Electrical conductivity, ionic conductivity, optical absorption, and gas separation properties of ionically conductive polymer membranes embedded with Si microwire arrays

    OpenAIRE

    Spurgeon, Joshua M.; Walter, Michael G.; Zhou, Junfeng; Kohl, Paul A.; Lewis, Nathan S.

    2011-01-01

    The optical absorption, ionic conductivity, electronic conductivity, and gas separation properties have been evaluated for flexible composite films of ionically conductive polymers that contain partially embedded arrays of ordered, crystalline, p-type Si microwires. The cation exchange ionomer Nafion, and a recently developed anion exchange ionomer, poly(arylene ether sulfone) that contains quaternary ammonium groups (QAPSF), produced composite microwire array/ionomer membrane films that were...

  16. A novel technique based on a plasma focus device for nano-porous gallium nitride formation on P-type silicon

    Science.gov (United States)

    Sharifi Malvajerdi, S.; Salar Elahi, A.; Habibi, M.

    2017-04-01

    A new deposition formation was observed with a Mather-type Plasma Focus Device (MPFD). MPFD was unitized to fabricate porous Gallium Nitride (GaN) on p-type Silicon (Si) substrate with a (100) crystal orientation for the first time in a deposition process. GaN was deposited on Si with 4 and 7 shots. The samples were subjected to a 3 phase annealing procedure. First, the semiconductors were annealed in the PFD with nitrogen plasma shots after their deposition. Second, a thermal chemical vapor deposition annealed the samples for 1 h at 1050 °C by nitrogen gas at a pressure of 1 Pa. Finally, an electric furnace annealed the samples for 1 h at 1150 °C with continuous flow of nitrogen. Porous GaN structures were observed by Field emission scanning electron microscopy and atomic force microscopy. Furthermore, X-Ray diffraction analysis was carried out to determine the crystallinity of GaN after the samples were annealed. Energy-Dispersive X-Ray Spectroscopy indicated the amount of gallium, nitrogen, and oxygen due to the self-oxidation of the samples. Photoluminescence spectroscopy revealed emissions at 2.94 eV and 3.39 eV, which shows that hexagonal wurtzite crystal structures were formed.

  17. Cat-doping: Novel method for phosphorus and boron shallow doping in crystalline silicon at 80 °C

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Hideki; Hayakawa, Taro; Ohta, Tatsunori; Nakashima, Yuki; Miyamoto, Motoharu; Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke [Japan Advanced Institute of Science and Technology (JAIST), Asahidai, Nomi-shi, Ishikawa-ken 923-1292 (Japan)

    2014-09-21

    Phosphorus (P) or boron (B) atoms can be doped at temperatures as low as 80 to 350 °C, when crystalline silicon (c-Si) is exposed only for a few minutes to species generated by catalytic cracking reaction of phosphine (PH₃) or diborane (B₂H₆) with heated tungsten (W) catalyzer. This paper is to investigate systematically this novel doping method, “Cat-doping”, in detail. The electrical properties of P or B doped layers are studied by the Van der Pauw method based on the Hall effects measurement. The profiles of P or B atoms in c-Si are observed by secondary ion mass spectrometry mainly from back side of samples to eliminate knock-on effects. It is confirmed that the surface of p-type c-Si is converted to n-type by P Cat-doping at 80 °C, and similarly, that of n-type c-Si is to p-type by B Cat-doping. The doping depth is as shallow as 5 nm or less and the electrically activated doping concentration is 10¹⁸ to 10¹⁹cm⁻³ for both P and B doping. It is also found that the surface potential of c-Si is controlled by the shallow Cat-doping and that the surface recombination velocity of minority carriers in c-Si can be enormously lowered by this potential control.

  18. Low-Temperature Sintering and Microwave Dielectric Properties of Zn2SiO4 Ceramic Added with Crystalline Zinc Borate

    Science.gov (United States)

    Chaware, Varsha; Deshmukh, Ravindra; Sarode, Chetan; Gokhale, Suresh; Phatak, Girish

    2015-07-01

    The physical and dielectric properties of composites of known microwave materials, Zn2SiO4 and Zn3B2O6, prepared by solid-state reaction, were investigated with the purpose of developing a low-loss dielectric material for low-temperature co-fired ceramic applications. An off-stoichiometric phase of Zn2SiO4 with extra SiO2 was used to avoid the occurrence of unreacted ZnO. During sintering, zinc borate was found to partially react with residual SiO2 to form Zn2SiO4. The residual zinc borate was converted to a boron-rich glassy phase which helped to reduce the sintering temperature of the composite. Good relative sintering density (>90%) at temperatures below the melting temperature of zinc borate is indicative of a sintering mechanism of diffusion-based mass transfer. Composites containing 15 wt.% zinc borate, 2.5 wt.% lithium carbonate and 20 wt.% zinc borate in zinc silicate had dielectric constants of 6.8 and 6.1, quality factors (Q×f) of 48,800 and 94,300 GHz when sintered at 900°C and 950°C, respectively. These quality factor results are close to the best values reported for zinc silicate at these sintering temperatures.

  19. 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.

  20. Role of surface fixed charge in the surface passivation of thermal atomic layer deposited Al2O3 on crystalline-Si

    Science.gov (United States)

    Dou, Y. N.; He, Y.; Huang, C. Y.; Zhou, C. L.; Ma, X. G.; Chen, R.; Chu, J. H.

    2012-11-01

    In this work, surface passivation of thermal atomic layer deposited (ALD) Al2O3 films on Si has been investigated. A quantitative analysis shows that field-effect passivation based on surface fixed charge combined with chemical passivation is assumed to contribute to the passivation performance and that a low defect density is critical to passivation quality. The surface fixed negative charge, which is exponentially modulated from ˜0 cm-2 to -2×1012 cm-2 by annealing, is proposed to have arisen from the reconstruction of the interfacial SiO x layer.

  1. 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.

  2. Investigation of charges carrier density in phosphorus and boron doped SiN{sub x}:H layers for crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Paviet-Salomon, B., E-mail: bertrand.paviet-salomon@epfl.ch [Commissariat à l’Énergie Atomique (CEA), Laboratoire d’Innovation pour les Technologies des Énergies Nouvelles et les nanomatériaux (LITEN), Institut National de l’Énergie Solaire - INES, 50 avenue du Lac Léman, 73377 Le Bourget du Lac (France); Gall, S. [Commissariat à l’Énergie Atomique (CEA), Laboratoire d’Innovation pour les Technologies des Énergies Nouvelles et les nanomatériaux (LITEN), Institut National de l’Énergie Solaire - INES, 50 avenue du Lac Léman, 73377 Le Bourget du Lac (France); Slaoui, A. [Institut de l’Électronique du Solide et des Systèmes (InESS), Unité Mixte de Recherche 7163 Centre National de la Recherche Scientifique-Université de Strasbourg (UMR 7163 CNRS-UDS), 23 rue du Loess, BP 20 CR, 67037 Strasbourg (France)

    2013-05-15

    Highlights: ► We investigate the properties of phosphorus and boron-doped silicon nitride films. ► Phosphorus-doped layers yield higher lifetimes than undoped ones. ► The fixed charges density decreases when increasing the films phosphorus content. ► Boron-doped films feature very low lifetimes. ► These doped layers are of particular interest for crystalline silicon solar cells. -- Abstract: Dielectric layers are of major importance in crystalline silicon solar cells processing, especially as anti-reflection coatings and for surface passivation purposes. In this paper we investigate the fixed charge densities (Q{sub fix}) and the effective lifetimes (τ{sub eff}) of phosphorus (P) and boron (B) doped silicon nitride layers deposited by plasma-enhanced chemical vapour deposition. P-doped layers exhibit a higher τ{sub eff} than standard undoped layers. In contrast, B-doped layers exhibit lower τ{sub eff}. A strong Q{sub fix} decrease is to be seen when increasing the P content within the film. Based on numerical simulations we also demonstrate that the passivation obtained with P- and B-doped layers are limited by the interface states rather than by the fixed charges.

  3. Correlation between SnO{sub 2} nanocrystals and optical properties of Eu{sup 3+} ions in SiO{sub 2} matrix: Relation of crystallinity, composition, and photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Bui Quang [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc, E-mail: hann@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); Khiem, Tran Ngoc, E-mail: khiem@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); Chien, Nguyen Duc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam); School of Engineering Physics (SEP), Hanoi University of Science and Technology (HUST), No.1 Dai Co Viet, Hanoi (Viet Nam)

    2015-07-15

    We report characteristics and optical properties of Eu{sup 3+}-doped SnO{sub 2} nanocrystals dispersed in SiO{sub 2} matrix. Samples are prepared by the sol–gel method. Crystallinity of SnO{sub 2} nanocrystals is examined by X-ray diffraction experiments. At annealing temperatures from 900 to 1200 °C, we observe the formation of single tetragonal rutile structure of SnO{sub 2} nanocrystals. Average sizes of SnO{sub 2} nanocrystals within 3–7 nm are estimated by Debye–Scherrer equation. Intense photoluminescent spectra of Eu{sup 3+} ions consist of a series of resolved emission bands within 570–645 nm, which are varied with different sample-preparation conditions. We show the efficient excitation process of Eu{sup 3+} ions through SnO{sub 2} nanocrystals in the materials. Microscopic structure of SnO{sub 2} nanoparticles and optical properties of Eu{sup 3+} ions are also presented and discussed. - Highlights: • Thin layers of Eu{sup 3+} doped SnO{sub 2} nanocrystals dispersed in SiO{sub 2} were prepared by sol-gel method and spin-coating process. • Formation of single-phase tetragonal rutile structure of SnO{sub 2} nanocrystals and highly efficient optical excitation of the Eu{sup 3+} dopants were exhibited. • Relations of the crystallinity and composition of SnO{sub 2} and optical properties of Eu{sup 3+} dopants were comprehensively investigated and presented. • Allocations of major optically-active Eu{sup 3+} ions in the materials were deduced from their emission bands.

  4. Comparative study. Thin-film technology (si-a) compared to crystalline silicon in real operating conditions; Estudio comparativo. Tecnologia de capa fina (Si-a) frente a silicio cristalino en condiciones reales de funcionamiento

    Energy Technology Data Exchange (ETDEWEB)

    Izard Gomez-Rodulfo, J.; Avellaner, J.; Sanchez, E.; Torreblanca, J.

    2010-07-01

    We present a comparative study of thin film solar modules (amorphous silicon) compared to crystalline silicon modules. This study was conducted in real operating conditions using a test bench able to obtain the characteristic curve of several modules in sequence. defined the parameter efficiency index to characterize the extent to which actual performance is close to ideal. Finally we have calculated the energy that would produce each module in the day and efficiency in relation to the energy which ideally should produce. (Author)

  5. In situ thermal evolution of B-B pairs in crystalline Si: a spectroscopic high resolution x-ray diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Bisognin, G; Salvador, D De; Napolitani, E; Carnera, A [MATIS CNR-INFM and Dipartimento di Fisica, Universita di Padova, via F Marzolo 8, 35131 Padova (Italy); Bruno, E; Mirabella, S; Piro, A M; Romano, L; Grimaldi, M G [MATIS CNR-INFM and Dipartimento di Fisica ed Astronomia, Universita di Catania, via S Sofia 64, 95123 Catania (Italy)], E-mail: bisognin@padova.infm.it

    2008-04-30

    The lattice strain induced by the thermal evolution of B-B pairs formed in a Si{sub 1-x}B{sub x}/Si layer as a consequence of He irradiation has been studied in situ in an N{sub 2} atmosphere, by using a high resolution x-ray diffractometer equipped with a hot stage sample holder. The collection of repeated rocking curves during a linear temperature (T) ramp allowed monitoring of the effects of the B-B pair thermal evolution on the epilayer lattice parameter a (and equally its strain) during the whole of the annealing from room T up to their complete dissolution (883 deg. C). By analysing the evolution of a(T) we extracted detailed information about the kinetics of B-B pair evolution. This allowed us to determine an experimental description of the B-B pair dissolution path in good agreement with recent ab initio calculations.

  6. An integrated driving circuit implemented with p-type LTPS TFTs for AMOLED

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-qing; WU Chun-ya; HAO Da-shou; YAO Ying; MENG Zhi-guo; XIONG Shao-zhen

    2009-01-01

    Based on the technology of low temperature poly silicon thin film transistors (poly-Si-TFTs), a novel p-type TFT AMOLED panel with self-scanned driving circuit is introduced in this paper. A shift register formed with novel p-type TFTs is pro-posed to realize the gate driver. A flip-latch cooperated with the shift register is designed to conduct the data writing. In order to verify the validity of the proposed design, the circuits are simulated with SILVACO TCAD tools, using the MODEL in which the parameters of LTPS TFTs were extracted from the LTPS TFTs made in our lab. The simulation results indicate that the circuit can fulfill the driving function.

  7. Improvement of the crystallinity of CdTe epitaxial film grown on Si substrates by molecular beam epitaxy using the two-step growth method

    Energy Technology Data Exchange (ETDEWEB)

    Han, M.S.; Ryu, Y.S.; Song, B.K.; Kang, T.W. [Dongguk Univ., Seoul (Korea, Republic of). Dept. of Phys.; Kim, T.W. [Department of Physics, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

    1997-01-05

    Molecular beam epitaxy growth of CdTe epitaxial layers on Si (100) substrates using the two-step growth method was performed to produce high-quality CdTe thin layers. The reflection high-energy electron diffraction patterns were streaky with clear Kikuchi lines, which is direct evidence for layer-by-layer two-dimensional growth of CdTe on Si. From the X-ray diffraction analysis, the grown layer was found to be a CdTe (111) epitaxial film, regardless of the film thickness. Photoluminescence (PL) measurements at 12 K showed that the defect density of the CdTe film grown on Si using two-step growth decreased in comparison with that grown using direct growth. The bound exciton appearing in the PL measurements shifted to the low energy side as the thickness of the CdTe increased. When the CdTe thickness increased from 1 to 1.8 {mu}m, the peak position of the bound exciton shifted by 7.2 meV, and the stress obtained from the exciton peak shift was -12.405 kbar. These results indicate that high quality CdTe films grown by two-step growth hold promise for applications as buffer layers for the subsequent growth of Hg{sub x}Cd{sub 1-x}Te. (orig.) 16 refs.

  8. Bietti's Crystalline Dystrophy

    Science.gov (United States)

    ... Dystrophy > Facts About Bietti's Crystalline Dystrophy Facts About Bietti's Crystalline Dystrophy This information was developed by the ... is the best person to answer specific questions. Bietti’s Crystalline Dystrophy Defined What is Bietti’s Crystalline Dystrophy? ...

  9. 纳米SiO2对UHMWPE溶液流变性质及其结晶性能的影响%Effects of Nano-SiO2 on the Rheological and Crystalline Properties of UHMWPE Solution

    Institute of Scientific and Technical Information of China (English)

    于俊荣; 胡祖明; 刘兆峰

    2005-01-01

    将纳米SiO2经偶联剂处理后,采用溶液共混法制成UHMWPE/纳米SiO2溶液.研究了表面处理后纳米SiO2在UHMWPE中的分散性能和纳米粒子及抗氧剂的添加对溶液粘度及结晶性能的影响.结果表明:表面处理后纳米SiO2在UHMWPE溶液中可达到纳米级均匀分散;溶液粘度及粘流活化能随纳米粒子加入量的增加而增大;抗氧剂和纳米粒子的添加对PE的结晶形态都没有影响;抗氧剂的加入使UHMWPE的结晶度变大,晶粒尺寸变小,而纳米SiO2粒子的加入使UHMWPE的结晶度变小,晶粒尺寸变大.

  10. Reliability tests of electroless barriers against copper diffusion under bias-temperature stress with n- and p-type substrates

    Science.gov (United States)

    Ueno, Kazuyoshi; Fujishima, Shota; Yamashita, Makoto; Mitsumori, Akiyoshi

    2016-05-01

    To investigate the similarity and difference of substrate conduction type in the time-dependent dielectric breakdown (TDDB) tests for the barrier integrity against Cu diffusion under bias-temperature stress (BTS), the TDDB reliability of electroless NiB and CoWP/NiB was determined by metal oxide semiconductor (MOS) structures on n-type Si (n-Si) substrates, and the test results were compared with those using p-type Si (p-Si) substrates. The TDDB results and mechanism were observed to be qualitatively the same as Cu diffusion for both conduction types. However, the TDDB lifetime using p-Si was found to be potentially shorter because of the reverse bias conditions than that using n-Si under the forward bias conditions.

  11. About the Nature of Electroluminescence Centers in Plastically Deformed Crystals of p-type Silicon

    Directory of Open Access Journals (Sweden)

    B.V. Pavlyk

    2015-10-01

    Full Text Available The paper describes research of dislocation electroluminescence of single crystal p-type silicon with a high concentration of dislocations on the surface (111. It is shown the reaction of the luminescence spectra and capacitive-modulation spectra of samples after high-temperature annealing in an atmosphere of flowing oxygen. The analysis of the results lets us to establish the nature of recombination centers and their reorganization under high-temperature annealing. It is shown that deposition of Al film on the substrate p-Si leads to the formation of strain capacity and the localization of defects in the surface layer that corresponds to luminescence centers.

  12. Single-structure heater and temperature sensor using a p-type polycrystalline diamond resistor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, G.S.; Aslam, D.M. [Michigan State Univ., East Lansing, MI (United States). Dept. of Electrical Engineering

    1996-05-01

    Heat generation and temperature sensing are required for heating applications and for liquid level sensors, mass flow meters, and vacuum and pressure gauges which are based on variations of heat dissipation. Heat generation and temperature sensing are reported in a single p-type diamond resistor fabricated on an oxidized Si substrate using diamond film technology compatible with integrated circuit (IC) processing. Power densities in excess of 600 W/in.{sup 2} are observed for the heaters. The temperature response of the sensor is characterized in the temperature range of 300--725 K. Such a diamond heater/sensor device is reported for the first time.

  13. Isomorphism of anhydrous tetrahedral halides and silicon chalcogenides: energy landscape of crystalline BeF2, BeCl2, SiO2, and SiS2.

    Science.gov (United States)

    Zwijnenburg, Martijn A; Corà, Furio; Bell, Robert G

    2008-08-20

    We employ periodic density functional theory calculations to compare the structural chemistry of silicon chalcogenides (silica, silicon sulfide) and anhydrous tetrahedral halides (beryllium fluoride, beryllium chloride). Despite the different formal oxidation states of the elements involved, the divalent halides are known experimentally to form crystal structures similar to known SiX2 frameworks; the rich polymorphic chemistry of SiO2 is however not matched by divalent halides, for which a very limited number of polymorphs are currently known. The calculated energy landscapes yield a quantitative match between the relative polymorphic stability in the SiO2/BeF2 pair, and a semiquantitative match for the SiS2/BeCl2 pair. The experimentally observed polymorphs are found to lie lowest in energy for each composition studied. For the two BeX2 compounds studied, polymorphs not yet synthesized are predicted to lie very low in energy, either slightly above or even in between the energy of the experimentally observed polymorphs. The experimental lack of polymorphism for tetrahedral halide materials thus does not appear to stem from a lack of low-energy polymorphs but more likely is the result of a lack of experimental exploration. Our calculations further indicate that the rich polymorphic chemistry of SiO2 can be potentially matched, if not extended, by BeF2, provided that milder synthetic conditions similar to those employed in zeolite synthesis are developed for BeF2. Finally, our work demonstrates that both classes of materials show the same behavior upon replacement of the 2p anion with the heavier 3p anion from the same group; the thermodynamic preference shifts from structures with large rings to structures with larger fractions of small two and three membered rings.

  14. Research on anti-PID performance of double-layer SiN film poly-crystalline silicon solar cell%双层SiN 膜多晶硅太阳电池抗PID性能研究

    Institute of Scientific and Technical Information of China (English)

    罗旌旺; 王祺; 芮春保; 孔凡建

    2014-01-01

    Double-layer SiN film poly-crystal ine silicon solar cel was the research point. Different refractive index and thickness double-layer SiN film solar cel by modifying PECVD process were prepared. The cel s with glass, EVA, backsheet etc were encapsulated. PID (Potential Induced Degradation) test at 85℃, 85%RH was conducted. The results show (1)that the cel s with a low refractive index of outer SiNx layer cause serious PID effect regardless of the refractive index or thickness of inner SiN layer;(2), but as the outer layer refractive index increasing the cel s PID effects decreased conspicuously, the cel s with a outer layer refractive index≥2.15 past PID 600 h test with a power loss less than 5%;(3) compared to conventional cel , double-layers SiN film anti-PID solar cel efficiency is a slightly lower, but the cel to module encapsulation power loss is smal er and its module power is equivalent to conventional cel 's. Therefore, the application of this anti-PID solar cel is promising.%以双层SiN 膜多晶硅太阳电池为研究对象,通过调整PECVD工艺参数制备不同折射率和厚度的双层氮化硅减反射膜太阳电池,并用玻璃、EVA和背板等将电池片封装成光伏组件,进行85℃、85%RH条件下组件电势诱导衰减(PID)实验。研究结果表明:(1)改变内层折射率和厚度保持外层较低的折射率时,双层氮化硅膜太阳电池均会发生严重的PID效应;(2)但随着外层折射率提高,电池PID效应显著减小,外层折射率≥2.15的电池PID实验600 h功率衰减小于5%;(3)双层氮化硅膜抗PID太阳电池的转化效率略低于普通太阳电池,但其组件的封装损失较小,与普通电池的组件功率相当,因此具有很好的应用前景。

  15. Contribution to the study of electronic structure of crystalline semiconductors (Si, Ge, GaAs, Gap, ZnTe, ZnSe

    Directory of Open Access Journals (Sweden)

    Bouhafs B.

    2012-06-01

    Full Text Available The band structure of semiconductors was described by several theorists since the Fifties. The main objective of the present paper is to do a comparative study between various families of semi-conductors IV (Si,Ge, III-V (GaAs, GaP and II-VI (ZnSe, ZnTe with both methods; tight Binding1 method and pseudo potential method2. This work enables us to understand as well as the mechanism of conduction process in these semiconductors and powers and limits of the above methods. The obtained results allow to conclude that both methods are in a good agreement to describe the morphology of band structures of the cited semiconductors. This encourages us to study in the future the electronic behaviour through the structure of bands for more complex systems such as the heterostructures.

  16. Ge-intercalated graphene: The origin of the p-type to n-type transition

    KAUST Repository

    Kaloni, Thaneshwor P.

    2012-09-01

    Recently huge interest has been focussed on Ge-intercalated graphene. In order to address the effect of Ge on the electronic structure, we study Ge-intercalated free-standing C 6 and C 8 bilayer graphene, bulk C 6Ge and C 8Ge, as well as Ge-intercalated graphene on a SiC(0001) substrate, by density functional theory. In the presence of SiC(0001), there are three ways to obtain n-type graphene: i) intercalation between C layers; ii) intercalation at the interface to the substrate in combination with Ge deposition on the surface; and iii) cluster intercalation. All other configurations under study result in p-type states irrespective of the Ge coverage. We explain the origin of the different doping states and establish the conditions under which a transition occurs. © Copyright EPLA, 2012.

  17. Electroluminescence of a-Si/c-Si heterojunction solar cells after high energy irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ferrara, Manuela

    2009-11-24

    The crystalline silicon as absorber material will certainly continue to dominate the market for space applications of solar cells. In the contribution under consideration the applicability of a-Si:H/c-Si heterojunction solar cells in space has been tested by the investigation of the cell modification by high energy protons and comparing the results to the degradation of homojunction crystalline silicon reference cells. The investigated solar cells have been irradiated with protons of different energies and doses. For all investigated solar cells the maximum damage happens for an energy of about 1.7 MeV and is mainly due to the decrease of the effective minority carrier diffusion length in the crystalline silicon absorber. Simulations carried out by AFORS-HET, a heterojunction simulation program, also confirmed this result. The main degradation mechanism for all types of devices is the monotonically decreasing charge carrier diffusion length in the p-type monocrystalline silicon absorber layer. For the heterojunction solar cell an enhancement of the photocurrent in the blue wavelength region has been observed but only in the case of heterojunction solar cell with intrinsic a-Si:H buffer layer. Additionally to the traditional characterization techniques the electroluminescence technique used for monitoring the modifications of the heteroluminescence technique used for monitoring the modifications of the heterointerface between amorphous silicon and crystalline silicon in solar cells after proton irradiation. A direct relation between minority carrier diffusion length and electroluminescence quantum efficiency has been observed but also details of the interface modification could be monitored by this technique.

  18. 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.

  19. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Science.gov (United States)

    Ambade, Swapnil B.; Mane, R. S.; Kale, S. S.; Sonawane, S. H.; Shaikh, Arif V.; Han, Sung-Hwan

    2006-12-01

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu 2- xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm 2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  20. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ambade, Swapnil B. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Mane, R.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Kale, S.S. [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of); Sonawane, S.H. [Department of Chemical Engineering, Vishwakarma Institute of Technology, Pune 411037 (India); Shaikh, Arif V. [Department of Electronic Science, AKI' s Poona College of Arts, Science and Commerce, Camp, Pune 411 001 (India); Han, Sung-Hwan [Inorganic Nanomaterials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea, Republic of)]. E-mail: shhan@hanyang.ac.kr

    2006-12-15

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 deg. C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu{sub 2-x}Se phase was confirmed by XRD pattern and spherical grains of 30 {+-} 4 - 40 {+-} 4 nm in size aggregated over about 130 {+-} 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm{sup 2} light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  1. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs

    Science.gov (United States)

    Bioud, Youcef A.; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-10-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  2. Crystalline and spin chiralities in multiferroics with langasite-type structure and Fe{sub 1–x}Co{sub x}Si crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, S. A., E-mail: pikin@ns.crys.ras.ru; Lyubutin, I. S.; Dudka, A. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2015-09-15

    It is shown that, when magnetic ordering occurs in layered iron-containing langasites (sp. gr. P321), one of the reasons for spin chiralities of different signs is the presence of structural chirality (the existence of inversion twins), which, in turn, is due to the nonsymmetricity of these crystals. Spin helicoids arise in these multiferroics at split sites of Fe{sup 3+} ions below the Néel point. The direction of electric polarization vectors coincides with the direction of the magnetic helicoid axes because of the piezoelectric properties of these materials. Due to the magnetostriction effects, structural chirality wave vector k{sub z} exceeds the magnetic helicoid wave vector by a factor of 2: k{sub z} = 2q{sub z}. The temperatures of transitions to the chiral structural and chiral magnetic states may differ. In particular, if the structural transition initial temperature exceeds the magnetic transition temperature (Τ{sub U}> Τ{sub M}), structural displacements may arise in the absence of magnetism at Τ{sub M} < Τ < Τ{sub U}. In noncentrosymmetric Fe{sub 1–x}Co{sub x}Si crystals (sp. gr. P2{sub 1}3), which are not multiferroics, magnetic chirality is due to the Dzyaloshinski–Moriya interaction. The dependence of the moduli of incommensurate wave number of the corresponding helicoid on the atomic composition of the crystals under consideration is nonmonotonic.

  3. Lateral photovoltaic effect in p-type silicon induced by surface states

    Science.gov (United States)

    Huang, Xu; Mei, Chunlian; Gan, Zhikai; Zhou, Peiqi; Wang, Hui

    2017-03-01

    A colossal lateral photovoltaic effect (LPE) was observed at the surface of p-type silicon, which differs from the conventional thought that a large LPE is only observed in Schottky junctions and PN junctions consisting of several layers with different conductivities. It shows a high sensitivity of 499.24 mV/mm and an ultra-broadband spectral responsivity (from 405 nm to 980 nm) at room temperature, which makes it an attractive candidate for near-infrared detection. We propose that this phenomenon can be understood by considering the surface band bending near the surface of p-Si induced by charged surface states. The energy band diagrams of the samples are shown based on X-ray photoelectron spectroscopy suggesting the correlation between the LPE and surface band bending. The conjectures are validated by changing the surface states of p-type silicon using Ni nano-films. These findings reveal a generation mechanism of the LPE and may lead to p-Si based, broadband-responsivity, low-cost, and high-precision optical and optoelectronic applications.

  4. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    Science.gov (United States)

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-07

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future.

  5. Crystalline Confinement

    CERN Document Server

    Banerjee, D; Jiang, F -J; Wiese, U -J

    2013-01-01

    We show that exotic phases arise in generalized lattice gauge theories known as quantum link models in which classical gauge fields are replaced by quantum operators. While these quantum models with discrete variables have a finite-dimensional Hilbert space per link, the continuous gauge symmetry is still exact. An efficient cluster algorithm is used to study these exotic phases. The $(2+1)$-d system is confining at zero temperature with a spontaneously broken translation symmetry. A crystalline phase exhibits confinement via multi-stranded strings between charge-anti-charge pairs. A phase transition between two distinct confined phases is weakly first order and has an emergent spontaneously broken approximate $SO(2)$ global symmetry. The low-energy physics is described by a $(2+1)$-d $\\mathbb{R}P(1)$ effective field theory, perturbed by a dangerously irrelevant $SO(2)$ breaking operator, which prevents the interpretation of the emergent pseudo-Goldstone boson as a dual photon. This model is an ideal candidat...

  6. 用稻壳硅源水热合成P型分子筛的研究%Study on the hydrothermal synthesis of P-type zeolite from rice husk silicon

    Institute of Scientific and Technical Information of China (English)

    杨君; 马红超; 付颖寰; 宋宇; 王永为; 于春玲; 董晓丽

    2011-01-01

    利用稻壳中丰富的氧化硅为硅源,以Al(OH)3为外加铝源,采用水热法合成P型分子筛.通过实验得到制备P型分子筛的最佳条件:硅铝摩尔比(SiO2/A12O3)为5.6,钠硅摩尔比(Na2O/SiO2)为1.43,水钠摩尔比(H2O/Na2O)为18.3,反应温度为85℃,反应时间为24 h.X射线衍射(XRD)与扫描电镜分析表明,该条件下合成的P型分子筛具有较高的结晶度,无杂相,其Ca2+(以CaCO3计)交换容量可达320 mg/g.该方法为农业副产物的再利用提供了一条有效途径.%P-type zeolite was hydrothermal synthesized with rice husk as silicon source and A1(OH)3 as Al source. Results showed that the optimum composition for synthesis of P-type zeolite was SiO2/AlzO3 molar ratio of 5. 6, Na2O/SiO2 molar ratio of 1. 43, and H2O/Na2O molar ratio of 18. 3, which could give maximum calcium ionic exchange capacity of P-type zeolite for 320 mg/g (equivalent to CaCO3) when the crystallization temperature was 85 ℃ and reacted for 24 h. Analysis of XRD and SEM indicated that the P zeolite synthesized under optimum condition had pure form, single phase and high crystalline, it could be used as wash auxiliary. The method provided an effective way for the reuse of agricultural by-products.

  7. Influence of a-Si:H deposition power on surface passivation property and thermal stability of a-Si:H/SiNx:H stacks

    Directory of Open Access Journals (Sweden)

    Hua Li

    2012-06-01

    Full Text Available The effectiveness of hydrogenated amorphous silicon (a-Si:H layers for passivating crystalline silicon surfaces has been well documented in the literature for well over a decade. One limitation of such layers however has arisen from their inability to withstand temperatures much above their deposition temperature without significant degradation. This limitation is of importance particularly with multicrystalline silicon materials where temperatures of at least 400°C are needed for effective hydrogenation of the crystallographic defects such as grain boundaries. To address this limitation, in this work the surface passivation quality and thermal stability of a stack passivating system, combining a layer of intrinsic a-Si:H and a capping layer of silicon nitride (SiNx:H, on p-type crystalline silicon wafers is studied and optimized. In particular the sensitivity of different microwave (MW power levels for underlying a-Si:H layer deposition are examined. Both effective minority carrier lifetime (ζeff measurement and Fourier transform infrared (FTIR spectrometry were employed to study the bonding configurations, passivating quality and thermal stability of the a-Si:H/SiNx:H stacks. It is established that the higher MW power could result in increased as-deposited ζeff and implied Voc (iVoc values, indicating likely improved surface passivation quality, but that this combination degrades more quickly when exposed to prolonged thermal treatments. The more dihydride-rich film composition corresponding to the higher MW power appears to be beneficial for bond restructuring by hydrogen interchanges when exposed to short term annealing, however it also appears more susceptible to providing channels for hydrogen out-effusion which is the likely cause of the poorer thermal stability for prolonged high temperature exposure compared with stacks with underlying a-Si:H deposited with lower MW power.

  8. Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangtao; Ingenito, Andrea; Hameren, Nienke van; Isabella, Olindo; Zeman, Miro [PVMD, Delft University of Technology, P.O. Box 5031, 2600 GA Delft (Netherlands)

    2016-01-18

    Ion-implanted passivating contacts based on poly-crystalline silicon (polySi) are enabled by tunneling oxide, optimized, and used to fabricate interdigitated back contact (IBC) solar cells. Both n-type (phosphorous doped) and p-type (boron doped) passivating contacts are fabricated by ion-implantation of intrinsic polySi layers deposited via low-pressure chemical vapor deposition and subsequently annealed. The impact of doping profile on the passivation quality of the polySi doped contacts is studied for both polarities. It was found that an excellent surface passivation could be obtained by confining as much as possible the implanted-and-activated dopants within the polySi layers. The doping profile in the polySi was controlled by modifying the polySi thickness, the energy and dose of ion-implantation, and the temperature and time of annealing. An implied open-circuit voltage of 721 mV for n-type and 692 mV for p-type passivating contacts was achieved. Besides the high passivating quality, the developed passivating contacts exhibit reasonable high conductivity (R{sub sh n-type} = 95 Ω/□ and R{sub sh p-type} = 120 Ω/□). An efficiency of 19.2% (V{sub oc} = 673 mV, J{sub sc} = 38.0 mA/cm{sup 2}, FF = 75.2%, and pseudo-FF = 83.2%) was achieved on a front-textured IBC solar cell with polySi passivating contacts as both back surface field and emitter. By improving the front-side passivation, a V{sub OC} of 696 mV was also measured.

  9. Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

    Science.gov (United States)

    Yang, Guangtao; Ingenito, Andrea; van Hameren, Nienke; Isabella, Olindo; Zeman, Miro

    2016-01-01

    Ion-implanted passivating contacts based on poly-crystalline silicon (polySi) are enabled by tunneling oxide, optimized, and used to fabricate interdigitated back contact (IBC) solar cells. Both n-type (phosphorous doped) and p-type (boron doped) passivating contacts are fabricated by ion-implantation of intrinsic polySi layers deposited via low-pressure chemical vapor deposition and subsequently annealed. The impact of doping profile on the passivation quality of the polySi doped contacts is studied for both polarities. It was found that an excellent surface passivation could be obtained by confining as much as possible the implanted-and-activated dopants within the polySi layers. The doping profile in the polySi was controlled by modifying the polySi thickness, the energy and dose of ion-implantation, and the temperature and time of annealing. An implied open-circuit voltage of 721 mV for n-type and 692 mV for p-type passivating contacts was achieved. Besides the high passivating quality, the developed passivating contacts exhibit reasonable high conductivity (Rsh n-type = 95 Ω/□ and Rsh p-type = 120 Ω/□). An efficiency of 19.2% (Voc = 673 mV, Jsc = 38.0 mA/cm2, FF = 75.2%, and pseudo-FF = 83.2%) was achieved on a front-textured IBC solar cell with polySi passivating contacts as both back surface field and emitter. By improving the front-side passivation, a VOC of 696 mV was also measured.

  10. Development in p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    YU Liping; ZHU Qiqiang; FAN Dayong; LAN Zili

    2012-01-01

    Zinc oxide (ZnO) is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications,such as the flat panel displays and solar cells used in sports tournament.Despite its advantages,the application of ZnO is hampered by the lack of stable p-type doping.In this paper,the recent progress in this field was briefly reviewed,and a comprehensive summary of the research was carried out on ZnO fabrication methods and its electrical,optical,and magnetic properties were presented.

  11. P-type conductivity in annealed strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Poole, Violet M.; Corolewski, Caleb D.; McCluskey, Matthew D., E-mail: mattmcc@wsu.edu [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814 (United States)

    2015-12-15

    Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO{sub 3}, or STO) samples that were annealed at 1200°C. Room-temperature mobilities above 100 cm{sup 2}/V s were measured, an order of magnitude higher than those for electrons (5-10 cm{sup 2}/V s). Average hole densities were in the 10{sup 9}-10{sup 10} cm{sup −3} range, consistent with a deep acceptor.

  12. Bi-Se doped with Cu, p-type semiconductor

    Science.gov (United States)

    Bhattacharya, Raghu Nath; Phok, Sovannary; Parilla, Philip Anthony

    2013-08-20

    A Bi--Se doped with Cu, p-type semiconductor, preferably used as an absorber material in a photovoltaic device. Preferably the semiconductor has at least 20 molar percent Cu. In a preferred embodiment, the semiconductor comprises at least 28 molar percent of Cu. In one embodiment, the semiconductor comprises a molar percentage of Cu and Bi whereby the molar percentage of Cu divided by the molar percentage of Bi is greater than 1.2. In a preferred embodiment, the semiconductor is manufactured as a thin film having a thickness less than 600 nm.

  13. SIMULATION OF HETEROJUNCTION SOLAR CELLS BASED ON p-TYPE SILICON WAFER%p型晶体硅异质结太阳电池光电特性模拟研究

    Institute of Scientific and Technical Information of China (English)

    程雪梅; 孟凡英; 汪建强; 李祥; 黄建华

    2012-01-01

    利用AFORS-HET软件模拟以p型晶体硅为衬底的异质结太阳电池的特性.太阳电池的基本结构为:TCO/n-a-Si∶ H/i-a-Si∶ H/p-c-Si/Ag,通过改变电池材料的特征参量,分析电池输出特性随相关参量变化的规律.结果表明,与ITO相比,以ZnO为透明导电极的电池在短波光和可见光波段光谱响应更强,短路电流密度和电池效率更高.此外,在所建立的电池模型中,限定掺杂型非晶硅层的厚度为10nm,改变本征非晶硅层厚度,模拟研究找到了电池的短路电流、开路电压、填充因子及光电转换效率随本征层厚度变化的规律和最优值,通过模拟研究发现有背场的双面电池比无背场电池的开路电压增加4.8%,最高转换效率达21.25%.%The performance of heterojunction solar cells was investigated in p-type silicon crystalline by using AFORS-HET. From the simulation results, it is found that comparing with using ITO as TCO, the absorption of solar cell with ZnO as its TCO is much stronger in visible light, and the short current(Jsc) is bigger than the former, so the efficiency(Eff) increase. After inserting a thin intrinsic amorphous silicon (a-Si) between the n a-Si and c-Si, the short current and the fill factor both increased rapidly, and the Eff raised. However, the thickness of the intrinsic layer must be strict controlled within 0. 1-1. 0nm in this model. The bifacial heterojunction solar cells with the structure ZnO(80nm)/a-Si n(10nm)/a-Si i(lnm)/c-Si p(0. 3cm)/a-Si i(lnm)/a-Si p+(10nm) was simulated, and the best performance of Eff is 21. 25% .

  14. Synthesis and electrical characterization of intrinsic and in situ doped Si nanowires using a novel precursor.

    Science.gov (United States)

    Molnar, Wolfgang; Lugstein, Alois; Wojcik, Tomasz; Pongratz, Peter; Auner, Norbert; Bauch, Christian; Bertagnolli, Emmerich

    2012-01-01

    Perchlorinated polysilanes were synthesized by polymerization of tetrachlorosilane under cold plasma conditions with hydrogen as a reducing agent. Subsequent selective cleavage of the resulting polymer yielded oligochlorosilanes Si(n)Cl(2) (n) (+2) (n = 2, 3) from which the octachlorotrisilane (n = 3, Cl(8)Si(3), OCTS) was used as a novel precursor for the synthesis of single-crystalline Si nanowires (NW) by the well-established vapor-liquid-solid (VLS) mechanism. By adding doping agents, specifically BBr(3) and PCl(3), we achieved highly p- and n-type doped Si-NWs by means of atmospheric-pressure chemical vapor deposition (APCVD). These as grown NWs were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as electrical measurements of the NWs integrated in four-terminal and back-gated MOSFET modules. The intrinsic NWs appeared to be highly crystalline, with a preferred growth direction of [111] and a specific resistivity of ρ = 6 kΩ·cm. The doped NWs appeared to be [112] oriented with a specific resistivity of ρ = 198 mΩ·cm for p-type Si-NWs and ρ = 2.7 mΩ·cm for n-doped Si-NWs, revealing excellent dopant activation.

  15. Metal Fluoride Inhibition of a P-type H+ Pump

    Science.gov (United States)

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  16. Improving the performance of amorphous and crystalline silicon heterojunction solar cells by monitoring surface passivation

    Energy Technology Data Exchange (ETDEWEB)

    Schuettauf, J.W.A.; Van der Werf, C.H.M.; Kielen, I.M.; Van Sark, W.G.J.H.M.; Rath, J.K.; Schropp, R.E.I. [Utrecht University, Debye Institute for Nanomaterials Science, Nanophotonics, Physics of Devices, Princetonplein 5, 3584 CC Utrecht (Netherlands)

    2012-09-15

    The influence of thermal annealing on the crystalline silicon surface passivating properties of selected amorphous silicon containing layer stacks (including intrinsic and doped films), as well as the correlation with silicon heterojunction solar cell performance has been investigated. All samples have been isochronally annealed for 1 h in an N{sub 2} ambient at temperatures between 150C and 300C in incremental steps of 15C. For intrinsic films and intrinsic/n-type stacks, an improvement in passivation quality is observed up to 255C and 270C, respectively, and a deterioration at higher temperatures. For intrinsic/n-type a-Si:H layer stacks, a maximum minority carrier lifetime of 13.3 ms at an injection level of 10{sup 15} cm{sup -3} has been measured. In contrast, for intrinsic/p-type a-Si:H layer stacks, a deterioration in passivation is observed upon annealing over the whole temperature range. Comparing the lifetime values and trends for the different layer stacks to the performance of the corresponding cells, it is inferred that the intrinsic/p-layer stack is limiting device performance. Furthermore, thermal annealing of p-type layers should be avoided entirely. We therefore propose an adapted processing sequence, leading to a substantial improvement in efficiency to 16.7%, well above the efficiency of 15.8% obtained with the 'standard' processing sequence.

  17. Recrystallization of Ge thin film on SiO2 substrates using a two-step annealing process

    Science.gov (United States)

    Kim, Sung Wook; Lee, Jaejun; Park, Youn Ho; Park, Jeong Min; Do, Hong Kyeong; Kim, Yeon Joo; Choi, Heon-Jin

    2017-01-01

    The fabrication of high-quality crystalline germanium thin films (GeTF) on an amorphous SiO2 layer is crucial for the realization of high performance-, low cost III-V solar cells used in many applications. Herein, we report the growth of a high-quality crystalline GeTF on SiO2/Si substrates using an ultra-vacuum chemical vapor deposition (UHV-CVD) method. GeTF was grown on the SiO2 layer using a two-step growth and multi-annealing processes. The fabrication method involved the deposition of a 1st seeding layer, annealing, and deposition of a 2nd main layer followed by three times of cyclic annealing. The crystallization of the seeding layer having a thickness of less than 10 nm could be ascribed to the evolution of polycrystalline structures in the main layer. The cyclic annealing performed after the deposition of the main layer is also found to be crucial for the formation of single crystalline, high-quality Ge films on SiO2 substrates with direction. The cyclic annealing results in a further reduction of the defects, thereby threading dislocations significantly to a density of 5.311 × 107 cm-2. Electrical measurements using the van der Pauw method revealed that the GeTF exhibits p-type characteristics and a high mobility of 360.10 cm2/Vs at room temperature. [Figure not available: see fulltext.

  18. The microstructure of Si surface layers after plasma-immersion He+ ion implantation and subsequent thermal annealing1

    Science.gov (United States)

    Lomov, Andrey; Shcherbachev, Kirill; Chesnokov, Yurii

    2017-01-01

    The structural changes in the surface layer of p-type Cz-Si(001) samples after high-dose low-energy (2 keV) He+ plasma-immersion ion implantation and subsequent thermal annealing were studied using a set of complementary methods: high-resolution X-ray reflectometry, high-resolution X-ray diffraction, transmission electron microscopy and atomic force microscopy. The formation of a three-layer structure was observed (an amorphous a-SiOx layer at the surface, an amorphous a-Si layer and a heavily damaged tensile-strained crystalline c-Si layer), which remained after annealing. Helium-filled bubbles were observed in the as-implanted sample. The influence of annealing on the evolution of the three-layer structure and the bubbles is considered. The bubbles are shown to grow after annealing. Their characteristic size is determined to be in the range of 5–20 nm. Large helium-filled bubbles are located in the amorphous a-Si layer. Small bubbles form inside the damaged crystalline Si layer. These bubbles are a major source of tensile strain in the c-Si layer.

  19. Impact of surface morphology of Si substrate on performance of Si/ZnO heterojunction devices grown by atomic layer deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Hazra, Purnima; Singh, Satyendra Kumar [Department of Electronics and Communication Engineering, Motilal Neheru National Institute of Technology, Allahabad 211004 (India); Jit, Satyabrata, E-mail: sjit.ece@itbhu.ac.in [Department of Electronics Engineering, Indian Institute of Technology (BHU), Varanasi 221005 (India)

    2015-01-01

    In this paper, the authors have investigated the structural, optical, and electrical characteristics of silicon nanowire (SiNW)/zinc oxide (ZnO) core–shell nanostructure heterojunctions and compared their characteristics with Si/ZnO planar heterojunctions to investigate the effect of surface morphology of Si substrate in the characteristics of Si/ZnO heterojunction devices. In this work, ZnO thin film was conformally deposited on both p-type 〈100〉 planar Si substrate and substrate with vertically aligned SiNW arrays by atomic layer deposition (ALD) method. The x-ray diffraction spectra show that the crystalline structures of Si/ZnO heterojunctions are having (101) preferred orientation, whereas vertically oriented SiNW/ZnO core–shell heterojunctions are having (002)-oriented wurtzite crystalline structures. The photoluminescence (PL) spectra of Si/ZnO heterojunctions show a very sharp single peak at 377 nm, corresponding to the bandgap of ZnO material with no other defect peaks in visible region; hence, these devices can have applications only in UV region. On the other hand, SiNW/ZnO heterojunctions are having band-edge peak at 378 nm along with a broad emission band, spreading almost throughout the entire visible region with a peak around 550 nm. Therefore, ALD-grown SiNW/ZnO heterojunctions can emit green and red light simultaneously. Reflectivity measurement of the heterojunctions further confirms the enhancement of visible region peak in the PL spectra of SiNW/ZnO heterojunctions, as the surface of the SiNW/ZnO heterojunctions exhibits extremely low reflectance (<3%) in the visible wavelength region compared to Si/ZnO heterojunctions (>20%). The current–voltage characteristics of both Si/ZnO and SiNW/ZnO heterojunctions are measured with large area ohmic contacts on top and bottom of the structure to compare the electrical characteristics of the devices. Due to large surface to-volume ratio of SiNW/ZnO core–shell heterojunction devices, the

  20. Low-temperature TCT characterization of heavily proton irradiated p-type magnetic Czochralski silicon detectors

    CERN Document Server

    Härkönen, J; Luukka, P; Kassamakov, I; Autioniemi, M; Tuominen, E; Sane, P; Pusa, P; Räisänen, J; Eremin, V; Verbitskaya, E; Li, Z

    2007-01-01

    n+/p−/p+ pad detectors processed at the Microelectronics Center of Helsinki University of Technology on boron-doped p-type high-resistivity magnetic Czochralski (MCz-Si) silicon substrates have been investigated by the transient current technique (TCT) measurements between 100 and 240 K. The detectors were irradiated by 9 MeV protons at the Accelerator Laboratory of University of Helsinki up to 1 MeV neutron equivalent fluence of 2×1015 n/cm2. In some of the detectors the thermal donors (TD) were introduced by intentional heat treatment at 430 °C. Hole trapping time constants and full depletion voltage values were extracted from the TCT data. We observed that hole trapping times in the order of 10 ns were found in heavily (above 1×1015 neq/cm2) irradiated samples. These detectors could be fully depleted below 500 V in the temperature range of 140–180 K.

  1. p-Type NiO Hybrid Visible Photodetector.

    Science.gov (United States)

    Mallows, John; Planells, Miquel; Thakare, Vishal; Bhosale, Reshma; Ogale, Satishchandra; Robertson, Neil

    2015-12-23

    A novel hybrid visible-light photodetector was created using a planar p-type inorganic NiO layer in a junction with an organic electron acceptor layer. The effect of different oxygen pressures on formation of the NiO layer by pulsed laser deposition shows that higher pressure increases the charge carrier density of the film and lowers the dark current in the device. The addition of a monolayer of small molecules containing conjugated π systems and carboxyl groups at the device interface was also investigated and with correct alignment of the energy levels improves the device performance with respect to the quantum efficiency, responsivity, and photogeneration. The thickness of the organic layer was also optimized for the device, giving a responsivity of 1.54 × 10(-2) A W(-1) in 460 nm light.

  2. Elucidating Functional Aspects of P-type ATPases

    DEFF Research Database (Denmark)

    Autzen, Henriette Elisabeth

    2015-01-01

    similar to that of the wild type (WT) protein. The discrepancy between the newly determined crystal structure of LpCopA and the functional manifestations of the missense mutation in human CopA, could indicate that LpCopA is insufficient in structurally elucidating the effect of disease-causing mutations...... cancer and pathogenic microbes. The goal of this Ph.D. dissertation was to functionally characterize SERCA1a and CopA from Legionella pneumophila (LpCopA) through a range of different methods within structural biology. Crystallographic studies of SERCA1a led to a newly determined crystal structure......P-type ATPases are proteins that act to maintain ion homeostasis and electrochemical gradients through the translocation of cations across cell membranes. Underscoring their significance in humans, dysfunction of the ATPases can lead to crucial diseases. Dysfunction of the sarco...

  3. Study on the p-type QWIP-LED device

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Honglou; XIONG; Dayuan; ZHOU; Xuchang; LI; Ning; SHAO; Jun; LU; Wei

    2006-01-01

    A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology.

  4. Basic research challenges in crystalline silicon photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Werner, J.H. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    1995-08-01

    Silicon is abundant, non-toxic and has an ideal band gap for photovoltaic energy conversion. Experimental world record cells of 24 % conversion efficiency with around 300 {mu}m thickness are only 4 % (absolute) efficiency points below the theoretical Auger recombination-limit of around 28 %. Compared with other photovoltaic materials, crystalline silicon has only very few disadvantages. The handicap of weak light absorbance may be mastered by clever optical designs. Single crystalline cells of only 48 {mu}m thickness showed 17.3 % efficiency even without backside reflectors. A technology of solar cells from polycrystalline Si films on foreign substrates arises at the horizon. However, the disadvantageous, strong activity of grain boundaries in Si could be an insurmountable hurdle for a cost-effective, terrestrial photovoltaics based on polycrystalline Si on foreign substrates. This talk discusses some basic research challenges related to a Si based photovoltaics.

  5. Large area growth and electrical properties of p-type WSe2 atomic layers.

    Science.gov (United States)

    Zhou, Hailong; Wang, Chen; Shaw, Jonathan C; Cheng, Rui; Chen, Yu; Huang, Xiaoqing; Liu, Yuan; Weiss, Nathan O; Lin, Zhaoyang; Huang, Yu; Duan, Xiangfeng

    2015-01-14

    Transition metal dichacogenides represent a unique class of two-dimensional layered materials that can be exfoliated into single or few atomic layers. Tungsten diselenide (WSe(2)) is one typical example with p-type semiconductor characteristics. Bulk WSe(2) has an indirect band gap (∼ 1.2 eV), which transits into a direct band gap (∼ 1.65 eV) in monolayers. Monolayer WSe(2), therefore, is of considerable interest as a new electronic material for functional electronics and optoelectronics. However, the controllable synthesis of large-area WSe(2) atomic layers remains a challenge. The studies on WSe(2) are largely limited by relatively small lateral size of exfoliated flakes and poor yield, which has significantly restricted the large-scale applications of the WSe(2) atomic layers. Here, we report a systematic study of chemical vapor deposition approach for large area growth of atomically thin WSe(2) film with the lateral dimensions up to ∼ 1 cm(2). Microphotoluminescence mapping indicates distinct layer dependent efficiency. The monolayer area exhibits much stronger light emission than bilayer or multilayers, consistent with the expected transition to direct band gap in the monolayer limit. The transmission electron microscopy studies demonstrate excellent crystalline quality of the atomically thin WSe(2). Electrical transport studies further show that the p-type WSe(2) field-effect transistors exhibit excellent electronic characteristics with effective hole carrier mobility up to 100 cm(2) V(-1) s(-1) for monolayer and up to 350 cm(2) V(-1) s(-1) for few-layer materials at room temperature, comparable or well above that of previously reported mobility values for the synthetic WSe(2) and comparable to the best exfoliated materials.

  6. Controlled synthesis of single-crystalline graphene

    Directory of Open Access Journals (Sweden)

    Wang Xueshen

    2014-02-01

    Full Text Available This paper reports the controlled synthesis of single-crystalline graphene on the back side of copper foil using CH4 as the precursor. The influence of growth time and the pressure ratio of CH4/H2 on the structure of graphene are examined. An optimized polymer-assisted method is used to transfer the synthesized graphene onto a SiO2/Si substrate. Scanning electron microscopy and Raman spectroscopy are used to characterize the graphene.

  7. Influence of Preparation Conditions on Electrical Properties of the Al/Alq3/Si Diode Structures

    Directory of Open Access Journals (Sweden)

    Irina ČERNIUKĖ

    2013-12-01

    Full Text Available Hybrid organic-inorganic diode structures, Al/Alq3/n-Si and Al/Alq3/p-Si based on thin films of tris(8-hydroxyquinoline aluminum (Alq3 have been investigated. The Alq3 films were evaporated in vacuum and spin coated onto patterned areas of crystalline n- and p-type Si substrates with chemically removed native SiO2 layer. Current-voltage characteristics of the diode structures demonstrated improved rectification property compared to similar Al/n-Si and Al/p-Si device structures. Increased barrier height values (0.90 eV ÷ 1.1 eV and 0.77 eV ÷ 0.91 eV for the Al/Alq3/n-Si and Al/Alq3/p-Si device structures, respectively certified presence of an interface dipole induced by the organic interlayer. Non-ideal behavior of forward current-voltage characteristics has been explained assuming non-uniformity of barrier height, presence of interface states, and influence of the organic film on diode series resistance and space charge limited current. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2733

  8. Crystalline and Crystalline International Disposal Activities

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-21

    This report presents the results of work conducted between September 2014 and July 2015 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program.

  9. Synthesis and electrical characterization of intrinsic and in situ doped Si nanowires using a novel precursor

    Directory of Open Access Journals (Sweden)

    Wolfgang Molnar

    2012-07-01

    Full Text Available Perchlorinated polysilanes were synthesized by polymerization of tetrachlorosilane under cold plasma conditions with hydrogen as a reducing agent. Subsequent selective cleavage of the resulting polymer yielded oligochlorosilanes SinCl2n+2 (n = 2, 3 from which the octachlorotrisilane (n = 3, Cl8Si3, OCTS was used as a novel precursor for the synthesis of single-crystalline Si nanowires (NW by the well-established vapor–liquid–solid (VLS mechanism. By adding doping agents, specifically BBr3 and PCl3, we achieved highly p- and n-type doped Si-NWs by means of atmospheric-pressure chemical vapor deposition (APCVD. These as grown NWs were investigated by means of scanning electron microscopy (SEM and transmission electron microscopy (TEM, as well as electrical measurements of the NWs integrated in four-terminal and back-gated MOSFET modules. The intrinsic NWs appeared to be highly crystalline, with a preferred growth direction of [111] and a specific resistivity of ρ = 6 kΩ·cm. The doped NWs appeared to be [112] oriented with a specific resistivity of ρ = 198 mΩ·cm for p-type Si-NWs and ρ = 2.7 mΩ·cm for n-doped Si-NWs, revealing excellent dopant activation.

  10. Passivation of c-Si surfaces by sub-nm amorphous silicon capped with silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Yimao, E-mail: yimao.wan@anu.edu.au; Yan, Di; Bullock, James; Zhang, Xinyu; Cuevas, Andres [Research School of Engineering, The Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

    2015-12-07

    A sub-nm hydrogenated amorphous silicon (a-Si:H) film capped with silicon nitride (SiN{sub x}) is shown to provide a high level passivation to crystalline silicon (c-Si) surfaces. When passivated by a 0.8 nm a-Si:H/75 nm SiN{sub x} stack, recombination current density J{sub 0} values of 9, 11, 47, and 87 fA/cm{sup 2} are obtained on 10 Ω·cm n-type, 0.8 Ω·cm p-type, 160 Ω/sq phosphorus-diffused, and 120 Ω/sq boron-diffused silicon surfaces, respectively. The J{sub 0} on n-type 10 Ω·cm wafers is further reduced to 2.5 ± 0.5 fA/cm{sup 2} when the a-Si:H film thickness exceeds 2.5 nm. The passivation by the sub-nm a-Si:H/SiN{sub x} stack is thermally stable at 400 °C in N{sub 2} for 60 min on all four c-Si surfaces. Capacitance–voltage measurements reveal a reduction in interface defect density and film charge density with an increase in a-Si:H thickness. The nearly transparent sub-nm a-Si:H/SiN{sub x} stack is thus demonstrated to be a promising surface passivation and antireflection coating suitable for all types of surfaces encountered in high efficiency c-Si solar cells.

  11. The Cosmic Crystallinity Conundrum: Clues from IRAS 17495-2534

    CERN Document Server

    Speck, Angela K; Tartar, Josh B

    2008-01-01

    Since their discovery, cosmic crystalline silicates have presented several challenges to understanding dust formation and evolution. The mid-infrared spectrum of IRAS 17495$-$2534, a highly obscured oxygen-rich asymptotic giant branch (AGB) star, is the only source observed to date which exhibits a clear crystalline silicate absorption feature. This provides an unprecedented opportunity to test competing hypotheses for dust formation. Observed spectral features suggest that both amorphous and crystalline dust is dominated by forsterite (Mg\\_2 SiO\\_4) rather than enstatite (MgSiO\\_3) or other silicate compositions. We confirm that high mass-loss rates should produce more crystalline material, and show why this should be dominated by forsterite. The presence of Mg\\_2 SiO\\_4 glass suggests that another factor (possibly C/O) is critical in determining astromineralogy. Correlation between crystallinity, mass-loss rate and initial stellar mass suggests that only the most massive AGB stars contribute significant qua...

  12. Design and analysis of nanowire p-type MOSFET coaxially having silicon core and germanium peripheral channel

    Science.gov (United States)

    Yu, Eunseon; Cho, Seongjae

    2016-11-01

    In this work, a nanowire p-type metal-oxide-semiconductor field-effect transistor (PMOSFET) coaxially having a Si core and a Ge peripheral channel is designed and characterized by device simulations. Owing to the high hole mobility of Ge, the device can be utilized for high-speed CMOS integrated circuits, with the effective confinement of mobile holes in Ge by the large valence band offset between Si and Ge. Source/drain doping concentrations and the ratio between the Si core and Ge channel thicknesses are determined. On the basis of the design results, the channel length is aggressively scaled down by evaluating the primary DC parameters in order to confirm device scalability and low-power applicability in sub-10-nm technology nodes.

  13. (Ga,Fe)Sb: A p-type ferromagnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh; Anh, Le Duc; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan)

    2014-09-29

    A p-type ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 3.9%–13.7%) has been grown by low-temperature molecular beam epitaxy (MBE) on GaAs(001) substrates. Reflection high energy electron diffraction patterns during the MBE growth and X-ray diffraction spectra indicate that (Ga,Fe)Sb layers have the zinc-blende crystal structure without any other crystallographic phase of precipitates. Magnetic circular dichroism (MCD) spectroscopy characterizations indicate that (Ga,Fe)Sb has the zinc-blende band structure with spin-splitting induced by s,p-d exchange interactions. The magnetic field dependence of the MCD intensity and anomalous Hall resistance of (Ga,Fe)Sb show clear hysteresis, demonstrating the presence of ferromagnetic order. The Curie temperature (T{sub C}) increases with increasing x and reaches 140 K at x = 13.7%. The crystal structure analyses, magneto-transport, and magneto-optical properties indicate that (Ga,Fe)Sb is an intrinsic ferromagnetic semiconductor.

  14. Infrared Transparent Spinel Films with p -Type Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Exarhos, Gregory J.; Ferris, Kim F.; Engelhard, Mark H.; Stewart, Donald C.

    2001-11-29

    Spinel oxide films containing at least two transition metal cations were found to exhibit p-type conductivity with high optical transparency from the visible to wavelengths near 15 micrometers. Resistivities as low as 0.003 ohm-cm were measured on 100 nm thick rf sputter deposited films that contained nickel and cobalt. Optical spectra, Raman scattering and XPS measurements indicated the valency of nickel localized on octahedral sites within the spinel lattice determines these properties. Electronic band structure calculations corroborated the experimental results. A resistivity minimum was found at the composition NiCo2O4 deposited from aqueous or alcoholic solutions followed by subsequent annealing at 400 degrees C in air. Solution deposited films richer in nickel than this stoichiometry always were found to phase separate into nickel oxide and a spinel phase with concomitant loss in conductivity. However, the phase stability region could be extended to higher nickel contents when rf-sputter deposition techniques were used. Sputter deposited spinel films having a nickel to cobalt ratio less than 2 were found to exhibit the highest conductivity. Results suggest that the phase stability region for these materials can be extended through appropriate choice of deposition conditions. A possible mechanism that promotes high conductivity in this system is thought to be charge transfer between the resident di- and trivalent cations that may be assisted by the magnetic nature of the oxide film.

  15. Electronic processes in uniaxially stressed p-type germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

    1996-02-01

    Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

  16. Photoconduction spectroscopy of p-type GaSb films

    Energy Technology Data Exchange (ETDEWEB)

    Shura, M.W., E-mail: Megersa.Shura@live.nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Wagener, V.; Botha, J.R.; Wagener, M.C. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 {mu}m. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley-Read-Hall lifetime and maximum value of the surface recombination velocity.

  17. Fabrication of p-type ZnSe:Sb nanowires for high-performance ultraviolet light photodetector application.

    Science.gov (United States)

    Nie, Biao; Luo, Lin-Bao; Chen, Jing-Jing; Hu, Ji-Gang; Wu, Chun-Yan; Wang, Li; Yu, Yong-Qiang; Zhu, Zhi-Feng; Jie, Jian-Sheng

    2013-03-08

    p-type ZnSe nanowires (NWs) with tunable electrical conductivity were fabricated on a large scale by evaporating a mixed powder composed of ZnSe and Sb in different ratios. According to the structural characterization, the Sb-doped ZnSe NWs are of single crystalline form and grow along the [001] direction. The presence of Sb in the ZnSe NWs was confirmed by XPS spectra. Electrical measurement of a single ZnSe:Sb NW based back-gate metal-oxide field-effect-transistor reveals that all the doped NWs exhibit typical p-type conduction characteristics, and the conductivity can be tuned over eight orders of magnitude, from 6.36 × 10(-7) S cm(-1) for the undoped sample to ∼37.33 S cm(-1) for the heavily doped sample. A crossed p-n nano-heterojunction photodetector made from the as-doped nanostructures displays pronounced rectification behavior, with a rectification ratio as high as 10(3) at ±5 V. Remarkably, it exhibits high sensitivity to ultraviolet light illumination with good reproducibility and quick photoresponse. Finally, the work mechanism of such a p-n junction based photodetector was elucidated. The generality of the above result suggests that the as-doped p-type ZnSe NWs will find wide application in future optoelectronics devices.

  18. Reaction Front Evolution during Electrochemical Lithiation of Crystalline Silicon Nanopillars

    KAUST Repository

    Lee, Seok Woo

    2012-12-01

    The high theoretical specific capacity of Si as an anode material is attractive in lithium-ion batteries, although the issues caused by large volume changes during cycling have been a major challenge. Efforts have been devoted to understanding how diffusion-induced stresses cause fracture, but recent observations of anisotropic volume expansion in single-crystalline Si nanostructures require new theoretical considerations of expansion behavior during lithiation. Further experimental investigation is also necessary to better understand the anisotropy of the lithiation process. Here, we present a method to reveal the crystalline core of partially lithiated Si nanopillars with three different crystallographic orientations by using methanol to dissolve the Li atoms from the amorphous Li-Si alloy. The exposed crystalline cores have flat {110} surfaces at the pillar sidewalls; these surfaces represent the position of the reaction front between the crystalline core and the amorphous Li-Si alloy. It was also found that an amorphous Si structure remained on the flat surfaces of the crystalline core after dissolution of the Li, which was presumed to be caused by the accumulation of Si atoms left over from the removal of Li from the Li-Si alloy. © 2012 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim.

  19. Novel Scheme of Amorphous/Crystalline Silicon Heterojunction Solar Cell

    Energy Technology Data Exchange (ETDEWEB)

    De Iuliis, S.; Geerligs, L.J. [ECN Solar Energy, Petten (Netherlands); Tucci, M.; Serenelli, L.; Salza, E. [ENEA Research Center Casaccia, Roma (Italy); De Cesare, G.; Caputo, D.; Ceccarelli, M. [University ' Sapienza' , Department of Electronic Engineering, Roma (Italy)

    2007-01-15

    In this paper we investigate in detail how the heterostructure concept can be implemented in an interdigitated back contact solar cell, in which both the emitters are formed on the back side of the c-Si wafer by amorphous/crystalline silicon heterostructure, and at the same time the grid-less front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire process, held at temperature below 300C, is photolithography-free, using a metallic self-aligned mask to create the interdigitated pattern, and we show that the alignment is feasible. An open-circuit voltage of 687 mV has been measured on a p-type monocrystalline silicon wafer. The mask-assisted deposition process does not influence the uniformity of the deposited amorphous silicon layers. Photocurrent limits factor has been investigated with the aid of one-dimensional modeling and quantum efficiency measurements. On the other hand several technological aspects that limit the fill factor and the short circuit current density still need improvements.

  20. The effect of light soaking on crystalline silicon surface passivation by atomic layer deposited Al2O3

    Science.gov (United States)

    Liao, Baochen; Stangl, Rolf; Mueller, Thomas; Lin, Fen; Bhatia, Charanjit S.; Hoex, Bram

    2013-01-01

    The effect of light soaking of crystalline silicon wafer lifetime samples surface passivated by thermal atomic layer deposited (ALD) Al2O3 is investigated in this paper. Contrary to other passivation materials used in solar cell applications (i.e., SiO2, SiNx), using thermal ALD Al2O3, an increase in effective carrier lifetime after light soaking under standard testing conditions is observed for both p-type (˜45%) and n-type (˜60%) FZ c-Si lifetime samples. After light soaking and storing the samples in a dark and dry environment, the effective lifetime decreases again and practically returns to the value before light soaking. The rate of lifetime decrease after light soaking is significantly slower than the rate of lifetime increase by light soaking. To investigate the underlying mechanism, corona charge experiments are carried out on p-type c-Si samples before and after light soaking. The results indicate that the negative fixed charge density Qf present in the Al2O3 films increases due to the light soaking, which results in an improved field-effect passivation. Numerical calculations also confirm that the improved field-effect passivation is the main contributor for the increased effective lifetime after light soaking. To further understand the light soaking phenomenon, a kinetic model—a charge trapping/de-trapping model—is proposed to explain the time dependent behavior of the lifetime increase/decrease observed under/after light soaking. The trap model fits the experimental results very well. The observed light enhanced passivation for ALD Al2O3 passivated c-Si is of technological relevance, because solar cell devices operate under illumination, thus an increase in solar cell efficiency due to light soaking can be expected.

  1. 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.

  2. Realization of stable p-type ZnO thin films using Li-N dual acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Rao, T. Prasada, E-mail: prasadview@gmail.com [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli- 620 015 (India); Kumar, M.C. Santhosh, E-mail: santhoshmc@nitt.edu [Advanced Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli- 620 015 (India)

    2011-09-01

    Highlights: > We have presented a promising Li-N dual acceptor doping method to realize p-type ZnO films via spray pyrolysis. > The influence of concentration of Li-N on the structural, electrical, and optical properties of p-type ZnO:(Li, N) films were investigated in detail. > It is found that (Li, N):ZnO films deposited on glass substrate show the preferential orientation of (002) plane. > The Hall Effect measurements exhibited p-type behaviour on (Li, N):ZnO thin films and the stability of the samples were verified by aging studies. - Abstract: Lithium and nitrogen dual acceptors-doped p-type ZnO thin films have been prepared using spray pyrolysis technique. The influence of dual acceptor (Li, N) doping on the structural, electrical, and optical properties of (Li, N):ZnO films are investigated in detail. The (Li, N):ZnO films exhibit good crystallinity with a preferred c-axis orientation. From AFM studies, it is found that the surface roughness of the thin films increases with the increase of doping percentage. The Hall Effect measurements showed p-type conductivity. The Hall measurements have been performed periodically up to seven months and it is observed that the films show p-type conductivity throughout the period of observation. The samples with Li:N ratio of 8:8 mol% showed the lowest resistivity of 35.78 {Omega} cm, while sample with Li:N ratio of 6:6 mol% showed highest carrier concentration. The PL spectra of (Li, N):ZnO films show a strong UV emission at room temperature. Furthermore, PL spectra show low intensity in deep level transition, indicating a low density of native defects. This indicates that the formation of intrinsic defects is effectively suppressed by dual acceptor (Li, N) doping in ZnO thin films. The chemical bonding states of N and Li in the films were examined by XPS analysis.

  3. Low temperature boron doping into crystalline silicon by boron-containing species generated in Cat-CVD apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Tatsunori, E-mail: s1130011@jaist.ac.jp [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Koyama, Koichi [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ohdaira, Keisuke [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Matsumura, Hideki [Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2015-01-30

    We have discovered that phosphorus (P) atoms can be doped into crystalline silicon (c-Si) at temperatures below 350 °C or even at 80 °C by using species generated by catalytic cracking reaction of phosphine (PH{sub 3}) molecules with heated tungsten (W) catalyzer in Cat-CVD apparatus. As further investigation, here, we study the feasibility of low temperature doping of boron (B) atoms into c-Si by using decomposed species generated similarly from diborane (B{sub 2}H{sub 6}) molecules. Dependency of properties of doped layers on catalyzer temperature (T{sub cat}) and substrate temperature (T{sub s}) is studied by both the Van der Pauw method based on the Hall-effect measurements and secondary ion mass spectroscopy (SIMS) for B doping in addition to P doping. It is found that, similarly to P doping, the surface of n-type c-Si is converted to p-type even at T{sub s} = 80 °C for T{sub cat} over 800 °C when c-Si is exposed to B{sub 2}H{sub 6} cracked species for a few minutes, and that the heat of substrate over 300 °C is likely to help for B doping contrary to P doping.

  4. Crystalline Bioceramic Materials

    Directory of Open Access Journals (Sweden)

    de Aza, P. N.

    2005-06-01

    Full Text Available A strong interest in the use of ceramics for biomedical engineering applications developed in the late 1960´s. Used initially as alternatives to metallic materials in order to increase the biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics; bioactive or surface reactive bioceramics and bioresorbable ceramics. This review will only refer to bioceramics “sensus stricto”, it is to say, those ceramic materials constituted for nonmetallic inorganic compounds, crystallines and consolidated by thermal treatments of powders to high temperatures. Leaving bioglasses, glass-ceramics and biocements apart, since, although all of them are obtained by thermal treatments to high temperatures, the first are amorphous, the second are obtained by desvitrification of a glass and in them vitreous phase normally prevails on the crystalline phases and the third are consolidated by means of a hydraulic or chemical reaction to room temperature. A review of the composition, physiochemical properties and biological behaviour of the principal types of crystalline bioceramics is given, based on the literature data and on the own experience of the authors.

    A finales de los años sesenta se despertó un gran interés por el uso de los materiales cerámicos para aplicaciones biomédicas. Inicialmente utilizados como una alternativa a los materiales metálicos, con el propósito de incrementar la biocompatibilidad de los implantes, las biocerámicas se han convertido en una clase diversa de biomateriales, incluyendo actualmente tres tipos: cerámicas cuasi inertes; cerámicas bioactivas o reactivas superficialmente y cerámicas reabsorbibles o biodegradables. En la presente revisión se hace referencia a las biocerámicas en sentido estricto, es decir, a aquellos materiales constitutitos por compuestos inorgánicos no metálicos, cristalinos y consolidados

  5. Crystalline and Crystalline International Disposal Activities

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, Hari S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chu, Shaoping [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffrey De' Haven [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-06

    This report presents the results of work conducted between September 2015 and July 2016 at Los Alamos National Laboratory in the crystalline disposal and crystalline international disposal work packages of the Used Fuel Disposition Campaign (UFDC) for DOE-NE’s Fuel Cycle Research and Development program. Los Alamos focused on two main activities during this period: Discrete fracture network (DFN) modeling to describe flow and radionuclide transport in complex fracture networks that are typical of crystalline rock environments, and a comprehensive interpretation of three different colloid-facilitated radionuclide transport experiments conducted in a fractured granodiorite at the Grimsel Test Site in Switzerland between 2002 and 2013. Chapter 1 presents the results of the DFN work and is divided into three main sections: (1) we show results of our recent study on the correlation between fracture size and fracture transmissivity (2) we present an analysis and visualization prototype using the concept of a flow topology graph for characterization of discrete fracture networks, and (3) we describe the Crystalline International work in support of the Swedish Task Force. Chapter 2 presents interpretation of the colloidfacilitated radionuclide transport experiments in the crystalline rock at the Grimsel Test Site.

  6. Photonic Properties of Er-Doped Crystalline Silicon

    NARCIS (Netherlands)

    Vinh, N. Q.; Ha, N. N.; T. Gregorkiewicz,

    2009-01-01

    During the last four decades, a remarkable research effort has been made to understand the physical properties of Si:Er material, as it is considered to be a promising approach towards improving the optical properties of crystalline Si. in this paper, we present a summary of the most important resul

  7. SIMILAR POINT-DEFECTS IN CRYSTALLINE AND AMORPHOUS-SILICON

    NARCIS (Netherlands)

    LIANG, ZN; NIESEN, L; VANDENHOVEN, GN; CUSTER, JS

    1994-01-01

    The microscopic nature of defects in ion-implanted crystalline silicon (c-Si) and amorphous silicon (a-Si) has been studied using Mossbauer spectroscopy. The evolution of the local structure around the probe atoms is followed during thermal annealing of ion-beam-created amorphous and ion-beam-damage

  8. Ultraviolet light-emitting diodes with polarization-doped p-type layer

    Science.gov (United States)

    Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Liangliang; Xia, Chao; Yuan, Songyang; Yin, Yian; Li, Shuti

    2016-09-01

    We report ultraviolet light emitting diode (LEDs) with polarization doped p-type layer. Fabricated LEDs with polarization doped p-type layer exhibited reduced forward voltage and enhanced light output power, compared to those with traditional p-type AlGaN layer. The improvement is attributed to improved hole concentration and the smooth valence band by the polarization enhanced p-type doping. Our simulated results reveal that this p-type layer can further enhance the performance of ultraviolet LEDs by removing the electron blocking layer (EBL).

  9. Crystalline Silica Primer

    Science.gov (United States)

    ,

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  10. Evidence for an iron-hydrogen complex in p-type silicon

    Science.gov (United States)

    Leonard, S.; Markevich, V. P.; Peaker, A. R.; Hamilton, B.; Murphy, J. D.

    2015-07-01

    Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90-120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at Ev + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10-17 cm2. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

  11. Porous silicon damage enhanced phosphorus and aluminium gettering of p-type Czochralski silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hassen, M. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia); Ben Jaballah, A. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia)]. E-mail: gadour2003@yahoo.fr; Hajji, M. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia); Rahmouni, H. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Faculte des Sciences de Monastir, Rue de Kairouan, 5000 Monastir (Tunisia); Selmi, A. [Laboratoire de Physique des Semiconducteurs et des Composants Electroniques, Faculte des Sciences de Monastir, Rue de Kairouan, 5000 Monastir (Tunisia); Ezzaouia, H. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, PB 95 2050 Hammam-Lif (Tunisia)

    2005-12-05

    In this work, porous silicon damage (PSD) is presented as a simple sequence for efficient external purification techniques. The method consists of using thin nanoporous p-type silicon on both sides of the silicon substrates with randomly hemispherical voids. Then, two main sample types are processed. In the first type, thin aluminium layers ({>=}1 {mu}m) are thermally evaporated followed by photo-thermal annealing treatments in N{sub 2} atmosphere at one of several temperatures ranging between 600 and 800 deg. C. In the second type, phosphorus is continually diffused in N{sub 2}/O{sub 2} ambient in a solid phase from POCl{sub 3} solution during heating at one of several temperatures ranging between 750 and 1000 deg. C for 1 h. Hall Effect and Van Der Pauw methods prove the existence of an optimum temperature in the case of phosphorus gettering at 900 deg. C yielding a Hall mobility of about 982 cm{sup 2} V{sup -1} s{sup -1}. However, in the case of aluminium gettering, there is no gettering limit in the as mentioned temperature range. Metal/Si Schottky diodes are elaborated to clarify these improvements. In this study, we demonstrate that enhanced metal solubility model cannot explain the gettering effect. The solid solubility of aluminium is higher than that of P atoms in silicon; however, the device yield confirms the effectiveness of phosphorus as compared to aluminium.

  12. P-type thin films transistors with solution-deposited lead sulfide films as semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo-Castillo, A.; Salas-Villasenor, A.; Mejia, I. [Department of Materials Science and Engineering, The University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Aguirre-Tostado, S. [Centro de Investigacion en Materiales Avanzados, S. C. Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica, Apodaca, Nuevo Leon, C.P. 666000 (Mexico); Gnade, B.E. [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Quevedo-Lopez, M.A., E-mail: mxq071000@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States)

    2012-01-31

    In this paper we demonstrate p-type thin film transistors fabricated with lead sulfide (PbS) as semiconductor deposited by chemical bath deposition methods. Crystallinity and morphology of the resulting PbS films were characterized using X-ray diffraction, atomic force microscopy and scanning electron microscopy. Devices were fabricated using photolithographic processes in a bottom gate configuration with Au as source and drain top contacts. Field effect mobility for as-fabricated devices was {approx} 0.09 cm{sup 2} V{sup -1} s{sup -1} whereas the mobility for devices annealed at 150 Degree-Sign C/h in forming gas increased up to {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Besides the thermal annealing, the entire fabrications process was maintained below 100 Degree-Sign C. The electrical performance of the PbS-thin film transistors was studied before and after the 150 Degree-Sign C anneal as well as a function of the PbS active layer thicknesses. - Highlights: Black-Right-Pointing-Pointer Thin film transistors with PbS as semiconductor deposited by chemical bath deposition. Black-Right-Pointing-Pointer Photolithography-based thin film transistors with PbS films at low temperatures. Black-Right-Pointing-Pointer Electron mobility for anneal-PbS devices of {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Black-Right-Pointing-Pointer Highest mobility reported in thin film transistors with PbS as the semiconductor.

  13. In-Situ Characterization of Potential-Induced Degradation in Crystalline Silicon Photovoltaic Modules Through Dark I–V Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Wei; Hacke, Peter; Singh, Jai Prakash; Chai, Jing; Wang, Yan; Ramakrishna, Seeram; Aberle, Armin G.; Khoo, Yong Sheng

    2017-01-01

    A temperature correction methodology for in-situ dark I-V(DIV) characterization of conventional p-type crystalline silicon photovoltaic (PV) modules undergoing potential-induced degradation (PID) is proposed.

  14. Mechanical, elastic and thermodynamic properties of crystalline lithium silicides

    CERN Document Server

    Schwalbe, Sebastian; Trepte, Kai; Biedermann, Franziska; Mertens, Florian; Kortus, Jens

    2016-01-01

    We investigate crystalline thermodynamic stable lithium silicides phases (LixSiy) with density functional theory (DFT) and a force-field method based on modified embedded atoms (MEAM) and compare our results with experimental data. This work presents a fast and accurate framework to calculate thermodynamic properties of crystal structures with large unit cells with MEAM based on molecular dynamics (MD). Mechanical properties like the bulk modulus and the elastic constants are evaluated in addition to thermodynamic properties including the phonon density of states, the vibrational free energy and the isochoric/isobaric specific heat capacity for Li, Li12Si7, Li7Si3, Li13Si4, Li15Si4, Li21Si5, Li17Si4, Li22Si5 and Si. For a selected phase (Li13Si4) we study the effect of a temperature dependent phonon density of states and its effect on the isobaric heat capacity.

  15. Properties of interfaces in amorphous/crystalline silicon heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Olibet, Sara; Vallat-Sauvain, Evelyne; Fesquet, Luc; Damon-Lacoste, Jerome; De Wolf, Stefaan; Ballif, Christophe [Ecole Polytechnique Federale de Lausanne (EPFL), IMT, Photovoltaics and Thin Film Electronics Laboratory, Breguet 2, 2000 Neuchatel (Switzerland); Monachon, Christian; Hessler-Wyser, Aicha [Ecole Polytechnique Federale de Lausanne (EPFL), Interdisciplinary Centre for Electron Microscopy (CIME), 1015 Lausanne (Switzerland)

    2010-03-15

    To study recombination at the amorphous/crystalline Si (a-Si:H/c-Si) heterointerface, the amphoteric nature of silicon (Si) dangling bonds is taken into account. Modeling interface recombination measured on various test structures provides insight into the microscopic passivation mechanisms, yielding an excellent interface defect density reduction by intrinsic a-Si:H and tunable field-effect passivation by doped layers. The potential of this model's applicability to recombination at other Si heterointerfaces is demonstrated. Solar cell properties of a-Si:H/c-Si heterojunctions are in good accordance with the microscopic interface properties revealed by modeling, that are, e.g., slight asymmetries in the neutral capture cross-sections and band offsets. The importance of atomically abrupt interfaces and the difficulties to obtain them on pyramidally textured c-Si is studied in combination with transmission electron microscopy. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. Delineation of Crystalline Extended Defects on Multicrystalline Silicon Wafers

    Directory of Open Access Journals (Sweden)

    Mohamed Fathi

    2007-01-01

    Full Text Available We have selected Secco and Yang etch solutions for the crystalline defect delineation on multicrystalline silicon (mc-Si wafers. Following experimentations and optimization of Yang and Secco etching process parameters, we have successfully revealed crystalline extended defects on mc-Si surfaces. A specific delineation process with successive application of Yang and Secco agent on the same sample has proved the increased sensitivity of Secco etch to crystalline extended defects in mc-Si materials. The exploration of delineated mc-Si surfaces indicated that strong dislocation densities are localized mainly close to the grain boundaries and on the level of small grains in size (below 1 mm. Locally, we have observed the formation of several parallel dislocation lines, perpendicular to the grain boundaries. The overlapping of several dislocations lines has revealed particular forms for etched pits of dislocations.

  17. Effect of Si/Si1-yCy/Si Barriers on the Characteristics of Si1-xGex/Si Resonant Tunneling Structures

    Institute of Scientific and Technical Information of China (English)

    HAN Ping; CHENG Xue-Mei; Masao Sakuraba; YoungCheon Jeong; Takashi Matsuura; Junichi Murota

    2000-01-01

    P-type double barrier resonant tunneling diodes (RTD) with the single Si0.6Ge0.4 quantum well and double Si0.6 Ge0.4 spacer have been realized by using an ultra clean low-pressure chemical vapor deposition system. The effect of Si1-yCy layer on the characteristics of the devices was shown by comparing the current-voltage (Ⅰ-Ⅴ) characteristics of RTD's of the barriers of Si layers with that of Si/Si1-yCy/Si structures. The peak voltage was gradually increased and the resonant current decreased obviously with increasing C content in the Si/Si1-yCy/Si barriers. The origin of the phenomena above can be attributed to the C related deep acceptor levels in the Si/Si1-yCy/Si barriers. The possible mechanism for the observed Ⅰ-Ⅴcharacteristics was shown more clearly by increasing C content to 3% and changing the thicknesses of Si and Si1-yCy layers in the Si/Si1-yCy/Si barriers.

  18. Crystalline boron nitride aerogels

    Science.gov (United States)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  19. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  20. Topological crystalline insulator SnTe nanoribbons

    Science.gov (United States)

    Dahal, Bishnu R.; Dulal, Rajendra P.; Pegg, Ian L.; Philip, John

    2017-03-01

    Topological crystalline insulators are systems in which a band inversion that is protected by crystalline mirror symmetry gives rise to nontrivial topological surface states. SnTe is a topological crystalline insulator. It exhibits p-type conductivity due to Sn vacancies and Te antisites, which leads to high carrier density in the bulk. Thus growth of high quality SnTe is a prerequisite for understanding the topological crystalline insulating behavior. We have grown SnTe nanoribbons using a solution method. The width of the SnTe ribbons varies from 500 nm to 2 μm. They exhibit rock salt crystal structure with a lattice parameter of 6.32 Å. The solution method that we have adapted uses low temperature, so the Sn vacancies can be controlled. The solution grown SnTe nanoribbons exhibit strong semiconducting behavior with an activation energy of 240 meV. This activation energy matches with the calculated band gap for SnTe with a lattice parameter of 6.32 Å, which is higher than that reported for bulk SnTe. The higher activation energy makes the thermal excitation of bulk charges very difficult on the surface. As a result, the topological surfaces will be free from the disturbance caused by the thermal excitations

  1. The electrical properties of photodiodes based on nanostructure gallium doped cadmium oxide/p-type silicon junctions

    Science.gov (United States)

    Çavaş, M.; Yakuphanoğlu, F.; Karataş, Ş.

    2017-01-01

    Gallium doped cadmium-oxide (CdO: Ga) thin films were successfully deposited by sol-gel spin coating method on p-type Si substrate. The electrical properties of the photodiode based on nanostructure Ga doped n-CdO/p-Si junctions were investigated. The current-voltage (I-V) characteristics of the structure were investigated under various light intensity and dark. It was observed that generated photocurrent of the Au/n-CdO/p-Si junctions depended on light intensity. The capacitance-voltage and conductance-voltage measurements were carried out for this diode in the frequency range between 100 and 1000 kHz at room temperature by steps of 100 kHz. The capacitance decreased with increasing frequency due to a continuous distribution of the interface states. These results suggested that the Au/n-CdO/p-Si Schottky junctions could be utilized as a photosensor. Furthermore, the voltage and frequency dependence of series resistance were calculated from the C-V and G/ω-V measurements and plotted as functions of voltage and frequency. The distribution profile of R S -V gave a peak in the depletion region at low frequencies and disappeared with increasing frequencies.

  2. Perovskite LaRhO{sub 3} as a p-type active layer in oxide photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masao, E-mail: masao.nakamura@riken.jp; Krockenberger, Yoshiharu [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Fujioka, Jun [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Kawasaki, Masashi; Tokura, Yoshinori [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan)

    2015-02-16

    Perovskite-type transition-metal oxides have a wide variety of physical properties and triggered intensive research on functional devices in the form of heteroepitaxial junctions. However, there is a missing component that is a p-type conventional band semiconductor. LaRhO{sub 3} (LRO) is one of very few promising candidates having its bandgap between filled t{sub 2g} and empty e{sub g} of Rh in low-spin state, but there has been no report on the synthesis of large-size single crystals or thin films. Here, we report on the junction properties of single-crystalline thin films of LRO grown on (110) oriented Nb-doped SrTiO{sub 3} substrates. The external quantum efficiency of the photo-electron conversion exceeds 1% in the visible-light region due to the wide depletion layer and long diffusion length of minority carriers in LRO. Clear indication of p-type band semiconducting character in a perovskite oxide of LRO will pave a way to explore oxide electronics of perovskite heterostructures.

  3. Sub-amorphous thermal conductivity in ultrathin crystalline silicon nanotubes.

    Science.gov (United States)

    Wingert, Matthew C; Kwon, Soonshin; Hu, Ming; Poulikakos, Dimos; Xiang, Jie; Chen, Renkun

    2015-04-08

    Thermal transport behavior in nanostructures has become increasingly important for understanding and designing next generation electronic and energy devices. This has fueled vibrant research targeting both the causes and ability to induce extraordinary reductions of thermal conductivity in crystalline materials, which has predominantly been achieved by understanding that the phonon mean free path (MFP) is limited by the characteristic size of crystalline nanostructures, known as the boundary scattering or Casimir limit. Herein, by using a highly sensitive measurement system, we show that crystalline Si (c-Si) nanotubes (NTs) with shell thickness as thin as ∼5 nm exhibit a low thermal conductivity of ∼1.1 W m(-1) K(-1). Importantly, this value is lower than the apparent boundary scattering limit and is even about 30% lower than the measured value for amorphous Si (a-Si) NTs with similar geometries. This finding diverges from the prevailing general notion that amorphous materials represent the lower limit of thermal transport but can be explained by the strong elastic softening effect observed in the c-Si NTs, measured as a 6-fold reduction in Young's modulus compared to bulk Si and nearly half that of the a-Si NTs. These results illustrate the potent prospect of employing the elastic softening effect to engineer lower than amorphous, or subamorphous, thermal conductivity in ultrathin crystalline nanostructures.

  4. Resonant Tunnelling and Storage of Electrons in Si Nanocrystals within a-SiNx/nc-Si/a-SiNx Structures

    Institute of Scientific and Technical Information of China (English)

    WANG Xiang; HUANG Jian; ZHANG Xian-Gao; DING Hong-Lin; YU Lin-Wei; HUANG Xin-Fan; LI Wei; XU Jun; CHEN Kun-Ji

    2008-01-01

    @@ The a-SiNx/nanocrystalline silicon (nc-Si)/a-SiNx sandwiched structures with asymmetric double-barrier are fabricated in a plasma enhanced chemical vapour deposition (PECVD) system on p-type Si substrates. The nc-Si layer in thickness 5nm is fabricated from a hydrogen-diluted silane gas by the layer-by-layer deposition technique. The thicknesses of tunnel and control SiNx layers are 3nm and 20nm,respectively. Frequency-dependent capacitance spectroscopy is used to study the electron tunnelling and the storage in the sandwiched structures.Distinct frequency-dependent capacitance peaks due to electrons tunnelling into the nc-Si dots and capacitance-voltage (C- V) hysteresis characteristic due to electrons storage in the nc-Si dots are observed with the same sample.

  5. Optimization of Al{sub 2}O{sub 3}/SiN{sub x} stacked antireflection structures for N-type surface-passivated crystalline silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu Dawei; Jia Rui; Ding Wuchang; Chen Chen; Wu Deqi; Chen Wei; Li Haofeng; Yue Huihui; Liu Xinyu, E-mail: wudawei@ime.ac.cn [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China)

    2011-09-15

    In the case of N-type solar cells, the anti-reflection property, as one of the important factors to further improve the energy-conversion efficiency, has been optimized using a stacked Al{sub 2}O{sub 3}/SiN{sub x} layer. The effect of SiN{sub x} layer thickness on the surface reflection property was systematically studied in terms of both experimental and theoretical measurement. In the stacked Al{sub 2}O{sub 3}/SiN{sub x} layers, results demonstrated that the surface reflection property can be effectively optimized by adding a SiN{sub x} layer, leading to the improvement in the final photovoltaic characteristic of the N-type solar cells. (semiconductor devices)

  6. Structural and photovoltaic properties of a-Si (SNc)/c-Si heterojunction fabricated by EBPVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Demiroğlu, D.; Kazmanli, K.; Urgen, M. [Department of Metallurgical and Materials Engineering, Istanbul Technical University, Ayazağa 34469, Istanbul (Turkey); Tatar, B. [Faculty of Arts and Sciences, Department of Physics, Namık Kemal University, Değirmenaltı, Tekirdağ (Turkey)

    2013-12-16

    In last two decades sculptured thin films are very attractive for researches. Some properties of these thin films, like high porosity correspondingly high large surface area, controlled morphology; bring into prominence on them. Sculptured thin films have wide application areas as electronics, optics, mechanics, magnetic and chemistry. Slanted nano-columnar (SnC) thin films are a type of sculptured thin films. In this investigation SnC thin films were growth on n-type crystalline Si(100) and p-type crystalline Si(111) via ultra-high vacuum electron beam evaporation technique. The structural and morphological properties of the amorphous silicon thin films were investigated by XRD, Raman and FE-SEM analysis. According to the XRD and Raman analysis the structure of thin film was amorphous and FE-SEM analysis indicated slanted nano-columns were formed smoothly. Slanted nano-columns a-Si/c-Si heterojunction were prepared as using a photovoltaic device. In this regard we were researched photovoltaic properties of these heterojunction with current-voltage characterization under dark and illumination conditions. Electrical parameters were determined from the current-voltage characteristic in the dark conditions zero-bias barrier height Φ{sub B0} = 0.83−1.00eV; diode ideality factor η = 11.71−10.73; series resistance R{sub s} = 260−31.1 kΩ and shunt resistance R{sub sh} = 25.71−63.5 MΩ SnC a-Si/n-Si and SnC a-Si/p-Si heterojunctions shows a pretty good photovoltaic behavior about 10{sup 3}- 10{sup 4} times. The obtained photovoltaic parameters are such as short circuit current density J{sub sc} 83-40 mA/m{sup 2}, open circuit voltage V{sub oc} 900-831 mV.

  7. Metal organic vapor phase epitaxy growth of (Al)GaN heterostructures on SiC/Si(111) templates synthesized by topochemical method of atoms substitution

    DEFF Research Database (Denmark)

    Rozhavskaia, Mariia M.; Kukushkin, Sergey A.; Osipov, Andrey

    2017-01-01

    crystalline interfaces with epitaxial relationship between SiC/Si and AlN/SiC layers. Optimization of SiC morphology and AlN seed layer thickness facilitates the growth of GaN layers free of pits (v-defects). It is also found that Si doping eliminates these defects in the case of growth on SiC templates...

  8. Surface passivation and optical characterization of Al2O3/a-SiCx stacks on c-Si substrates.

    Science.gov (United States)

    López, Gema; Ortega, Pablo R; Voz, Cristóbal; Martín, Isidro; Colina, Mónica; Morales, Anna B; Orpella, Albert; Alcubilla, Ramón

    2013-01-01

    The aim of this work is to study the surface passivation of aluminum oxide/amorphous silicon carbide (Al2O3/a-SiCx) stacks on both p-type and n-type crystalline silicon (c-Si) substrates as well as the optical characterization of these stacks. Al2O3 films of different thicknesses were deposited by thermal atomic layer deposition (ALD) at 200 °C and were complemented with a layer of a-SiCx deposited by plasma-enhanced chemical vapor deposition (PECVD) to form anti-reflection coating (ARC) stacks with a total thickness of 75 nm. A comparative study has been carried out on polished and randomly textured wafers. We have experimentally determined the optimum thickness of the stack for photovoltaic applications by minimizing the reflection losses over a wide wavelength range (300-1200 nm) without compromising the outstanding passivation properties of the Al2O3 films. The upper limit of the surface recombination velocity (S eff,max) was evaluated at a carrier injection level corresponding to 1-sun illumination, which led to values below 10 cm/s. Reflectance values below 2% were measured on textured samples over the wavelength range of 450-1000 nm.

  9. Surface passivation and optical characterization of Al2O3/a-SiCx stacks on c-Si substrates

    Directory of Open Access Journals (Sweden)

    Gema López

    2013-11-01

    Full Text Available The aim of this work is to study the surface passivation of aluminum oxide/amorphous silicon carbide (Al2O3/a-SiCx stacks on both p-type and n-type crystalline silicon (c-Si substrates as well as the optical characterization of these stacks. Al2O3 films of different thicknesses were deposited by thermal atomic layer deposition (ALD at 200 °C and were complemented with a layer of a-SiCx deposited by plasma-enhanced chemical vapor deposition (PECVD to form anti-reflection coating (ARC stacks with a total thickness of 75 nm. A comparative study has been carried out on polished and randomly textured wafers. We have experimentally determined the optimum thickness of the stack for photovoltaic applications by minimizing the reflection losses over a wide wavelength range (300–1200 nm without compromising the outstanding passivation properties of the Al2O3 films. The upper limit of the surface recombination velocity (Seff,max was evaluated at a carrier injection level corresponding to 1-sun illumination, which led to values below 10 cm/s. Reflectance values below 2% were measured on textured samples over the wavelength range of 450–1000 nm.

  10. A novel mechanism of P-type ATPase autoinhibition involving both termini of the protein

    DEFF Research Database (Denmark)

    Ekberg, Kira; Palmgren, Michael; Veierskov, Bjarke;

    2010-01-01

    The activity of many P-type ATPases is found to be regulated by interacting proteins or autoinhibitory elements located in N- or C-terminal extensions. An extended C terminus of fungal and plant P-type plasma membrane H+-ATPases has long been recognized to be part of a regulatory apparatus...

  11. Demethoxycurcumin is a potent inhibitor of P-type ATPases from diverse kingdoms of life

    DEFF Research Database (Denmark)

    Dao, Trong Tuan; Sehgal, Pankaj; Thanh Tung, Truong;

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used ...

  12. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    Science.gov (United States)

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  13. Application of neutron transmutation doping method to initially p-type silicon material.

    Science.gov (United States)

    Kim, Myong-Seop; Kang, Ki-Doo; Park, Sang-Jun

    2009-01-01

    The neutron transmutation doping (NTD) method was applied to the initially p-type silicon in order to extend the NTD applications at HANARO. The relationship between the irradiation neutron fluence and the final resistivity of the initially p-type silicon material was investigated. The proportional constant between the neutron fluence and the resistivity was determined to be 2.3473x10(19)nOmegacm(-1). The deviation of the final resistivity from the target for almost all the irradiation results of the initially p-type silicon ingots was at a range from -5% to 2%. In addition, the burn-up effect of the boron impurities, the residual (32)P activity and the effect of the compensation characteristics for the initially p-type silicon were studied. Conclusively, the practical methodology to perform the neutron transmutation doping of the initially p-type silicon ingot was established.

  14. Calculation of Growth Stress in SiO2 Scales Formed by Oxidation of SiC Fibers (PREPRINT)

    Science.gov (United States)

    2012-07-01

    Kinetics of High - Purity Silicon Carbide from 800 to 1100 C. J. Am. Ceram. Soc. 79, 2897-2911 (1996). 45 Ogbuji, U. J. T. & Opila, E. J. A Comparison...to SiO2 generates very large growth stresses. Microstructural evidence for these stresses exists for crystalline scales on SiC fibers. High ...dislocation densities in crystalline SiO2 near the SiC -SiO2 interface suggest high shear stresses exist during growth of new crystalline scale.1 Axial cracks

  15. Crystalline-silicon photovoltaics: Necessary and sufficient

    Science.gov (United States)

    Basore, P. A.; Gee, J. M.

    Photovoltaic (PV) energy systems have always been dominated by crystalline-silicon (c-Si) technology, and recent developments persuasively suggest that c-Si will continue to be the dominant technology well into the next century. The authors explain why c-Si technology is fairing much better than previously expected, and discuss the impact of improvements currently under development. They use a ground-up, engineering-based approach to predict the expected evolution of this type of PV system, and argue that c-Si PV will be in a position to compete for the US residential power market starting in about the year 2010. This market alone will provide the opportunity for PV to supply several percent of the electrical energy used in the United States. Crystalline-silicon technology is therefore not just necessary for building a near-term PV industry; it also offers a low-risk approach to meeting long-term goals for PV energy systems.

  16. Tailoring crystallinity and configuration of silica nanotubes by electron irradiation

    Science.gov (United States)

    Taguchi, Tomitsugu; Yamaguchi, Kenji

    2015-05-01

    SiO2 nanotubes show potential in applications such as nanoscale electronic and optical devices, bioseparation, biocatalysis, and nanomedicine. As-grown SiO2 nanotubes in the previous studies always have an amorphous wall, and here we demonstrate the successful synthesis of single-crystal nanotubes for the first time by the heat treatment of SiC nanotubes at 1300 °C for 10 h under low-vacuum conditions. According to TEM observations, the single-crystal SiO2 was α-cristobalite. We also demonstrate that single-crystal SiO2 nanotubes can be transformed into amorphous SiO2 nanotubes by electron beam irradiation. Moreover, we synthesized a crystalline/amorphous SiO2 composite nanotube, in which crystalline and amorphous SiO2 coexisted in different localized regions. In addition, for biomedical applications such as drug delivery systems, controlling the configuration of the open end, the diameter, and capsulation of SiO2 nanotubes is crucial. We can also obturate, capsulate, and cut a SiO2 nanotube, as well as modify the inner diameter of the nanotube at a specific, nanometer-sized region using the focused electron beam irradiation technique.

  17. Morphology and Curie temperature engineering in crystalline La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films on Si by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Nori, Rajashree, E-mail: rajsre@ee.iitb.ac.in; Ganguly, U.; Ravi Chandra Raju, N.; Pinto, R.; Ramgopal Rao, V. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology-Bombay (IIT-B), Mumbai 400076 (India); Kale, S. N. [Department of Applied Physics, Defence Institute of Advanced Technology (DIAT), Pune 411025 (India); Sutar, D. S. [Central Surface Analytical Facility, Indian Institute of Technology-Bombay (IIT-B), Mumbai 400076 (India)

    2014-01-21

    Of all the colossal magnetoresistant manganites, La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) exhibits magnetic and electronic state transitions above room temperature, and therefore holds immense technological potential in spintronic devices and hybrid heterojunctions. As the first step towards this goal, it needs to be integrated with silicon via a well-defined process that provides morphology and phase control, along with reproducibility. This work demonstrates the development of pulsed laser deposition (PLD) process parameter regimes for dense and columnar morphology LSMO films directly on Si. These regimes are postulated on the foundations of a pressure-distance scaling law and their limits are defined post experimental validation. The laser spot size is seen to play an important role in tandem with the pressure-distance scaling law to provide morphology control during LSMO deposition on lattice-mismatched Si substrate. Additionally, phase stability of the deposited films in these regimes is evaluated through magnetometry measurements and the Curie temperatures obtained are 349 K (for dense morphology) and 355 K (for columnar morphology)—the highest reported for LSMO films on Si so far. X-ray diffraction studies on phase evolution with variation in laser energy density and substrate temperature reveals the emergence of texture. Quantitative limits for all the key PLD process parameters are demonstrated in order enable morphological and structural engineering of LSMO films deposited directly on Si. These results are expected to boost the realization of top-down and bottom-up LSMO device architectures on the Si platform for a variety of applications.

  18. On the c-Si surface passivation mechanism by the negative-charge-dielectric Al2O3

    Science.gov (United States)

    Hoex, B.; Gielis, J. J. H.; van de Sanden, M. C. M.; Kessels, W. M. M.

    2008-12-01

    Al2O3 is a versatile high-κ dielectric that has excellent surface passivation properties on crystalline Si (c-Si), which are of vital importance for devices such as light emitting diodes and high-efficiency solar cells. We demonstrate both experimentally and by simulations that the surface passivation can be related to a satisfactory low interface defect density in combination with a strong field-effect passivation induced by a negative fixed charge density Qf of up to 1013 cm-2 present in the Al2O3 film at the interface with the underlying Si substrate. The negative polarity of Qf in Al2O3 is especially beneficial for the passivation of p-type c-Si as the bulk minority carriers are shielded from the c-Si surface. As the level of field-effect passivation is shown to scale with Qf2, the high Qf in Al2O3 tolerates a higher interface defect density on c-Si compared to alternative surface passivation schemes.

  19. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    Science.gov (United States)

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  20. Effect of Etching Time on Optical and Thermal Properties of p-Type Porous Silicon Prepared by Electrical Anodisation Method

    Directory of Open Access Journals (Sweden)

    Kasra Behzad

    2012-01-01

    Full Text Available The porous silicon (PSi layers were formed on p-type silicon (Si wafer. The six samples were anodised electrically with 30 mA/cm2 fixed current density for different etching times. The structural, optical, and thermal properties of porous silicon on silicon substrates were investigated by photoluminescence (PL, photoacoustic spectroscopy (PAS, and UV-Vis-NIR spectrophotometer. The thickness and porosity of the layers were measured using the gravimetric method. The band gap of the samples was measured through the photoluminescence (PL peak and absorption spectra, then they were compared. It shows that band gap value increases by raising the porosity. Photoacoustic spectroscopy (PAS was carried out for measuring the thermal diffusivity (TD of the samples.

  1. Very low surface recombination velocities on p-type silicon wafers passivated with a dielectric with fixed negative charge

    Energy Technology Data Exchange (ETDEWEB)

    Agostinelli, G.; Delabie, A.; Dekkers, H.F.W.; De Wolf, S.; Beaucarne, G. [IMEC vzw, Kapeldreef 75, Leuven (Belgium); Vitanov, P.; Alexieva, Z. [CL SENES, Sofia (Bulgaria)

    2006-11-23

    Surface recombination velocities as low as 10cm/s have been obtained by treated atomic layer deposition (ALD) of Al{sub 2}O{sub 3} layers on p-type CZ silicon wafers. Low surface recombination is achieved by means of field induced surface passivation due to a high density of negative charges stored at the interface. In comparison to a diffused back surface field, an external field source allows for higher band bending, that is, a better performance. While this process yields state of the art results, it is not suited for large-scale production. Preliminary results on an industrially viable, alternative process based on a pseudo-binary system containing Al{sub 2}O{sub 3} are presented, too. With this process, surface recombination velocities of 500-1000cm/s have been attained on mc-Si wafers. (author)

  2. Electronic structure of p type Delta doped systems; Estructura electronica de sistemas dopadas con Delta de tipo p

    Energy Technology Data Exchange (ETDEWEB)

    Gaggero S, L.M.; Perez A, R. [Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey s/n, 28040 Madrid (Spain)

    1998-12-31

    We summarize of the results obtained for the electronic structure of quantum wells that consist in an atomic layer doped with impurities of p type. The calculations are made within the frame worth of the wrapper function approach to independent bands and with potentials of Hartree. We study the cases reported experimentally (Be in GaAs and B in Si). We present the levels of energy, the wave functions and the rate of the electronic population between the different subbands, as well as the dependence of these magnitudes with the density of impurities in the layer. The participation of the bans of heavy holes is analysed, light and split-off band in the total electronic population. The effect of the temperature is discussed and we give a possible qualitative explanation of the experimental optical properties. (Author)

  3. Experimental realization of a new type of crystalline undulator.

    Science.gov (United States)

    Wistisen, Tobias N; Andersen, Kristoffer K; Yilmaz, Serdar; Mikkelsen, Rune; Hansen, John Lundsgaard; Uggerhøj, Ulrik I; Lauth, Werner; Backe, Hartmut

    2014-06-27

    A new scheme of making crystalline undulators was recently proposed and investigated theoretically by Andriy Kostyuk, concluding that a new type of crystalline undulator would be not only viable, but better than the previous scheme. This article describes the first experimental measurement of such a crystalline undulator, produced by using Si(1-x)Ge(x)-graded composition and measured at the Mainzer Microtron facility at beam energies of 600 and 855 MeV. We also present theoretical models developed to compare with the experimental data.

  4. Silicon Monoxide at 1 atm and Elevated Pressures: Crystalline or Amorphous?

    KAUST Repository

    AlKaabi, Khalid

    2014-03-05

    The absence of a crystalline SiO phase under ordinary conditions is an anomaly in the sequence of group 14 monoxides. We explore theoretically ordered ground-state and amorphous structures for SiO at P = 1 atm, and crystalline phases also at pressures up to 200 GPa. Several competitive ground-state P = 1 atm structures are found, perforce with Si-Si bonds, and possessing Si-O-Si bridges similar to those in silica (SiO2) polymorphs. The most stable of these static structures is enthalpically just a little more stable than a calculated random bond model of amorphous SiO. In that model we find no segregation into regions of amorphous Si and amorphous SiO2. The P = 1 atm structures are all semiconducting. As the pressure is increased, intriguing new crystalline structures evolve, incorporating Si triangular nets or strips and stishovite-like regions. A heat of formation of crystalline SiO is computed; it is found to be the most negative of all the group 14 monoxides. Yet, given the stability of SiO2, the disproportionation 2SiO (s) → Si(s)+SiO2(s) is exothermic, falling right into the series of group 14 monoxides, and ranging from a highly negative ΔH of disproportionation for CO to highly positive for PbO. There is no major change in the heat of disproportionation with pressure, i.e., no range of stability of SiO with respect to SiO2. The high-pressure SiO phases are metallic. © 2014 American Chemical Society.

  5. The human crystallin gene families

    Directory of Open Access Journals (Sweden)

    Wistow Graeme

    2012-12-01

    Full Text Available Abstract Crystallins are the abundant, long-lived proteins of the eye lens. The major human crystallins belong to two different superfamilies: the small heat-shock proteins (α-crystallins and the βγ-crystallins. During evolution, other proteins have sometimes been recruited as crystallins to modify the properties of the lens. In the developing human lens, the enzyme betaine-homocysteine methyltransferase serves such a role. Evolutionary modification has also resulted in loss of expression of some human crystallin genes or of specific splice forms. Crystallin organization is essential for lens transparency and mutations; even minor changes to surface residues can cause cataract and loss of vision.

  6. 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).

  7. Thermodynamics of Crystalline States

    CERN Document Server

    Fujimoto, Minoru

    2010-01-01

    Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattices, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. This book is divided into three parts. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. In the third part, the multi-electron system is discussed theoretically, as a quantum-mechanical example, for the superconducting state in metallic crystals. Throughout the book, the role played by the lattice is emphasized and examined in-depth. Thermodynamics of Crystalline States is an introductory treatise and textbook on meso...

  8. Thermal effect mechanism of magnetoresistance in p-type diamond films

    Institute of Scientific and Technical Information of China (English)

    Qin Guo-Ping; Kong Chun-Yang; Ruan Hai-Bo; Huang Gui-Juan; Cui Yu-Ting; Fang Liang

    2010-01-01

    Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance(MR) of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films (Corbino discs). It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.

  9. Characterization of plasma etching damage on p -type GaN using Schottky diodes

    OpenAIRE

    2008-01-01

    The plasma etching damage in p-type GaN has been characterized. From current-voltage and capacitance-voltage characteristics of Schottky diodes, it was revealed that inductively coupled plasma (ICP) etching causes an increase in series resistance of the Schottky diodes and compensation of acceptors in p-type GaN. We investigated deep levels near the valence band of p-type GaN using current deep level transient spectroscopy (DLTS), and no deep level originating from the ICP etching damage was ...

  10. High quality boron-doped epitaxial layers grown at 200°C from SiF4/H2/Ar gas mixtures for emitter formation in crystalline silicon solar cells

    Science.gov (United States)

    Léal, Ronan; Haddad, Farah; Poulain, Gilles; Maurice, Jean-Luc; Roca i Cabarrocas, Pere

    2017-02-01

    Controlling the doping profile in solar cells emitter and front/back surface field is mandatory to reach high efficiencies. In the current state of the art, these doped layers are made by dopant diffusion at around 900°C, which implies potential temperature induced damages in the c-Si absorber and for which a precise control of doping is difficult. An alternative solution based on boron-doped epitaxial silicon layers grown by plasma-enhanced chemical vapor deposition (PECVD) from 200°C using SiF4/H2/Ar/B2H6 chemistry is reported. The structural properties of the doped and undoped epitaxial layers were assessed by spectroscopic ellipsometry (SE), high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). The incorporation of boron has been studied via plasma profiling time of flight mass spectrometry (PP-TOFMS) and secondary ion mass spectrometry (SIMS) measurements. The boron-doped epitaxial layers revealed excellent structural and electrical properties even for high carrier concentrations (>1019cm-3). Sheet resistances between 100 and 130 Ω/sq can been obtained depending on the thickness and the doping concentration, which is within the range of targeted values for emitters in c-Si solar cells. Electrochemical capacitance voltage (ECV) revealed a uniform doping profile around 3.1019 cm-3 and by comparing with SIMS measurement a doping efficiency around 50% has been found.

  11. High quality boron-doped epitaxial layers grown at 200°C from SiF4/H2/Ar gas mixtures for emitter formation in crystalline silicon solar cells

    Directory of Open Access Journals (Sweden)

    Ronan Léal

    2017-02-01

    Full Text Available Controlling the doping profile in solar cells emitter and front/back surface field is mandatory to reach high efficiencies. In the current state of the art, these doped layers are made by dopant diffusion at around 900°C, which implies potential temperature induced damages in the c-Si absorber and for which a precise control of doping is difficult. An alternative solution based on boron-doped epitaxial silicon layers grown by plasma-enhanced chemical vapor deposition (PECVD from 200°C using SiF4/H2/Ar/B2H6 chemistry is reported. The structural properties of the doped and undoped epitaxial layers were assessed by spectroscopic ellipsometry (SE, high resolution transmission electron microscopy (HR-TEM and X-ray diffraction (XRD. The incorporation of boron has been studied via plasma profiling time of flight mass spectrometry (PP-TOFMS and secondary ion mass spectrometry (SIMS measurements. The boron-doped epitaxial layers revealed excellent structural and electrical properties even for high carrier concentrations (>1019cm-3. Sheet resistances between 100 and 130 Ω/sq can been obtained depending on the thickness and the doping concentration, which is within the range of targeted values for emitters in c-Si solar cells. Electrochemical capacitance voltage (ECV revealed a uniform doping profile around 3.1019 cm-3 and by comparing with SIMS measurement a doping efficiency around 50% has been found.

  12. Characterization of ZnO thin films grown on different p-Si substrate elaborated by solgel spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chebil, W., E-mail: Chbil.widad@live.fr [Laboratoire Physico-chimie des Matériaux, Unité de Service Commun de Recherche “High resolution X-ray diffractometer”, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Fouzri, A. [Laboratoire Physico-chimie des Matériaux, Unité de Service Commun de Recherche “High resolution X-ray diffractometer”, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Institut Supérieur des Sciences Appliquées et de Technologie de Sousse, Université de Sousse (Tunisia); Fargi, A. [Laboratoire de Microélectronique et Instrumentation, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l’environnement, 5019 Monastir (Tunisia); Azeza, B.; Zaaboub, Z. [Laboratoire Micro-Optoélectroniques et Nanostructures, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l' environnement, 5019 Monastir (Tunisia); and others

    2015-10-15

    Highlights: • High quality ZnO thin films grown on different p-Si substrates were successful obtained by sol–gel process. • PL measurement revealed that ZnO thin film grown on porous Si has the better optical quality. • I–V characteristics for all heterojunctions exhibit successful diode formation. • The diode ZnO/PSi shows a better photovoltaic effect under illumination with a maximum {sub Voc} of 0.2 V. - Abstract: In this study, ZnO thin films are deposited by sol–gel technique on p-type crystalline silicon (Si) with [100] orientation, etched silicon and porous silicon. The structural analyses showed that the obtained thin films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented along the c-axis direction. Morphological study revealed the presence of rounded and facetted grains irregularly distributed on the surface of all samples. PL spectra at room temperature revealed that ZnO thin film grown on porous Si has a strong UV emission with low defects in the visible region comparing with ZnO grown on plat Si and etched Si surface. The heterojunction parameters were evaluated from the (I–V) under dark and illumination at room temperature. The ideality factor, barrier height and series resistance of heterojunction grown on different p-Si substrates are determined by using different methods. Best electrical properties are obtained for ZnO layer deposited on porous silicon.

  13. Origin of the p-type character of AuCl3 functionalized carbon nanotubes

    KAUST Repository

    Murat, Altynbek

    2014-02-13

    The microscopic origin of the p-type character of AuCl3 functionalized carbon nanotubes (CNTs) is investigated using first-principles self-interaction corrected density functional theory (DFT). Recent DFT calculations suggest that the p-type character of AuCl3 functionalized CNTs is due to the Cl atoms adsorbed on the CNTs. We test this hypothesis and show that adsorbed Cl atoms only lead to a p-type character for very specific concentrations and arrangements of the Cl atoms, which furthermore are not the lowest energy configurations. We therefore investigate alternative mechanisms and conclude that the p-type character is due to the adsorption of AuCl4 molecules. The unraveling of the exact nature of the p-doping adsorbates is a key step for further development of AuCl3 functionalized CNTs in water sensor applications. © 2014 American Chemical Society.

  14. Theoretical prediction of p-type transparent conductivity in Zn-doped TiO2.

    Science.gov (United States)

    Han, Xiaoping; Shao, Guosheng

    2013-06-28

    It is very difficult and yet extremely important to fill the wide technological gap in developing transparent conducting oxides (TCOs) that exhibit excellent p-type conducting characteristics. Here, on the basis of extensive first-principles calculations, we discover for the first time potentially promising p-type transparent conductivity in Zn-doped TiO2 under oxygen rich conditions. Efforts have been made to elaborate the effects of possible defects and their interaction with Zn doping on the p-type transparent conductivity. This work offers a fundamental road map for cost-effective development of p-type TCOs based on TiO2, which is a cheap and stable material system of large natural resources.

  15. Origin and evolution of metal P-type ATPases in Plantae (Archaeplastida)

    OpenAIRE

    2014-01-01

    Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium and possibly copper and calcium. So fa...

  16. a-Si/c-Si heterojunction solar cells on SiSiC ceramic substrates

    Institute of Scientific and Technical Information of China (English)

    LI Xudong; XU Ying; CHE Xiaoqi

    2006-01-01

    Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great changein cell's structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell's efficiency.A conversion efficiency of 3.42% has been achieved on 1cm2 a-Si/c-Si heterojunction solar cell ( Isc =16.93 mA, Voc =310.9 mV, FF =06493, AM =1.5 G,24 ℃), while the cell with diffused homojunction only gotan efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.

  17. Liquid crystalline dihydroazulene photoswitches

    DEFF Research Database (Denmark)

    Petersen, Anne Ugleholdt; Jevric, Martyn; Mandle, Richard J.

    2015-01-01

    A large selection of photochromic dihydroazulene (DHA) molecules incorporating various substituents at position 2 of the DHA core was prepared and investigated for their ability to form liquid crystalline phases. Incorporation of an octyloxy-substituted biphenyl substituent resulted in nematic...

  18. Convergence of valence bands for high thermoelectric performance for p-type InN

    Science.gov (United States)

    Li, Hai-Zhu; Li, Ruo-Ping; Liu, Jun-Hui; Huang, Ming-Ju

    2015-12-01

    Band engineering to converge the bands to achieve high valley degeneracy is one of effective approaches for designing ideal thermoelectric materials. Convergence of many valleys in the valence band may lead to a high Seebeck coefficient, and induce promising thermoelectric performance of p-type InN. In the current work, we have systematically investigated the electronic structure and thermoelectric performance of wurtzite InN by using the density functional theory combined with semiclassical Boltzmann transport theory. Form the results, it can be found that intrinsic InN has a large Seebeck coefficient (254 μV/K) and the largest value of ZeT is 0.77. The transport properties of p-type InN are better than that of n-type one at the optimum carrier concentration, which mainly due to the large Seebeck coefficient for p-type InN, although the electrical conductivity of n-type InN is larger than that of p-type one. We found that the larger Seebeck coefficient for p-type InN may originate from the large valley degeneracy in the valence band. Moreover, the low minimum lattice thermal conductivity for InN is one key factor to become a good thermoelectric material. Therefore, p-type InN could be a potential material for further applications in the thermoelectric area.

  19. Direct ultrasensitive electrical detection of prostate cancer biomarkers with CMOS-compatible n- and p-type silicon nanowire sensor arrays

    Science.gov (United States)

    Gao, Anran; Lu, Na; Dai, Pengfei; Fan, Chunhai; Wang, Yuelin; Li, Tie

    2014-10-01

    Sensitive and quantitative analysis of proteins is central to disease diagnosis, drug screening, and proteomic studies. Here, a label-free, real-time, simultaneous and ultrasensitive prostate-specific antigen (PSA) sensor was developed using CMOS-compatible silicon nanowire field effect transistors (SiNW FET). Highly responsive n- and p-type SiNW arrays were fabricated and integrated on a single chip with a complementary metal oxide semiconductor (CMOS) compatible anisotropic self-stop etching technique which eliminated the need for a hybrid method. The incorporated n- and p-type nanowires revealed complementary electrical response upon PSA binding, providing a unique means of internal control for sensing signal verification. The highly selective, simultaneous and multiplexed detection of PSA marker at attomolar concentrations, a level useful for clinical diagnosis of prostate cancer, was demonstrated. The detection ability was corroborated to be effective by comparing the detection results at different pH values. Furthermore, the real-time measurement was also carried out in a clinically relevant sample of blood serum, indicating the practicable development of rapid, robust, high-performance, and low-cost diagnostic systems.Sensitive and quantitative analysis of proteins is central to disease diagnosis, drug screening, and proteomic studies. Here, a label-free, real-time, simultaneous and ultrasensitive prostate-specific antigen (PSA) sensor was developed using CMOS-compatible silicon nanowire field effect transistors (SiNW FET). Highly responsive n- and p-type SiNW arrays were fabricated and integrated on a single chip with a complementary metal oxide semiconductor (CMOS) compatible anisotropic self-stop etching technique which eliminated the need for a hybrid method. The incorporated n- and p-type nanowires revealed complementary electrical response upon PSA binding, providing a unique means of internal control for sensing signal verification. The highly

  20. Sign reversal of junction magnetoresistance in p-La0.7Ca0.3MnO3/SiO2/n-Si heterostructure: a possibility in spintronics application.

    Science.gov (United States)

    Giri, S K; Nath, T K

    2012-10-01

    We have fabricated a p-La0.7Ca0.3MnO3/SiO2/n-Si heterostructure, consisting of a p-type manganite (La0.7Ca0.3MnO3) and n-type Si with a interfacial layer of SiO2 with typical thickness of about 9 nm using pulsed laser deposition technique. The junction exhibits rectifying behavior over the temperature range of 10-300 K with rectification factor 52 at room temperature. Investigation on the electrical properties of p-La0.7Ca0.3MnO3/SiO2/n-Si heterostructure exhibits nonlinear J-V characteristics in a wide temperature range. A crossover from negative to positive junction magnetoresistance (JMR) is observed in p-La0.7Ca0.3MnO3/SiO2/n-Si heterostructure in current perpendicular to film plane (CPP) geometry. The temperature dependent sign of junction magnetoresistance of the heterojunction has been investigated carefully in details. It is found that the junction exhibits the positive junction magnetoresistance when the temperature is greater than the ferromagnetic to paramagnetic transition temperature (Tc) of the top highly spin-polarized half-metallic ferromagnetic La0.7Ca0.3MnO3 manganite film layer. The relation between junction magnetoresistance and external magnetic field is found to be of (delta rho/rho approximately equal alphaHbeta) type having both alpha and beta temperature dependent. We attribute the emergence of negative JMR at lower temperature ( Tc) to the quantum mechanical tunneling transport mechanism across the heterojunction. Our results might be very useful to fabricate artificial devices using the manganite-based heterojunction grown on single crystalline n-Si (100) in spintronics device applications.

  1. The low resistive and transparent Al-doped SnO{sub 2} films: p-type conductivity, nanostructures and photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Benouis, C.E. [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Benhaliliba, M., E-mail: mbenhaliliba@gmail.com [Department of Material Technology, Physics Faculty, USTOMB University, BP1505 Oran (Algeria); Mouffak, Z. [Department of Electrical and Computer Engineering California State University, Fresno, CA (United States); Avila-Garcia, A. [Cinvestav-IPN, Dept. Ingeniería Eléctrica-SEES, Apdo. Postal 14-740, 07000 México, D.F. (Mexico); Tiburcio-Silver, A. [ITT-DIE, Apdo, Postal 20, Metepec 3, 52176 Estado de Mexico (Mexico); Ortega Lopez, M.; Romano Trujillo, R. [Centro de Investigación en Dispositivos Semiconductores, Instituto de Ciencias-BUAP, 14 Sur y Av. San Claudio, C.U. Puebla, Pue. (Mexico); Ocak, Y.S. [Dicle University, Education Faculty, Science Department, 21280 Diyarbakir (Turkey)

    2014-08-01

    Highlights: • Low resistive and high transparency Al doped SnO{sub 2} films. • Films are deposited onto ITO substrate by spray pyrolysis. • Nanostructured films are revealed. • p-Type conductivity is exhibited. • Photoluminescence of films is studied. - Abstract: In this work, we study the crystalline structure, surface morphology, transmittance, optical bandgap and n/p type inversion of tin oxide (SnO{sub 2}). The Nanostructured films of Al-doped SnO{sub 2} were successfully produced onto ITO-coated glass substrates via the spray pyrolysis method at a deposition temperature of 300 °C. A (1 0 1) and (2 1 1)-oriented tetragonal crystal structure was confirmed by X-ray patterns; and grain sizes varied within the range 8−42 nm. The films were polycrystalline, showing a high transparency in the visible (VIS) and infrared (IR) spectra. The optical bandgap was estimated to be around 3.4 eV. The atomic force microscopy (AFM) analysis showed the nanostructures consisting of nanotips, nanopatches, nanopits and nanobubbles. The samples exhibited high conductivity that ranged from 0.55 to 10{sup 4} (S/cm) at ambient and showed an inversion from n to p-type as well as a degenerate semiconductor characters with a bulk concentration reaching 1.7 x 10{sup 19} cm{sup −3}. The photoluminescence measurements reveal the detection of violet, green and yellow emissions.

  2. Preparation of p-type NiO films by reactive sputtering and their application to CdTe solar cells

    Science.gov (United States)

    Ishikawa, Ryousuke; Furuya, Yasuaki; Araki, Ryouichi; Nomoto, Takahiro; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Tsuboi, Nozomu

    2016-02-01

    Transparent p-type NiO films were prepared by reactive sputtering using the facing-target system under Ar-diluted O2 gas at Tsub of 30 and 200 °C. The increasing intensity of dominant X-ray diffraction (XRD) peaks indicates improvements in the crystallinity of NiO films upon Cu doping. In spite of the crystallographic and optical changes after Cu-doping, the electrical properties of Cu-doped NiO films were slightly improved. Upon Ag-doping at 30 °C under low O2 concentration, on the other hand, the intensity of the dominant (111) XRD peaks was suppressed and p-type conductivity increased from ˜10-3 to ˜10-1 S cm-1. Finally, our Ag-doped NiO films were applied as the back contact of CdTe solar cells. CdTe solar cells with a glass/ITO/CdS/CdTe/NiO structure exhibited an efficiency of 6.4%, suggesting the high potential of using p-type NiO for the back-contact film in thin-film solar cells.

  3. Post-implantation annealing of aluminum in 6H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Ottaviani, L.; Planson, D.; Locatelli, M.L.; Chante, J.P. [INSA de Lyon, Villeurbanne (France). CEGELY; Canut, B.; Ramos, S. [Dept. de Physique de Materiaux, Univ. C. Bernard Lyon 1, Villeurbanne (France)

    1998-08-01

    Two double aluminum implantations at room temperature were performed in two p-type epitaxial 6H-SiC wafers, with a maximum energy of 320 keV and a total fluence of 1.6{sup *}10{sup 15}cm{sup -2}. The two samples were then annealed in a rf furnace at 1700 C during 30 minutes, one with a SiC plate inside the reactor and the other without. RBS/C spectra were recorded on the implanted faces of each sample, before and after annealing. We observed that the implantation induced the amorphization of the material, and that the damaged layer of the sample annealed with the SiC plate was less extended in depth than the other. Moreover, the solid phase epitaxy appears to occur at two interfaces in the first case, that is the recrystallization arises from the volume and from the surface. The explanation of this phenomenon could be outlined from the XPS results, which show a better surface stoichiometry when the SiC plate is inside the reactor. This plate gives therefore interesting effects and improvements on the crystallinity and stoichiometry of the annealed sample. (orig.) 7 refs.

  4. Practical routes to (SiH₃)₃P: applications in group IV semiconductor activation and in group III-V molecular synthesis.

    Science.gov (United States)

    Tice, Jesse B; Chizmeshya, A V G; Tolle, J; D' Costa, V R; Menendez, J; Kouvetakis, J

    2010-05-21

    The (SiH₃)₃P hydride is introduced as a practical source for n-doping of group IV semiconductors and as a highly-reactive delivery agent of -(SiH₃)₂P functionalities in exploratory synthesis. In contrast to earlier methods, the compound is produced here in high purity quantitative yields via a new single-step method based on reactions of SiH₃Br and (Me₃Sn)₃P, circumventing the need for toxic and unstable starting materials. As an initial demonstration of its utility we synthesized monosubstituted Me₂M-P(SiH₃)₂ (M = Al, Ga, In) derivatives of Me₃M containing the (SiH₃)₂P ligand for the first time, in analogy to the known Me₂M-P(SiMe₃)₂ counterparts. A dimeric structure of Me₂M-P(SiH₃)₂ is proposed on the basis of spectroscopic characterizations and quantum chemical simulations. Next, in the context of materials synthesis, the (SiH₃)₃P compound was used to dope germanium for the first time by building a prototype p(++)Si(100)/i-Ge/n-Ge photodiode structure. The resultant n-type Ge layers contained active carrier concentrations of 3-4 × 10¹⁹ atoms cm⁻³ as determined by spectroscopic ellipsometry and confirmed by SIMS. Strain analysis using high resolution XRD yielded a Si content of 4 × 10²⁰ atoms cm⁻³ in agreement with SIMS and within the range expected for incorporating Si₃P type units into the diamond cubic Ge matrix. Extensive characterizations for structure, morphology and crystallinity indicate that the Si co-dopant plays essentially a passive role and does not compromise the device quality of the host material nor does it fundamentally alter its optical properties.

  5. 晶硅切磨废弃硅粉为原料的反应烧结Si3N4结合SiC复相陶瓷的正交实验研究%Orthogonal Optimum Design of Reaction Sintered Silicon Nitride Bonding Silicon Carbide Multiphase Ceramics using Crystalline Silicon Cutting Waste Silicon Powder as Raw Material

    Institute of Scientific and Technical Information of China (English)

    翟向乐; 张雅倩; 罗绍华; 陈宇红; 耿桂宏; 腾飞

    2012-01-01

    以磨切单晶硅废料Si粉和SiC为原料,Y2O3-Al2O3-Fe2O3为复合烧结助剂,反应烧结法制备Si3N4/SiC复相陶瓷材料.运用L9 (34)正交设计,研究了原料中Si、助剂Al2O3、Y2O3和Fe2O3的含量对陶瓷材料力学性能的影响和优化.采用X射线衍射(XRD)和扫描电镜(SEM)对复合材料的相组成、断口形貌进行分析.结果表明,反应烧结后试样生成Si3N4结合SiC晶粒为主相,及少量SiALON与未反应的Si相的烧结体.Si含量对力学性能的影响最为显著,对于抗弯强度性能,正交试验获得的工艺优化参数:ω(Si):20%、ω(Al2O3):3.2%、ω(Fe2O3):0.8%和ω(Y2O3):2%.

  6. Room temperature p-type conductivity and coexistence of ferroelectric order in ferromagnetic Li doped ZnO nanoparticles

    KAUST Repository

    Awan, Saif Ullah

    2014-10-28

    Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic order simultaneously. We reported multiferroic behavior in Zn1-yLiyO(0.00≤y≤0.10) nanoparticles. The analysis of transmission electron micrographs confirmed the hexagonal morphology and wurtzite crystalline structure. We investigated p-type conductivity in doped samples and measured hole carriers in range 2.4×1017/cc to 7.3×1017/cc for different Li contents. We found that hole carriers are responsible for long range order ferromagnetic coupling in Li doped samples. Room temperature ferroelectric hysteresis loops were observed in 8% and 10% Li doped samples. We demonstrated ferroelectric coercivity (remnant polarization) 2.5kV/cm (0.11 μC/cm2) and 2.8kV/cm (0.15 μC/cm2) for y=0.08 and y=0.10 samples. We propose that the mechanism of Li induced ferroelectricity in ZnO is due to indirect dipole interaction via hole carriers. We investigated that if the sample has hole carriers ≥5.3×1017/cc, they can mediate the ferroelectricity. Ferroelectric and ferromagnetic measurements showed that higher electric polarization and larger magnetic moment is attained when the hole concentration is larger and vice versa. Our results confirmed the hole dependent coexistence of ferromagnetic and ferroelectric behavior at room temperature, which provide potential applications for switchable and memory devices.

  7. Enhancement of photocathodic stability of p-type copper(I) oxide electrodes by surface etching treatment

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Fumiaki, E-mail: amano@kitakyu-u.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Chemical and Environmental Engineering, The University of Kitakyushu, Kitakyushu 808-0135 (Japan); Ebina, Toshihiro [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Ohtani, Bunsho [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2014-01-01

    The photoelectrochemical properties of electrodeposited p-type copper(I) oxide (Cu{sub 2}O) films were investigated using methyl viologen (MV{sup 2+}) as an electron acceptor. The pristine Cu{sub 2}O films were deactivated during the photocathodic reaction as a result of self-reduction, whereas the (111)-oriented Cu{sub 2}O films treated in an aqueous solution containing hexamethylenetetramine at pH 5 and 90 °C exhibited stable photocurrent for MV{sup 2+} reduction into the cation radical. Scanning electron microscope images showed that the treated films contained smaller crystal grains than untreated ones. X-ray photoelectron spectroscopy revealed that the treatment etched the thin layer of copper(II) oxide from the Cu{sub 2}O polycrystalline surface. Etching of the film surface enhanced the stability and steady-state photocurrent for photocathodic reduction of MV{sup 2+}, suggesting that the crystalline composition and structures exposed on the outermost surface of Cu{sub 2}O polycrystalline films have a considerable influence on the selectivity for the photocathodic reaction over self-reduction. - Highlights: • Photoelectrochemical reduction of methyl viologen by (111)-oriented Cu{sub 2}O thin films • Cu{sub 2}O films are etched using an aqueous solution containing hexamethylenetetramine. • Etching decreases crystal grain size and removes the thin layer of CuO. • Etching enhances the stability of Cu{sub 2}O photoelectrodes.

  8. Performance of six functionals (LDA, PBE, PBESOL, B3LYP, PBE0, and WC1LYP) in the simulation of vibrational and dielectric properties of crystalline compounds. The case of forsterite Mg2SiO4.

    Science.gov (United States)

    De la Pierre, M; Orlando, R; Maschio, L; Doll, K; Ugliengo, P; Dovesi, R

    2011-07-15

    The performance of six different density functionals (LDA, PBE, PBESOL, B3LYP, PBE0, and WC1LYP) in describing the infrared spectrum of forsterite, a crystalline periodic system with orthorhombic unit cell (28 atoms in the primitive cell, Pbmn space group), is investigated by using the periodic ab initio CRYSTAL09 code and an all-electron Gaussian-type basis set. The transverse optical (TO) branches of the 35 IR active modes are evaluated at the equilibrium geometry together with the oscillator strengths and the high-frequency dielectric tensor ϵ(∞) . These quantities are essential to compute the dielectric function ϵ(ν), and then the reflectance spectrum R(ν), which is compared with experiment. It turns out that hybrid functionals perform better than LDA and GGA, in general; that B3LYP overperforms WC1LYP and, in turn, PBE0; that PBESOL is better than PBE; that LDA is the worst performing functional among the six under study.

  9. Annealing Behavior of New Micro-defects in p-type Large-diameter CZ-Si Crystal

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    New types of defects in 15.24 cm diameter and 20.32 cm diameter Czochralski silicon crystals were found after SCI cleaning. Their annealing behavior was studied. It was suggested that these defects become larger during high temperature annealing and disappear by annealing at 1250℃.

  10. Progress in N-type Si Solar Cell and Module Technology for High Efficiency and Low Cost

    Energy Technology Data Exchange (ETDEWEB)

    Song, Dengyuan; Xiong, Jingfeng; Hu, Zhiyan; Li, Gaofei; Wang, Hongfang; An, Haijiao; Yu, Bo; Grenko, Brian; Borden, Kevin; Sauer, Kenneth; Cui, Jianhua; Wang, Haitao [Yingli Green Energy Holding Co., LTD, 071051 Boading (China); Roessler, T. [Yingli Green Energy Europe GmbH, Heimeranstr. 37, 80339 Munich (Germany); Bultman, J. [ECN Solar Energy, P.O. Box 1, NL-1755 ZG Petten (Netherlands); Vlooswijk, A.H.G.; Venema, P.R. [Tempress Systems BV, Radeweg 31, 8171 Vaassen (Netherlands)

    2012-06-15

    A novel high efficiency solar cell and module technology, named PANDA, using crystalline n-type CZ Si wafers has moved into large-scale production at Yingli. The first commercial sales of the PANDA modules commenced in mid 2010. Up to 600MW of mass production capacity from crystal-Si growth, wafer slicing, cell processing and module assembly have been implemented by the end of 2011. The PANDA technology was developed specifically for high efficiency and low cost. In contrast to the existing n-type Si solar cell manufacturing methods in mass production, this new technology is largely compatible with a traditional p-type Si solar cell production line by conventional diffusion, SiNx coating and screen-printing technology. With optimizing all technologies, Yingli's PANDA solar cells on semi-square 6-inch n-type CZ wafers (cell size 239cm{sup 2}) have been improved to currently have an average efficiency on commercial production lines exceeding 19.0% and up to 20.0% in pilot production. The PANDA modules have been produced and were certified according to UL1703, IEC 61215 and IEC 61730 standards. Nearly two years of full production on scale-up lines show that the PANDA modules have a high efficiency and power density, superior high temperature performance, near zero initial light induced degradation, and excellent efficiency at low irradiance.

  11. Tailoring crystallinity and configuration of silica nanotubes by electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, Tomitsugu, E-mail: taguchi.tomitsugu@jaea.go.jp; Yamaguchi, Kenji

    2015-05-01

    Highlights: •Single-crystal SiO{sub 2} nanotubes were successfully synthesized for the first time. •The single-crystal SiO{sub 2} was α-crystobalite. •Desired area of single-crystal nanotube can be changed to amorphous by electron irradiation. •The configuration of nanotube can be controlled using the focused electron irradiation technique. -- Abstract: SiO{sub 2} nanotubes show potential in applications such as nanoscale electronic and optical devices, bioseparation, biocatalysis, and nanomedicine. As-grown SiO{sub 2} nanotubes in the previous studies always have an amorphous wall, and here we demonstrate the successful synthesis of single-crystal nanotubes for the first time by the heat treatment of SiC nanotubes at 1300 °C for 10 h under low-vacuum conditions. According to TEM observations, the single-crystal SiO{sub 2} was α-cristobalite. We also demonstrate that single-crystal SiO{sub 2} nanotubes can be transformed into amorphous SiO{sub 2} nanotubes by electron beam irradiation. Moreover, we synthesized a crystalline/amorphous SiO{sub 2} composite nanotube, in which crystalline and amorphous SiO{sub 2} coexisted in different localized regions. In addition, for biomedical applications such as drug delivery systems, controlling the configuration of the open end, the diameter, and capsulation of SiO{sub 2} nanotubes is crucial. We can also obturate, capsulate, and cut a SiO{sub 2} nanotube, as well as modify the inner diameter of the nanotube at a specific, nanometer-sized region using the focused electron beam irradiation technique.

  12. Controlled vapor phase growth of single crystalline, two-dimensional GaSe crystals with high photoresponse.

    Science.gov (United States)

    Li, Xufan; Lin, Ming-Wei; Puretzky, Alexander A; Idrobo, Juan C; Ma, Cheng; Chi, Miaofang; Yoon, Mina; Rouleau, Christopher M; Kravchenko, Ivan I; Geohegan, David B; Xiao, Kai

    2014-06-30

    Compared with their bulk counterparts, atomically thin two-dimensional (2D) crystals exhibit new physical properties, and have the potential to enable next-generation electronic and optoelectronic devices. However, controlled synthesis of large uniform monolayer and multi-layer 2D crystals is still challenging. Here, we report the controlled synthesis of 2D GaSe crystals on SiO2/Si substrates using a vapor phase deposition method. For the first time, uniform, large (up to ~60 μm in lateral size), single-crystalline, triangular monolayer GaSe crystals were obtained and their structure and orientation were characterized from atomic scale to micrometer scale. The size, density, shape, thickness, and uniformity of the 2D GaSe crystals were shown to be controllable by growth duration, growth region, growth temperature, and argon carrier gas flow rate. The theoretical modeling of the electronic structure and Raman spectroscopy demonstrate a direct-to-indirect bandgap transition and progressive confinement-induced bandgap shifts for 2D GaSe crystals. The 2D GaSe crystals show p-type semiconductor characteristics and high photoresponsivity (~1.7 A/W under white light illumination) comparable to exfoliated GaSe nanosheets. These 2D GaSe crystals are potentially useful for next-generation electronic and optoelectronic devices such as photodetectors and field-effect transistors.

  13. Crystalline systems. [Book chapter

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, L.D.

    The use of two double resonance methods, electron-nuclear double resonance (ENDOR) and electron-electron double resonance (ELDOR) in the study of free radicals in solids is reviewed. Included are descriptions of how crystalline-phase ENDOR is used to determine small hyperfine splittings, quadrupoly couplings, and reaction mechanisms or radical formation and how crystalline phase ELDOR is used to determine large hyperfine splittings, to identify radicals with large quadrupole moments and to study spin exchange processes. The complementary role played by the ENDOR and ELDOR spectroscopy in the separation of overlapping EPR spectra, in the study of proton-deuterium exchange, in the study of methyl groups undergoing tunneling rotation, and in the determination of the rates of intermolecular motion are dealt with. 13 figures, 1 table. (DP)

  14. Thermodynamics of Crystalline States

    CERN Document Server

    Fujimoto, Minoru

    2013-01-01

    Thermodynamics is a well-established discipline of physics for properties of matter in thermal equilibrium with the surroundings. Applying to crystals, however, the laws encounter undefined properties of crystal lattice, which therefore need to be determined for a clear and well-defined description of crystalline states. Thermodynamics of Crystalline States explores the roles played by order variables and dynamic lattices in crystals in a wholly new way. The book begins by clarifying basic concepts for stable crystals. Next, binary phase transitions are discussed to study collective motion of order variables, as described mostly as classical phenomena. New to this edition is the examination of magnetic crystals, where magnetic symmetry is essential for magnetic phase transitions. The multi-electron system is also discussed  theoretically, as a quantum-mechanical example, for superconductivity in metallic crystals. Throughout the book, the role played by the lattice is emphasized and studied in-depth. Thermod...

  15. Observation by conductive-probe atomic force microscopy of strongly inverted surface layers at the hydrogenated amorphous silicon/crystalline silicon heterojunctions

    Science.gov (United States)

    Maslova, O. A.; Alvarez, J.; Gushina, E. V.; Favre, W.; Gueunier-Farret, M. E.; Gudovskikh, A. S.; Ankudinov, A. V.; Terukov, E. I.; Kleider, J. P.

    2010-12-01

    Heterojunctions made of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) are examined by conducting probe atomic force microscopy. Conductive channels at both (n )a-Si:H/(p)c-Si and (p)a-Si:H/(n)c-Si interfaces are clearly revealed. These are attributed to two-dimension electron and hole gases due to strong inversion layers at the c-Si surface in agreement with previous planar conductance measurements. The presence of a hole gas in (p )a-Si:H/(n)c-Si structures implies a quite large valence band offset (EVc-Si-EVa-Si:H>0.25 eV).

  16. Formation of p-type ZnO thin film through co-implantation

    Science.gov (United States)

    Chuang, Yao-Teng; Liou, Jhe-Wei; Woon, Wei-Yen

    2017-01-01

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N+ implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (1019 cm-3) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of PZn-4NO complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  17. Nanostructured p-Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes

    Directory of Open Access Journals (Sweden)

    Matteo Bonomo

    2016-05-01

    Full Text Available This review reports the properties of p-type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs. Light absorption is crucial for the activation of the reduction processes occurring at the p-type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (ET process from photocathode to a redox shuttle in the oxidized form are also crucial since the flow of electrons will take place correctly if the ET rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e., if the semiconductor itself or the chemisorbed dye-sensitizer, different energy levels will be involved in the cathodic ET process. An analysis of the general properties and requirements of electrodic materials of p-type for being efficient photoelectrocatalysts of reduction processes in dye-sensitized solar cells (DSC will be given. The working principle of p-type DSCs will be described and extended to other p-type PECs conceived and developed for the conversion of the solar radiation into chemical products of energetic/chemical interest like non fossil fuels or derivatives of carbon dioxide.

  18. Recent Developments in p-Type Oxide Semiconductor Materials and Devices

    KAUST Repository

    Wang, Zhenwei

    2016-02-16

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  19. CuNb3O8: A p-Type Semiconducting Metal Oxide Photoelectrode.

    Science.gov (United States)

    Joshi, Upendra A; Maggard, Paul A

    2012-06-07

    A new p-type CuNb3O8 polycrystalline photoelectrode was investigated and was determined to have indirect and direct bandgap sizes of 1.26 and 1.47 eV, respectively. The p-type polycrystalline film could be prepared on fluorine-doped tin oxide glass and yielded a cathodic photocurrent under visible-light irradiation (λ > 420 nm) with incident photon-to-current efficiencies of up to ∼6-7% and concomitant hydrogen evolution. A Mott-Schottky analysis yielded a flat band potential of +0.35 V versus RHE (pH = 6.3) and a calculated p-type dopant concentration of ∼7.2 × 10(15) cm(-3). The conduction band energies are found to be negative enough for the reduction of water under visible light irradiation. A hole mobility of ∼145 cm(2)/V·s was obtained from J(I)-V(2) measurements using the Mott-Gurney relation, which is ∼50% higher than that typically found for p-type Cu2O. DFT-based electronic structure calculations were used to probe the atomic and structural origins of the band gap transitions and carrier mobility. Thus, a new p-type semiconductor is discovered for potential applications in solar energy conversion.

  20. Chemical-free n-type and p-type multilayer-graphene transistors

    Energy Technology Data Exchange (ETDEWEB)

    Dissanayake, D. M. N. M., E-mail: nandithad@voxtel-inc.com [Voxtel Inc, Lockey Laboratories, University of Oregon, Eugene Oregon 97402 (United States); Eisaman, M. D. [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, New York 11794 (United States); Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-08-01

    A single-step doping method to fabricate n- and p-type multilayer graphene (MG) top-gate field effect transistors (GFETs) is demonstrated. The transistors are fabricated on soda-lime glass substrates, with the n-type doping of MG caused by the sodium in the substrate without the addition of external chemicals. Placing a hydrogen silsesquioxane (HSQ) barrier layer between the MG and the substrate blocks the n-doping, resulting in p-type doping of the MG above regions patterned with HSQ. The HSQ is deposited in a single fabrication step using electron beam lithography, allowing the patterning of arbitrary sub-micron spatial patterns of n- and p-type doping. When a MG channel is deposited partially on the barrier and partially on the glass substrate, a p-type and n-type doping profile is created, which is used for fabricating complementary transistors pairs. Unlike chemically doped GFETs in which the external dopants are typically introduced from the top, these substrate doped GFETs allow for a top gate which gives a stronger electrostatic coupling to the channel, reducing the operating gate bias. Overall, this method enables scalable fabrication of n- and p-type complementary top-gated GFETs with high spatial resolution for graphene microelectronic applications.

  1. Recent Developments in p-Type Oxide Semiconductor Materials and Devices.

    Science.gov (United States)

    Wang, Zhenwei; Nayak, Pradipta K; Caraveo-Frescas, Jesus A; Alshareef, Husam N

    2016-05-01

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  2. Photoelectrochemistry and Etching of SiC: a Comparison with Si

    NARCIS (Netherlands)

    Kelly, J.J.; van Dorp, D.H.; Weyher, J.L.

    2007-01-01

    The anodic electrochemistry and etching of the group IV compound semiconductor SiC was studied in both KOH and acidic fluoride solutions. The results for p-type and n-type electrodes are compared with those obtained for the group IV elemental semiconductor Si. We point out a number of interesting ap

  3. Nickel Electroless Plating: Adhesion Analysis for Mono-Type Crystalline Silicon Solar Cells.

    Science.gov (United States)

    Shin, Eun Gu; Rehman, Atteq ur; Lee, Sang Hee; Lee, Soo Hong

    2015-10-01

    The adhesion of the front electrodes to silicon substrate is the most important parameters to be optimized. Nickel silicide which is formed by sintering process using a silicon substrate improves the mechanical and electrical properties as well as act as diffusion barrier for copper. In this experiment p-type mono-crystalline czochralski (CZ) silicon wafers having resistivity of 1.5 Ω·cm were used to study one step and two step nickel electroless plating process. POCl3 diffusion process was performed to form the emitter with the sheet resistance of 70 ohm/sq. The Six, layer was set down as an antireflection coating (ARC) layer at emitter surface by plasma enhanced chemical vapor deposition (PECVD) process. Laser ablation process was used to open SiNx passivation layer locally for the formation of the front electrodes. Nickel was deposited by electroless plating process by one step and two step nickel electroless deposition process. The two step nickel plating was performed by applying a second nickel deposition step subsequent to the first sintering process. Furthermore, the adhesion analysis for both one step and two steps process was conducted using peel force tester (universal testing machine, H5KT) after depositing Cu contact by light induced plating (LIP).

  4. Sprayed and Spin-Coated Multilayer Antireflection Coating Films for Nonvacuum Processed Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    Abdullah Uzum

    2017-01-01

    Full Text Available Using the simple and cost-effective methods, spin-coated ZrO2-polymer composite/spray-deposited TiO2-compact multilayer antireflection coating film was introduced. With a single TiO2-compact film on the surface of a crystalline silicon wafer, 5.3% average reflectance (the reflectance average between the wavelengths of 300 nm and 1100 nm was observed. Reflectance decreased further down to 3.3% after forming spin-coated ZrO2 on the spray-deposited TiO2-compact film. Silicon solar cells were fabricated using CZ-Si p-type wafers in three sets: (1 without antireflection coating (ARC layer, (2 with TiO2-compact ARC film, and (3 with ZrO2-polymer composite/TiO2-compact multilayer ARC film. Conversion efficiency of the cells improved by a factor of 0.8% (from 15.19% to 15.88% owing to the multilayer ARC. Jsc was improved further by 2 mA cm−2 (from 35.3 mA cm−2 to 37.2 mA cm−2 when compared with a single TiO2-compact ARC.

  5. Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

    Energy Technology Data Exchange (ETDEWEB)

    Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J. [Department of Materials Science and Engineering, NC State University, EB-1, Raleigh, North Carolina 27695-7907 (United States)

    2013-06-21

    We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 Multiplication-Sign 10{sup -9} s) at lower energies. Microstructural studies, conducted by X-ray diffraction ({theta}-2{theta} and {phi} techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO<111 > Double-Vertical-Line Double-Vertical-Line c-YSZ<001> and in-plane NiO<110> Double-Vertical-Line Double-Vertical-Line c-YSZ<100>. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min{sup -1} for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies

  6. Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

    Science.gov (United States)

    Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J.

    2013-06-01

    We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 × 10-9 s) at lower energies. Microstructural studies, conducted by X-ray diffraction (θ-2θ and φ techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO⟨111 ⟩||c-YSZ⟨001⟩ and in-plane NiO⟨110⟩||c-YSZ⟨100⟩. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min-1 for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies ease the adsorption of 4-chlorophenol, hydroxyl, and water molecules to the surface. Thus, n

  7. Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

    KAUST Repository

    Caraveo-Frescas, J. A.

    2013-11-25

    p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p-type oxide semiconductor processed at similar temperature. Compared to thin film transistors, the SnO nanowire transistors exhibit five times higher mobility and one order of magnitude lower subthreshold swing. The SnO nanowire transistors show three times lower threshold voltages (−1 V) than the best reported SnO thin film transistors and fifteen times smaller than p-type Cu 2O nanowire transistors. Gate dielectric and process temperature are critical to achieving such performance.

  8. DyP-type peroxidases comprise a novel heme peroxidase family.

    Science.gov (United States)

    Sugano, Y

    2009-04-01

    Dye-decolorizing peroxidase (DyP) is produced by a basidiomycete (Thanatephorus cucumeris Dec 1) and is a member of a novel heme peroxidase family (DyP-type peroxidase family) that appears to be distinct from general peroxidases. Thus far, 80 putative members of this family have been registered in the PeroxiBase database (http://peroxibase.isbsib.ch/) and more than 400 homologous proteins have been detected via PSI-BLAST search. Although few studies have characterized the function and structure of these proteins, they appear to be bifunctional enzymes with hydrolase or oxygenase, as well as typical peroxidase activities. DyP-type peroxidase family suggests an ancient root compared with other general peroxidases because of their widespread distribution in the living world. In this review, firstly, an outline of the characteristics of DyP from T. cucumeris is presented and then interesting characteristics of the DyP-type peroxidase family are discussed.

  9. Demethoxycurcumin is a potent inhibitor of P-type ATPases from diverse kingdoms of life

    DEFF Research Database (Denmark)

    Dao, Trong Tuan; Sehgal, Pankaj; Thanh Tung, Truong;

    2016-01-01

    the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site......P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used...... as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among...

  10. Simulation analysis of the effects of a back surface field on a p-a-Si:H/n-c-Si/n+-a-Si:H heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Hu Yuehui; Zhang Xiangwen; Qu Minghao; Wang Lifu; Zeng Tao; Xie Yaojiang

    2009-01-01

    In order to investigate the effects of a back surface field (BSF) on the performance of a p-doped amorphous silicon (p-a-Si:H)/n-doped crystalline silicon (n-c-Si) solar cell, a heterojunction solar cell with a p-a-Si:H/nc-Si/n+-a-Si:H structure was designed. An n+-a-Si:H film was deposited on the back of an n-c-Si wafer as the BSF.The photovoltaic performance of p-a-Si:H/n-c-Si/n+-a-Si:H solar cells were simulated. It was shown that the BSF of the p-a-Si:H/n-c-Si/n+-a-Si:H solar cells could effectively inhibit the decrease of the cell performance caused by interface states.

  11. A simple model to estimate the optimal doping of p - Type oxide superconductors

    Directory of Open Access Journals (Sweden)

    Adir Moysés Luiz

    2008-12-01

    Full Text Available Oxygen doping of superconductors is discussed. Doping high-Tc superconductors with oxygen seems to be more efficient than other doping procedures. Using the assumption of double valence fluctuations, we present a simple model to estimate the optimal doping of p-type oxide superconductors. The experimental values of oxygen content for optimal doping of the most important p-type oxide superconductors can be accounted for adequately using this simple model. We expect that our simple model will encourage further experimental and theoretical researches in superconducting materials.

  12. High surface hole concentration p-type GaN using Mg implantation

    CERN Document Server

    Long Tao; Zhang Guo Yi

    2001-01-01

    Mg ions were implanted on Mg-doped GaN grown by metalorganic chemical vapor deposition (MOCVD). The p-type GaN was achieved with high hole concentration (8.28 x 10 sup 1 sup 7 cm sup - sup 3) conformed by Van derpauw Hall measurement after annealing at 800 degree C for 1 h. this is the first experimental report of Mg implantation on Mg-doped GaN and achieving p-type GaN with high surface hole concentration

  13. Hall and thermoelectric evaluation of p-type InAs

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M.C., E-mail: magnus.wagener@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Wagener, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2009-12-15

    This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

  14. Thermoelectric properties of epitaxial β-FeSi2 thin films grown on Si(111) substrates with various film qualities

    Science.gov (United States)

    Watanabe, Kentaro; Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Suzuki, Takeyuki; Fujita, Takeshi; Nakamura, Yoshiaki

    2017-05-01

    Si-based epitaxial β-FeSi2 thin films are attractive as materials for on-chip thermoelectric power generators. We investigated the structure, crystallinity, and thermoelectric properties of β-FeSi2 thin films epitaxially grown on Si(111) substrates by using three different techniques: conventional reactive deposition epitaxy followed by molecular beam epitaxy (RDE+MBE), solid phase epitaxy (SPE) based on codeposition of Fe and Si presented previously, and SPE followed by MBE (SPE+MBE) presented newly by this work. Their epitaxial growth temperatures were fixed at 530 °C for comparison. RDE+MBE thin films exhibited high crystalline quality, but rough surfaces and rugged β-FeSi2/Si(111) interfaces. On the other hand, SPE thin films showed flat surfaces and abrupt β-FeSi2/Si(111) interfaces but low crystallinity. We found that SPE+MBE thin films realized crystallinity higher than SPE thin films, and also had flatter surfaces and sharper interfaces than RDE+MBE thin films. In SPE+MBE thin film growth, due to the initial SPE process with low temperature codeposition, thermal interdiffusion of Fe and Si was suppressed, resulting in the surface flatness and abrupt interface. Second high temperature MBE process improved the crystallinity. We also investigated thermoelectric properties of these β-FeSi2 thin films. Structural factors affecting the thermoelectric properties of RDE+MBE, SPE, and SPE+MBE thin films were investigated.

  15. Fabrication and evaluation of propagation loss of Si/SiGe/Si photonic-wire waveguides for Si based optical modulator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Younghyun, E-mail: yhkim@mosfet.t.u-tokyo.ac.jp [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takenaka, Mitsuru [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Osada, Takenori; Hata, Masahiko [Sumitomo Chemical Co. Ltd., 6 Kitahara, Tsukuba, Ibaraki 300-3294 (Japan); Takagi, Shinichi [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-04-30

    We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs for Si-based optical modulators. The Si (80 nm)/Si{sub 0.72}Ge{sub 0.28} (40 nm) layers grown on Si-on-insulator by molecular beam epitaxy for optical modulators were evaluated by in-situ reflection high-energy electron diffraction, atomic force microscope, X-ray diffraction and Raman spectroscopy, exhibiting that the fully-strained highly-crystalline SiGe layer was obtained. We have evaluated the propagation loss of the Si/strained SiGe/Si photonic-wire waveguides. The wavelength dependence of the propagation loss exhibits the bandgap narrowing of the strained Si{sub 0.72}Ge{sub 0.28}, while the optical absorption of the strained Si{sub 0.72}Ge{sub 0.28} is not significant for the optical modulator application at 1.55-μm wavelength. - Highlights: • We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs. • The Si/Si{sub 0.72}Ge{sub 0.28} grown on Si-on-insulator were evaluated to be fully strained. • We have fabricated and evaluated the Si/strained SiGe/Si photonic-wire waveguides. • The wavelength dependence exhibits bandgap narrowing of the strained Si{sub 0.72}Ge{sub 0.28}. • Optical absorption of the SiGe is not significant for optical modulators at 1.55 μm.

  16. Impact of mechanical stress on gate tunneling currents of germanium and silicon p-type metal-oxide-semiconductor field-effect transistors and metal gate work function

    Science.gov (United States)

    Choi, Youn Sung; Numata, Toshinori; Nishida, Toshikazu; Harris, Rusty; Thompson, Scott E.

    2008-03-01

    Uniaxial four-point wafer bending stress-altered gate tunneling currents are measured for germanium (Ge)/silicon (Si) channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with HfO2/SiO2 gate dielectrics and TiN/P+ poly Si electrodes. Carrier separation is used to measure electron and hole currents. The strain-altered hole tunneling current from the p-type inversion layer of Ge is measured to be ˜4 times larger than that for the Si channel MOSFET, since the larger strain-induced valence band-edge splitting in Ge results in more hole repopulation into a subband with a smaller out-of-plane effective mass and a lower tunneling barrier height. The strain-altered electron tunneling current from the metal gate is measured and shown to change due to strain altering the metal work function as quantified by flatband voltage shift measurements of Si MOS capacitors with TaN electrodes.

  17. Crystalline mesoporous metal oxide

    Institute of Scientific and Technical Information of China (English)

    Wenbo Yue; Wuzong Zhou

    2008-01-01

    Since the discovery of many types of mesoporous silicas, such as SBA-15, KIT-6, FDU-12 and SBA-16, porous crystalline transition metal oxides, such as Cr2O3, Co3O4, In2O3, NiO, CeO2, WO3, Fe2O3 and MnO2, have been synthesized using the mesoporous silicas as hard templates. Several synthetic methods have been developed. These new porous materials have high potential applications in catalysis, Li-ion rechargeable batteries and gas sensors. This article gives a brief review of the research of porous crystals of metal oxides in the last four years.

  18. Realization of Ag-S codoped p-type ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian Ning, E-mail: xtn9886@zju.edu.cn [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Li, Xiang; Lu, Zhong [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Chen, Yong Yue [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Sui, Cheng Hua [Department of Science, Zhijiang College of Zhejiang University of Technology, Hangzhou, Zhejiang 310024 (China); Wu, Hui Zhen [Department of Physics, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

    2014-10-15

    Highlights: • Ag-S codoped p-type ZnO thin films have been fabricated. • The films exhibit low resistivity and high Hall mobility and hole concentration. • A ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction has been fabricated and shows rectifying behaviors. - Abstract: Ag-S codoped ZnO films have been grown on quartz substrates by e-beam evaporation at low temperature (100 °C). The effects of Ag{sub 2}S content on the structural and electrical properties of the films were investigated. The results showed that 2 wt% Ag{sub 2}S doped films exhibited p-type conduction, with a resistivity of 0.0347 Ω cm, a Hall mobility of 9.53 cm{sup 2} V{sup −1} s{sup −1}, and a hole concentration of 1.89 × 10{sup 19} cm{sup −3} at room temperature. The X-ray photoelectron spectroscopy measurements showed that Ag and S have been incorporated into the films. To further confirm the p-type conduction of Ag-S codoped ZnO films, a ZnO:(Ag, S)/i-ZnO/ZnO:Al homojunction was fabricated and rectifying behaviors of which was measured. High electrical performance and low growth temperature indicate that Ag{sub 2}S is a promising dopant to fabricate p-type Ag-S codoped ZnO films.

  19. Relative Frequencies of G and P Types among Rotaviruses from Indian Diarrheic Cow and Buffalo Calves

    Science.gov (United States)

    Gulati, Baldev R.; Nakagomi, Osamu; Koshimura, Yumi; Nakagomi, Toyoko; Pandey, Ramayan

    1999-01-01

    While an increasing number of studies suggest that there is a high prevalence of rotaviruses with P8[11], a typical P type of bovine rotavirus (BRV), among human neonates or infants in India, no data are available on the distribution of G and P types of Indian BRVs. Thus, fecal specimens were collected from cow and buffalo calves under 1 month of age on organized dairy farms in India during the period between 1994 and 1997, and 36 rotavirus-positive specimens were used to determine the relative frequencies of the G and P types of Indian BRVs. As to the G type, G10 was predominant (83%), followed by G6 (6%). The majority (94%) of BRVs had P8[11], and only one isolate possessed P6[1]. The most common combination of G and P types was G10P8[11] (81%), followed by G6P6[1] (3%) and G6P8[11] (3%). The high prevalence of BRVs possessing P8[11] VP4s strongly supports the hypothesis that BRVs may cross the host species barrier and circulate among neonates in India. PMID:10325385

  20. Characterization of 3D-DDTC detectors on p-type substrates

    CERN Document Server

    Betta, G -F Dalla; Bosisio, Luciano; Darbo, Giovanni; Gabos, Paolo; Gemme, Claudia; Koehler, Michael; La Rosa, Alessandro; Parzefall, Ulrich; Pernegger, Heinz; Piemonte, Claudio; Povoli, Marco; Rachevskaia, Irina; Ronchin, Sabina; Wiik, Liv; Zoboli, Aanrea; Zorzi, Nicola

    2009-01-01

    We report on the electrical and functional characterization of 3D Double-side, Double-Type-Column (3D- DDTC) detectors fabricated on p-type substrates. Results relevant to detectors in the diode, strip and pixel configurations are presented, and demonstrate a clear improvement in the charge collection performance compared to the first prototypes of these detectors.

  1. Origin and evolution of metal p-Type ATPases in Plantae (Archaeplastida

    Directory of Open Access Journals (Sweden)

    Marc eHanikenne

    2014-01-01

    Full Text Available Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium and possibly copper and calcium. So far, few efforts have been devoted to elucidating the origin and evolution of these proteins in Eukaryotes. In this work, we use large-scale phylogenetics to show that metal P-type ATPases form a homogenous group among P-type ATPases and that their specialisation into either monovalent (Cu or divalent (Zn, Cd… metal transport stems from a gene duplication that took place early in the evolution of Life. Then, we demonstrate that the four subgroups of plant metal ATPases all have a different evolutionary origin and a specific taxonomic distribution, only one tracing back to the cyanobacterial progenitor of the chloroplast. Finally, we examine the subsequent evolution of these proteins in green plants and conclude that the genes thoroughly characterised in model organisms are often the result of lineage-specific gene duplications, which calls for caution when attempting to infer function from sequence similarity alone in non-model organisms.

  2. Synthesis of p-type and n-type nickel ferrites and associated electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Šutka, Andris, E-mail: andris.sutka@rtu.lv [Faculty of Material Science and Applied Chemistry, Riga Technical University, Paula Valdena 3, Riga, LV-1048 (Latvia); Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Pärna, Rainer [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia); Käämbre, Tanel [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Kisand, Vambola [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia)

    2015-01-01

    We used sol–gel auto combustion to synthesize nickel ferrites of p-type and n-type conductivity by controlling the relative amounts of nickel and iron during synthesis. The obtained samples have been characterized by XRD, FE-SEM, electrical measurements and XPS. We observe huge differences in the effect of grain size on the electrical resistivity between the p-type and the n-type material when the grain size increases from nano to micro scale during annealing at temperatures from 900 {sup o}C to 1300 {sup o}C. The observed resistivity decrease (due to grain size) is four orders of magnitude in the n-type nickel ferrite, whereas the p-type material remains virtually unaffected. We rationalize this drastic difference to stem from a reverse contrast of the surface (grain shell) versus bulk (grain core) conductivity between p- and n-type ferrite. With the grain shells in p-type the easier charge carrier path the effect of scatter at grain boundaries is accordingly diminished, whereas in the n-type charge transport properties are controlled by (the number of) grain boundaries in a conduction path.

  3. A structural and functional perspective of DyP-type peroxidase family.

    Science.gov (United States)

    Yoshida, Toru; Sugano, Yasushi

    2015-05-15

    Dye-decolorizing peroxidase from the basidiomycete Bjerkandera adusta Dec 1 (DyP) is a heme peroxidase. This name reflects its ability to degrade several anthraquinone dyes. The substrate specificity, the amino acid sequence, and the tertiary structure of DyP are different from those of the other heme peroxidase (super)families. Therefore, many proteins showing the similar amino acid sequences to that of DyP are called DyP-type peroxidase which is a new family of heme peroxidase identified in 2007. In fact, all structures of this family show a similar structure fold. However, this family includes many proteins whose amino acid sequence identity to DyP is lower than 15% and/or whose catalytic efficiency (kcat/Km) is a few orders of magnitude less than that of DyP. A protein showing an activity different from peroxidase activity (dechelatase activity) has been also reported. In addition, the precise physiological roles of DyP-type peroxidases are unknown. These facts raise a question of whether calling this family DyP-type peroxidase is suitable. Here, we review the differences and similarities of structure and function among this family and propose the reasonable new classification of DyP-type peroxidase family, that is, class P, I and V. In this contribution, we discuss the adequacy of this family name.

  4. Photoluminescence and structural properties of Si/SiC core–shell nanowires growth by HWCVD

    Energy Technology Data Exchange (ETDEWEB)

    Nazarudin, Nur Fatin Farhanah Binti; Mohd Noor, Nurul Jannah Binti; Rahman, Saadah Abdul; Goh, Boon Tong, E-mail: boontong77@yahoo.com

    2015-01-15

    Si/SiC core–shell nanowires grown by hot-wire chemical vapor deposition were studied. Ni nanoparticles act as metal nano-templates to catalyze the growth of these core–shell nanowires. These nanowires were grown at different deposition pressures of 0.5 and 1 mbar. The nanowires showed a tapered-like morphology at deposition pressure 0.5 mbar. Increase in pressure to 1 mbar leads to a formation of agglomerated grains at the root of the nanowires. The results show that these nanowires consisted of crystalline Si core and amorphous SiC shell nanowires. Increase in pressure enhanced the formation of SiC phase in the shell of the nanowires. On the other hand, the formation of the agglomerated grains attributed to an increasing of the SiC phase at higher deposition pressure. The presence of Si and SiC nano-crystallites embedded within an amorphous matrix exhibited a room temperature PL emission in the range of 400–1000 nm. The effects of the deposition pressure on the optical and structural properties of the nanowires are also discussed. - Highlights: • Growth of Si/SiC core–shell nanowires by HWCVD. • The nanowires consisted of crystalline Si core and amorphous SiC shell. • Metal nano-templates catalyzed the growth of Si core nanowires. • Increase in deposition pressure enhanced the SiC phase. • The presence of nano-crystallites exhibited a room temperature PL.

  5. 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)

  6. N型单晶硅衬底上非晶硅/单晶硅异质结太阳电池计算机模拟%COMPUTER SIMULATION OF a-Si:H/c-Si HETERJUNCTION SOLAR CELLS ON N-TYPE SILICON CRYSTALLINE

    Institute of Scientific and Technical Information of China (English)

    任丙彦; 张燕; 郭贝; 张兵; 李洪源; 许颖; 王文静

    2008-01-01

    采用德国HMI研发的AFORS-HET软件模拟了N型衬底非晶硅,单晶硅异质结太阳电池的特性,结果表明随着发射层厚度的增加,短路电流下降,电池的短波响应变差.在非晶硅,单晶硅异质结界面处加入不同的界面态密度(Dit).发现当Dit1012cm-2·eV-1时,电池的开路电压和填充因子均大幅减小,导致电池效率降低.当在非晶硅,单晶硅异质结界面处加入本征非晶缓冲层后,电池性能明显改善,但是缓冲层厚度应控制在30nm以内.模拟的a-Si/i-a-Si:H/c-Si/i-a-Si:H/n+a-Si双面异质结太阳电池的最高转换效率达到28.47%.

  7. Characterization of stain etched p-type silicon in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Mogoda, A.S., E-mail: awad_mogoda@hotmail.com [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt); Ahmad, Y.H.; Badawy, W.A. [Department of Chemistry, Faculty of Science, Cairo University, Giza (Egypt)

    2011-04-15

    Research highlights: {yields} Stain etching of p-Si in aqueous HF solutions containing HNO{sub 3} or KMnO{sub 4} was investigated. {yields} The electrical conductivity of the etched Si surfaces was measured using impedance technique. {yields} Scanning electron microscope and energy disperse X-ray were used to analyze the etched surfaces. {yields} Etching in aqueous HF solution containing HNO{sub 3} led to formation of a porous silicon layer. {yields} The formation of the porous silicon layer in HF/KMnO{sub 4} was accompanied by deposition of K{sub 2}SiF{sub 6} on the pores surfaces. - Abstract: Stain etching of p-type silicon in hydrofluoric acid solutions containing nitric acid or potassium permanganate as an oxidizing agent has been examined. The effects of etching time, oxidizing agent and HF concentrations on the electrochemical behavior of etched silicon surfaces have been investigated by electrochemical impedance spectroscopy (EIS). An electrical equivalent circuit was used for fitting the impedance data. The morphology and the chemical composition of the etched Si surface were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques, respectively. A porous silicon layer was formed on Si etched in HF solutions containing HNO{sub 3}, while etching in HF solutions containing KMnO{sub 4} led to the formation of a porous layer and simultaneous deposition of K{sub 2}SiF{sub 6} inside the pores. The thickness of K{sub 2}SiF{sub 6} layer increases with increasing the KMnO{sub 4} concentration and decreases as the concentration of HF increases.

  8. Low temperature acetone detection by p-type nano-titania thin film: Equivalent circuit model and sensing mechanism

    Science.gov (United States)

    Bhowmik, B.; Dutta, K.; Hazra, A.; Bhattacharyya, P.

    2014-09-01

    Undoped nanocrystalline anatase p-type TiO2 thin film was deposited by sol-gel method on thermally oxidized p-Si (2-5 Ω cm, ) substrates. The thin film was characterized by X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) to confirm the formation of nanocrystalline anatase titania and to determine the crystallite size (∼7 nm). The resistive sensor structure was fabricated employing two lateral Pd electrodes on top of the TiO2 sensing layer. The developed sensor was tested in the temperature range of 50-200 °C for the detection of low ppm acetone (0.5-50 ppm). The maximum response of ∼115% was obtained at 150 °C with response/recovery time of 14 s/22 s at 50 ppm acetone (in air). Moreover, the sensors were capable of detecting acetone as low as 0.5 ppm with acceptable response magnitude. As titania acetone sensors are mostly n-TiO2 based, the acetone sensing mechanism for p-TiO2 is yet to be established authentically. To address the issue, an equivalent circuit model, based on the corresponding band diagram of nanocrystalline p-TiO2 with Pd electrode, was developed to describe the electron transfer mechanism through grain, grain boundary and Pd electrode under the influence of acetone vapor.

  9. Revival of interband crystalline reflectance from nanocrystallites in porous silicon by immersion plating

    Energy Technology Data Exchange (ETDEWEB)

    Yamani, Z.; Alaql, A.; Therrien, J.; Nayfeh, O.; Nayfeh, M. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    1999-06-01

    We prepared porous silicon for which the UV reflectance (3.3{endash}6 eV) is nearly eliminated, and exhibits no features at the Si interband bulk transitions 3.3, 4.3, and 5.5 eV. Plating with a thin layer of copper is found to cause recovery of the UV bulk-like crystalline reflectance and interband resonances. This provides evidence that the loss of crystalline absorption is reversible and is not due to a permanent loss in the crystalline structure. This may relate to a recent model in which the optical activity of ultra small nanocrystallites is produced by a new Si{endash}Si crystalline configuration (or phase), distinct from but interconnected to the diamond-like configuration by a potential barrier. {copyright} {ital 1999 American Institute of Physics.}

  10. High quality crystalline silicon surface passivation by combined intrinsic and n-type hydrogenated amorphous silicon

    NARCIS (Netherlands)

    Schuttauf, J.A.; van der Werf, C.H.M.; Kielen, I.M.; van Sark, W.G.J.H.M.; Rath, J.K.

    2011-01-01

    We investigate the influence of thermal annealing on the passivation quality of crystalline silicon (c-Si) surfaces by intrinsic and n-type hydrogenated amorphous silicon (a-Si:H) films. For temperatures up to 255 C, we find an increase in surface passivation quality, corresponding to a decreased da

  11. Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

    Science.gov (United States)

    Liao, Baochen; Hoex, Bram; Aberle, Armin G.; Chi, Dongzhi; Bhatia, Charanjit S.

    2014-06-01

    In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiOx) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiOx films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiOx films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiOx films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiOx has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiOx in the field of high-efficiency silicon wafer solar cells.

  12. Excellent c-Si surface passivation by low-temperature atomic layer deposited titanium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Baochen, E-mail: liaobaochen@nus.edu.sg [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Singapore 117574 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); A*STAR Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602 (Singapore); Hoex, Bram [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Singapore 117574 (Singapore); Aberle, Armin G.; Bhatia, Charanjit S., E-mail: elebcs@nus.edu.sg [Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, Singapore 117574 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Chi, Dongzhi [A*STAR Institute of Materials Research and Engineering (IMRE), 3 Research Link, Singapore 117602 (Singapore)

    2014-06-23

    In this work, we demonstrate that thermal atomic layer deposited (ALD) titanium oxide (TiO{sub x}) films are able to provide a—up to now unprecedented—level of surface passivation on undiffused low-resistivity crystalline silicon (c-Si). The surface passivation provided by the ALD TiO{sub x} films is activated by a post-deposition anneal and subsequent light soaking treatment. Ultralow effective surface recombination velocities down to 2.8 cm/s and 8.3 cm/s, respectively, are achieved on n-type and p-type float-zone c-Si wafers. Detailed analysis confirms that the TiO{sub x} films are nearly stoichiometric, have no significant level of contaminants, and are of amorphous nature. The passivation is found to be stable after storage in the dark for eight months. These results demonstrate that TiO{sub x} films are also capable of providing excellent passivation of undiffused c-Si surfaces on a comparable level to thermal silicon oxide, silicon nitride, and aluminum oxide. In addition, it is well known that TiO{sub x} has an optimal refractive index of 2.4 in the visible range for glass encapsulated solar cells, as well as a low extinction coefficient. Thus, the results presented in this work could facilitate the re-emergence of TiO{sub x} in the field of high-efficiency silicon wafer solar cells.

  13. Liquid crystalline order in polymers

    CERN Document Server

    Blumstein, Alexandre

    1978-01-01

    Liquid Crystalline Order in Polymers examines the topic of liquid crystalline order in systems containing rigid synthetic macromolecular chains. Each chapter of the book provides a review of one important area of the field. Chapter 1 discusses scattering in polymer systems with liquid crystalline order. It also introduces the field of liquid crystals. Chapter 2 treats the origin of liquid crystalline order in macromolecules by describing the in-depth study of conformation of such macromolecules in their unassociated state. The chapters that follow describe successively the liquid crystalli

  14. Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design.

    Science.gov (United States)

    An, Yonghao; Wood, Brandon C; Ye, Jianchao; Chiang, Yet-Ming; Wang, Y Morris; Tang, Ming; Jiang, Hanqing

    2015-07-21

    Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity. This produces a much more uniform volume expansion, significantly reducing strain concentration. Based on a new, validated methodology that improves previous models of anisotropic swelling of c-Si, we propose optimal morphological designs for c-Si pillars and particles. The advantages of the new morphologies are clearly demonstrated by mesoscale simulations and verified by experiments on engineered c-Si micropillars. The results of this study illustrate that morphological design is effective in improving the fracture resistance of micron-sized Si electrodes, which will facilitate their practical application in next-generation Li-ion batteries. The model and design approach present in this paper also have general implications for the study and mitigation of mechanical failure of electrode materials that undergo large anisotropic volume change upon ion insertion and extraction.

  15. Infrared absorption and visible transparency in heavily doped p-type BaSnO3

    Science.gov (United States)

    Li, Yuwei; Sun, Jifeng; Singh, David J.

    2017-01-01

    The recent experimental work shows that perovskite BaSnO3 can be heavily doped by K to become a stable p-type semiconductor. Here, we find that p-type perovskite BaSnO3 retains transparency for visible light while absorbing strongly in the infrared below 1.5 eV. The origin of the remarkable optical transparency even with heavy doping is that the interband transitions that are enabled by empty states at the top of the valence band are concentrated mainly in the energy range from 0.5 to 1.5 eV, i.e., not extending past the near IR. In contrast to n-type, the Burstein-Moss shift is slightly negative, but very small reflecting the heavier valence bands relative to the conduction bands.

  16. CCE measurements and annealing studies on proton-irradiated p-type MCz silicon diodes

    CERN Document Server

    Hoedlmoser, H; Köhler, M; Nordlund, H

    2007-01-01

    Magnetic Czochralski (MCz) silicon has recently been investigated for the development of radiation tolerant detectors for future high-luminosity HEP experiments. A study of p-type MCz Silicon diodes irradiated with protons up to a fluence of has been performed by means of Charge Collection Efficiency (CCE) measurements as well as standard CV/IV characterizations. The changes of CCE, full depletion voltage and leakage current as a function of fluence are reported. A subsequent annealing study of the irradiated detectors shows an increase in effective doping concentration and a decrease in the leakage current, whereas the CCE remains basically unchanged. Two different series of detectors have been compared differing in the implantation dose of p-spray isolation as well as effective doping concentration (Neff) of the p-type bulk presumably due to a difference in thermal donor (TD) activation during processing. The series with the higher concentration of TDs shows a delayed reverse annealing of Neff after irradia...

  17. Fabrication of p-type lithium niobate crystals by molybdenum doping and polarization

    Science.gov (United States)

    Tian, Tian; Kong, Yongfa; Liu, Hongde; Liu, Shiguo; Li, Wei; Chen, Shaolin; Xu, Jiayue

    2017-06-01

    The lack of p-type lithium niobate limits it serving as an active material. A series of Mo-doped and pure congruent lithium niobate crystals were grown by Czochralski method under different polarization conditions. Their dominant carrier species were characterized by holographic experiment. The results showed dominant charge carrier species may be changed from electrons to holes when lithium niobate crystal was doped with Mo ions and polarized under the current of 70mA for 30 minutes. It indicated that p-type lithium niobate crystal could be fabricated by Mo-doping and suitably controlling the polarization condition. Mo-doped lithium niobate crystals can be a promising candidate for active components.

  18. Enhancement of p-type mobility in tin monoxide by native defects

    KAUST Repository

    Granato, D. B.

    2013-05-31

    Transparent p-type materials with good mobility are needed to build completely transparent p-n junctions. Tin monoxide (SnO) is a promising candidate. A recent study indicates great enhancement of the hole mobility of SnO grown in Sn-rich environment [E. Fortunato et al., Appl. Phys. Lett. 97, 052105 (2010)]. Because such an environment makes the formation of defects very likely, we study defect effects on the electronic structure to explain the increased mobility. We find that Sn interstitials and O vacancies modify the valence band, inducing higher contributions of the delocalized Sn 5p orbitals as compared to the localized O 2p orbitals, thus increasing the mobility. This mechanism of valence band modification paves the way to a systematic improvement of transparent p-type semiconductors.

  19. A Density Functional Theory Study of Doped Tin Monoxide as a Transparent p-type Semiconductor

    KAUST Repository

    Bianchi Granato, Danilo

    2012-05-01

    In the pursuit of enhancing the electronic properties of transparent p-type semiconductors, this work uses density functional theory to study the effects of doping tin monoxide with nitrogen, antimony, yttrium and lanthanum. An overview of the theoretical concepts and a detailed description of the methods employed are given, including a discussion about the correction scheme for charged defects proposed by Freysoldt and others [Freysoldt 2009]. Analysis of the formation energies of the defects points out that nitrogen substitutes an oxygen atom and does not provide charge carriers. On the other hand, antimony, yttrium, and lanthanum substitute a tin atom and donate n-type carriers. Study of the band structure and density of states indicates that yttrium and lanthanum improves the hole mobility. Present results are in good agreement with available experimental works and help to improve the understanding on how to engineer transparent p-type materials with higher hole mobilities.

  20. Comment on 'Electronic Properties of Red P-Type T12S5 Single Crystals'

    Institute of Scientific and Technical Information of China (English)

    M. Cankurtaran; H. (C)elik

    2007-01-01

    Recently, Gamal et al. [Chin. Phys. Lett. 22 (2005) 1530] reported the results of electrical conductivity, Hall effect and thermoelectric measurements on p-type Th2S5 single crystals. From the experimental data for the temperature dependence of differential thermoelectric power, Gamal et al. determined the values of 2.66 × 10-41 kg and 2.50 × 10-41 kg, respectively, for the effective masses of electrons and holes in p-type Tl2S5, which are about ten orders of magnitude smaller than the free electron mass (9.11 × 10-31 kg). We argue that the anomalously small values obtained for the effective mass of charge carriers in Tl2S5 have no physical significance.

  1. Measurement of the dead layer thickness in a p-type point contact germanium detector

    Science.gov (United States)

    Jiang, Hao; Yue, Qian; Li, Yu-Lan; Kang, Ke-Jun; Li, Yuan-Jing; Li, Jin; Lin, Shin-Ted; Liu, Shu-Kui; Ma, Hao; Ma, Jing-Lu; Su, Jian; Tsz-King Wong, Henry; Yang, Li-Tao; Zhao, Wei; Zeng, Zhi

    2016-09-01

    A 994 g mass p-type PCGe detector has been deployed during the first phase of the China Dark matter EXperiment, aiming at direct searches for light weakly interacting massive particles. Measuring the thickness of the dead layer of a p-type germanium detector is an issue of major importance since it determines the fiducial mass of the detector. This work reports a method using an uncollimated 133Ba source to determine the dead layer thickness. The experimental design, data analysis and Monte Carlo simulation processes, as well as the statistical and systematic uncertainties are described. A dead layer thickness of 1.02 mm was obtained based on a comparison between the experimental data and the simulated results. Supported by National Natural Science Foundation of China (10935005, 10945002, 11275107, 11175099)

  2. Preparation and Photovoltaic Properties of p-Type Nano-ZnFe2O4

    Institute of Scientific and Technical Information of China (English)

    LI Zi-heng; ZOU Xu; LI Gen; ZOU Guang-tian

    2012-01-01

    p-Type nano-ZnFe2O4 semiconductors were gained by high-prssure treatment.Surface photovoltaic spectrum(SPS) and transient photovoltaic technology(TPV) were used for studying the photogenerated charge of nano-ZnFe2O4.Results show that the photovoltaic behavior of nano-ZnFe2O4 changed as the processing pressure increased.When the processing pressure was higher than 2 GPa,both SPS response interval and peak changed significantly.XPS results show that the non-lattice oxygen entered into the lattice and the content of lattice oxygen increased with the increase of processing pressure.The material changed from oxygen vacancy type to oxygen excess type and the photoelectric properties changed from n-type to p-type when the processing pressure is higher than 2GPa.

  3. Piezoelectric Nanogenerator Using p-Type ZnO Nanowire Arrays

    KAUST Repository

    Lu, Ming-Pei

    2009-03-11

    Using phosphorus-doped ZnO nanowire (NW) arrays grown on silicon substrate, energy conversion using the p-type ZnO NWs has been demonstrated for the first time. The p-type ZnO NWs produce positive output voltage pulses when scanned by a conductive atomic force microscope (AFM) in contact mode. The output voltage pulse is generated when the tip contacts the stretched side (positive piezoelectric potential side) of the NW. In contrast, the n-type ZnO NW produces negative output voltage when scanned by the AFM tip, and the output voltage pulse is generated when the tip contacts the compressed side (negative potential side) of the NW. In reference to theoretical simulation, these experimentally observed phenomena have been systematically explained based on the mechanism proposed for a nanogenerator. © 2009 American Chemical Society.

  4. In and out of the cation pumps: P-type ATPase structure revisited

    DEFF Research Database (Denmark)

    Bublitz, Maike; Poulsen, Hanne; Morth, Jens Preben

    2010-01-01

    Active transport across membranes is a crucial requirement for life. P-type ATPases build up electrochemical gradients at the expense of ATP by forming and splitting a covalent phosphoenzyme intermediate, coupled to conformational changes in the transmembrane section where the ions are translocated....... The marked increment during the last three years in the number of crystal structures of P-type ATPases has greatly improved our understanding of the similarities and differences of pumps with different ion specificities, since the structures of the Ca2+-ATPase, the Na+,K+-ATPase and the H+-ATPase can now...... be compared directly. Mechanisms for ion gating, charge neutralization and backflow prevention are starting to emerge from comparative structural analysis; and in combination with functional studies of mutated pumps this provides a framework for speculating on how the ions are bound and released as well...

  5. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    Science.gov (United States)

    Mori, T.

    2016-10-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  6. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    Energy Technology Data Exchange (ETDEWEB)

    Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Kaltenegger, Lisa [MPIA, Koenigstuhl 17, Heidelberg, D-69117 (Germany)

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  7. Low-temperature deposition of crystalline silicon nitride nanoparticles by hot-wire chemical vapor deposition

    Science.gov (United States)

    Kim, Chan-Soo; Youn, Woong-Kyu; Lee, Dong-Kwon; Seol, Kwang-Soo; Hwang, Nong-Moon

    2009-07-01

    The nanocrystalline alpha silicon nitride (α-Si 3N 4) was deposited on a silicon substrate by hot-wire chemical vapor deposition at the substrate temperature of 700 °C under 4 and 40 Torr at the wire temperatures of 1430 and 1730 °C, with a gas mixture of SiH 4 and NH 3. The size and density of crystalline nanoparticles on the substrate increased with increasing wire temperature. With increasing reactor pressure, the crystallinity of α-Si 3N 4 nanoparticles increased, but the deposition rate decreased.

  8. Characterization of deposited CdS thin films by Spray Pyrolysis method and used in Cd/CdS/p-Si/Al structure

    Science.gov (United States)

    Özakın, Oǧuzhan; Aktaş, Şeydanur; Güzeldir, Betül; Saǧlam, Mustafa

    2017-04-01

    In our study, as p-type crystalline Si substrate was used. Omic contact was performed by evaporating Al metal on the matt surface of crystal. On the other surface of it CdS thin film were enlarged with the technique of Spray Pyrolysis. Structural characteristics of the grown thin film was examined SEM and EDAX image. When examining SEM image of CdS thin film were totally covered the p-Si crystal surface of it was nearly homogeneous and The EDAX spectra showed that the expected different ratios metal percent exist in the alloys, approximately. On the CdS films whose surface features were investigated, at 10-7 torr pressure was obtained Cd/CdS/p-Si/Al sandwich structure by evaporating Cd. Firstly, the I-V (current-voltage) characteristics on 80K between 320K at room temperature of this structure was measured. I-V characteristics of the examined at parameters diodes calculation, Thermionic Emission, were used. The characteristic parameters such as barrier height and ideality factor of this structure have been calculated from the forward bias I-V characteristics. Consequently, it was seen that CdS thin film grown on p-Si semiconductor will be used confidently in Cd/p-Si metal-semiconductor contacts thanks to Spray Pyrolysis method.

  9. Carrier transport mechanism of highly-sensitive niobium doped titanium dioxide/p-Si heterojunction photodiode under illuminations by solar simulated light

    Science.gov (United States)

    Gautam, Subodh K.; Das, Arkaprava; Singh, R. G.; Kumar, V. V. S.; Singh, Fouran

    2016-12-01

    Nano-crystalline Nb doped anatase TiO2 (NTO) thin film was deposited on p-type Si substrate for fabrication of n-NTO/p-Si heterojunction photodiode using RF magnetron sputtering technique. Rutherford backscattering spectrometry and Raman spectroscopy results suggest the substitutional incorporation of Nb5+ ions in anatase TiO2 lattice, which is evidenced from large stiffening of Eg(1) and softening of B1g Raman modes. The current density-voltage (J-V) characteristics are measured and important diode parameters of n-NTO/p-Si heterojunction diode are determined, such as ideality factor, barrier height, and series resistance. Diode exhibits excellent behavior under dark condition as rectification ratio is found to be ˜7 × 102 with high forward current density ˜1.54 A/cm2 at 5 V. The n-NTO/p-Si heterojunction works as an efficient photodiode in reverse bias under simulated solar light illumination with high contrast ratio ˜225 at -2 V and very high photo responsivity ˜2.7 A/W at -5 V. The high photo responsivity of photodiode is mainly due to the generation of high density electron-hole plasma in NTO depletion region by the absorption of incident UV range photons. Thus n-NTO/p-Si heterojunction diode is suitable device for highly sensitive Ultra-Violet photodiode applications.

  10. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B

  11. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  12. Investigation of negative photoconductivity in p-type Pb1-xSnxTe film

    Science.gov (United States)

    Tavares, M. A. B.; da Silva, M. J.; Peres, M. L.; de Castro, S.; Soares, D. A. W.; Okazaki, A. K.; Fornari, C. I.; Rappl, P. H. O.; Abramof, E.

    2017-01-01

    We investigated the negative photoconductivity (NPC) effect that was observed in a p-type Pb1-xSnxTe film for temperatures varying from 300 K down to 85 K. We found that this effect is a consequence of defect states located in the bandgap which act as trapping levels, changing the relation between generation and recombination rates. Theoretical calculations predict contributions to the NPC from both conduction and valence bands, which are in accordance with the experimental observations.

  13. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  14. Radiation damage studies of multi-guard ring p-type bulk diodes

    CERN Document Server

    Bortoletto, D; Günther, M; Grim, G P; Lander, R L; Willard, S; Li, Z

    1999-01-01

    Several diodes with different multi-guard ring structures were fabricated from 10 k OMEGA cm p-type bulk material. Studies on the performance of such devices are presented here. They include the measurement of the leakage current, breakdown voltage and charge collection efficiency before and after 2x10 sup 1 sup 4 p/cm sup 2 irradiation with 63.3 MeV kinetic protons. (author)

  15. Kinetics of self-interstitials reactions in p-type silicon irradiated with alpha particles

    Energy Technology Data Exchange (ETDEWEB)

    Makarenko, L.F., E-mail: makarenko@bsu.by [Department of Applied Mathematics and Computer Science, Belarusian State University, Independence Ave. 4, 220030 Minsk (Belarus); Moll, M. [CERN, Geneva (Switzerland); Evans-Freeman, J.H. [University of Canterbury, Christchurch (New Zealand); Lastovski, S.B.; Murin, L.I.; Korshunov, F.P. [Scientific-Practical Materials Research Centre of NAS of Belarus, Minsk (Belarus)

    2012-08-01

    New findings on the self-interstitial migration in p-type silicon are presented. They are based on experimental studies of the formation kinetics of defects related to interstitial carbon after irradiation with alpha particles. The main parameters characterizing the interaction rate of silicon self-interstitials with substitutional carbon atoms have been determined. A preliminary interpretation of the experimental data is given. The interpretation takes into account different diffusivities of self-interstitials in their singly and doubly ionized states.

  16. Method for producing high carrier concentration p-Type transparent conducting oxides

    Science.gov (United States)

    Li, Xiaonan; Yan, Yanfa; Coutts, Timothy J.; Gessert, Timothy A.; Dehart, Clay M.

    2009-04-14

    A method for producing transparent p-type conducting oxide films without co-doping plasma enhancement or high temperature comprising: a) introducing a dialkyl metal at ambient temperature and a saturated pressure in a carrier gas into a low pressure deposition chamber, and b) introducing NO alone or with an oxidizer into the chamber under an environment sufficient to produce a metal-rich condition to enable NO decomposition and atomic nitrogen incorporation into the formed transparent metal conducting oxide.

  17. Record mobility in transparent p-type tin monoxide films and devices by phase engineering

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso

    2013-06-25

    Here, we report the fabrication of nanoscale (15 nm) fully transparent p-type SnO thin film transistors (TFT) at temperatures as low as 180 C with record device performance. Specifically, by carefully controlling the process conditions, we have developed SnO thin films with a Hall mobility of 18.71 cm2 V-1 s-1 and fabricated TFT devices with a linear field-effect mobility of 6.75 cm2 V-1 s -1 and 5.87 cm2 V-1 s-1 on transparent rigid and translucent flexible substrates, respectively. These values of mobility are the highest reported to date for any p-type oxide processed at this low temperature. We further demonstrate that this high mobility is realized by careful phase engineering. Specifically, we show that phase-pure SnO is not necessarily the highest mobility phase; instead, well-controlled amounts of residual metallic tin are shown to substantially increase the hole mobility. A detailed phase stability map for physical vapor deposition of nanoscale SnO is constructed for the first time for this p-type oxide. © 2013 American Chemical Society.

  18. Electronic inhomogeneity in n- and p-type PbTe detected by 125Te NMR

    Science.gov (United States)

    Levin, E. M.; Heremans, J. P.; Kanatzidis, M. G.; Schmidt-Rohr, K.

    2013-09-01

    125Te nuclear magnetic resonance spectra and spin-lattice relaxation of n- and p-type PbTe, self-doping narrow band-gap semiconductors, have been studied and compared to those of p-type GeTe. Spin-lattice relaxation in GeTe can be fit by one component, while that in both PbTe samples must be fit by at least two components, showing electronically homogeneous and inhomogeneous materials, respectively. For PbTe-based materials, the spin-lattice relaxation rate 1/T1 increases linearly with carrier concentration. The data for GeTe fall on the same line and allow us to extend this plot to higher concentrations. Long and short T1 components in both PbTe samples reflect “low,” ˜1017 cm-3, and “high,” ˜1018 cm-3, carrier concentration components. Carrier concentrations in both n- and p-type PbTe samples obtained from the Hall and Seebeck effects generally match the “high” carrier concentration component, and to some extent, ignore the “low” one. This demonstrates that the Hall and Seebeck effects may have a limited ability for the determination of carrier concentration in complex thermoelectric PbTe-based and other multicomponent materials.

  19. P-type electronic and thermal transport properties of Mg2Sn1-xSix

    Science.gov (United States)

    Kim, Sunphil; Wiendlocha, Bartlomiej; Heremans, Joseph P.

    2013-03-01

    P-type Mg2Sn doped with various acceptors(1)(2) has been studied as a potential thermoelectric material. Because of its narrow band gap and high lattice thermal conductivity, the zT values of the binary compound are limited: zTmax reported is 0.3(3). In this work, we synthesize and characterize p-type-doped Mg2Sn1-xSix with various acceptors. Silicon is added in order to widen the band gap and scatter the phonons. The conduction band degeneracy that yields excellent zT in n-type material in the Mg2Sn1-xSix alloy system unfortunately does not apply to p-type material. Thermomagnetic and galvanomagnetic properties (electrical resistivity, Seebeck, Hall, and Nernst coefficients) are measured, along with thermal conductivity and band gap measurements. Finally, zT values are reported. (1) H. Y. Chen et al. Journal of Electronic Materials, Vol. 38, No. 7, 2009 (2) S. Choi et al. Journal of Electronic Materials, Vol. 41, No. 6, 2012 (3) H. Y. Chen et al. Phys. Status Solidi A 207, No. 11, 2523-2531 (2010) The work is supported by the joint NSF/DOE program on thermoelectrics, NSF-CBET-1048622

  20. Effective p-type N-doped WS{sub 2} monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xu, E-mail: zhaoxu@htu.cn; Xia, Congxin; Wang, Tianxing; Peng, Yuting; Dai, Xianqi

    2015-11-15

    Based on density functional theory, the characteristics of n- and p-type dopants are investigated by means of group V and VII atoms substituting sulfur in the WS{sub 2} monolayer. Numerical results show that for each doping case, the formation energy is lower under W-rich condition, which indicates that it is energy favorable to incorporate group V and VII atoms into WS{sub 2} under W-rich experimental conditions. Moreover, compared with other dopant cases, N-doped WS{sub 2} monolayer owns the lowest formation energy. In particular, the transition level of (−1/0) is only 75 meV in the N-doped case, which indicates that N impurities can offer effective p-type carriers in the WS{sub 2} monolayer. - Highlights: • The formation energy is lower under W-rich conditions. • N-doped system owns the lowest formation energy compared with other atoms. • The transition level of N-doping in WS{sub 2} is 75 meV. • N impurities can offer effective p-type carriers in the WS{sub 2}.

  1. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life.

    Science.gov (United States)

    Dao, Trong Tuan; Sehgal, Pankaj; Tung, Truong Thanh; Møller, Jesper Vuust; Nielsen, John; Palmgren, Michael; Christensen, Søren Brøgger; Fuglsang, Anja Thoe

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material.

  2. p-Type Quasi-Mono Silicon Solar Cell Fabricated by Ion Implantation

    Directory of Open Access Journals (Sweden)

    Chien-Ming Lee

    2013-01-01

    Full Text Available The p-type quasi-mono wafer is a novel type of silicon material that is processed using a seed directional solidification technique. This material is a promising alternative to traditional high-cost Czochralski (CZ and float-zone (FZ material. Here, we evaluate the application of an advanced solar cell process featuring a novel method of ion implantation on p-type quasi-mono silicon wafer. The ion implantation process has simplified the normal industrial process flow by eliminating two process steps: the removal of phosphosilicate glass (PSG and the junction isolation process that is required after the conventional thermal POCl3 diffusion process. Moreover, the good passivation performance of the ion implantation process improves Voc. Our results show that, after metallization and cofiring, an average cell efficiency of 18.55% can be achieved using 156 × 156 mm p-type quasi-mono silicon wafer. Furthermore, the absolute cell efficiency obtained using this method is 0.47% higher than that for the traditional POCl3 diffusion process.

  3. Enhanced thermopower and low thermal conductivity in p-type polycrystalline ZrTe5

    Science.gov (United States)

    Hooda, M. K.; Yadav, C. S.

    2017-07-01

    Thermoelectric properties of polycrystalline p-type ZrTe5 are reported in the temperature (T) range of 2-340 K. Thermoelectric power (S) is positive and reaches up to 458 μV/K at 340 K on increasing T. The value of Fermi energy 16 meV suggests a low carrier density of ≈9.5 × 1018 cm-3. A sharp anomaly in S data is observed at 38 K, which seems intrinsic to p-type ZrTe5. The thermal conductivity (κ) value is low (2 W/m K at T = 300 K) with major contribution from the lattice part. Electrical resistivity data show the metal to semiconductor transition at T ˜ 150 K and non-Arrhenius behavior in the semiconducting region. The figure of merit zT (0.026 at T = 300 K) is ˜63% higher than that of HfTe5 (0.016) and better than those of the conventional SnTe, p-type PbTe, and bipolar pristine ZrTe5 compounds.

  4. Efficient synthesis of triarylamine-based dyes for p-type dye-sensitized solar cells

    Science.gov (United States)

    Wild, Martin; Griebel, Jan; Hajduk, Anna; Friedrich, Dirk; Stark, Annegret; Abel, Bernd; Siefermann, Katrin R.

    2016-05-01

    The class of triarylamine-based dyes has proven great potential as efficient light absorbers in inverse (p-type) dye sensitized solar cells (DSSCs). However, detailed investigation and further improvement of p-type DSSCs is strongly hindered by the fact that available synthesis routes of triarylamine-based dyes are inefficient and particularly demanding with regard to time and costs. Here, we report on an efficient synthesis strategy for triarylamine-based dyes for p-type DSSCs. A protocol for the synthesis of the dye-precursor (4-(bis(4-bromophenyl)amino)benzoic acid) is presented along with its X-ray crystal structure. The dye precursor is obtained from the commercially available 4(diphenylamino)benzaldehyde in a yield of 87% and serves as a starting point for the synthesis of various triarylamine-based dyes. Starting from the precursor we further describe a synthesis protocol for the dye 4-{bis[4‧-(2,2-dicyanovinyl)-[1,1‧-biphenyl]-4-yl]amino}benzoic acid (also known as dye P4) in a yield of 74%. All synthesis steps are characterized by high yields and high purities without the need for laborious purification steps and thus fulfill essential requirements for scale-up.

  5. Selective functionalization and loading of biomolecules in crystalline silicon nanotube field-effect-transistors.

    Science.gov (United States)

    Kwon, Soonshin; Chen, Zack C Y; Noh, Hyunwoo; Lee, Ju Hun; Liu, Hang; Cha, Jennifer N; Xiang, Jie

    2014-07-21

    Crystalline silicon nanotubes (Si NTs) provide distinctive advantages as electrical and biochemical analysis scaffolds through their unique morphology and electrical tunability compared to solid nanowires or amorphous/non-conductive nanotubes. Such potential is investigated in this report. Gate-dependent four-probe current-voltage analysis reveals electrical properties such as resistivity to differ by nearly 3 orders of magnitude between crystalline and amorphous Si NTs. Analysis of transistor transfer characteristics yields a field effect mobility of 40.0 cm(2) V(-1) s(-1) in crystalline Si NTs. The hollow morphology also allows selective inner/outer surface functionalization and loading capability either as a carrier for molecular targets or as a nanofluidic channel for biomolecular assays. We present for the first time a demonstration of internalization of fluorescent dyes (rhodamine) and biomolecules (BSA) in Si NTs as long as 22 μm in length.

  6. COLD DRAWING IN CRYSTALLINE POLYMERS

    Science.gov (United States)

    alcohols, phenol) in Nylon 6 produced changes in the crystalline structure as well as plasticizer action; these two effects must therefore be carefully...distinguished. Changes in the crystalline structure were followed by changes in the infrared spectrum. Dynamic mechanical and thermogravimetric analysis

  7. Prediction of a hexagonal SiO2 phase affecting stabilities of MgSiO3 and CaSiO3 at multimegabar pressures.

    Science.gov (United States)

    Tsuchiya, Taku; Tsuchiya, Jun

    2011-01-25

    Ultrahigh-pressure phase relationship of SiO(2) silica in multimegabar pressure condition is still quite unclear. Here, we report a theoretical prediction on a previously uncharacterized stable structure of silica with an unexpected hexagonal Fe(2)P-type form. This phase, more stable than the cotunnite-type structure, a previously postulated postpyrite phase, was discovered to stabilize at 640 GPa through a careful structure search by means of ab initio density functional computations over various structure models. This is the first evidential result of the pressure-induced phase transition to the Fe(2)P-type structure among all dioxide compounds. The crystal structure consists of closely packed, fairly regular SiO(9) tricapped trigonal prisms with a significantly compact lattice. Additional investigation further elucidates large effects of this phase change in SiO(2) on the stability of MgSiO(3) and CaSiO(3) at multimegabar pressures. A postperovskite phase of MgSiO(3) breaks down at 1.04 TPa along an assumed adiabat of super-Earths and yields Fe(2)P-type SiO(2) and CsCl (B2)-type MgO. CaSiO(3) perovskite, on the other hand, directly dissociates into SiO(2) and metallic CaO, skipping a postperovskite polymorph. Predicted ultrahigh-pressure and temperature phase diagrams of SiO(2), MgSiO(3), and CaSiO(3) indicate that the Fe(2)P-type SiO(2) could be one of the dominant components in the deep mantles of terrestrial exoplanets and the cores of gas giants.

  8. Low Temperature Deposition of PECVD Polycrystalline Silicon Thin Films using SiF4 / SiH4 mixture

    Science.gov (United States)

    Syed, Moniruzzaman; Inokuma, Takao; Kurata, Yoshihiro; Hasegawa, Seiichi

    2016-03-01

    Polycrystalline silicon films with a strong (110) texture were prepared at 400°C by a plasma-enhanced chemical vapor deposition using different SiF4 flow rates ([SiF4] = 0-0.5 sccm) under a fixed SiH4 flow rate ([SiH4] = 1 or 0.15 sccm). The effects of the addition of SiF4 to SiH4 on the structural properties of the films were studied by Raman scattering, X-ray diffraction (XRD), Atomic force microscopy and stress measurements. For [SiH4] = 1 sccm, the crystallinity and the (110) XRD grain size monotonically increased with increasing [SiF4] and their respective maxima reach 90% and 900 Å. However, for [SiH4] = 0.15 sccm, both the crystallinity and the grain size decreased with [SiF4]. Mechanisms causing the change in crystallinity are discussed, and it was suggested that an improvement in the crystallinity, due to the addition of SiF4, is likely to be caused by the effect of a change in the surface morphology of the substrates along with the effect of in situ chemical cleaning.

  9. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    KAUST Repository

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  10. Fabrication and Characterization of N-Type Zinc Oxide/P-Type Boron Doped Diamond Heterojunction

    National Research Council Canada - National Science Library

    Marián Marton; Miroslav Mikolášek; Jaroslav Bruncko; Ivan Novotný; Tibor Ižák; Marian Vojs; Halyna Kozak; Marián Varga; Anna Artemenko; Alexander Kromka

    2015-01-01

    .... Semiconducting boron doped diamond (BDD) thin films were grown on Si and UV grade silica glass substrates by HFCVD method with various boron concentration in the gas mixture. Doped zinc oxide (ZnO:Al, ZnO:Ge...

  11. Evaluation of photovoltaic properties of nanocrystalline-FeSi2/Si heterojunctions

    Science.gov (United States)

    Shaban, Mahmoud; Bayoumi, Amr M.; Farouk, Doaa; Saleh, Mohamed B.; Yoshitake, Tsuyoshi

    2016-09-01

    In this paper, an application of nanocrystalline iron disilicide (NC-FeSi2) combined with nanocrystalline-Si (NC-Si) in a heterostructured solar cell is introduced and numerically evaluated in detail. The proposed cell structure is studied based on an experimental investigation of photovoltaic properties of NC-FeSi2/crystalline-Si heterojunctions, composed of unintentionally-doped NC-FeSi2 thin film grown on Si substrate. Photoresponse measurement of NC-FeSi2/crystalline-Si heterojunction confirmed ability of NC-FeSi2 to absorb NIR light and to generate photocarriers. However, collection of these carriers was not so efficient and a radical improvement in design of the device is required. Therefore, a modified device structure, comprising of NC-FeSi2 layer sandwiched between two heavily-doped p- and n-type NC-Si, is suggested and numerically evaluated. Simulation results showed that the proposed structure would exhibit a relatively high conversion efficiency of 25%, due to an improvement in collection efficiency of photogenerated carriers in the NC-FeSi2 and NC-Si layers. To attain such efficiency, defect densities in NC-FeSi2 and NC-Si layers should be kept less than 1014 and 1016 cm-3 eV-1, respectively. Remarkable optical and electrical properties of NC-FeSi2, employed in the proposed structure, facilitate improving device quantum efficiency spectrum providing significant spectrum extension into the near-infrared region beyond Si bandgap.

  12. Hydrogen passivation of multi-crystalline silicon solar cells

    Institute of Scientific and Technical Information of China (English)

    胡志华; 廖显伯; 刘祖明; 夏朝凤; 陈庭金

    2003-01-01

    The effects of hydrogen passivation on multi-crystalline silicon (mc-Si) solar cells are reported in this paper.Hydrogen plasma was generated by means of ac glow discharge in a hydrogen atmosphere. Hydrogen passivation was carried out with three different groups of mc-Si solar cells after finishing contacts. The experimental results demonstrated that the photovoltaic performances of the solar cell samples have been improved after hydrogen plasma treatment, with a relative increase in conversion efficiency up to 10.6%. A calculation modelling has been performed to interpret the experimental results using the model for analysis of microelectronic and photonic structures developed at Pennsylvania State University.

  13. Ivermectin is a nonselective inhibitor of mammalian P-type ATPases.

    Science.gov (United States)

    Pimenta, Paulo Henrique Cotrim; Silva, Claudia Lucia Martins; Noël, François

    2010-02-01

    Ivermectin is a large spectrum antiparasitic drug that is very safe at the doses actually used. However, as it is being studied for new applications that would require higher doses, we should pay attention to its effects at high concentrations. As micromolar concentrations of ivermectin have been reported to inhibit the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA), we decided to investigate its putative inhibitory effect on other two important P-type ATPases, namely the Na(+) , K(+)-ATPase and H(+)/K(+)-ATPase. We first extended the data on SERCA, using preparations from rat enriched in SERCA1a (extensor digitorum longus) and 1b (heart) isoforms. Secondly, we tested the effect of ivermectin in two preparations of rat Na(+), K(+)-ATPase in order to appreciate its putative selectivity towards the alpha(1) isoform (kidney) and the alpha(2)/alpha(3) isoforms (brain), and in an H(+)/K(+)-ATPase preparation from rat stomach. Ivermectin inhibited all these ATPases with similar IC(50) values (6-17 microM). With respect to the inhibition of the Na(+), K(+)-ATPase, ivermectin acts by a mechanism different from the classical cardiac glycosides, based on selectivity towards the isoforms, sensibility to the antagonistic effect of K(+) and to ionic conditions favoring different conformations of the enzyme. We conclude that ivermectin is a nonselective inhibitor of three important mammalian P-type ATPases, which is indicative of putative important adverse effects if this drug were used at high doses. As a consequence, we propose that novel analogs of ivermectin should be developed and tested both for their parasitic activity and in vitro effects on P-type ATPases.

  14. Enhanced photovoltaic effect of ruthenium complex-modified graphene oxide with P-type conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei, E-mail: jj_zw_js@sina.com.cn; Bai, Huicong; Zhang, Yu; Sun, Ying; Lin, Shen; Liu, Jian; Yang, Qi; Song, Xi-Ming, E-mail: songlab@lnu.edu.cn

    2014-10-15

    A graphene oxide nanocomposite with bis(1,10-phenanthroline)(N-(2-aminoethyl)-4-(4-methyl-2,2-bipyridine-4-yl) formamide) ruthenium (Ru(phen){sub 2}(bpy-NH{sub 2})(PF{sub 6}){sub 2}), a ruthenium complex, was synthesized by amidation reaction between amino group of the ruthenium complex and carboxyl group of GO. The as-prepared Ru(II)–GO composite was characterized by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, fluorescence spectra, surface photovoltage (SPV) spectrum and transient photovoltage (TPV) technology. This nanocomposite showed a typical p-type character and an enhanced photovoltaic effect at long timescale of about 3 × 10{sup −3} s compared to GO alone. A reversible rise/decay of the photocurrent in response to the on/off illumination step was also observed in a photoelectrochemical cell of the Ru(II)–GO composite. The photocurrent response of the Ru(II)–GO film was remarkably higher than that of GO film. Therefore, this Ru(II)–GO composite is believed to be a promising p-type photoelectric conversion material for further photovoltaic applications. - Highlights: • A new dye-sensitized graphene oxide nanocomposite was reported. • A photo-induced charge transfer process in this nanocomposite was confirmed. • This composite showed a typical p-type conductivity. • This composite showed an enhanced photovoltaic effect at a long timescale.

  15. 27Al nuclear quadrupole resonance study of crystalline aluminosilicates

    Science.gov (United States)

    Lee, Donghoon; Bray, P. J.

    27Al NQR responses have been obtained from the three different forms of crystalline Al 2SiO 5, andalusite, kyanite, and sillimanite, by a very sensitive Robinson-type continuous wave NQR spectrometer at 77 K or at room temperature. From the NQR responses the values of Qcc and of η were determined for all the aluminum coordinations in the powdered samples. The values are compared with those obtained by nuclear magnetic resonance studies of single crystals.

  16. Growth of single-crystal columns of CoSi2 embedded in epitaxial Si on Si(111) by molecular beam epitaxy

    Science.gov (United States)

    Fathauer, R. W.; Nieh, C. W.; Xiao, Q. F.; Hashimoto, Shin

    1989-01-01

    The codeposition of Si and Co on a heated Si(111) substrate is found to result in epitaxial columns of CoSi2 if the Si:Co ratio is greater than approximately 3:1. These columns are surrounded by an Si matrix which shows bulk-like crystalline quality based on transmission electron microscopy and ion channeling. This phenomenon has been studied as functions of substrate temperature and Si:Co ratio. Samples with columns ranging in average diameter from approximately 25 to 130 nm have been produced.

  17. Electroforming-free resistive switching memory effect in transparent p-type tin monoxide

    KAUST Repository

    Hota, M. K.

    2014-04-14

    We report reproducible low bias bipolar resistive switching behavior in p-type SnO thin film devices without extra electroforming steps. The experimental results show a stable resistance ratio of more than 100 times, switching cycling performance up to 180 cycles, and data retention of more than 103 s. The conduction mechanism varied depending on the applied voltage range and resistance state of the device. The memristive switching is shown to originate from a redox phenomenon at the Al/SnO interface, and subsequent formation/rupture of conducting filaments in the bulk of the SnO layer, likely involving oxygen vacancies and Sn interstitials.

  18. Does p-type ohmic contact exist in WSe2-metal interfaces?

    Science.gov (United States)

    Wang, Yangyang; Yang, Ruo Xi; Quhe, Ruge; Zhong, Hongxia; Cong, Linxiao; Ye, Meng; Ni, Zeyuan; Song, Zhigang; Yang, Jinbo; Shi, Junjie; Li, Ju; Lu, Jing

    2015-12-01

    Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for

  19. Initial results from 3D-DDTC detectors on p-type substrates

    Energy Technology Data Exchange (ETDEWEB)

    Zoboli, A., E-mail: zoboli@disi.unitn.i [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, and INFN, Sezione di Padova (Gruppo Collegato di Trento), Via Sommarive, 14, I-38100 Povo di Trento (Italy); Boscardin, M. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi, Via Sommarive, 18, I-38100 Povo di Trento (Italy); Bosisio, L. [Dipartimento di Fisica, Universita di Trieste, and INFN, Sezione di Trieste, Via A. Valerio, 2, I-34127 Trieste (Italy); Dalla Betta, G.-F. [Dipartimento di Ingegneria e Scienza dell' Informazione, Universita di Trento, and INFN, Sezione di Padova (Gruppo Collegato di Trento), Via Sommarive, 14, I-38100 Povo di Trento (Italy); Piemonte, C.; Ronchin, S.; Zorzi, N. [Fondazione Bruno Kessler, Centro per i Materiali e i Microsistemi, Via Sommarive, 18, I-38100 Povo di Trento (Italy)

    2010-01-11

    Owing to their superior radiation hardness compared to planar detectors, 3D detectors are one of the most promising technologies for the LHC upgrade foreseen in 2017. Fondazione Bruno Kessler has developed 3D Double-side Double-Type Column (3D-DDTC) detectors providing a technological simplifications with respect to a standard 3D process while aiming at comparable detector performance. We present selected results from the electrical characterization of 3D-DDTC structures from the second batch made on p-type substrates, supported also by TCAD simulations.

  20. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg; Meloni, Gabriele

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (Znt....... The structures reveal a similar fold to Cu+-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn2+ ions by the transporter. The E2P structure...

  1. P-Type Silicon Strip Sensors for the new CMS Tracker at HL-LHC

    Science.gov (United States)

    Adam, W.; Bergauer, T.; Brondolin, E.; Dragicevic, M.; Friedl, M.; Frühwirth, R.; Hoch, M.; Hrubec, J.; König, A.; Steininger, H.; Waltenberger, W.; Alderweireldt, S.; Beaumont, W.; Janssen, X.; Lauwers, J.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Beghin, D.; Brun, H.; Clerbaux, B.; Delannoy, H.; De Lentdecker, G.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, Th.; Léonard, A.; Luetic, J.; Postiau, N.; Seva, T.; Vanlaer, P.; Vannerom, D.; Wang, Q.; Zhang, F.; Abu Zeid, S.; Blekman, F.; De Bruyn, I.; De Clercq, J.; D'Hondt, J.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Van Mulders, P.; Van Parijs, I.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; Delaere, C.; Delcourt, M.; De Visscher, S.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Michotte, D.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Szilasi, N.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Härkönen, J.; Lampén, T.; Luukka, P.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Eerola, P.; Tuuva, T.; Baulieu, G.; Boudoul, G.; Caponetto, L.; Combaret, C.; Contardo, D.; Dupasquier, T.; Gallbit, G.; Lumb, N.; Mirabito, L.; Perries, S.; Vander Donckt, M.; Viret, S.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bonnin, C.; Brom, J.-M.; Chabert, E.; Chanon, N.; Charles, L.; Conte, E.; Fontaine, J.-Ch.; Gross, L.; Hosselet, J.; Jansova, M.; Tromson, D.; Autermann, C.; Feld, L.; Karpinski, W.; Kiesel, K. M.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Pierschel, G.; Preuten, M.; Rauch, M.; Schael, S.; Schomakers, C.; Schulz, J.; Schwering, G.; Wlochal, M.; Zhukov, V.; Pistone, C.; Fluegge, G.; Kuensken, A.; Pooth, O.; Stahl, A.; Aldaya, M.; Asawatangtrakuldee, C.; Beernaert, K.; Bertsche, D.; Contreras-Campana, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Gallo, E.; Garay Garcia, J.; Hansen, K.; Haranko, M.; Harb, A.; Hauk, J.; Keaveney, J.; Kalogeropoulos, A.; Kleinwort, C.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Pitzl, D.; Reichelt, O.; Savitskyi, M.; Schuetze, P.; Walsh, R.; Zuber, A.; Biskop, H.; Buhmann, P.; Centis-Vignali, M.; Garutti, E.; Haller, J.; Hoffmann, M.; Lapsien, T.; Matysek, M.; Perieanu, A.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Schwandt, J.; Sonneveld, J.; Steinbrück, G.; Vormwald, B.; Wellhausen, J.; Abbas, M.; Amstutz, C.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Caselle, M.; Colombo, F.; Dierlamm, A.; Freund, B.; Hartmann, F.; Heindl, S.; Husemann, U.; Kornmayer, A.; Kudella, S.; Muller, Th.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Anagnostou, G.; Asenov, P.; Assiouras, P.; Daskalakis, G.; Kyriakis, A.; Loukas, D.; Paspalaki, L.; Siklér, F.; Veszprémi, V.; Bhardwaj, A.; Dalal, R.; Jain, G.; Ranjan, K.; Bakhshiansohl, H.; Behnamian, H.; Khakzad, M.; Naseri, M.; Cariola, P.; Creanza, D.; De Palma, M.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Silvestris, L.; Maggi, G.; Martiradonna, S.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuve, C.; Barbagli, G.; Brianzi, M.; Ciaranfi, R.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Latino, G.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Scarlini, E.; Sguazzoni, G.; Strom, D.; Viliani, L.; Ferro, F.; Lo Vetere, M.; Robutti, E.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Pedrini, D.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Pozzobon, N.; Tosi, M.; De Canio, F.; Gaioni, L.; Manghisoni, M.; Nodari, B.; Riceputi, E.; Re, V.; Traversi, G.; Comotti, D.; Ratti, L.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Checcucci, B.; Ciangottini, D.; Fanò, L.; Gentsos, C.; Ionica, M.; Leonardi, R.; Manoni, E.; Mantovani, G.; Marconi, S.; Mariani, V.; Menichelli, M.; Modak, A.; Morozzi, A.; Moscatelli, F.; Passeri, D.; Placidi, P.; Postolache, V.; Rossi, A.; Saha, A.; Santocchia, A.; Storchi, L.; Spiga, D.; Androsov, K.; Azzurri, P.; Arezzini, S.; Bagliesi, G.; Basti, A.; Boccali, T.; Borrello, L.; Bosi, F.; Castaldi, R.; Ciampa, A.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Magazzu, G.; Martini, L.; Mazzoni, E.; Messineo, A.; Moggi, A.; Morsani, F.; Palla, F.; Palmonari, F.; Raffaelli, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Bellan, R.; Costa, M.; Covarelli, R.; Da Rocha Rolo, M.; Demaria, N.; Rivetti, A.; Dellacasa, G.; Mazza, G.; Migliore, E.; Monteil, E.; Pacher, L.; Ravera, F.; Solano, A.; Fernandez, M.; Gomez, G.; Jaramillo Echeverria, R.; Moya, D.; Gonzalez Sanchez, F. J.; Vila, I.; Virto, A. L.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bianchi, G.; Blanchot, G.; Bonnaud, J.; Caratelli, A.; Ceresa, D.; Christiansen, J.; Cichy, K.; Daguin, J.; D'Auria, A.; Detraz, S.; Deyrail, D.; Dondelewski, O.; Faccio, F.; Frank, N.; Gadek, T.; Gill, K.; Honma, A.; Hugo, G.; Jara Casas, L. M.; Kaplon, J.; Kornmayer, A.; Kottelat, L.; Kovacs, M.; Krammer, M.; Lenoir, P.; Mannelli, M.; Marchioro, A.; Marconi, S.; Mersi, S.; Martina, S.; Michelis, S.; Moll, M.; Onnela, A.; Orfanelli, S.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Petrucciani, G.; Postema, H.; Rose, P.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Vichoudis, P.; Verlaat, B.; Zwalinski, L.; Bachmair, F.; Becker, R.; di Calafiori, D.; Casal, B.; Berger, P.; Djambazov, L.; Donega, M.; Grab, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M.; Perozzi, L.; Roeser, U.; Starodumov, A.; Tavolaro, V.; Wallny, R.; Zhu, D.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Jacob, J.; Seif El Nasr-Storey, S.; Cole, J.; Hoad, C.; Hobson, P.; Morton, A.; Reid, I. D.; Auzinger, G.; Bainbridge, R.; Dauncey, P.; Hall, G.; James, T.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Garabedian, A.; Heintz, U.; Narain, M.; Nelson, J.; Sagir, S.; Speer, T.; Swanson, J.; Tersegno, D.; Watson-Daniels, J.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Yohay, R.; Burt, K.; Ellison, J.; Hanson, G.; Olmedo, M.; Si, W.; Yates, B. R.; Gerosa, R.; Sharma, V.; Vartak, A.; Yagil, A.; Zevi Della Porta, G.; Dutta, V.; Gouskos, L.; Incandela, J.; Kyre, S.; Mullin, S.; Patterson, A.; Qu, H.; White, D.; Dominguez, A.; Bartek, R.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Apresyan, A.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cheung, H. W. K.; Chramowicz, J.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Grünendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Kahlid, F.; Lei, C. M.; Lipton, R.; Lopes De Sá, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Schneider, B.; Sellberg, G.; Shenai, A.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Berry, D. R.; Chen, X.; Ennesser, L.; Evdokimov, A.; Evdokimov, O.; Gerber, C. E.; Hofman, D. J.; Makauda, S.; Mills, C.; Sandoval Gonzalez, I. D.; Alimena, J.; Antonelli, L. J.; Francis, B.; Hart, A.; Hill, C. S.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Tan, P.; Baringer, P.; Bean, A.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Wilson, G.; Ivanov, A.; Mendis, R.; Mitchell, T.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Monroy, J.; Siado, J.; Hahn, K.; Sevova, S.; Sung, K.; Trovato, M.; Bartz, E.; Gershtein, Y.; Halkiadakis, E.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Norberg, S.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kharchilava, A.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; McDermott, K.; Mirman, N.; Rinkevicius, A.; Ryd, A.; Salvati, E.; Skinnari, L.; Soffi, L.; Tao, Z.; Thom, J.; Tucker, J.; Zientek, M.; Akgün, B.; Ecklund, K. M.; Kilpatrick, M.; Nussbaum, T.; Zabel, J.; Betchart, B.; Covarelli, R.; Demina, R.; Hindrichs, O.; Petrillo, G.; Eusebi, R.; Osipenkov, I.; Perloff, A.; Ulmer, K. A.

    2017-06-01

    The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

  2. Elastic constants determined by nanoindentation for p-type thermoelectric half-Heusler

    Energy Technology Data Exchange (ETDEWEB)

    Gahlawat, S.; Wheeler, L.; White, K. W., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); He, R.; Chen, S.; Ren, Z. F., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States)

    2014-08-28

    This paper presents a study of the elastic properties of the p-type thermoelectric half-Heusler material, Hf{sub 0.44}Zr{sub 0.44}Ti{sub 0.12}CoSb{sub 0.8}Sn{sub 0.2}, using nanoindentation. Large grain-sized polycrystalline specimens were fabricated for these measurements, providing sufficient indentation targets within single grains. Electron Backscatter Diffraction methods indexed the target grains for the correlation needed for our elastic analysis of individual single crystals for this cubic thermoelectric material. Elastic properties, including the Zener ratio and the Poisson ratio, obtained from the elasticity tensor are also reported.

  3. Ferromagnetic-resonance induced electromotive forces in Ni81Fe19 | p-type diamond

    Science.gov (United States)

    Fukui, Naoki; Morishita, Hiroki; Kobayashi, Satoshi; Miwa, Shinji; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-10-01

    We report on direct-current (DC) electromotive forces (emfs) in a nickel-iron alloy (Ni81 Fe19) | p-type diamond under the ferromagnetic resonance of the Ni81Fe19 layer at room temperature. The observed DC emfs take its maximum around the ferromagnetic resonant frequency of the Ni81Fe19, and their signs are reversed by reversing the direction of an externally-applied magnetic field; it shows that the observed DC emfs are spin-related emfs.

  4. Methods for enhancing P-type doping in III-V semiconductor films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Feng; Stringfellow, Gerald; Zhu, Junyi

    2017-08-01

    Methods of doping a semiconductor film are provided. The methods comprise epitaxially growing the III-V semiconductor film in the presence of a dopant, a surfactant capable of acting as an electron reservoir, and hydrogen, under conditions that promote the formation of a III-V semiconductor film doped with the p-type dopant. In some embodiments of the methods, the epitaxial growth of the doped III-V semiconductor film is initiated at a first hydrogen partial pressure which is increased to a second hydrogen partial pressure during the epitaxial growth process.

  5. Transient expression of P-type ATPases in tobacco epidermal cells

    DEFF Research Database (Denmark)

    Pedas, Lisbeth Rosager; Palmgren, Michael Broberg; Lopez Marques, Rosa Laura

    2016-01-01

    Transient expression in tobacco cells is a convenient method for several purposes such as analysis of protein-protein interactions and the subcellular localization of plant proteins. A suspension of Agrobacterium tumefaciens cells carrying the plasmid of interest is injected into the intracellular...... for example protein-protein interaction studies. In this chapter, we describe the procedure to transiently express P-type ATPases in tobacco epidermal cells, with focus on subcellular localization of the protein complexes formed by P4-ATPases and their β-subunits....

  6. Above bandgap luminescence of p-type GaAs epitaxial layers

    Science.gov (United States)

    Sapriel, J.; Chavignon, J.; Alexandre, F.; Azoulay, R.; Sermage, B.; Rao, K.; Voos, M.

    1991-08-01

    New photoluminescence bands are observed in p-type GaAs epitaxial layers at 300 and 80 K, above the bandgap. These bands are independent of the nature of the dopant (Zn, Be, C) and of the growth technique (MBE or MOCVD). Their intensities increase as a function of the p doping (1 × 10 17 < p < 2 × 10 20cm-3) and peak at energies which correspond to transitions between the Γ 6, L 6 and X 6 minima of the conduction band and the Γ 8 and Γ 7 maxima of the valence band.

  7. Genetics Home Reference: Bietti crystalline dystrophy

    Science.gov (United States)

    ... Understand Genetics Home Health Conditions Bietti crystalline dystrophy Bietti crystalline dystrophy Enable Javascript to view the expand/ ... boxes. Download PDF Open All Close All Description Bietti crystalline dystrophy is a disorder in which numerous ...

  8. Terahertz Spectroscopy of Crystalline and Non-Crystalline Solids

    DEFF Research Database (Denmark)

    Parrott, Edward P. J.; Fischer, Bernd M.; Gladden, Lynn F.

    2013-01-01

    Terahertz spectroscopy of crystalline and non-crystalline solids is probably one of the most active research fields within the terahertz community. Many potential applications, amongst which spectral recognition is probably one of the most prominent, have significantly stimulated the development...... selected examples, the potential the technique holds for various different applications. A particular focus will be given to data analysis and, in particular, how we may account for effects resulting from non-ideal sample preparation....

  9. A study on the properties of C-doped Ge8Sb2Te11 thin films during an amorphous-to-crystalline phase transition

    Science.gov (United States)

    Park, Cheol-Jin; Kong, Heon; Lee, Hyun-Yong; Yeo, Jong-Bin

    2016-04-01

    In this work, we evaluated the structural, electrical and optical properties of carbon-doped Ge8Sb2Te11 thin films. In a previous work, GeSbTe alloys were doped with different materials in an attempt to improve the thermal stability. Ge8Sb2Te11 and carbon-doped Ge8Sb2Te11 films of 250 nm in thickness were deposited on p-type Si (100) and glass substrates by using a RF magnetron reactive co-sputtering system at room temperature. The fabricated films were annealed in a furnance in the 0 ~ 400°C temperature range. The structural properties were analyzed by using X-ray diffraction (XRD), and the result showed that the carbon-doped Ge8Sb2Te11 had a face-centeredcubic (fcc) crystalline structure and an increased crystallization temperature ( T c ). An increase in the T c leads to thermal stability in the amorphous state. The optical properties were analyzed by using an UV-Vis-IR spectrophotometer, and the result showed an increase in the optical-energy band gap ( E op ) in the crystalline materials and an increase in the E op difference (Δ E op ), which is a good effect for reducing the noise in the memory device. The electrical properties were analyzed by using a 4-point probe, which showed an increase in the sheet resistance ( R s ) in the amorphous state and the crystalline state, which means a reduced programming current in the memory device.

  10. Giant Magneto-impedance in Fe63.5Cr10Cu1Nb3Si13.5B9 Amorphous and Nano-crystalline Alloys%Fe63.5Cr10Cu1Nb3Si13.5B9非晶和纳米晶合金的巨磁阻抗效应

    Institute of Scientific and Technical Information of China (English)

    李印峰; 尹世忠; 赵双义; 封素芹; VAZQUEZ M

    2000-01-01

    研究了退火处理引起结构上的变化对Fe63.5Cr10Cu1Nb3Si13.5B9非晶合金磁阻抗效应的影响,实验结果的分析表明,在测量的频段(0.2~10MHz)内巨磁阻抗效应可归因于偏置场引起的环向磁化率的改变,良好的软磁性是获得大的磁阻抗效应的重要条件.

  11. The performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate

    Directory of Open Access Journals (Sweden)

    Shulong Wang

    2016-11-01

    Full Text Available In this study, the performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate is studied with the help of atomic layer deposition (ALD and magnetron sputtering technology. The surface morphology of the bilayer films with different structures are observed after rapid thermal annealing (RTA by atomic force microscopy (AFM. The results show that Y2O3/Al2O3/Si structure has a larger number of small spikes on the surface and its surface roughness is worse than Al2O3/Y2O3/Si structure. The reason is that the density of Si substrate surface is much higher than that of ALD growth Al2O3. With the help of high-frequency capacitance-voltage(C-V measurement and conductivity method, the density of interface traps can be calculated. After a high temperature annealing, the metal silicate will generate at the substrate interface and result in silicon dangling bond and interface trap charge, which has been improved by X-ray photoelectron spectroscopy (XPS and interface trap charge density calculation. The interface trapped charge density of La2O3/Al2O3/Si stacked gate structure is lower than that of La2O3/Y2O3/Si gate structure. If Y2O3 is used to replace Al2O3 as the interfacial layer, the accumulation capacitance will increase obviously, which means lower equivalent oxide thickness (EOT. Our results show that interface layer Y2O3 grown by magnetron sputtering can effectively ensure the interface traps near the substrate at relative small level while maintain a relative higher dielectric constant than Al2O3.

  12. A P-type ATPase importer that discriminates between essential and toxic transition metals.

    Science.gov (United States)

    Lewinson, Oded; Lee, Allen T; Rees, Douglas C

    2009-03-24

    Transition metals, although being essential cofactors in many physiological processes, are toxic at elevated concentrations. Among the membrane-embedded transport proteins that maintain appropriate intracellular levels of transition metals are ATP-driven pumps belonging to the P-type ATPase superfamily. These metal transporters may be differentiated according to their substrate specificities, where the majority of pumps can extrude either silver and copper or zinc, cadmium, and lead. In the present report, we have established the substrate specificities of nine previously uncharacterized prokaryotic transition-metal P-type ATPases. We find that all of the newly identified exporters indeed fall into one of the two above-mentioned categories. In addition to these exporters, one importer, Pseudomonas aeruginosa Q9I147, was also identified. This protein, designated HmtA (heavy metal transporter A), exhibited a different substrate recognition profile from the exporters. In vivo metal susceptibility assays, intracellular metal measurements, and transport experiments all suggest that HmtA mediates the uptake of copper and zinc but not of silver, mercury, or cadmium. The substrate selectivity of this importer ensures the high-affinity uptake of essential metals, while avoiding intracellular contamination by their toxic counterparts.

  13. Thermal oxidation of Ni films for p-type thin-film transistors

    KAUST Repository

    Jiang, Jie

    2013-01-01

    p-Type nanocrystal NiO-based thin-film transistors (TFTs) are fabricated by simply oxidizing thin Ni films at temperatures as low as 400 °C. The highest field-effect mobility in a linear region and the current on-off ratio are found to be 5.2 cm2 V-1 s-1 and 2.2 × 103, respectively. X-ray diffraction, transmission electron microscopy and electrical performances of the TFTs with "top contact" and "bottom contact" channels suggest that the upper parts of the Ni films are clearly oxidized. In contrast, the lower parts in contact with the gate dielectric are partially oxidized to form a quasi-discontinuous Ni layer, which does not fully shield the gate electric field, but still conduct the source and drain current. This simple method for producing p-type TFTs may be promising for the next-generation oxide-based electronic applications. © 2013 the Owner Societies.

  14. Analysis of carrier concentration, lifetime, and electron mobility on p-type HgCdTe

    Science.gov (United States)

    Yoo, Sang Dong; Kwack, Kae Dal

    1998-03-01

    Minority carrier transport characteristics of vacancy-doped p-type HgCdTe such as carrier concentration, lifetime, and mobility are investigated. In the calculation of the carrier concentration two acceptor levels—a donor level and a trap level—were taken into account. The acceptor levels have been described by two models—two independent singly ionized levels and a divalent level with two ionization energies. When each model was examined by calculating electron mobility as a function of temperature, the latter was found to be more accurate. Electron mobility as a function of majority carrier concentration was also presented for both n-type and p-type HgCdTe with 0.225 Cd mole fraction. Steady state electron lifetime was computed assuming the acceptor levels and the trap level would act as Schokley-Read-Hall type recombination centers. The calculated results using the divalent acceptor model were in good agreement with the experimental data.

  15. The development of p-type silicon detectors for the high radiation regions of the LHC

    CERN Document Server

    Hanlon, M D L

    1998-01-01

    This thesis describes the production and characterisation of silicon microstrip detectors and test structures on p-type substrates. An account is given of the production and full parameterisation of a p-type microstrip detector, incorporating the ATLAS-A geometry in a beam test. This detector is an AC coupled device incorporating a continuous p-stop isolation frame and polysilicon biasing and is typical of n-strip devices proposed for operation at the LHC. It was successfully read out using the FELix-128 analogue pipeline chip and a signal to noise (s/n) of 17+-1 is reported, along with a spatial resolution of 14.6+-0.2 mu m. Diode test structures were fabricated on both high resistivity float zone material and on epitaxial material and subsequently irradiated with 24 GeV protons at the CERN PS up to a dose of (8.22+-0.23) x 10 sup 1 sup 4 per cm sup 2. An account of the measurement program is presented along with results on the changes in the effective doping concentration (N sub e sub f sub f) with irradiat...

  16. Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

    Institute of Scientific and Technical Information of China (English)

    Li Shang-Sheng; Ma Hong-An; Li Xiao-Lei; Su Tai-Chao; Huang Guo-Feng; Li Yong; Jia Xiao-Peng

    2011-01-01

    High-quality p-type boron-doped II0b diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.

  17. EEG/MEG forward simulation through h- and p-type finite elements

    Energy Technology Data Exchange (ETDEWEB)

    Pursiainen, S [Institute of Mathematics, Box 1100, FI-02015 Helsinki University of Technology (Finland)], E-mail: sampsa.pursiainen@tkk.fi

    2008-07-15

    Electro/Magnetoencephalography (EEG/MEG) is a non-invasive imaging modality, in which a primary current density generated by the neural activity in the brain is to be reconstructed from external electric potential/magnetic field measurements. This work focuses on effective and accurate simulation of the EEG/MEG forward model through the h- and p-versions of the finite element method (h- and p-FEM). The goal is to compare the effectiveness of these two versions in forward simulation. Both h- and p-type forward simulations are described and implemented, and the technical solutions found are discussed. These include, for example, suitable ways to generate a finite element mesh for a real head geometry through the use of different element types. Performances of the two implemented forward simulation types are compared by measuring directly the forward modeling error, as well as by computing reconstructions through a regularized FOCUSS (FOCal Underdetermined System Solver) algorithm. The results obtained suggest that the p-type performs better in terms of the forward modeling error. However, both types perform well in regularized FOCUSS reconstruction.

  18. Wide band gap p-type windows by CBD and SILAR methods

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R.; Goncalves, E.; Ennaoui, A.; Lux-Steiner, M.Ch

    2004-03-22

    Chemical deposition methods, namely, chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) have been used to deposit wide band gap p-type CuI and CuSCN thin films at room temperature (25 deg. C) in aqueous medium. Growth of these films requires the use of Cu (I) cations as a copper ions source. This is achieved by complexing Cu (II) ions using Na{sub 2}S{sub 2}O{sub 3}. The anion sources are either KI as iodine or KSCN as thiocyanide ions for CuI and CuSCN films, respectively. The preparative parameters are optimized with the aim to use these p-type materials as windows for solar cells. Different substrates are used, namely: glass, fluorine doped tin oxide coated glass and CuInS{sub 2} (CIS). X-ray diffraction, scanning electron microscopy, atomic force microscopy and optical absorption spectroscopy are used for structural, surface morphological and optical studies, and the results are discussed.

  19. Carrier induced local moment magnetization in p-type Sn1-xMnxTe

    Science.gov (United States)

    Behera, Sashi S.; Tripathi, Pratibha; Nayak, Sanjeev K.; Tripathi, Gouri S.

    2017-08-01

    We derive a theory of carrier induced local moment magnetization of p-type Sn1-xMnxTe based on the Hubbard model, k → · π → electronic structure method (k → is the electronic wave vector and π → is the relativistic momentum operator) and the statistical paramagnetic approach for the localized moments. The Hubbard model is used to derive an internal exchange magnetic field. The difference in exchange self-energy is expressed in terms of an internal exchange field that is proportional to the parameter U, the onsite Coulomb repulsion, and the spin-density of carriers. In the present theory, the k → · π → + U model is integrated with the statistical paramagnetic theory for localized spins, which is then solved in a self-consistent manner by adding the exchange field to the applied field. The technique is applied to study the magnetic properties of p-type Sn1-xMnxTe, an important material for spintronics devices. The local moment magnetization calculated using the total magnetic field self-consistently agrees with the experimental observations. Magnetization and the exchange field studied as functions of the applied field, temperature and carrier concentration yield results on expected lines. Ours is a mechanism that is different from the RKKY interaction, normally invoked for carrier induced ferromagnetism and is thus a novelty.

  20. Anabaena sp. DyP-type peroxidase is a tetramer consisting of two asymmetric dimers.

    Science.gov (United States)

    Yoshida, Toru; Ogola, Henry Joseph Oduor; Amano, Yoshimi; Hisabori, Toru; Ashida, Hiroyuki; Sawa, Yoshihiro; Tsuge, Hideaki; Sugano, Yasushi

    2016-01-01

    DyP-type peroxidases are a newly discovered family of heme peroxidases distributed from prokaryotes to eukaryotes. Recently, using a structure-based sequence alignment, we proposed the new classes, P, I and V, as substitutes for classes A, B, C, and D [Arch Biochem Biophys 2015;574:49-55]. Although many class V enzymes from eukaryotes have been characterized, only two from prokaryotes have been reported. Here, we show the crystal structure of one of these two enzymes, Anabaena sp. DyP-type peroxidase (AnaPX). AnaPX is tetramer formed from Cys224-Cys224 disulfide-linked dimers. The tetramer of wild-type AnaPX was stable at all salt concentrations tested. In contrast, the C224A mutant showed salt concentration-dependent oligomeric states: in 600 mM NaCl, it maintained a tetrameric structure, whereas in the absence of salt, it dissociated into monomers, leading to a reduction in thermostability. Although the tetramer exhibits non-crystallographic, 2-fold symmetry in the asymmetric unit, two subunits forming the Cys224-Cys224 disulfide-linked dimer are related by 165° rotation. This asymmetry creates an opening to cavities facing the inside of the tetramer, providing a pathway for hydrogen peroxide access. Finally, a phylogenetic analysis using structure-based sequence alignments showed that class V enzymes from prokaryotes, including AnaPX, are phylogenetically closely related to class V enzymes from eukaryotes.

  1. Use of hexamethyldisiloxane for p-type microcrystalline silicon oxycarbide layers

    Directory of Open Access Journals (Sweden)

    Goyal Prabal

    2016-01-01

    Full Text Available The use of hexamethyldisiloxane (HMDSO as an oxygen source for the growth of p-type silicon-based layers deposited by Plasma Enhanced Chemical Vapor Deposition is evaluated. The use of this source led to the incorporation of almost equivalent amounts of oxygen and carbon, resulting in microcrystalline silicon oxycarbide thin films. The layers were examined with characterisation techniques including Spectroscopic Ellipsometry, Dark Conductivity, Fourier Transform Infrared Spectroscopy, Secondary Ion Mass Spectrometry and Transmission Electron Microscopy to check material composition and structure. Materials studies show that the refractive indices of the layers can be tuned over the range from 2.5 to 3.85 (measured at 600 nm and in-plane dark conductivities over the range from 10-8 S/cm to 1 S/cm, suggesting that these doped layers are suitable for solar cell applications. The p-type layers were tested in single junction amorphous silicon p-i-n type solar cells.

  2. Atomic layer deposition of undoped TiO2 exhibiting p-type conductivity.

    Science.gov (United States)

    Iancu, Andrei T; Logar, Manca; Park, Joonsuk; Prinz, Fritz B

    2015-03-11

    With prominent photocatalytic applications and widespread use in semiconductor devices, TiO2 is one of the most popular metal oxides. However, despite its popularity, it has yet to achieve its full potential due to a lack of effective methods for achieving p-type conductivity. Here, we show that undoped p-type TiO2 films can be fabricated by atomic layer deposition (ALD) and that their electrical properties can be controlled across a wide range using proper postprocessing anneals in various ambient environments. Hole mobilities larger than 400 cm(2)/(V·s) are accessible superseding the use of extrinsic doping, which generally produces orders of magnitude smaller values. Through a combination of analyses and experiments, we provide evidence that this behavior is primarily due to an excess of oxygen in the films. This discovery enables entirely new categories of TiO2 devices and applications, and unlocks the potential to improve existing ones. TiO2 homojunction diodes fabricated completely by ALD are developed as a demonstration of the utility of these techniques and shown to exhibit useful rectifying characteristics even with minimal processing refinement.

  3. Piezo-phototronic effect on electroluminescence properties of p-type GaN thin films.

    Science.gov (United States)

    Hu, Youfan; Zhang, Yan; Lin, Long; Ding, Yong; Zhu, Guang; Wang, Zhong Lin

    2012-07-11

    We present that the electroluminescence (EL) properties of Mg-doped p-type GaN thin films can be tuned by the piezo-phototronic effect via adjusting the minority carrier injection efficiency at the metal-semiconductor (M-S) interface by strain induced polarization charges. The device is a metal-semiconductor-metal structure of indium tin oxide (ITO)-GaN-ITO. Under different straining conditions, the changing trend of the transport properties of GaN films can be divided into two types, corresponding to the different c-axis orientations of the films. An extreme value was observed for the integral EL intensity under certain applied strain due to the adjusted minority carrier injection efficiency by piezoelectric charges introduced at the M-S interface. The external quantum efficiency of the blue EL at 430 nm was changed by 5.84% under different straining conditions, which is 1 order of magnitude larger than the change of the green peak at 540 nm. The results indicate that the piezo-phototronic effect has a larger impact on the shallow acceptor states related EL process than on the one related to the deep acceptor states in p-type GaN films. This study has great significance on the practical applications of GaN in optoelectronic devices under a working environment where mechanical deformation is unavoidable such as for flexible/printable light emitting diodes.

  4. New photovoltaic devices based on the sensitization of p-type semiconductors: challenges and opportunities.

    Science.gov (United States)

    Odobel, Fabrice; Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol

    2010-08-17

    Because solar energy is the most abundant renewable energy resource, the clear connection between human activity and global warming has strengthened the interest in photovoltaic science. Dye-sensitized solar cells (DSSCs) provide a promising low-cost technology for harnessing this energy source. Until recently, much of the research surrounding DSSCs had been focused on the sensitization of n-type semiconductors, such as titanium dioxide (Gratzel cells). In an n-type dye-sensitized solar cell (n-DSSC), an electron is injected into the conduction band of an n-type semiconductor (n-SC) from the excited state of the sensitizer. Comparatively few studies have examined the sensitization of wide bandgap p-type semiconductors. In a p-type DSSC (p-DSSC), the photoexcited sensitizer is reductively quenched by hole injection into the valence band of a p-type semiconductor (p-SC). The study of p-DSSCs is important both to understand the factors that control the rate of hole photoinjection and to aid the rational design of efficient p-DSSCs. In theory, p-DSSCs should be able to work as efficiently as n-DSSCs. In addition, this research provides a method for preparing tandem DSSCs consisting of a TiO(2)-photosensitized anode and a photosensitized p-type SC as a cathode. Tandem DSSCs are particularly important because they represent low-cost photovoltaic devices whose photoconversion efficiencies could exceed 15%. This Account describes recent research results on p-DSSCs. Because these photoelectrochemical devices are the mirror images of conventional n-DSSCs, they share some structural similarities, but they use different materials and have different charge transfer kinetics. In this technology, nickel oxide is the predominant p-SC material used, but much higher photoconversion efficiencies could be achieved with new p-SCs materials with deeper valence band potential. Currently, iodide/triiodide is the main redox mediator of electron transport within these devices, but we expect

  5. p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

    Science.gov (United States)

    Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

    2014-11-25

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

  6. Amorphization of Crystalline Water Ice

    CERN Document Server

    Zheng, Weijun; Kaiser, Ralf I

    2008-01-01

    We conducted a systematic experimental study to investigate the amorphization of crystalline ice by irradiation in the 10-50 K temperature range with 5 keV electrons at a dose of ~140 eV per molecule. We found that crystalline water ice can be converted partially to amorphous ice by electron irradiation. Our experiments showed that some of the 1.65-micrometer band survived the irradiation, to a degree that depends on the temperature, demonstrating that there is a balance between thermal recrystallization and irradiation-induced amorphization, with thermal recrystallizaton dominant at higher temperatures. At 50 K, recrystallization due to thermal effects is strong, and most of the crystalline ice survived. Temperatures of most known objects in the solar system, including Jovian satellites, Saturnian satellites, and Kuiper belt objects, are equal to or above 50 K, this might explain why water ice detected on those objects is mostly crystalline.

  7. Liquid-crystalline lanthanide complexes

    OpenAIRE

    Binnemans, Koen

    1999-01-01

    The paper describes the recent developments in the field of liquid-crystalline lanthanide complexes. The role of trivalent lanthanide ions as the central metal ion in metallomesogens is considered. An outlook for the future is given.

  8. Diffusion in porous crystalline materials

    NARCIS (Netherlands)

    Krishna, R.

    2012-01-01

    The design and development of many separation and catalytic process technologies require a proper quantitative description of diffusion of mixtures of guest molecules within porous crystalline materials. This tutorial review presents a unified, phenomenological description of diffusion inside meso-

  9. Hierarchical Cd4SiS6/SiO2 Heterostructure Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Liu Jian

    2009-01-01

    Full Text Available Abstract Novel hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays were fabricated on silicon substrates by a one-step thermal evaporation of CdS powder. The as-grown products were characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Studies reveal that a typical hierarchical Cd4SiS6/SiO2 heterostructure nanowire is composed of a single crystalline Cd4SiS6 nanowire core sheathed with amorphous SiO2 sheath. Furthermore, secondary nanostructures of SiO2 nanowires are highly dense grown on the primary Cd4SiS6 core-SiO2 sheath nanowires and formed hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays which stand vertically on silicon substrates. The possible growth mechanism of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays is proposed. The optical properties of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays are investigated using Raman and Photoluminescence spectroscopy.

  10. A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

    Science.gov (United States)

    Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

    2017-04-01

    This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

  11. NbFeSb based p-type half-Heusler for power generation applications

    Science.gov (United States)

    Joshi, Giri; He, Ran; Engber, Michael; Samsonidze, Georgy; Pantha, Tej; Dahal, Ekraj; Dahal, Keshab; Yang, Jian; Lan, Yucheng; Kozinsky, Boris; Ren, Zhifeng

    2015-03-01

    We report a peak dimensionless figure-of-merit (ZT) of ~1 at 700 oC in nanostructured p-type Nb0.6Ti0.4FeSb0.95Sn0.05composition. Even though the power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is improved by 25% in comparison to the previously reported p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, the ZT value is not increased due to a higher thermal conductivity. However, the higher power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition led to a 15% increase in power output of a thermoelectric device in comparison to a device made from the previous best material Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. The n-type material used to make the unicouple device is the best reported nanostructured Hf0.25Zr0.75NiSn0.99Sb0.01 composition with the lowest hafnium (Hf) content. Both the p- and n-type nanostructured samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. Moreover, the raw material cost of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is more than six times lower compared to the cost of the previous best p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. This cost reduction is crucial for these materials to be used in large-scale quantities for vehicle and industrial waste heat recovery applications. DOE:DE-EE0004840.

  12. Sub-band transport mechanism and switching properties for resistive switching nonvolatile memories with structure of silver/aluminum oxide/p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanhong; Li, La; Wang, Song; Gao, Ping; Pan, Lujun; Zhang, Jialiang [School of Physics and Optoelectronic Engineering, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024 (China); Zhou, Peng [Department of Microelectronics, State Key Laboratory of ASIC and System, Fudan University, Shanghai 200433 (China); Li, Jinhua; Weng, Zhankun [Center for Nano Metrology and Manufacturing Technologies and International Joint Research Center for Nanophotonics and Biophotonics, Changchun University of Science and Technology, Changchun 130022 (China)

    2015-02-09

    In this paper, we discuss a model of sub-band in resistive switching nonvolatile memories with a structure of silver/aluminum oxide/p-type silicon (Ag/Al{sub x}O{sub y}/p-Si), in which the sub-band is formed by overlapping of wave functions of electron-occupied oxygen vacancies in Al{sub x}O{sub y} layer deposited by atomic layer deposition technology. The switching processes exhibit the characteristics of the bipolarity, discreteness, and no need of forming process, all of which are discussed deeply based on the model of sub-band. The relationships between the SET voltages and distribution of trap levels are analyzed qualitatively. The semiconductor-like behaviors of ON-state resistance affirm the sub-band transport mechanism instead of the metal filament mechanism.

  13. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    Science.gov (United States)

    Du, Juan; Xia, Congxin; Liu, Yaming; Li, Xueping; Peng, Yuting; Wei, Shuyi

    2017-04-01

    More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm2 V-1 s-1, which is much higher than that of MoS2 monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  14. How thermoelectric properties of p-type Tl-filled skutterudites are improved

    Directory of Open Access Journals (Sweden)

    Donghun Kim

    2013-09-01

    Full Text Available The high-temperature thermoelectric properties of p-type Tl-filled skutterudites TlxFe1Co3Sb12 (x = 0, 0.2, 0.4, 0.6, and 0.8 were examined. While samples with x ≤ 0.4 were single-phase Tl-filled skutterudite, samples with x = 0.6 and 0.8 were composed of two phases: TlxFe1Co3Sb12 (x ≈ 0.4 as the matrix phase and a Tl-Fe-Sb ternary alloy. The thermal conductivity (κ was reduced effectively by Tl addition, but the secondary phase increased κ slightly. The maximum value of the dimensionless figure of merit ZT (=S2T/ρ/κ, where T is the absolute temperature was 0.36 at 723 K for Tl0.2Fe1Co3Sb12.

  15. P-type calcium channels are blocked by the alkaloid daurisoline.

    Science.gov (United States)

    Lu, Y M; Fröstl, W; Dreessen, J; Knöpfel, T

    1994-07-21

    IN looking for a structurally defined non-peptide P-channel blocker we have tested the alkaloid daurisoline which has been isolated from traditional Chinese medicinal herb (Menispermum dauricum) used for the treatment of epilepsy, hypertension and asthma. We have found that daurisoline is an inhibitor of omega-Aga-IVA sensitive barium currents in cerebellar Purkinje cells and of excitatory postsynaptic potentials evoked in Purkinje cells by stimulating parallel fibres in acutely prepared cerebellar slices. Daurisoline did not significantly affect omega-Aga-IVA-insensitive barium currents recorded from granule cells freshly isolated from rat cerebellum. Daurisoline passes the blood-brain barrier and will, therefore, facilitate the functional characterization of brain calcium channels as well as the exploration of P-type calcium channels as possible drug targets.

  16. A re-examination of cobalt-related defects in n- and p-type silicon

    Energy Technology Data Exchange (ETDEWEB)

    Scheffler, Leopold; Kolkovsky, Vladimir; Weber, Joerg [Technische Universitaet Dresden, 01069 Dresden (Germany)

    2012-10-15

    In the present work cobalt-doped n- and p-type silicon samples were studied by means of deep level transient spectroscopy (DLTS) and Laplace-DLTS (LDLTS). We demonstrate that two dominant DLTS peaks previously assigned to a substitutional Co defect have different annealing behaviour and therefore belong to different defects. After wet chemical etching three other peaks (E90, E140 and H160) were observed in the samples. The intensity of the peaks becomes larger in the H-plasma treated samples. This together with depth profiling demonstrates that the peaks are hydrogen-related defects. The origin of the peaks will be discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Nanoscale Cross-Point Resistive Switching Memory Comprising p-Type SnO Bilayers

    KAUST Repository

    Hota, Mrinal Kanti

    2015-02-23

    Reproducible low-voltage bipolar resistive switching is reported in bilayer structures of p-type SnO films. Specifically, a bilayer homojunction comprising SnOx (oxygen-rich) and SnOy (oxygen-deficient) in nanoscale cross-point (300 × 300 nm2) architecture with self-compliance effect is demonstrated. By using two layers of SnO film, a good memory performance is obtained as compared to the individual oxide films. The memory devices show resistance ratio of 103 between the high resistance and low resistance states, and this difference can be maintained for up to 180 cycles. The devices also show good retention characteristics, where no significant degradation is observed for more than 103 s. Different charge transport mechanisms are found in both resistance states, depending on the applied voltage range and its polarity. The resistive switching is shown to originate from the oxygen ion migration and subsequent formation/rupture of conducting filaments.

  18. Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency

    Science.gov (United States)

    Guo, Qilong; Luo, Sijun

    2015-12-01

    We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of 0.8 at 700 K which is a 60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb-based material have been discussed.

  19. Origin of resistivity anomaly in p-type leads chalcogenide multiphase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Aminorroaya Yamini, Sima, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu; Dou, Shi Xue [Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Mitchell, David R. G. [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Wang, Heng [Materials Science, California Institute of Technology, Pasadena, CA 91125 (United States); Gibbs, Zachary M. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States); Pei, Yanzhong [School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Snyder, G. Jeffrey, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); ITMO University, Saint Petersburg (Russian Federation)

    2015-05-15

    The electrical resistivity curves for binary phase compounds of p-type lead chalcogenide (PbTe){sub (0.9−x)}(PbSe){sub 0.1}(PbS){sub x,} (x = 0.15, 0.2, 0.25), which contain PbS-rich secondary phases, show different behaviour on heating and cooling between 500-700 K. This is contrast to single phase compounds which exhibit similar behaviour on heating and cooling. We correlate these anomalies in the electrical resistivities of multiphase compounds to the variation in phase composition at high temperatures. The inhomogeneous distribution of dopants between the matrix and secondary phase is found to be crucial in the electronic transport properties of the multiphase compounds. These results can lead to further advances in designing composite Pb-chalcogenides with high thermoelectric performance.

  20. Microhardness of carbon-doped (111) p-type Czochralski silicon

    Science.gov (United States)

    Danyluk, S.; Lim, D. S.; Kalejs, J.

    1985-01-01

    The effect of carbon on (111) p-type Czochralski silicon is examined. The preparation of the silicon and microhardness test procedures are described, and the equation used to determine microhardness from indentations in the silicon wafers is presented. The results indicate that as the carbon concentration in the silicon increases the microhardness increases. The linear increase in microhardness is the result of carbon hindering dislocation motion, and the effect of temperature on silicon deformation and dislocation mobility is explained. The measured microhardness was compared with an analysis which is based on dislocation pinning by carbon; a good correlation was observed. The Labusch model for the effect of pinning sites on dislocation motion is given.

  1. Photostable p-type dye-sensitized photoelectrochemical cells for water reduction.

    Science.gov (United States)

    Ji, Zhiqiang; He, Mingfu; Huang, Zhongjie; Ozkan, Umit; Wu, Yiying

    2013-08-14

    A photostable p-type NiO photocathode based on a bifunctional cyclometalated ruthenium sensitizer and a cobaloxime catalyst has been created for visible-light-driven water reduction to produce H2. The sensitizer is anchored firmly on the surface of NiO, and the binding is resistant to the hydrolytic cleavage. The bifunctional sensitizer can also immobilize the water reduction catalyst. The resultant photoelectrode exhibits superior stability in aqueous solutions. Stable photocurrents have been observed over a period of hours. This finding is useful for addressing the degradation issue in dye-sensitized photoelectrochemical cells caused by desorption of dyes and catalysts. The high stability of our photocathodes should be important for the practical application of these devices for solar fuel production.

  2. Improved performance of P-type DSCs with a compact blocking layer coated by different thicknesses

    Science.gov (United States)

    Ho, Phuong; Bao, Le Quoc; Cheruku, Rajesh; Kim, Jae Hong

    2016-09-01

    The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells ( p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency ( η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

  3. Nanopore formation on low-doped p-type silicon under illumination

    Energy Technology Data Exchange (ETDEWEB)

    Chiboub, N. [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria); Chazalviel, J.-N.; Ozanam, F. [Physique de la Matiere Condensee, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Moulay, S. [Universite Saad Dahleby, B.P. 270, Route de Soumaa, Blida (Algeria); Manseri, A. [UDTS, 02 Bd. Frantz Fanon, B.P. 140, Alger-7 Merveilles, 16200 Algiers (Algeria)

    2010-04-01

    Porous silicon layers were elaborated by anodization of highly resistive p-type silicon in HF/ethylene glycol solution under front side illumination, as a function of etching time, HF concentration and illumination intensity. The porous layer morphology was investigated by scanning electron microscopy (SEM). The illumination during anodization was provided by a tungsten lamp or lasers of different wavelengths. Under anodization, a microporous layer is formed up to a critical thickness above which macropores appear. Under illumination, the instability limiting the growth of the microporous layer occurs at a critical thickness much larger than in the dark. This critical thickness depends on HF concentration, illumination wavelength and intensity. These non-trivial dependencies are rationalized in a model in which photochemical etching in the electrochemically formed porous layer plays the central role.

  4. Empirical model predicting the layer thickness and porosity of p-type mesoporous silicon

    Science.gov (United States)

    Wolter, Sascha J.; Geisler, Dennis; Hensen, Jan; Köntges, Marc; Kajari-Schröder, Sarah; Bahnemann, Detlef W.; Brendel, Rolf

    2017-04-01

    Porous silicon is a promising material for a wide range of applications because of its versatile layer properties and the convenient preparation by electrochemical etching. Nevertheless, the quantitative dependency of the layer thickness and porosity on the etching process parameters is yet unknown. We have developed an empirical model to predict the porosity and layer thickness of p-type mesoporous silicon prepared by electrochemical etching. The impact of the process parameters such as current density, etching time and concentration of hydrogen fluoride is evaluated by ellipsometry. The main influences on the porosity of the porous silicon are the current density, the etching time and their product while the etch rate is dominated by the current density, the concentration of hydrogen fluoride and their product. The developed model predicts the resulting layer properties of a certain porosification process and can, for example be used to enhance the utilization of the employed chemicals.

  5. Membrane Anchoring and Ion-Entry Dynamics in P-type ATPase Copper Transport

    DEFF Research Database (Denmark)

    Grønberg, Christina; Sitsel, Oleg; Lindahl, Erik

    2016-01-01

    Cu(+)-specific P-type ATPase membrane protein transporters regulate cellular copper levels. The lack of crystal structures in Cu(+)-binding states has limited our understanding of how ion entry and binding are achieved. Here, we characterize the molecular basis of Cu(+) entry using molecular......-dynamics simulations, structural modeling, and in vitro and in vivo functional assays. Protein structural rearrangements resulting in the exposure of positive charges to bulk solvent rather than to lipid phosphates indicate a direct molecular role of the putative docking platform in Cu(+) delivery. Mutational analyses...... and simulations in the presence and absence of Cu(+) predict that the ion-entry path involves two ion-binding sites: one transient Met148-Cys382 site and one intramembranous site formed by trigonal coordination to Cys384, Asn689, and Met717. The results reconcile earlier biochemical and x-ray absorption data...

  6. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  7. Bulk and Surface Event Identification in p-type Germanium Detectors

    CERN Document Server

    Yang, L T; Jia, L P; Jiang, H; Li, J; Lin, F K; Lin, S T; Liu, S K; Ma, J L; Sharma, V; Singh, L; Singh, M K; Soma, A K; Yang, S W; Wang, L; Wang, Q; Wong, H T; Yue, Q; Zhao, W

    2016-01-01

    The p-type point-contact germanium detectors, due to its sub-keV sensitivities and low internal radioactivity background, are demonstrated to be competitive tools for light dark matter WIMPs searches and may have potential applications in neutrino physics. These detectors exhibit anomalous surface behavior, which has been characterized and dealt with in previous analysis. However, the analysis method rely on spectral shape assumptions and must use external calibration sources. In this report, we purpose an improved method, where in situ data could be used as calibration sources. Data from CDEX-1 and TEXONO experiments will be re-examined and the results are shown to be consistent with both analysis.

  8. Wide bandgap n-type and p-type semiconductor porous junction devices as photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan-Pai; Horng, Sheng-Fu [Institute of Electronics Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chao, Yu-Chiang; Meng, Hsin-Fei [Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan (China); Zan, Hsiao-Wen, E-mail: yuchiangchao@gmail.com, E-mail: meng@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2011-10-12

    In junction absorber photovoltaics doped wide bandgap n-type and p-type semiconductors form a porous interpenetrating junction structure with a layer of low bandgap absorber at the interface. The doping concentration is high enough such that the junction depletion width is smaller than the pore size. The highly conductive neutral region then has a dentrite shape with fingers reaching the absorber to effectively collect the photo-carriers swept out by the junction electric field. With doping of 10{sup 19} cm{sup -3} corresponding to a depletion width of 25 nm, pore size of 32 nm, absorber thickness close to exciton diffusion length of 17 nm, absorber bandgap of 1.4 eV and carrier mobility over 10{sup -5} cm{sup 2} V{sup -1} s{sup -1}, numerical calculation shows the power conversion efficiency is as high as 19.4%. It rises to 23% for a triplet exciton absorber.

  9. InP nanowire p-type doping via Zinc indiffusion

    Science.gov (United States)

    Haggren, Tuomas; Otnes, Gaute; Mourão, Renato; Dagyte, Vilgaile; Hultin, Olof; Lindelöw, Fredrik; Borgström, Magnus; Samuelson, Lars

    2016-10-01

    We report an alternative pathway for p-type InP nanowire (NW) doping by diffusion of Zn species from the gas phase. The diffusion of Zn was performed in a MOVPE reactor at 350-500 °C for 5-20 min with either H2 environment or additional phosphorus in the atmosphere. In addition, Zn3P2 shells were studied as protective caps during post-diffusion annealing. This post-diffusion annealing was performed to outdiffuse and activate Zn in interstitial locations. The characterization methods included photoluminescence and single NW conductivity and carrier concentration measurements. The acquired carrier concentrations were in the order of >1017 cm-3 for NWs without post-annealing, and up to 1018 cm-3 for NWs annealed with the Zn3P2 shells. The diffused Zn caused redshift to the photoluminescence signal, and the degree of redshift depended on the diffusion process.

  10. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-01-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design. PMID:28145438

  11. Luminescence properties of p-type thin CdS films prepared by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Ullrich, B. [Tokyo Univ. (Japan). Dept. of Physics; Ezumi, H. [Department of Electrical Engineering, Hiroshima-Denki Institute of Technology, Hiroshima 739-03 (Japan); Keitoku, S. [Hiroshima Women`s University, Hiroshima 734 (Japan); Kobayashi, T. [Tokyo Univ. (Japan). Dept. of Physics

    1995-12-01

    Investigations of the luminescence of p-type CdS:Cu thin (less than or equal to 2 {mu}m) films on glass substrate prepared by laser ablation were performed for the first time. The dependences of the luminescence on the Cu content in the thin films were studied at 300 K with argon laser lines at 457.9 nm, 488.0 nm and 514.5 nm. It is demonstrated that the luminescence excited with the 514.5 nm line corresponds to the donor-acceptor transition. Furthermore, it is shown that the intensity of the red emission of CdS:Cu films can be efficiently bleached by Cu doping. (orig.)

  12. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors.

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  13. Asymptotics of the trap-dominated Gunn effect in p-type Ge

    Science.gov (United States)

    Bonilla, L. L.; Hernando, P. J.; Herrero, M. A.; Kindelan, M.; Velázquez, J. J. L.

    1997-09-01

    We present an asymptotic analysis of the Gunn effect in a drift-diffusion model - including electric-field-dependent generation-recombination processes - for long samples of strongly compensated p-type Ge at low temperature and under d.c. voltage bias. During each Gunn oscillation, there are different stages corresponding to the generation, motion and annihilation of solitary waves. Each stage may be described by one evolution equation for only one degree of freedom (the current density), except for the generation of each new wave. The wave generation is a faster process that may be described by solving a semiinfinite canonical problem. As a result of our study we have found that (depending on the boundary condition) one or several solitary waves may be shed during each period of the oscillation. Examples of numerical simulations validating our analysis are included.

  14. Growth Stress in SiO2 during Oxidation of SiC Fibers (Preprint)

    Science.gov (United States)

    2011-11-01

    for crystalline scales using the very limited data available for cristobalite viscosity.36-38 These calculations are compared with microstructural...Unfortunately, SiC oxidation kinetics for crystalline scales ( cristobalite and tridymite) are not well characterized, and there is even less data on creep rates... cristobalite refractories suggests that at 1550° - 1650°C creep is negligible at very low stress (0.2 to 0.6 MPa), but further quantification was not

  15. Hopping conductivity in Mn-doped β-FeSi2 single crystals

    Science.gov (United States)

    Arushanov, E.; Lisunov, K. G.; Vinzelberg, H.; Behr, G.; Schumann, J.; Schmidt, O. G.

    2008-09-01

    The article gives a report on resistivity measurements on Mn-doped p-type FeSi2 single crystals and analyzes the data within the framework of different hopping conductivity models. Both the Mott [N. Mott and E. A. Davies, Electron Processes in Non-Crystalline Materials (Clarendon, Oxford, 1979)] and the Shklovskii-Efros [B. I. Shklovskii and A. L. Efros, Electronic Properties o0066 Doped Semiconductors (Springer, Berlin, 1984)] regimes of the variable-range hopping (VRH) conductivity are observed. It is shown that the temperature dependence of the resistivity of Mn-doped β-FeSi2 crystals, which follows a VRH conduction mechanism, can be expressed by a scaling expression of the form ln(ρ /ρ0)=Af(T /Tx). The characteristic and transition temperatures, as well as the complete set of parameters describing the properties of the localized holes (the localization radius, the dielectric permittivity, the width of the Coulomb gap Δ, and the values of the density of states at the Fermi level) are determined. The data above indicate existence of a rigid gap δ in the spectrum of the DOS in addition to Δ and point out to the polaronic nature of the charge carriers in the investigated compound.

  16. The influence of glass composition on crystalline phase stability in glass-ceramic wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Maddrell, Ewan, E-mail: ewan.r.maddrell@nnl.co.uk [National Nuclear Laboratory, Sellafield, Seascale, Cumbria CA20 1PG (United Kingdom); Thornber, Stephanie; Hyatt, Neil C. [Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2015-01-15

    Highlights: • Crystalline phase formation shown to depend on glass matrix composition. • Zirconolite forms as the sole crystalline phase only for most aluminous glasses. • Thermodynamics indicate that low silica activity glasses stabilise zirconolite. - Abstract: Zirconolite glass-ceramic wasteforms were prepared using a suite of Na{sub 2}O–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3}–SiO{sub 2} glass matrices with variable Al:B ratios. Zirconolite was the dominant crystalline phase only for the most alumina rich glass compositions. As the Al:B ratio decreased zirconolite was replaced by sphene, zircon and rutile. Thermodynamic data were used to calculate a silica activity in the glass melt below which zirconolite is the favoured crystalline phase. The concept of the crystalline reference state of glass melts is then utilised to provide a physical basis for why silica activity varies with the Al:B ratio.

  17. Workshop on hydrology of crystalline basement rocks

    Energy Technology Data Exchange (ETDEWEB)

    Davis, S.N. (comp.)

    1981-08-01

    This workshop covered the following subjects: measurements in relatively shallow boreholes; measurement and interpretation of data from deep boreholes; hydrologic properties of crystalline rocks as interpreted by geophysics and field geology; rock mechanics related to hydrology of crystalline rocks; the possible contributions of modeling to the understanding of the hydrology of crystalline rocks; and geochemical interpretations of the hydrology of crystalline rocks. (MHR)

  18. Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

    KAUST Repository

    Bahabry, R. R.

    2016-11-30

    We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

  19. The radiation damage of crystalline silicon PN diode in tritium beta-voltaic battery.

    Science.gov (United States)

    Lei, Yisong; Yang, Yuqing; Liu, Yebing; Li, Hao; Wang, Guanquan; Hu, Rui; Xiong, Xiaoling; Luo, Shunzhong

    2014-08-01

    A tritium beta-voltaic battery using a crystalline silicon convertor composed of (100)Si/SiO2/Si3N4 film degrades remarkably with radiation from a high intensity titanium tritide film. Simulation and experiments were carried out to investigate the main factor causing the degradation. The radiation damages mainly comes from the x-ray emitted from the titanium tritide film and beta particle can relieve the damages. The x-ray radiation induced positive charges in the SiO2 film destroying the output property of the PN diode with the induction of an electric field.

  20. Continuous SiC fiber, CVI SiC matrix composites for nuclear applications: Properties and irradiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, Yutai, E-mail: katohy@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Ozawa, Kazumi; Shih, Chunghao; Nozawa, Takashi [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Shinavski, Robert J. [Hyper-Therm High Temperature Composites, Inc., Huntington Beach, CA (United States); Hasegawa, Akira [Tohoku University, Sendai, Miyagi-ken (Japan); Snead, Lance L. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    2014-05-01

    Silicon carbide (SiC) continuous fiber-reinforced, SiC-matrix composites (SiC/SiC composites) are industrially available materials that are promising for applications in nuclear environments. The SiC/SiC composites consisting of near-stoichiometric SiC fibers, stoichiometric and fully crystalline SiC matrices, and the pyrocarbon (PyC) or multilayered PyC/SiC interphase between the fiber and the matrix are considered particularly resistant to very high radiation environments. This paper provides a summary compilation of the properties of these composites, specifically those with the chemically vapor-infiltrated (CVI) SiC matrices, including newly obtained results. The properties discussed are both in unirradiated condition and after neutron irradiation to intermediate fluence levels (most data are for <∼10 displacement per atom) at 300–1300 °C.