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Sample records for deposited cvd silicon

  1. Deposition of device quality silicon nitride with ultra high deposition rate (> 7 nm/s) using hot-wire CVD

    NARCIS (Netherlands)

    Verlaan, V.; Houweling, Z.S.; van der Werf, C.H.M.; Romijn, I.G.; Schropp, R.E.I.; Goldbach, H.D.

    2008-01-01

    The application of hot-wire (HW) CVD deposited silicon nitride (SiNx) as passivating anti-reflection coating on multicrystalline silicon (mc-Si) solar cells is investigated. The highest efficiency reached is 15.7% for SiNx layers with an N/Si ratio of 1.20 and a high mass density of 2.9 g/cm3. These

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  3. The optoelectronic properties of silicon films deposited by inductively coupled plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Qin Yanli; Yan Hengqing; Li Fei; Qiao Li; Liu Qiming [Department of Physics, Lanzhou University, Lanzhou 730000 (China); He Deyan, E-mail: hedy@lzu.edu.cn [Department of Physics, Lanzhou University, Lanzhou 730000 (China)

    2010-11-15

    Hydrogenated amorphous and microcrystalline silicon films were deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) at low substrate temperatures using H{sub 2}-diluted SiH{sub 4} as a source gas. High-density plasma generated by inductively coupled excitation facilitates the crystallization of silicon films at low temperatures, and microcrystalline silicon films were obtained at the substrate temperature as low as 180 deg. C. The columnar structure of the films becomes more and more compact with an increase of their crystallinity. The reduction of hydrogen content in the films causes a narrowing of the optical bandgap and an enhancement of the absorption with increasing the substrate temperature. The microcrystalline silicon films show two electronic transport mechanisms: one is related to the density of state distribution in the temperature region near room temperature and the other is the variable range hopping between localized electronic states close to the Fermi level below 170 K. A reasonable explanation is presented for the dependence of the optoelectronic properties on the microstructure of the silicon films. The films prepared at a substrate temperature of 300 deg. C have highly crystalline and compact columnar structure, high optical absorption coefficient and electrical conductivity, and a low hydrogen content of 3.8%.

  4. Hot wire CVD deposition of nanocrystalline silicon solar cells on rough substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongbo B.T., E-mail: h.li@uu.n [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Werf, Karine H.M. van der; Rath, Jatin K.; Schropp, Ruud E.I. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, P.O. Box 80000, 3508 TA Utrecht (Netherlands)

    2009-04-30

    In silicon thin film solar cell technology, frequently rough or textured substrates are used to scatter the light and enhance its absorption. The important issue of the influence of substrate roughness on silicon nanocrystal growth has been investigated through a series of nc-Si:H single junction p-i-n solar cells containing i-layers deposited with Hot-wire CVD. It is shown that silicon grown on the surface of an unoptimized rough substrate contains structural defects, which deteriorate solar cell performance. By introducing parameter v, voids/substrate area ratio, we could define a criterion for the morphology of light trapping substrates for thin film silicon solar cells: a preferred substrate should have a v value of less than around 1 x 10{sup -6}, correlated to a substrate surface rms value of lower than around 50 nm. Our Ag/ZnO substrates with rms roughness less than this value typically do not contain microvalleys with opening angles smaller than {approx} 110{sup o}, resulting in solar cells with improved output performance. We suggest a void-formation model based on selective etching of strained Si-Si atoms due to the collision of growing silicon film surface near the valleys of the substrate.

  5. Effect of substrate bias on deposition behaviour of charged silicon nanoparticles in ICP-CVD process

    Science.gov (United States)

    Yoo, Seung-Wan; You, Shin-Jae; Kim, Jung-Hyung; Seong, Dae-Jin; Seo, Byong-Hoon; Hwang, Nong-Moon

    2017-01-01

    The effect of a substrate bias on the deposition behaviour of crystalline silicon films during inductively coupled plasma chemical vapour deposition (ICP-CVD) was analysed by consideration of non-classical crystallization, in which the building block is a nanoparticle rather than an individual atom or molecule. The coexistence of positively and negatively charged nanoparticles in the plasma and their role in Si film deposition are confirmed by applying bias voltages to the substrate, which is sufficiently small as not to affect the plasma potential. The sizes of positively and negatively charged nanoparticles captured on a carbon membrane and imaged using TEM are, respectively, 2.7-5.5 nm and 6-13 nm. The film deposited by positively charged nanoparticles has a typical columnar structure. In contrast, the film deposited by negatively charged nanoparticles has a structure like a powdery compact with the deposition rate about three times higher than that for positively charged nanoparticles. All the films exhibit crystallinity even though the substrate is at room temperature, which is attributed to the deposition of crystalline nanoparticles formed in the plasma. The film deposited by negatively charged nanoparticles has the highest crystalline fraction of 0.84.

  6. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    Science.gov (United States)

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca i

    2017-01-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C. PMID:28262840

  7. Silicon-Germanium Films Deposited by Low Frequency PE CVD: Effect of H2 and Ar Dilution

    Energy Technology Data Exchange (ETDEWEB)

    Kosarev, A; Torres, A; Hernandez, Y; Ambrosio, R; Zuniga, C; Felter, T E; Asomoza, R R; Kudriavtsev, Y; Silva-Gonzalez, R; Gomez-Barojas, E; Ilinski, A; Abramov, A S

    2005-09-22

    We have studied structure and electrical properties of Si{sub 1-Y}Ge{sub Y}:H films deposited by low frequency PE CVD over the entire composition range from Y=0 to Y=1. The deposition rate of the films and their structural and electrical properties were measured for various ratios of the germane/silane feed gases and with and without dilution by Ar and by H{sub 2}. Structure and composition was studied by Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS) and Fourier transform infrared (FTIR) spectroscopy. Surface morphology was characterized by atomic force microscopy (AFM). We found: (1) The deposition rate increased with Y maximizing at Y=1 without dilution. (2) The relative rate of Ge and Si incorporation is affected by dilution. (3) Hydrogen preferentially bonds to silicon. (4) Hydrogen content decreases for increasing Y. In addition, optical measurements showed that as Y goes for 0 to 1, the Fermi level moves from mid gap to the conduction band edge, i.e. the films become more n-type. No correlation was found between the pre-exponential and the activation energy of conductivity. The behavior of the conductivity {gamma}-factor suggests a local minimum in the density of states at E {approx} 0.33 eV for the films grown with or without H-dilution and E {approx} 0.25 eV for the films with Ar dilution.

  8. Growth and Characterization of Silicon Carbide (SiC) Nanowires by Chemical Vapor Deposition (CVD) for Electronic Device Applications

    Science.gov (United States)

    Moore, Karina

    In recent years nanowires have gained a generous amount of interest because of the possible application of nanowires within electronic devices. A nanowire is a one dimensional semiconductor nanostructure with a diameter less than 100 nm. Nanowires have the potential to be a replacement for the present day complimentary metal oxide semiconductor (CMOS) technology; it is believed by 2020, a 5--6 nm gate length within field effect transistors (FET) would be realized and cease further miniaturization of electronic devices. SiC processes several unique chemical and physical properties that make it an attractive alternative to Si as a semiconductor material. Silicon carbide's properties make it a perfect candidate for applications such as high temperature sensors, x-ray emitters and high radiation sensors. The main objective of this thesis is to successfully grow silicon carbide nanowires on silicon substrates with the assistance of a metal catalyst, by the process of chemical vapor deposition (CVD). The contributions made by the work carried out in this thesis are broad. This is the first study that has carried out a comprehensive investigation into a wide range of metal catalyst for the growth of SiC nanowires by the process of chemical vapor deposition. The study proved that the surface tension interactions between the silicon substrate and the metal catalyst are the controlling factor in the determination of the diameter of the nanowires grown. This study also proved that the silicon substrate orientation has no impact on the growth of the nanowires, similar growth patterns occurred on both Si and Si substrates. The nanowires grown were characterized by a variety of different methods including scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and raman spectroscopy. The effect of temperature, growth temperature, growth time and the catalyst type used are investigated to determine the most suitable conditions necessary for SiC nanowire

  9. Effect of surface irradiation during the photo-CVD deposition of a-Si:H thin films. Hikari CVD ho ni yoru amorphous silicon sakuseiji no kiban hikari reiki koka

    Energy Technology Data Exchange (ETDEWEB)

    Tasaka, K.; Doering, H.; Hashimoto, K.; Fujishima, A. (The University of Tokyo, Tokyo (Japan))

    1990-12-06

    This paper shows the impact of the irradiation from an additional light source during the deposition of hydrogenated amorphous silicon by photo-CVD deposition. Using a mercury sensitized photo-CVD process from Disilan (Si {sub 2} H {sub 6}) and hydrogen, silicon was deposited. A 40W low pressure mercury lamp was applied as the light source. A portion of the substrate was in addition irradiated using an Xg-He lamp through a thermal filter. Irradiation of the substrate using only Xg-He lamp produced no deposition, since this light has a wavelength which is too long to produce the SiH {sub 3}-radicals needed for Si deposition. The additional Xg-He light source was discovered to cause an increased thickness of deposited a-Si:H film and a transmission of the band structure. The reasons of these are considered that the influence of irradiation is not limited to film thickness, but that irradiation also impacts the composition of the a-Si:H film so as to cause a reduction in the hydrogen content. 10 figs., 1 tab.

  10. Epitaxial Growth of beta-Silicon Carbide (SiC) on a Compliant Substrate via Chemical Vapor Deposition (CVD)

    Science.gov (United States)

    Mitchell, Sharanda L.

    1996-01-01

    Many lattice defects have been attributed to the lattice mismatch and the difference in the thermal coefficient of expansion between SiC and silicon (Si). Stacking faults, twins and antiphase boundaries are some of the lattice defects found in these SiC films. These defects may be a partial cause of the disappointing performance reported for the prototype devices fabricated from beta-SiC films. The objective of this research is to relieve some of the thermal stress due to lattice mismatch when SiC is epitaxially grown on Si. The compliant substrate is a silicon membrane 2-4 microns thick. The CVD process includes the buffer layer which is grown at 1360 C followed by a very thin epitaxial growth of SiC. Then the temperature is raised to 1500 C for the subsequent growth of SiC. Since silicon melts at 1415 C, the SiC will be grown on molten Silicon which is absorbed by a porous graphite susceptor eliminating the SiC/Si interface. We suspect that this buffer layer will yield less stressed material to help in the epitaxial growth of SiC.

  11. Microcrystalline silicon from very high frequency plasma deposition and hot-wire CVD for ``micromorph`` tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Brummack, H.; Brueggemann, R.; Wanka, H.N.; Hierzenberger, A.; Schubert, M.B. [Univ. Stuttgart (Germany). Inst. fuer Physikalische Elektronik

    1997-12-31

    The authors have grown microcrystalline silicon from a glow discharge at very high frequencies of 55 MHz and 170 MHz with high hydrogen dilution, and also, at more than 10 times higher growth rates, similar films by hot-wire chemical vapor deposition. Both kinds of materials have extensively been characterized and compared in terms of structural, optical and electronic properties, which greatly improve by deposition in a multi- instead of a single-chamber system. Incorporation of these different materials into pin solar cells results in open circuit voltages of about 400 mV as long as the doped layers are microcrystalline and rise to more than 870 mV if amorphous p- and n-layers are used. Quantum efficiencies and fill factors are still poor but leave room for further improvement, as clearly demonstrated by a remarkable reverse bias quantum efficiency gain.

  12. Deposition and Coating Properties on CVD Tungsten

    Institute of Scientific and Technical Information of China (English)

    DU Ji-hong; LI Zheng-xiang; LIU Gao-jian; ZHOU Hui-Huang; CHUN liang

    2004-01-01

    Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.

  13. Deposition of silicon nitride thin films by hot-wire CVD at 100 {sup o}C and 250 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Alpuim, P., E-mail: palpuim@fisica.uminho.p [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Goncalves, L.M. [Departamento de Electronica Industrial, Universidade do Minho, 4800-058 Guimaraes (Portugal); Marins, E.S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Viseu, T.M.R. [Departamento de Fisica, Universidade do Minho, 4710-057 Braga (Portugal); Ferdov, S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Bouree, J.E. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France)

    2009-04-30

    Silicon nitride thin films for use as passivation layers in solar cells and organic electronics or as gate dielectrics in thin-film transistors were deposited by the Hot-wire chemical vapor deposition technique at a high deposition rate (1-3 A/s) and at low substrate temperature. Films were deposited using NH{sub 3}/SiH{sub 4} flow rate ratios between 1 and 70 and substrate temperatures of 100 {sup o}C and 250 {sup o}C. For NH{sub 3}/SiH{sub 4} ratios between 40 and 70, highly transparent (T {approx} 90%), dense films (2.56-2.74 g/cm{sup 3}) with good dielectric properties and refractive index between 1.93 and 2.08 were deposited on glass substrates. Etch rates in BHF of 2.7 A/s and < 0.5 A/s were obtained for films deposited at 100 {sup o}C and 250 {sup o}C, respectively. Films deposited at both substrate temperatures showed electrical conductivity {approx} 10{sup -14} {Omega}{sup -1} cm{sup -1} and breakdown fields > 10 MV cm{sup -1}.

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  15. Simulation and experimental study of CVD process for low temperature nanocrystalline silicon carbide coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, Amit; Prakash, Jyoti, E-mail: jprakash@barc.gov.in; Dasgupta, Kinshuk; Chakravartty, Jayanta K.

    2016-07-15

    Highlights: • Parametric simulation was carried out for specially designed CVD reactor. • Effect of fluid velocity, heat flow and concentration were studied in CVD reactor. • Coating study carried out using low temperature and environmental safe CVD process. • Dense and uniform nanocrystalline SiC film was coated on zircaloy substrate. - Abstract: There is a huge requirement for development of a coating technique in nuclear industry, which is environmentally safe, economical and applicable to large scale components. In this view, simulation of gas-phase behavior in specially designed CVD reactor was carried out using computational tool, COMSOL. There were two important zones in CVD reactor first one is precursor vaporization zone and second one is coating zone. Optimized parameters for coating were derived from the simulation of gas phase dynamics in both zone of CVD reactor. The overall effect of fluid velocity, heat flow and concentration profile showed that Re = 54 is the optimum reaction condition for uniform coating in CVD system. In CVD coating experiments a synthesized halogen free, non-toxic and non-corrosive silicon carbide precursor was used. Uniform coating of SiC was obtained on zircaloy substrate at 900 °C using as synthesized organosilicon precursor. The X-ray diffraction and scanning electron microscopy analysis show that dense nano crystalline SiC film was deposited on zircaloy substrate.

  16. High-temperature CVD for crystalline-silicon thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Faller, F.R.; Hurrle, A.

    1999-10-01

    The fundamentals of thermal CVD for the deposition of silicon at high temperatures are briefly discussed and applied to the conditions in the CVD system that the authors have constructed and characterized. The system fulfills basic requirements to be met for solar cell application; solar cells made from epitaxial layers on various substrates were fabricated. The high-quality cells achieved 17.6% efficiency proving the excellent performance of the system, the cells on economically relevant substrates achieved 8% efficiency which still needs improvement.

  17. Influence of hydrogen dilution on structural, electrical and optical properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films prepared by plasma enhanced chemical vapour deposition (PE-CVD)

    Energy Technology Data Exchange (ETDEWEB)

    Funde, A.M.; Bakr, Nabeel Ali; Kamble, D.K. [School of Energy Studies, University of Pune, Pune 411 007 (India); Hawaldar, R.R.; Amalnerkar, D.P. [Center for Materials for Electronics Technology (C-MET), Panchawati, Pune 411 008 (India); Jadkar, S.R. [Department of Physics, University of Pune, Ganeshkhind Road, Pune 411 007 (India)

    2008-10-15

    Hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited from pure silane (SiH{sub 4}) and hydrogen (H{sub 2}) gas mixture by conventional plasma enhanced chemical vapour deposition (PE-CVD) method at low temperature (200 C) using high rf power. The structural, optical and electrical properties of these films are carefully and systematically investigated as a function of hydrogen dilution of silane (R). Characterization of these films with low angle X-ray diffraction and Raman spectroscopy revealed that the crystallite size in the films tends to decrease and at same time the volume fraction of crystallites increases with increase in R. The Fourier transform infrared (FTIR) spectroscopic analysis showed at low values of R, the hydrogen is predominantly incorporated in the nc-Si:H films in the mono-hydrogen (Si-H) bonding configuration. However, with increasing R the hydrogen bonding in nc-Si:H films shifts from mono-hydrogen (Si-H) to di-hydrogen (Si-H{sub 2}) and (Si-H{sub 2}){sub n} complexes. The hydrogen content in the nc-Si:H films decreases with increase in R and was found less than 10 at% over the entire studied range of R. On the other hand, the Tauc's optical band gap remains as high as 2 eV or much higher. The quantum size effect may responsible for higher band gap in nc-Si:H films. A correlation between electrical and structural properties has been found. For optimized deposition conditions, nc-Si:H films with crystallite size {proportional_to}7.67 nm having good degree of crystallinity ({proportional_to}84%) and high band gap (2.25 eV) were obtained with a low hydrogen content (6.5 at%). However, for these optimized conditions, the deposition rate was quite small (1.6 Aa/s). (author)

  18. The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Marzik, J V; Croft, W J; Staples, R J; MoberlyChan, W J

    2006-12-05

    Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6{trademark} silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

  19. Numerical modeling of chemical vapor deposition (CVD) in a horizontal reactor

    Science.gov (United States)

    Sheikholeslami, M. Z.; Jasinski, T.; Fretz, K. W.

    1988-01-01

    In the present numerical prediction of the deposition rate of silicon from silane in a CVD process, the conservation equations for mass, momentum, energy, and chemical species are solved on a staggered grid using the SIMPLE algorithm, while the rate of chemical reactions in the gas phase and on the susceptor surface is obtained from an Arrhenius rate equation. Predicted deposition rates as a function of position along the susceptor with and without the gas phase chemical reaction are compared with the available experimental and numerical data; agreement is excellent except at the leading edge of the susceptor, where the deposition rate is overpredicted.

  20. Electronic properties of embedded graphene: doped amorphous silicon/CVD graphene heterostructures

    Science.gov (United States)

    Arezki, Hakim; Boutchich, Mohamed; Alamarguy, David; Madouri, Ali; Alvarez, José; Cabarrocas, Pere Roca i.; Kleider, Jean-Paul; Yao, Fei; Lee, Young Hee

    2016-10-01

    Large-area graphene film is of great interest for a wide spectrum of electronic applications, such as field effect devices, displays, and solar cells, among many others. Here, we fabricated heterostructures composed of graphene (Gr) grown by chemical vapor deposition (CVD) on copper substrate and transferred to SiO2/Si substrates, capped by n- or p-type doped amorphous silicon (a-Si:H) deposited by plasma-enhanced chemical vapor deposition. Using Raman scattering we show that despite the mechanical strain induced by the a-Si:H deposition, the structural integrity of the graphene is preserved. Moreover, Hall effect measurements directly on the embedded graphene show that the electronic properties of CVD graphene can be modulated according to the doping type of the a-Si:H as well as its phase i.e. amorphous or nanocrystalline. The sheet resistance varies from 360 Ω sq-1 to 1260 Ω sq-1 for the (p)-a-Si:H/Gr (n)-a-Si:H/Gr, respectively. We observed a temperature independent hole mobility of up to 1400 cm2 V-1 s-1 indicating that charge impurity is the principal mechanism limiting the transport in this heterostructure. We have demonstrated that embedding CVD graphene under a-Si:H is a viable route for large scale graphene based solar cells or display applications.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-30

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

  2. Room Temperature Growth of Hydrogenated Amorphous Silicon Films by Dielectric Barrier Discharge Enhanced CVD

    Institute of Scientific and Technical Information of China (English)

    GUO Yu; ZHANG Xiwen; HAN Gaorong

    2007-01-01

    Hydrogenated amorphous silicon (a-Si:H) films were deposited on Si (100) and glass substrates by dielectric barrier discharge enhanced chemical vapour deposition (DBD-CVD)in (SiH4+H2) atmosphere at room temperature.Results of the thickness measurement,SEM (scanning electron microscope),Raman,and FTIR (Fourier transform infrared spectroscopy) show that with the increase in the applied peak voltage,the deposition rate and network order of the films increase,and the hydrogen bonding configurations mainly in di-hydrogen (Si-H2) and poly hydrogen (SiH2)n are introduced into the films.The UV-visible transmission spectra show that with the decrease in Sill4/ (SiH4+H2) the thin films'band gap shifts from 1.92 eV to 2.17 eV.These experimental results are in agreement with the theoretic analysis of the DBD discharge.The deposition of a-Si:H films by the DBD-CVD method as reported here for the first time is attractive because it allows fast deposition of a-Si:H films on large-area low-melting-point substrates and requires only a low cost of production without additional heating or pumping equipment.

  3. Aluminum and aluminum/silicon coatings on ferritic steels by CVD-FBR technology

    Energy Technology Data Exchange (ETDEWEB)

    Perez, F.J. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)]. E-mail: fjperez@quim.ucm.es; Hierro, M.P. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Trilleros, J.A. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Carpintero, M.C. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Sanchez, L. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Bolivar, F.J. [Grupo de Investigacion de Ingenieria de Superficies, Departamento de Ciencia de los Materiales, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2006-05-10

    The use of chemical vapor deposition by fluidized bed reactors (CVD-FBR) offers some advantages in comparison to other coating techniques such as pack cementation, because it allows coating deposition at lower temperatures than pack cementation and at atmospheric pressure without affecting the mechanical properties of material due to heat treatments of the bulk during coating process. Aluminum and aluminum/silicon coatings have been obtained on two different ferritics steels (P-91 and P-92). The coatings were analyzed using several techniques like SEM/EDX and XRD. The results indicated that both coatings were form by Fe{sub 2}Al{sub 5} intermetallic compound, and in the co-deposition the Si was incorporated to the Fe{sub 2}Al{sub 5} structure in small amounts.

  4. Nanomorph Silicon Thin Films Prepared by Using an HW-MWECR CVD System

    Institute of Scientific and Technical Information of China (English)

    HU Yue-Hui; MA Zhan-Jie; ZHOU Huai-En; ZHU Xiu-Hong; CHEN Guang-Hua; ZHOU Jian-Er; RONG Yan-Dong; LI Ying; SONG Xue-Mei; ZHANG Wen-Li; DING Yi; GAO Zhuo

    2005-01-01

    @@ We have prepared hydrogenated nano-amorph silicon (na-Si:H) films by using a hot-wire-assisted microwave electron-cyclotron-resonance (HW-MWECR) chemical vapour deposition (CVD) system. The films are deposited in two steps: in the first 9min, a hydrogenated amorphous silicon layer is deposited by using hydrogen-diluted silane with a concentration of SiH4/(SiH4+H2) = 20%, and then a nanocrystalline silicon (nc-Si) layer is deposited by using various highly hydrogen-diluted silane. The Raman TO-like mode peak of the films was found in the range 497-508 cm-1. When the silane concentration used for preparation of the nc-Si layer is 14.3%, the film has a large crystalline volume fraction of 65.4%, a wide optical band gap of 1.89eV and a low hydrogen content of 9.5at.%. Moreover, the na-Si:H films rather than nc-Si possess high photosensitivity of about 15.

  5. Development of laser-fired contacts for amorphous silicon layers obtained by Hot-Wire CVD

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D. [XaRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain)], E-mail: delfina@eel.upc.edu; Voz, C.; Blanque, S. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain); Ibarz, D.; Bertomeu, J. [XaRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain); Alcubilla, R. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain)

    2009-03-15

    In this work we study aluminium laser-fired contacts for intrinsic amorphous silicon layers deposited by Hot-Wire CVD. This structure could be used as an alternative low temperature back contact for rear passivated heterojunction solar cells. An infrared Nd:YAG laser (1064 nm) has been used to locally fire the aluminium through the thin amorphous silicon layers. Under optimized laser firing parameters, very low specific contact resistances ({rho}{sub c} {approx} 10 m{omega} cm{sup 2}) have been obtained on 2.8 {omega} cm p-type c-Si wafers. This investigation focuses on maintaining the passivation quality of the interface without an excessive increase in the series resistance of the device.

  6. Novel photochemical vapor deposition reactor for amorphous silicon solar cell deposition

    Science.gov (United States)

    Rocheleau, Richard E.; Hegedus, Steven S.; Buchanan, Wayne A.; Jackson, Scott C.

    1987-07-01

    A novel photochemical vapor deposition (photo-CVD) reactor having a flexible ultraviolet-transparent Teflon curtain and a secondary gas flow to eliminate deposition on the window has been used to deposit amorphous silicon films and p-i-n solar cells. The background levels of atmospheric contaminants (H2O, CO2, N2) depend strongly on the vacuum procedures but not on the presence of a Teflon curtain in the reactor. Intrinsic films with a midgap density of states of 3×1015 eV-1 cm-3 and all-photo-CVD pin solar cells with efficiencies of 8.5% have been deposited.

  7. Field emission from carbon films deposited by VHF CVD on difference substrates

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, A A; Andronov, A N; Felter, T E; Ioffe, A F; Kosarev, A I; Shotov, M V; Vinogradov, A J

    1999-04-01

    As previously demonstrated, non-diamond carbon (NDC) films deposited at low temperatures 200-300 C on silicon tips reduced the threshold of field emission. In this paper we will present the results of the study of field emission from flat NDC films prepared by VHF CVD. Emission measurements were performed in a diode configuration at approximately 10{sup {minus}10} Torr. NDC films were deposited on ceramic and on c-Si substrates sputter coated with layers of Ti, Cu, Ni and Pt. The back contact material influences the emission characteristics but not as a direct correlation to work function. A model of field emission from metal-NDC film structures will be discussed.

  8. High-rate diamond deposition by microwave plasma CVD

    Science.gov (United States)

    Li, Xianglin

    In this dissertation, the growth of CVD (Chemical Vapor Deposition) diamond thin films is studied both theoretically and experimentally. The goal of this research is to deposit high quality HOD (Highly Oriented Diamond) films with a growth rate greater than 1 mum/hr. For the (100)-oriented HOD films, the growth rate achieved by the traditional process is only 0.3 mum/hr while the theoretical limit is ˜0.45 mum/hr. This research increases the growth rate up to 5.3 mum/hr (with a theoretical limit of ˜7 mum/hr) while preserving the crystal quality. This work builds a connection between the theoretical study of the CVD process and the experimental research. The study is extended from the growth of regular polycrystalline diamond to highly oriented diamond (HOD) films. For the increase of the growth rate of regular polycrystalline diamond thin films, a scaling growth model developed by Goodwin is introduced in details to assist in the understanding of the MPCVD (Microwave Plasma CVD) process. Within the Goodwin's scaling model, there are only four important sub-processes for the growth of diamond: surface modification, adsorption, desorption, and incorporation. The factors determining the diamond growth rate and film quality are discussed following the description of the experimental setup and process parameters. Growth rate and crystal quality models are reviewed to predict and understand the experimental results. It is shown that the growth rate of diamond can be increased with methane input concentration and the amount of atomic hydrogen (by changing the total pressure). It is crucial to provide enough atomic hydrogen to conserve crystal quality of the deposited diamond film. The experimental results demonstrate that for a fixed methane concentration, there is a minimum pressure for growth of good diamond. Similarly, for a fixed total pressure, there is a maximum methane concentration for growth of good diamond, and this maximum methane concentration increases

  9. Spectroscopic ellipsometry characterization of microwave CVD grown silicon nanoparticles embedded in a silicon nitride matrix

    Energy Technology Data Exchange (ETDEWEB)

    Keita, A-S; Naciri, A En [LPMD, Universite Paul Verlaine-Metz, 1 Bd Arago, 57070 Metz - France (France); Delachat, F; Carrada, M; Ferblantier, G; Slaoui, A, E-mail: alsaleh.keita@univ-metz.fr [InESS, CNRS/UdS, 23 rue du Loess, BP 20, 67037, Strasbourg Cedex 2 (France)

    2009-11-15

    Plasma Enhanced Vapour Deposition (PECVD) is used to elaborate silicon nanoparticles (np-Si) embedded in silicon nitride (Si{sub 3}N{sub 4}) layers. The samples have been produced for various NH{sub 3} flows. The np-Si dielectric function (DF) have been determined by spectroscopic ellipsometry (SE) in the wavelength range from 210 nm to 880 nm. Thanks to ellipsometric modeling it has been possible to study the np-Si physical properties.

  10. Preparation of hydrogenated microcrystalline silicon films with hot-wire-assisted MWECR-CVD system

    Institute of Scientific and Technical Information of China (English)

    He Bin; Chen Guang-Hua; Zhu Xiu-Hong; Zhang Wen-Li; Ding Yi; Ma Zhan-Jie; Gao Zhi-Hua; Song Xue-Mei; Deng Jin-Xiang

    2006-01-01

    Intrinsic hydrogenated microcrystalline silicon (μc-Si:H) films have been prepared by hot-wire-assisted microwave electron-cyclotron-resonance chemical vapour deposition (Hw-MwECR-CVD) under different deposition conditions.Fourier-transform infrared spectra and Raman spectra were measured.Optical band gap WaS determined by Tauc plots,and experiments of photo-induced degradation were performed.It was observed that hydrogen dilution plays a more essential role than substrate temperature in microcrystalline transformation at low temperatures. Crystalline volume fraction and mean grain size in the films increase with the dilution ratio (R=H2/(H2+SiH4)).With the rise of crystallinity in the films,the optical band gap tends to become narrower while the hydrogen content and photo-induced degradation decrease dramatically.The samples,were identified as μc-Si:H films,by calculating the optical band gap.It is considered that hydrogen dilution has an effect on reducing the crystallization activation energy of the material,which promotes the heterogeneous solid-state phase transition characterized by the Johnson-Mehl-Avrami (JMA) equation.The films with the needed structure can be prepared by balancing deposition and crystaUization through controlling process parameters.

  11. EFFECTS OF OPERATING CONDITIONS ON THE DEPOSITION OF GaAs IN A VERTICAL CVD REACTOR

    OpenAIRE

    JAE-SANG BAEK; JIN-HYO BOO; YOUN-JEA KIM

    2008-01-01

    A numerical study is needed to gain insight into the growth mechanism and improve the reactor design or optimize the deposition condition in chemical vapor deposition (CVD). In this study, we have performed a numerical analysis of the deposition of gallium arsenide (GaAs) from trimethyl gallium (TMG) and arsine in a vertical CVD reactor. The effects of operating parameters, such as the rotation velocity of susceptor, inlet velocity, and inlet TMG fraction, are investigated and presented. The ...

  12. Rare earth-doped alumina thin films deposited by liquid source CVD processes

    Energy Technology Data Exchange (ETDEWEB)

    Deschanvres, J.L.; Meffre, W.; Joubert, J.C.; Senateur, J.P. [Ecole Nat. Superieure de Phys. de Grenoble, St. Martin d`Heres (France). Lab. des Materiaux et du Genie Phys.; Robaut, F. [Consortium des Moyens Technologiques Communs, Institut National Polytechnique de Grenoble, BP 75, 38402 St Martin d`Heres (France); Broquin, J.E.; Rimet, R. [Laboratoire d`Electromagnetisme, Microondes et Optoelectronique, CNRS-Ecole Nationale Superieure d`Electronique et Radioelectricite de Grenoble, BP 257, 38016 Grenoble, Cedex (France)

    1998-07-24

    Two types of liquid-source CVD processes are proposed for the growth of rare earth-doped alumina thin films suitable as amplifying media for integrated optic applications. Amorphous, transparent, pure and erbium- or neodymium-doped alumina films were deposited between 573 and 833 K by atmospheric pressure aerosol CVD. The rare earth doping concentration increases by decreasing the deposition temperature. The refractive index of the alumina films increases as a function of the deposition temperature from 1.53 at 573 K to 1.61 at 813 K. Neodymium-doped films were also obtained at low pressure by liquid source injection CVD. (orig.) 7 refs.

  13. Tantalum Coating of Steel, Copper, Aluminum, and Titanium by Thermal Chemical Vapor Deposition (CVD)

    DEFF Research Database (Denmark)

    Christensen, Erik; Bjerrum, Niels

    1998-01-01

    Tantalum coatings ranging from 0.5 to 120 mm has been deposited by CVD at 625-1000 C using tantalum pentachloride as precursor. Deposition rates range from 1 to 80mm/h and an activation energy of 103 kJ/mole is calculated. Well adhering deposits has been obtained on stainless steel, carbon steels...

  14. Stability of high temperature chemical vapor deposited silicon based structures on metals for solar conversion.

    Science.gov (United States)

    Gelard, Isabelle; Chichignoud, Guy; Blanquet, Elisabeth; Xuan, Hoan Nguyen; Cruz, Ruben; Jimenez, Carmen; Sarigiannidou, Eirini; Zaidat, Kader

    2011-09-01

    Highly crystallized silicon layers were grown on metal sheets at high temperature (950 degrees C) by thermal CVD from silane. An intermediate buffer layer was mandatory to prevent interdiffusion and silicide formation but also to compensate lattice parameters and thermal expansion coefficients mismatches between metal and silicon and ideally transfer some crystalline properties (grain size, texture) from the substrate to the silicon layer. After a thermodynamic study, aluminum nitride or titanium nitride diffusion barrier layers were selected and processed by CVD. The structure and the interfaces stabilities of these silicon/nitride/metal stacks were studied by field effect gun scanning and transmission electron microscopy, X-ray diffraction, Raman and energy dispersive X-ray spectroscopy. As a result, TiN deposited by CVD appears to be an efficient material as a buffer layer between steel and silicon.

  15. Chemical vapor deposition (CVD) of uranium for alpha spectrometry; Deposicion quimica de vapor (CVD) de uranio para espectrometria alfa

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez V, M. L.; Rios M, C.; Ramirez O, J.; Davila R, J. I.; Mireles G, F., E-mail: luisalawliet@gmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2015-09-15

    The uranium determination through radiometric techniques as alpha spectrometry requires for its proper analysis, preparation methods of the source to analyze and procedures for the deposit of this on a surface or substrate. Given the characteristics of alpha particles (small penetration distance and great loss of energy during their journey or its interaction with the matter), is important to ensure that the prepared sources are thin, to avoid problems of self-absorption. The routine methods used for this are the cathodic electro deposition and the direct evaporation, among others. In this paper the use of technique of chemical vapor deposition (CVD) for the preparation of uranium sources is investigated; because by this, is possible to obtain thin films (much thinner than those resulting from electro deposition or evaporation) on a substrate and comprises reacting a precursor with a gas, which in turn serves as a carrier of the reaction products to achieve deposition. Preliminary results of the chemical vapor deposition of uranium are presented, synthesizing and using as precursor molecule the uranyl acetylacetonate, using oxygen as carrier gas for the deposition reaction on a glass substrate. The uranium films obtained were found suitable for alpha spectrometry. The variables taken into account were the precursor sublimation temperatures and deposition temperature, the reaction time and the type and flow of carrier gas. Of the investigated conditions, two depositions with encouraging results that can serve as reference for further work to improve the technique presented here were selected. Alpha spectra obtained for these depositions and the characterization of the representative samples by scanning electron microscopy and X-ray diffraction are also presented. (Author)

  16. Purification of Single-walled Carbon Nanotubes Grown by a Chemical Vapour Deposition (CVD) Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A procedure for purification of single-walled carbon nanotubes(SWNTs) grown by the chemical vapour deposition (CVD) of carbon monooxide has been developed. Based on the result from TGA/DTA of as-prepared sample, the oxidation temperature was determined. The process included sonication, oxidation and acid washing steps. The purity and yield after purification were determined and estimated by TEM. Moreover, for the first time, a loop structure for CVD SWNTs has been observed.

  17. Low temperature back-surface-field contacts deposited by hot-wire CVD for heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, D. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain)], E-mail: delfina@eel.upc.edu; Voz, C.; Martin, I.; Orpella, A.; Alcubilla, R. [Universitat Politecnica de Catalunya, Grup de Recerca en Micro i Nanotecnologies, Jordi Girona 1-3, Barcelona 08034 (Spain); Villar, F.; Bertomeu, J.; Andreu, J. [CeRMAE-Universitat de Barcelona, Departament de Fisica Aplicada i Optica, Diagonal 647, Barcelona 08028 (Spain); Roca-i-Cabarrocas, P. [LPICM-Ecole Polytechnique, CNRS 91128 Palaiseau (France)

    2008-08-30

    The growing interest in using thinner wafers (< 200 {mu}m) requires the development of low temperature passivation strategies for the back contact of heterojunction solar cells. In this work, we investigate low temperature deposited back contacts based on boron-doped amorphous silicon films obtained by Hot-Wire CVD. The influence of the deposition parameters and the use of an intrinsic buffer layer have been considered. The microstructure of the deposited thin films has been comprehensively studied by Spectroscopic Ellipsometry in the UV-visible range. The effective recombination velocity at the back surface has been measured by the Quasi-Steady-State Photoconductance technique. Complete double-side heterojunction solar cells (1 cm{sup 2}) have been fabricated and characterized by External Quantum Efficiency and current-voltage measurements. Total-area conversion efficiencies up to 14.5% were achieved in a fully low temperature process (< 200 deg. C)

  18. Improved CVD Techniques for Depositing Passivation Layers of ICs

    Science.gov (United States)

    1975-10-01

    went into compressive stress of 1.3 x 10 dynes/cm2. Results NX • thus show that room-temperature stress in CVD films can be reduced to nearly 35 -4 0...fluorescence working curves. X-ray fluorescence radiation measurements were carried out using a Siemens Crystalloflex 4 x-ray generator with a chromium target x...ray tube (2000 W) and a Siemens Vacuum X-Ray Spectrometer Model VRS. Sample area of measurement was usually 0.50 cm2 . 2= Experimental results will be

  19. Thin alumina and silica films by chemical vapor deposition (CVD)

    OpenAIRE

    Hofman, R.; Morssinkhof, R.W.J.; Fransen, T.; Westheim, J.G.F.; Gellings, P.J.

    1993-01-01

    Alumina and silica coatings have been deposited by MOCVD (Metal Organic Chemical Vapor Deposition) on alloys to protect them against high temperature corrosion. Aluminium Tri-lsopropoxide (ATI) and DiAcetoxyDitertiaryButoxySilane (DAOBS) have been used as metal organic precursors to prepare these ceramic coatings. The influence of several process steps on the deposition rate and surface morphology is discussed. The deposition of SiO2 at atmospheric pressure is kinetically limited below 833 K ...

  20. A Study on Medium Temperature Chemical Vapor Deposition (MT-CVD) Technology and Super Coating Materials

    Institute of Scientific and Technical Information of China (English)

    GAO Jian; LI Jian-ping; ZENG Xiang-cai; MA Wen-cun

    2004-01-01

    In this paper, the dense and columnar crystalline TiCN coating layers with very good bonding strength between a layer and another layer was deposited using Medium Temperature Chemical Vapor Deposition (MT-CVD) where CH3CN organic composite with C/N atomic clusters etc. was utilized at 700 ~ 900 ℃. Effect of coating processing parameters, such as coating temperature, pressure and different gas flow quantity on structures and properties of TiCN coating layers were investigated. The super coating mechanis mand structures were analyzed. The new coating processing parameters and properties of carbide inserts with super coating layers were gained by using the improved high temperature chemical vapor deposition (HTCVD) equipment and HT-CVD, in combination with MT-CVD technology.

  1. Thin alumina and silica films by chemical vapor deposition (CVD)

    NARCIS (Netherlands)

    Hofman, R.; Morssinkhof, R.W.J.; Fransen, T.; Westheim, J.G.F.; Gellings, P.J.

    1993-01-01

    Alumina and silica coatings have been deposited by MOCVD (Metal Organic Chemical Vapor Deposition) on alloys to protect them against high temperature corrosion. Aluminium Tri-lsopropoxide (ATI) and DiAcetoxyDitertiaryButoxySilane (DAOBS) have been used as metal organic precursors to prepare these ce

  2. Oxidation Resistance of CVD (Chemical Vapor Deposition) Coatings

    Science.gov (United States)

    1987-02-01

    carbonaceous residuoe were overcome, and dense, iadherent, coat-ings which :ýtop oxidat-ion Of the substrate art! reliably produced. The iridium deposition...flow, pressure and geometry within the reaction chamber, and substrate material. For the coating to have high integrity and adhesion to the substrate...entirely produced by Ultramet using chemical vapor deposition and a novel integrated fabrication technique. Coating the inside of a long chamber presents

  3. Deposited low temperature silicon GHz modulator

    CERN Document Server

    Lee, Yoon Ho Daniel; Lipson, Michal

    2013-01-01

    The majority of silicon photonics is built on silicon-on-insulator (SOI) wafers while the majority of electronics, including CPUs and memory, are built on bulk silicon wafers, limiting broader acceptance of silicon photonics. This discrepancy is a result of silicon photonics's requirement for a single-crystalline silicon (c-Si) layer and a thick undercladding for optical guiding that bulk silicon wafers to not provide. While the undercladding problem can be partially addressed by substrate removal techniques, the complexity of co-integrating photonics with state-of-the-art transistors and real estate competition between electronics and photonics remain problematic. We show here a platform for deposited GHz silicon photonics based on polycrystalline silicon with high optical quality suitable for high performance electro-optic devices. We demonstrate 3 Gbps polysilicon electro-optic modulator fabricated on a deposited polysilicon layer fully compatible with CMOS backend integration. These results open up an arr...

  4. Optimization of process parameters in a large-area hot-wire CVD reactor for the deposition of amorphous silicon (a-Si:H) for solar cell application with highly uniform material quality

    Energy Technology Data Exchange (ETDEWEB)

    Pflueger, A.; Mukherjee, C.; Schroeder, B. [Department of Physics, Center of Materials Science, University of Kaiserslautern, P.O. Box 3049, D-67653 Kaiserslautern (Germany)

    2002-07-01

    Scale-up of a-Si:H-based thin film applications such as solar cells, entirely or partly prepared by hot-wire chemical vapor deposition (HWCVD), requires research on the deposition process in a large-area HWCVD system. The influence of gas supply and filament geometry on thickness uniformity has already been reported, but their influence on material quality is systematically studied for the first time. The optimization of deposition parameters for obtaining best material quality in our large-area HWCVD system resulted in an optimum filament temperature, T{sub fil}{approx}1600C, pressure, p=8mTorr and silane flow, F(SiH{sub 4})=100sccm, keeping the substrate temperature at T{sub S}=200C. A special gas supply (gas shower with tiny holes of uniform size) and a filament grid, consisting of six filaments with an interfilament distance, d{sub fil}=4cm were used. The optimum filament-to-substrate distance was found to be d{sub fil-S}=8.4cm. While studying the influence of different d{sub fil} and gas supply configurations on the material quality, the above-mentioned setup and parameters yield best results for both uniformity and material quality. With the setup mentioned, we could achieve device quality a-Si:H films with a thickness uniformity of {+-}2.5% on a circular area of 20cm in diameter. The material, grown at a deposition rate of r{sub d}{approx}4A/s, was characterized on nine positions of the 30cmx30cm substrate area, and revealed reasonable uniformity of the opto-electronic properties, e.g photosensitivity, {sigma}{sub Ph}/{sigma}{sub D}=(2.46{+-}0.7)x10{sup 5}, microstructure factor, R=0.17{+-}0.05, defect densities, N{sub d(PDS)}=(2.06{+-}0.6)x10{sup 17}cm{sup -3} and N{sub d(CPM)}=(2.05{+-}0.5)x10{sup 16}cm{sup -3} (film properties are given as mean values and standard deviations). Finally, we fabricated pin solar cells, with the i-layer deposited on small-area p-substrates distributed over an area of 20cmx20cm in this large-area deposition system, and

  5. Thin film zinc oxide deposited by CVD and PVD

    Science.gov (United States)

    Hamelmann, Frank U.

    2016-10-01

    Zinc oxide is known as a mineral since 1810, but it came to scientific interest after its optoelectronic properties found to be tuneable by p-type doping. Since the late 1980’s the number of publications increased exponentially. All thin film deposition technologies, including sol-gel and spray pyrolysis, are able to produce ZnO films. However, for outstanding properties and specific doping, only chemical vapor deposition and physical vapor deposition have shown so far satisfying results in terms of high conductivity and high transparency. In this paper the different possibilities for doping will be discussed, some important applications of doped ZnO thin films will be presented. The deposition technologies used for industrial applications are shown in this paper. Especially sputtering of aluminium doped Zinc Oxide (ZnO:Al or AZO) and LPCVD of boron doped Zinc Oxide (ZnO:B or BZO) are used for the commercial production of transparent conductive oxide films on glass used for thin film photovoltaic cells. For this special application the typical process development for large area deposition is presented, with the important trade-off between optical properties (transparency and ability for light scattering) and electrical properties (conductivity). Also, the long term stability of doped ZnO films is important for applications, humidity in the ambient is often the reason for degradation of the films. The differences between the mentioned materials are presented.

  6. Flexible a-Si:H/nc-Si:H tandem thin film silicon solar cells on plastic substrates with i-layers made by hot-wire CVD

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongbo; Werf, C.H.M. van der; Rath, J.K. [Utrecht University, Faculty of Science, SID - Physics of Devices, Utrecht (Netherlands); Borreman, A. [Helianthos b.v., Arnhem (Netherlands); Schropp, Ruud E.I.

    2008-08-15

    In this letter we report the result of an a-Si:H/nc-Si:H tandem thin film silicon solar mini-module fabricated on plastic foil containing intrinsic silicon layers made by hot-wire CVD (efficiency 7.4%, monolithically series-connected, aperture area 25 cm{sup 2}). We used the Helianthos cell transfer process. The cells were first deposited on a temporary aluminum foil carrier, which allows the use of the optimal processing temperatures, and then transferred to a plastic foil. This letter reports the characteristics of the flexible solar cells obtained in this manner, and compares the results with those obtained on reference glass substrates. The research focus for implementation of the hot-wire CVD technique for the roll-to-roll process is also discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Silicon Nitride Film Deposition by Photochemical Vapor Deposition Using an Argon Excimer Lamp

    Science.gov (United States)

    Maezono, Yoshinari; Toshikawa, Kiyohiko; Kurosawa, Kou; Amari, Kouichi; Ishimura, Sou; Katto, Masahito; Yokotani, Atsushi

    2007-06-01

    In this paper, we report the deposition of silicon nitride (SiNx) films for the production of semiconductor devices and flat panel displays, by chemical vapor deposition with vacuum ultraviolet excimer lamps (VUV-CVD) using SiH4 and NH3 as raw materials. An Ar2* excimer lamp (λ=126 nm, hν=9.8 eV) with a high photon energy was used to directly excite and dissociate SiH4 through a photochemical reaction. SiNx films were successfully formed at a low temperature of 100 °C with the Ar2* excimer lamp. Although the Si-rich films were obtained using an Ar2* lamp, they showed a quality almost similar to that of films obtained by conventional plasma-CVD at 400 °C.

  8. 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...

  9. Advances in the chemical vapor deposition (CVD) of Tantalum

    DEFF Research Database (Denmark)

    Mugabi, James Atwoki; Eriksen, Søren; Christensen, Erik

    2014-01-01

    The chemical stability of tantalum in hot acidic media has made it a key material in the protection of industrial equipment from corrosion under such conditions. The Chemical Vapor Deposition of tantalum to achieve such thin corrosion resistant coatings is one of the most widely mentioned examples...

  10. Chemical vapour deposition of tungsten and tungsten silicide layers for applications in novel silicon technology

    CERN Document Server

    Li, F X

    2002-01-01

    This work was a detailed investigation into the Chemical Vapour Deposition (CVD) of tungsten and tungsten silicide for potential applications in integrated circuit (IC) and other microelectronic devices. These materials may find novel applications in contact schemes for transistors in advanced ICs, buried high conductivity layers in novel Silicon-On-Insulator (SOI) technology and in power electronic devices. The CVD techniques developed may also be used for metal coating of recessed or enclosed features which may occur in novel electronic or electromechanical devices. CVD of tungsten was investigated using the silicon reduction reaction of WF sub 6. W layers with an optimum self-limiting thickness of 100 nm and resistivity 20 mu OMEGA centre dot cm were produced self-aligned to silicon. A hydrogen passivation technique was developed as part of the wafer pre-clean schedule and proved essential in achieving optimum layer thickness. Layers produced by this approach are ideal for intimate contact to shallow junct...

  11. Surface nitridation of silicon nano-particles using double multi-hollow discharge plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Giichiro; Yamamoto, Kosuke; Kawashima, Yuki; Sato, Muneharu; Nakahara, Kenta; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu [Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka (Japan); Kamataki, Kunihiro [Center for Reserch and Advancement in Higher Education, Kyushu University, Fukuoka (Japan); Kondo, Michio [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki (Japan)

    2011-10-15

    We present production of silicon nano-particles and their surface nitridation for efficient multiple-exciton generation. Nitridated silicon nano-particles were produced using double multi-hollow discharge plasma CVD, where generation of silicon particles and their nitridation were independently performed using SiH{sub 4}/H{sub 2} and N{sub 2} multi-hollow discharge plasmas. We succeeded in controlling nitrogen content in a silicon nano-particle by varying a number density of N radicals irradiated to the Si particle. We also observed strong photoluminescence (PL) emission around 300-500 nm from silicon nano-particles, where the PL peak energy is about 2.5 and 3.1 eV for pure Si nano-particles, and 2.5, 3.1, and 4.1 eV for nitridated Si nano-particles. The additional UV-peak of 4.1 eV from nitridated Si particles is closely related to the nitridation surface layer on Si nano-particles (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. 8% Efficient thin-film polycrystalline-silicon solar cells based on aluminium-induced crystallization and thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, I.; Carnel, L.; Van Gestel, D.; Beaucarne, G.; Poortmans, J. [IMEC VZW, Leuven (Belgium)

    2006-07-01

    A considerable cost reduction could be achieved in photovoltaics if efficient solar cells could be made from polycrystalline-silicon (pc-Si) thin films on inexpensive substrates. We recently showed promising solar cells results using pc-Si layers obtained by aluminium-induced crystallization (AlC) of amorphous silicon in combination with thermal chemical vapor deposition (CVD). To obtain highly efficient pc-Si solar cells, however, the material quality has to be optimized and cell processes different from those applied for standard bulk-Si solar cells have to be developed. In this work, we present the different process steps that we recently developed to enhance the efficiency of pc-Si solar cells on alumina substrates made by AlC in combination with thermal CVD. Our present pc-Si solar cell process yields cells in substrate configuration with efficiencies so far of up to 8.0%. Spin-on oxides are used to smoothen the alumina substrate surface to enhance the electronic quality of the absorber layers. The cells have heterojunction emitters consisting of thin a-Si layers that yield much higher V{sub oc} values than classical diffused emitters. Base and emitter contacts are on top of the cell in interdigitated finger patterns, leading to fill factors above 70%. The front surface of the cells is plasma textured to increase the current density. Our present pc-Si solar cell efficiency of 8% together with the fast progression that we have made over the last few years indicate the large potential of pc-Si solar cells based on the AlC seed layer approach. (author)

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

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  14. Synthesis of silicon carbide nanowires by solid phase source chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    NI Jie; LI Zhengcao; ZHANG Zhengjun

    2007-01-01

    In this paper,we report a simple approach to synthesize silicon carbide(SiC)nanowires by solid phase source chemical vapor deposition(CVD) at relatively low temperatures.3C-SiC nanowires covered by an amorphous shell were obtained on a thin film which was first deposited on silicon substrates,and the nanowires are 20-80 am in diameter and several μm in length,with a growth direction of[200].The growth of the nanowires agrees well on vapor-liquid-solid (VLS)process and the film deposited on the substrates plays an important role in the formation of nanowires.

  15. Effect of trichloroethylene enhancement on deposition rate of low-temperature silicon oxide films by silicone oil and ozone

    Science.gov (United States)

    Horita, Susumu; Jain, Puneet

    2017-08-01

    A low-temperature silcon oxide film was deposited at 160 to 220 °C using an atmospheric pressure CVD system with silicone oil vapor and ozone gases. It was found that the deposition rate is markedly increased by adding trichloroethylene (TCE) vapor, which is generated by bubbling TCE solution with N2 gas flow. The increase is more than 3 times that observed without TCE, and any contamination due to TCE is hardly observed in the deposited Si oxide films from Fourier transform infrared spectra.

  16. A novel Mo-W interlayer approach for CVD diamond deposition on steel

    Directory of Open Access Journals (Sweden)

    Vojtěch Kundrát

    2015-04-01

    Full Text Available Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference in the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42 substrates using a multi-structured molybdenum (Mo – tungsten (W interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.

  17. A novel Mo-W interlayer approach for CVD diamond deposition on steel

    Energy Technology Data Exchange (ETDEWEB)

    Kundrát, Vojtěch; Sullivan, John; Ye, Haitao, E-mail: h.ye@aston.ac.uk [School of Engineering and Applied Science, Aston University, Birmingham, B4 7ET (United Kingdom); Zhang, Xiaoling; Cooke, Kevin; Sun, Hailin [Miba Coating Group: Teer Coatings Ltd, West-Stone-House, West-Stone, Berry-Hill-Industrial-Estate, WR9 9AS, Droitwich (United Kingdom)

    2015-04-15

    Steel is the most widely used material in engineering for its cost/performance ratio and coatings are routinely applied on its surface to further improve its properties. Diamond coated steel parts are an option for many demanding industrial applications through prolonging the lifetime of steel parts, enhancement of tool performance as well as the reduction of wear rates. Direct deposition of diamond on steel using conventional chemical vapour deposition (CVD) processes is known to give poor results due to the preferential formation of amorphous carbon on iron, nickel and other elements as well as stresses induced from the significant difference in the thermal expansion coefficients of those materials. This article reports a novel approach of deposition of nanocrystalline diamond coatings on high-speed steel (M42) substrates using a multi-structured molybdenum (Mo) – tungsten (W) interlayer to form steel/Mo/Mo-W/W/diamond sandwich structures which overcome the adhesion problem related to direct magnetron sputtering deposition of pure tungsten. Surface, interface and tribology properties were evaluated to understand the role of such an interlayer structure. The multi-structured Mo-W interlayer has been proven to improve the adhesion between diamond films and steel substrates by acting as an effective diffusion barrier during the CVD diamond deposition.

  18. Stable dropwise condensation for enhancing heat transfer via the initiated chemical vapor deposition (iCVD) of grafted polymer films.

    Science.gov (United States)

    Paxson, Adam T; Yagüe, Jose L; Gleason, Karen K; Varanasi, Kripa K

    2014-01-22

    Ultra-thin copolymer films are deposited by initiated chemical deposition (iCVD) to investigate their performance under the condensation of water vapor. By forming a grafted interface between the coating and the substrate, the films exhibit stable dropwise condensation even when subjected to 100 °C steam. The applicability of the iCVD to complex substrate geometries is demonstrated on a copper condenser coil.

  19. A sub-atmospheric chemical vapor deposition process for deposition of oxide liner in high aspect ratio through silicon vias.

    Science.gov (United States)

    Lisker, Marco; Marschmeyer, Steffen; Kaynak, Mehmet; Tekin, Ibrahim

    2011-09-01

    The formation of a Through Silicon Via (TSV) includes a deep Si trench etching and the formation of an insulating layer along the high-aspect-ratio trench and the filling of a conductive material into the via hole. The isolation of the filling conductor from the silicon substrate becomes more important for higher frequencies due to the high coupling of the signal to the silicon. The importance of the oxide thickness on the via wall isolation can be verified using electromagnetic field simulators. To satisfy the needs on the Silicon dioxide deposition, a sub-atmospheric chemical vapor deposition (SA-CVD) process has been developed to deposit an isolation oxide to the walls of deep silicon trenches. The technique provides excellent step coverage of the 100 microm depth silicon trenches with the high aspect ratio of 20 and more. The developed technique allows covering the deep silicon trenches by oxide and makes the high isolation of TSVs from silicon substrate feasible which is the key factor for the performance of TSVs for mm-wave 3D packaging.

  20. Zirconium influence on microstructure of aluminide coatings deposited on nickel substrate by CVD method

    Indian Academy of Sciences (India)

    Jolanta Romanowska; Maryana Zagula-Yavorska; Jan Sieniawski

    2013-11-01

    Influence of Zr on the microstructure and phase characteristics of aluminide diffusion coatings deposited on the nickel substrate has been investigated in this study. The coatings with and without zirconium were deposited by CVD method. The cross-section chemical composition investigations revealed that during the coatings formation, there is an inward aluminum diffusion and outward nickel diffusion in both types of coatings (with and without zirconium), whereas zirconium is located far below the coating surface, at a depth of ∼17 m, between -NiAl phase and '-Ni3Al phase. XRD examinations showed that -NiAl, -NiAl and '-Ni3Al were the main components of the deposited coatings. -NiAl phase is on the surface of the coatings, whereas -NiAl and '-Ni3Al form deeper parts of the coatings. Zirconium is dissolved in NiAl on the border between -NiAl and '-Ni3Al.

  1. Optical and mechanical properties of diamond like carbon films deposited by microwave ECR plasma CVD

    Indian Academy of Sciences (India)

    S B Singh; M Pandey; N Chand; A Biswas; D Bhattacharya; S Dash; A K Tyagi; R M Dey; S K Kulkarni; D S Patil

    2008-10-01

    Diamond like carbon (DLC) films were deposited on Si (111) substrates by microwave electron cyclotron resonance (ECR) plasma chemical vapour deposition (CVD) process using plasma of argon and methane gases. During deposition, a d.c. self-bias was applied to the substrates by application of 13.56 MHz rf power. DLC films deposited at three different bias voltages (–60 V, –100 V and –150 V) were characterized by FTIR, Raman spectroscopy and spectroscopic ellipsometry to study the variation in the bonding and optical properties of the deposited coatings with process parameters. The mechanical properties such as hardness and elastic modulus were measured by load depth sensing indentation technique. The DLC film deposited at –100 V bias exhibit high hardness (∼ 19 GPa), high elastic modulus (∼ 160 GPa) and high refractive index (∼ 2.16–2.26) as compared to films deposited at –60 V and –150 V substrate bias. This study clearly shows the significance of substrate bias in controlling the optical and mechanical properties of DLC films.

  2. Atomic-layer deposition of silicon nitride

    CERN Document Server

    Yokoyama, S; Ooba, K

    1999-01-01

    Atomic-layer deposition (ALD) of silicon nitride has been investigated by means of plasma ALD in which a NH sub 3 plasma is used, catalytic ALD in which NH sub 3 is dissociated by thermal catalytic reaction on a W filament, and temperature-controlled ALD in which only a thermal reaction on the substrate is employed. The NH sub 3 and the silicon source gases (SiH sub 2 Cl sub 2 or SiCl sub 4) were alternately supplied. For all these methods, the film thickness per cycle was saturated at a certain value for a wide range of deposition conditions. In the catalytic ALD, the selective deposition of silicon nitride on hydrogen-terminated Si was achieved, but, it was limited to only a thin (2SiO (evaporative).

  3. Deposition of ZnO Films on Freestanding CVD Thick Diamond Films

    Institute of Scientific and Technical Information of China (English)

    SUN Jian; BAI Yi-Zhen; YANG Tian-Peng; XU Yi-Bin; WANG Xin-Sheng; DU Guo-Tong; WU Han-Hua

    2006-01-01

    @@ For ZnO/diamond structured surface acoustic wave (SAW) filters, performance is sensitively dependent on the quality of the ZnO films. In this paper, we prepare highly-oriented and fine grained polycrystalline ZnO thin films with excellent surface smoothness on the smooth nucleation surfaces of freestanding CVD diamond films by metal organic chemical vapour deposition (MOCVD). The properties of the ZnO films are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectrum. The influences of the deposition conditions on the quality of ZnO films are discussed briefly. ZnO/freestanding thick-diamond-film layered SAW devices with high response frequencies are expected to be developed.

  4. An economic CVD technique for pure SnO2 thin films deposition: Temperature effects

    Indian Academy of Sciences (India)

    M Maleki; S M Rozati

    2013-04-01

    A modified new method of CVD for formation of pure layers of tin oxide films was developed. This method is very simple and inexpensive and produces films with good electrical properties. The effect of substrate temperature on the sheet resistance, resistivity, mobility, carrier concentration and transparency of the films has been studied. The best sheet resistance obtained at substrate temperature of 500 ◦C was about 27 /cm2. X-ray diffraction showed that the structure of deposited films was polycrystalline with a grain size between 150–300 Å. The preferred orientation was (211) for films deposited at substrate temperature of about 500 °C. FESEM micrographs revealed that substrate temperature is an important factor for increasing grain size and modifies electrical parameters. UV-visible measurement showed reduction of transparency and bandgap of the layers with increasing substrate temperature.

  5. THERMODYNAMIC ANALYSIS AND EXPERIMENTAL VERIFICATION FOR SYNTHESIZING SILICON NITRIDE NANOPARTICLES USING RF PLASMA CVD

    Institute of Scientific and Technical Information of China (English)

    Ruoyu Hong; Jianmin Ding; Hongzhong Li

    2003-01-01

    Silicon nitride nanoparticles were synthesized by radio-frequency (RF) plasma chemical vapor deposition (PCVD) using silicon tetrachloride and ammonia as precursors, and argon as carrier gas. By assuming chemical thermodynamic equilibrium in the system, a computer program based on chemical thermodynamics was used to calculate the compositions of the system at different initial concentrations and final temperatures. At first, five elements and thirty-four species were considered. The effects of temperatures, and concentrations of ammonia, hydrogen and nitrogen on the equilibrium compositions were analyzed. It was found that the optimal reaction temperature range should be 1200 to 1500 K to obtain the highest conversion and yield of Si3N4. The inlet position of ammonia should be lower than that of silicon tetrachloride, and both should be located at the tail of the plasma torch. The best mole ratio of ammonia to silicon tetrachloride was found to be about 6. Later, the influences of water (and oxygen) were considered, and 17 additional species were included in the computations. It was found that oxygen or water content in the raw materials should be as low as possible in order to have high nitride content in the produced Si3N4. Nitrogen or hydrogen might be used to replace some or even all the argon to improve the yield of silicon nitride and reduce the cost. The ratio of ammonia to silicon tetrachloride should be high enough to obtain high conversion, but not excessively high to reduce the oxygen content due to the existence of water in ammonia. The simulated results were verified by experiments.

  6. Amorphous Silicon Film Deposition from SiH4 by Chemical Vapor Deposition with Argon Excimer Lamp

    Science.gov (United States)

    Toshikawa, Kiyohiko; Yokotani, Atsushi; Kurosawa, Kou

    2005-11-01

    We have deposited amorphous silicon thin films from monosilane (SiH4) gas by photochemical vapor deposition using a vacuum ultraviolet excimer lamp (VUV-CVD). We used an argon excimer lamp (λ=126 nm, hν=9.8 eV) whose photons are strongly absorbed by SiH4 gas. The substrate temperatures were changed from 25 to 300°C. When the temperature was lower than 150°C, the films included H--Si--H units and H2 molecules in its structure. When it was higher than 150°C, the main structural unit was Si--H.

  7. Simultaneous synthesis of nanodiamonds and graphene via plasma enhanced chemical vapor deposition (MW PE-CVD) on copper.

    Science.gov (United States)

    Gottlieb, Steven; Wöhrl, Nicolas; Schulz, Stephan; Buck, Volker

    2016-01-01

    The simultaneous growth of both nanodiamonds and graphene on copper samples is described for the first time. A PE-CVD process is used to synthesize graphene layers and nanodiamond clusters from a hydrogen/methane gas mixture as it is typically done successfully in thermal CVD processes for graphene synthesis. However, the standard thermal CVD process is not without problems since the deposition of graphene is affected by the evaporation of a notable amount of copper caused by the slow temperature increase typical for thermal CVD resulting in a long process time. In sharp contrast, the synthesis of graphene by PE-CVD can circumvent this problem by substantially shortening the process time at holding out the prospect of a lower substrate temperature. The reduced thermal load and the possibility to industrially scale-up the PE-CVD process makes it a very attractive alternative to the thermal CVD process with respect to the graphene production in the future. Nanodiamonds are synthesized in PE-CVD reactors for a long time because these processes offer a high degree of control over the film's nanostructure and simultaneously providing a significant high deposition rate. To model the co-deposition process, the three relevant macroscopic parameters (pressure, gas mixture and microwave power) are correlated with three relevant process properties (plasma ball size, substrate temperature and C2/Hα-ratio) and the influence on the quality of the deposited carbon allotropes is investigated. For the evaluation of the graphene as well as the nanodiamond quality, Raman spectroscopy used whereas the plasma properties are measured by optical methods. It is found that the diamond nucleation can be influenced by the C2/Hα-ratio in the plasma, while the graphene quality remains mostly unchanged by this parameter. Moreover it is derived from the experimental data that the direct plasma contact with the copper surface is beneficial for the nucleation of the diamond while the growth and

  8. Initiated Chemical Vapor Deposition (iCVD) Polymer Thin Films: Structure-Property Effects on Thermal Degradation and Adhesion

    Science.gov (United States)

    Bharamaiah Jeevendrakumar, Vijay Jain

    Opportunities and challenges for chemical vapor deposition (CVD) of polymer thin films stems from their applications in electronics, sensors, and adhesives with demands for control over film composition, conformity and stability. Initiated chemical vapor deposition (iCVD) is a subset of the CVD technique that conjoins bulk free-radical polymerization chemistry with gas-phase processing. The novelty of iCVD technique stems from the use of an initiator that can be activated at low energies (150 -- 300 °C) to react with surface adsorbed monomer to form a polymer film. This reduces risk for potential unwarranted side-reactions. Until recently, majority of iCVD research was limited to understanding the deposition kinetics with monomer properties being the principal parameters. However, there is a lack of study on the properties of deposited films which is critical for utilizing the technique in any real-world applications. The work presented here aims to advance investigation in this direction by characterizing the thermal properties of iCVD polymer films with primary focus on the initiators. A detailed characterization of custom-built iCVD system served as ground work for following investigations. Poly(neopentyl methacrylate) (PnPMA) thin films were deposited with tert-butyl peroxide (TBPO) initiators and their Tg, CTE and thermal degradation properties were investigated. iCVD PnPMA films presented low-temperature degradation peaks attributed to weak linkages from H-abstraction and beta-scission reactions of TBPO. To test this hypothesis, PnPMA films were deposited with tert-butyl peroxybenzoate (TBPOB) which is selective towards vinyl addition. Contrary to expected results, TBPOB initiated films showed degradation at lower temperatures compared to TBPO initiated films. It is postulated that with TBPOB, the surface initiator concentration is higher and consequently small oligomeric molecules were formed that degraded easily. Following these investigations, poly

  9. 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.

  10. Hydrogenated Silicon Carbide Thin Films Prepared with High Deposition Rate by Hot Wire Chemical Vapor Deposition Method

    Directory of Open Access Journals (Sweden)

    M. M. Kamble

    2014-01-01

    Full Text Available Structural, optical, and electrical properties of hydrogenated silicon carbide (SiC:H films, deposited from silane (SiH4 and methane (CH4 gas mixture by HW-CVD method, were investigated. Film properties are carefully and systematically studied as function of deposition pressure which is varied between 200 mTorr and 500 mTorr. The deposition rate is found to be reasonably high (9.4 nm/s deposition pressure amorphization occurs in SiC:H films. FTIR spectroscopy analysis shows that bond density of C–H decreases while Si–C and Si–H bond densities increase with increasing deposition pressure. Total hydrogen content increases with increasing deposition pressure and was found to be <20 at.%. The absence of band ~1300–1600 cm−1 in the Raman spectra implies negligible C–C bond concentration and formation of nearly stoichiometric SiC:H films. The band gap shows increasing trend with increasing deposition pressure. The high value of Urbach energy suggests increased structural disorder in SiC:H films. Finally, it has been concluded that CH4 can be used as effective carbon source in HW-CVD method to prepare stoichiometric SiC:H films.

  11. The life-cycle environmental impacts of etching silicon wafers and (PE)CVD chamber cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Schottler, M. [M and W Zander FE, Stuttgart (Germany); De Wild-Scholten, M.J. [ECN Solar Energy, Petten (Netherlands)

    2008-09-15

    Fluorinated gases are used by the semiconductor and photovoltaic industry for etching silicon wafers and (PE)CVD chamber cleaning. The desired result is due to F atoms and other reactive species, but the emission of the undecomposed PFC (perfluorinated) gases is unwanted because they have a high global warming effect and high atmospheric life-time. In this study a full life-cycle assessment is used in order to (1) compare the environmental impacts of the different technologies and (2) to indicate improvement options. The steps in the life cycle are the following: synthesis of the compounds, transportation, distribution in the fab (connection of cylinders), use in the process, abatement to destroy the unreacted gases and take-back of cylinders. Emissions from each step can be direct (from emission of the fluorinated gases) or indirect (from energy use). Results, partly based on best guesses, indicate that fugitive emissions of the fluorinated gases during synthesis, downtime of abatement system and cleaning of the not completely empty cylinders dominate the life-cycle global warming effect. This means that the global warming effect of the gas itself determines the effect being the highest for SF6. F2 turns out to be clearly in advantage over the other fluorinated compounds because it has a global warming potential of zero with moderate efforts for synthesis. Possible improvement options to minimize the use and emission of fluorinated gas are (1) strict procedure for connection of cylinders, (2) complete usage or reliable abatement of the gas from the bottle, (3) the recovery or reliable abatement of unused gases from the process and (4) end-point detection of the process.

  12. High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yansheng [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tu, Rong, E-mail: turong@whut.edu.cn [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Goto, Takashi [Institute for Materials Research, Tohoku University, Aoba-ku, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2013-08-01

    Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

  13. Molybdenum enhanced low-temperature deposition of crystalline silicon nitride

    Science.gov (United States)

    Lowden, Richard A.

    1994-01-01

    A process for chemical vapor deposition of crystalline silicon nitride which comprises the steps of: introducing a mixture of a silicon source, a molybdenum source, a nitrogen source, and a hydrogen source into a vessel containing a suitable substrate; and thermally decomposing the mixture to deposit onto the substrate a coating comprising crystalline silicon nitride containing a dispersion of molybdenum silicide.

  14. Chemical vapor deposition of silicon carbide for large area mirrors

    Science.gov (United States)

    Gentilman, R. L.; Maguire, E. A.

    1982-05-01

    CVD-SiC has been identified as the leading mirror material for high energy synchrotron radiation because of its high K/alpha ratio and its ability to be super-polished to less than or equal to 10 A rms roughness. Technology already exists for depositing SiC over large areas (approximately 70 cm x 20 cm). The CVD process, substrate selection, and mirror design considerations are discussed.

  15. Defect studies in 4H- Silicon Carbide PVT grown bulk crystals, CVD grown epilayers and devices

    Science.gov (United States)

    Byrappa, Shayan M.

    Silicon Carbide [SiC] which exists as more than 200 different polytypes is known for superior high temperature and high power applications in comparison to conventional semiconductor materials like Silicon and Germanium. The material finds plethora of applications in a diverse fields due to its unique properties like large energy bandgap, high thermal conductivity and high electric breakdown field. Though inundated with superior properties the potential of this material has not been utilized fully due to impeding factors such as defects especially the crystalline ones which limit their performance greatly. Lots of research has been going on for decades to reduce these defects and there has been subsequent improvement in the quality as the diameter of SiC commercial wafers has reached 150mm from 25mm since its inception. The main focus of this thesis has been to study yield limiting defect structures in conjunction with several leading companies and national labs using advanced characterization tools especially the Synchrotron source. The in depth analysis of SiC has led to development of strategies to reduce or eliminate the density of defects by studying how the defects nucleate, replicate and interact in the material. The strategies discussed to reduce defects were proposed after careful deliberation and analysis of PVT grown bulk crystals and CVD grown epilayers. Following are some of the results of the study: [1] Macrostep overgrowth mechanism in SiC was used to study the deflection of threading defects onto the basal plane resulting in stacking faults. Four types of stacking faults associated with deflection of c/c+a threading defects have been observed to be present in 76mm, 100mm and 150mm diameter wafers. The PVT grown bulk crystals and CVD grown epilayers in study were subjected to contrast studies using synchrotron white beam X-ray topography [SWBXT]. The SWBXT image contrast studies of these stacking faults with comparison of calculated phase shifts for

  16. Properties of Boron-dopedμc-Ge:H Films Deposited by Hot-wire CVD

    Institute of Scientific and Technical Information of China (English)

    HUANG Haibin; SHEN Honglie; WU Tianru; LU Linfeng; TANG Zhengxia; SHEN Jiancang

    2015-01-01

    Boron-doped hydrogenated microcrystalline Germanium (μc-Ge:H)fi lms were deposited by hot-wire CVD. H2 diluted GeH4 and B2H6 were used as precursors and the substrate temperature was kept at 300ć. The properties of the samples were analyzed by XRD, Raman spectroscopy, Fourier transform infrared spectrometer and Hall Effect measurement with Van der Pauw method. It is found that thefi lms are partially crystallized, with crystalline fractions larger than 45% and grain sizes smaller than 50 nm. The B-doping can enhance the crystallization but reduce the grain sizes, and also enhance the preferential growth of Ge (220). The conductivity of thefi lms increases and tends to be saturated with increasingdiborane-to-germane ratio . All the Hall mobilities of the samples are larger than 3.8 cm2·V-1·s-1. A high conductivity of 41.3Ω-1ίcm-1 is gained at=6.7%.

  17. On the development of single and multijunction solar cells with hot-wire CVD deposited active layers

    NARCIS (Netherlands)

    Li, H. B. T.; Franken, R.H.; Stolk, R.L.; Schuttauf, J.A.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2008-01-01

    We present an overview of the scientific challenges and achievements during the development of thin film silicon based single and multijunction solar cells with hot-wire chemical vapor deposition (HWCVD) of the active silicon layers. The highlights discussed include the development of Ag/ZnO coating

  18. AFM Morphology Study of Si1-Y GeY:H Films Deposited by LF PE CVD from Silane-Germane with Different

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, L; Kosarev, A

    2005-03-28

    The morphology of Si{sub 1-Y} Ge{sub Y}:H films in the range of Y=0.23 to 0.9 has been studied by AFM. The films were deposited by Low Frequency (LF) PE CVD at substrate temperature T{sub s}=300 C and discharge frequency f=110 kHz from silane+germane mixture with and without, Ar and H{sub 2} dilution. The films were deposited on silicon and glass substrates. AFM images were taken and analyzed for 2 x 2 mm{sup 2} area. All the images demonstrated ''grain'' like structure, which was characterized by the height distribution function F(H) average roughness , standard height deviation Rq, lateral correlation length L{sub c} area distribution function F(s), mean grain area , diameter distribution function F(d), and mean grain diameter . The roughness of the films monotonically increases with Y for all dilutions, but more significantly in the films deposited without dilution. L{sub c} continuously grows with Y in the films deposited without dilution, while more complex behavior L{sub c}(Y) is observed in the films deposited with H- or Ar dilution. The sharpness of F(H) characterized by curtosis {gamma} depends on dilution and the sharpest F(H) are for the films deposited with Ar ({gamma}=5.30,Y=0.23) and without dilution ({gamma}=4.3, Y=0.45). Isothermal annealing caused increase of , L{sub c} in the films deposited with H- and Ar dilutions, while in the films prepared without dilution the behavior was more complex, depending on the substrates. Significant narrowing of the height distribution was observed in the films deposited with H dilution or without dilution.

  19. Evaluating electrically insulating films deposited on V-4% Cr-4% Ti by reactive CVD

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.H.; Cho, W.D. [Argonne National Lab., IL (United States)

    1997-04-01

    Previous CaO coatings on V-4%Cr-4%Ti exhibited high-ohmic insulator behavior even though a small amount of vanadium from the alloy was incorporated in the coating. However, when the vanadium concentration in the coatings is > 15 wt%, the coating becomes conductive. When the vanadium concentration is high in localized areas, a calcium vanadate phase that exhibits semiconductor behavior can form. To explore this situation, CaO and Ca-V-O coatings were produced on vanadium alloys by chemical vapor deposition (CVD) and by a metallic-vapor process to investigate the electrical resistance of the coatings. Initially, the vanadium alloy specimens were either charged with oxygen in argon that contained trace levels of oxygen, or oxidized for 1.5-3 h in a 1% CO-CO{sub 2} gas mixture or in air to form vanadium oxide at 625-650{degrees}C. Most of the specimens were exposed to calcium vapor at 800-850{degrees}C. Initial and final weights were obtained to monitor each step, and surveillance samples were removed for examination by optical and scanning electron microscopy and electron-energy-dispersive and X-ray diffraction analysis; the electrical resistivity was also measured. The authors found that Ca-V-O films exhibited insulator behavior when the ratio of calcium concentration to vanadium concentration R in the film was > 0.9, and semiconductor or conductor behavior for R < 0.8. However, in some cases, semiconductor behavior was observed when CaO-coated samples with R > 0.98 were exposed in liquid lithium. Based on these studies, the authors conclude that semiconductor behavior occurs if a conductive calcium vanadate phase is present in localized regions in the CaO coating.

  20. Organo-Functionalization of Silicon Nanocrystals Synthesized by Inductively Coupled Plasma Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Don-Sung; Choe, Dong-Hoe; Jeong, Hyun-Dam [Chonnam National University, Gwangju (Korea, Republic of); Yoo, Seung-Wan; Kim, Jung-Hyung [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2016-05-15

    Octadecyl-terminated silicon nanocrystals (ODE-Si NCs) are obtained via a surface-initiated thermal hydrosilylation reaction on hydride-terminated Si NCs (H-Si NCs). Pristine Si NCs were synthesized at the gram scale by using inductively coupled plasma chemical vapor deposition (ICP-CVD) . The H-Si NCs were produced through a chemical etching process with hydrofluoric acid (HF), ethanol (EtOH), and distilled water (d-H{sub 2}O). The results obtained from X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) indicate that the synthesized Si NCs obtained via ICP-CVD have diamond cubic-structured silicon with a grain size of 10 nm and a densely packed Si NC array consisting of individual NCs. Organo-functionalized Si NCs, i.e., ODE-Si NCs, are well soluble in organic solvent whereas pristine Si NCs synthesized through ICP-CVD are not. The surface chemistry of the ODE-Si NCs was confirmed via Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy ({sup 1}H-NMR), and field emission transmission electron microscopy (FE-TEM). Thereby, these newly synthesized and scalable organo-functionalized Si NCs are applicable as raw materials for practical use in devices by tuning the surface chemistry with various capping molecules.

  1. Deposition of TiC film on titanium for abrasion resistant implant material by ion-enhanced triode plasma CVD

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Yuhe, E-mail: zyh1120@hotmail.co.jp [School of Stomatology, China Medical University, Shen Yang (China); Wang Wei; Jia Xingya [School of Stomatology, China Medical University, Shen Yang (China); Akasaka, Tsukasa [Department of Health Science, School of Dental Medicine Hokkaido University, Sapporo (Japan); Liao, Susan [School of Materials Science and Engineering, Nanyang Technological University (Singapore); Watari, Fumio [Department of Health Science, School of Dental Medicine Hokkaido University, Sapporo (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Deposition of Titanium Carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method. Black-Right-Pointing-Pointer The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance. Black-Right-Pointing-Pointer Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. - Abstract: Deposition of titanium carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method using a TiCl{sub 4} + CH{sub 4} + H{sub 2} gas mixture. Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. X-ray diffraction (XRD) showed that the specimen was consisted of TiC and Ti. Carbide layer of about 6 {mu}m thickness was observed on the cross section of the specimen by scanning electron microscopy (SEM). The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance.

  2. Purification and deposition of silicon by an iodide disproportionation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tihu (Littleton, CO); Ciszek, Theodore F. (Evergreen, CO)

    2002-01-01

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  3. Chemical vapor deposition and characterization of polysilanes polymer based thin films and their applications in compound semiconductors and silicon devices

    Science.gov (United States)

    Oulachgar, El Hassane

    . This work has demonstrated that a polysilane polymeric source can be used to deposit a wide range of thin film materials exhibiting similar properties with conventional ceramic materials such as silicon carbide (SiC), silicon oxynitride (SiON), silicon oxycarbide (SiOC) silicon dioxide (SiO2) and silicon nitride (Si3N4). The strict control of the deposition process allows precise control of the electrical, optical and chemical properties of polymer-based thin films within a broad range. This work has also demonstrated for the first time that poly(dimethylsilmaes) polymers deposited by CVD can be used to effectively passivate both silicon and gallium arsenide MOS devices. This finding makes polymer-based thin films obtained by CVD very promising for the development of high-kappa dielectric materials for next generation high-mobility CMOS technology. Keywords. Thin films, Polymers, Vapor Phase Deposition, CVD, Nanodielectrics, Organosilanes, Polysilanes, GaAs Passivation, MOSFET, Silicon Oxynitride, Integrated Waveguide, Silicon Carbide, Compound Semiconductors.

  4. Ionizing Energy Depositions After Fast Neutron Interactions in Silicon

    CERN Document Server

    Bergmann, Benedikt; Caicedo, Ivan; Kierstead, James; Takai, Helio; Frojdh, Erik

    2016-01-01

    In this study we present the ionizing energy depositions in a 300 μm thick silicon layer after fast neutron impact. With the Time-of-Flight (ToF) technique, the ionizing energy deposition spectra of recoil silicons and secondary charged particles were assigned to (quasi-)monoenergetic neutron energies in the range from 180 keV to hundreds of MeV. We show and interpret representative measured energy spectra. By separating the ionizing energy losses of the recoil silicon from energy depositions by products of nuclear reactions, the competition of ionizing (IEL) and non-ionizing energy losses (NIEL) of a recoil silicon within the silicon lattice was investigated. The data give supplementary information to the results of a previous measurement and are compared with different theoretical predictions.

  5. Exploring the deposition of oxides on silicon for photovoltaic cells by pulsed laser deposition

    NARCIS (Netherlands)

    Doeswijk, Lianne M.; Moor, de Hugo H.C.; Rogalla, Horst; Blank, Dave H.A.

    2002-01-01

    Since most commercially available solar cells are still made from silicon, we are exploring the introduction of passivating qualities in oxides, with the potential to serve as an antireflection coating. Pulsed laser deposition (PLD) was used to deposit TiO2 and SrTiO3 coatings on silicon substrates.

  6. Growth of boron doped hydrogenated nanocrystalline cubic silicon carbide (3C-SiC) films by Hot Wire-CVD

    Energy Technology Data Exchange (ETDEWEB)

    Pawbake, Amit [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Mayabadi, Azam; Waykar, Ravindra; Kulkarni, Rupali; Jadhavar, Ashok [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Waman, Vaishali [Modern College of Arts, Science and Commerce, Shivajinagar, Pune 411 005 (India); Parmar, Jayesh [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Bhattacharyya, Somnath [Department of Metallurgical and Materials Engineering, IIT Madras, Chennai 600 036 (India); Ma, Yuan‐Ron [Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China); Devan, Rupesh; Pathan, Habib [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Jadkar, Sandesh, E-mail: sandesh@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-04-15

    Highlights: • Boron doped nc-3C-SiC films prepared by HW-CVD using SiH{sub 4}/CH{sub 4}/B{sub 2}H{sub 6}. • 3C-Si-C films have preferred orientation in (1 1 1) direction. • Introduction of boron into SiC matrix retard the crystallanity in the film structure. • Film large number of SiC nanocrystallites embedded in the a-Si matrix. • Band gap values, E{sub Tauc} and E{sub 04} (E{sub 04} > E{sub Tauc}) decreases with increase in B{sub 2}H{sub 6} flow rate. - Abstract: Boron doped nanocrystalline cubic silicon carbide (3C-SiC) films have been prepared by HW-CVD using silane (SiH{sub 4})/methane (CH{sub 4})/diborane (B{sub 2}H{sub 6}) gas mixture. The influence of boron doping on structural, optical, morphological and electrical properties have been investigated. The formation of 3C-SiC films have been confirmed by low angle XRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red (FTIR) spectroscopy and high resolution-transmission electron microscopy (HR-TEM) analysis whereas effective boron doping in nc-3C-SiC have been confirmed by conductivity, charge carrier activation energy, and Hall measurements. Raman spectroscopy and HR-TEM analysis revealed that introduction of boron into the SiC matrix retards the crystallanity in the film structure. The field emission scanning electron microscopy (FE-SEM) and non contact atomic force microscopy (NC-AFM) results signify that 3C-SiC film contain well resolved, large number of silicon carbide (SiC) nanocrystallites embedded in the a-Si matrix having rms surface roughness ∼1.64 nm. Hydrogen content in doped films are found smaller than that of un-doped films. Optical band gap values, E{sub Tauc} and E{sub 04} decreases with increase in B{sub 2}H{sub 6} flow rate.

  7. Protective silicon coating for nanodiamonds using atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lu, J. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004 (China); Wang, Y.H. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004 (China); Zang, J.B. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China) and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004 (China)]. E-mail: diamondzjb@163.com; Li, Y.N. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei 066004 (China)

    2007-01-30

    Ultrathin silicon coating was deposited on nanodiamonds using atomic layer deposition (ALD) from gaseous monosilane (SiH{sub 4}). The coating was performed by sequential reaction of SiH{sub 4} saturated adsorption and in situ decomposition. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were utilized to investigate the structural and morphological properties of the coating. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to compare the thermal stability of nanodiamonds before and after silicon coating. The results confirmed that the deposited cubic phase silicon coating was even and continuous. The protective silicon coating could effectively improve the oxidation resistance of nanodiamonds in air flow, which facilitates the applications of nanodiamonds that are commonly hampered by their poor thermal stability.

  8. Silicon carbide and other films and method of deposition

    Science.gov (United States)

    Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy (Inventor)

    2011-01-01

    A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

  9. Comparison of tungsten films grown by CVD and hot-wire assisted atomic layer deposition in a cold-wall reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Mengdi, E-mail: M.Yang@utwente.nl; Aarnink, Antonius A. I.; Kovalgin, Alexey Y.; Gravesteijn, Dirk J.; Wolters, Rob A. M.; Schmitz, Jurriaan [MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2016-01-15

    In this work, the authors developed hot-wire assisted atomic layer deposition (HWALD) to deposit tungsten (W) with a tungsten filament heated up to 1700–2000 °C. Atomic hydrogen (at-H) was generated by dissociation of molecular hydrogen (H{sub 2}), which reacted with WF{sub 6} at the substrate to deposit W. The growth behavior was monitored in real time by an in situ spectroscopic ellipsometer. In this work, the authors compare samples with tungsten grown by either HWALD or chemical vapor deposition (CVD) in terms of growth kinetics and properties. For CVD, the samples were made in a mixture of WF{sub 6} and molecular or atomic hydrogen. Resistivity of the WF{sub 6}-H{sub 2} CVD layers was 20 μΩ·cm, whereas for the WF{sub 6}-at-H-CVD layers, it was 28 μΩ·cm. Interestingly, the resistivity was as high as 100 μΩ·cm for the HWALD films, although the tungsten films were 99% pure according to x-ray photoelectron spectroscopy. X-ray diffraction reveals that the HWALD W was crystallized as β-W, whereas both CVD films were in the α-W phase.

  10. 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.

  11. Preparation of microcrystalline single junction and amorphous-microcrystalline tandem silicon solar cells entirely by hot-wire CVD

    Energy Technology Data Exchange (ETDEWEB)

    Kupich, M.; Grunsky, D.; Kumar, P.; Schroeder, B. [University of Kaiserslautern (Germany). Department of Physics

    2004-01-25

    The hot-wire chemical vapour deposition (HWCVD) has been used to prepare highly conducting p- and n-doped microcrystalline silicon thin layers as well as highly photoconducting, low defect density intrinsic microcrystalline silicon films. These films were incorporated in all-HWCVD, all-microcrystalline nip and pin solar cells, achieving conversion efficiencies of {eta}=5.4% and 4.5%, respectively. At present, only the nip-structures are found to be stable against light-induced degradation. Furthermore, microcrystalline nip and pin structures have been successfully incorporated as bottom cells in all-hot-wire amorphous-microcrystalline nipnip- and pinpin-tandem solar cells for the first time. So far, the highest conversion efficiencies of the 'micromorph' tandem structures are {eta}=5.7% for pinpin-solar cells and 7.0% for nipnip solar cells. (author)

  12. The Effect of Annealing at 1500 C on Migration and Release of Ion Implanted Silver in CVD Silicon Carbide

    Energy Technology Data Exchange (ETDEWEB)

    HJ MacLean; RG Ballinger; LE Kolaya; SA Simonson; N Lewis; M Hanson

    2004-10-07

    The transport of silver in CVD {beta}-SiC has been studied using ion implantation. Silver ions were implanted in {beta}-SiC using the ATLAS accelerator facility at the Argonne National Laboratory. Ion beams with energies of 93 and 161 MeV were used to achieve deposition with peak concentrations at depths of approximately 9 and 13 {micro}m, respectively. As-implanted samples were then annealed at 1500 C for 210 or 480 hours. XPS, SEM, TEM, STEM, and optical methods were used to analyze the material before and after annealing. Silver concentration profiles were determined using XPS before and after annealing. STEM and SEM equipped with quantitative chemical analysis capability were used to more fully characterize the location and morphology of the silver before and after annealing. The results show that, within the uncertainty of measurement techniques, there is no silver migration, via either inter- or intragrannular paths, for the times and temperature studied. Additionally, the silver was observed to phase separate within the SiC after annealing. The irradiation damage from the implantation process resulted in a three-layer morphology in the as-implanted condition: (1) a layer of unaltered SiC, followed by (2) a layer of crystallized SiC, followed by (3) an amorphized layer which contained essentially all of the implanted silver. After annealing the layer structure changed. Layer 1 was unaltered. The grains in layer 2 recrystallized to form an epitaxial (columnar) layer. Layer 3 recrystallized to form a fine grain equiaxed layer. The results of this work do not support the long held assumption that silver release from CVD SiC, used for gas-reactor coated particle fuel, is dominated by grain boundary diffusion.

  13. Deposition rate and morphology of carbon nanotubes at different positions in a CVD reactor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Carbon nanotubes (CNTs) were synthesized through the catalytic decomposition of a ferroeene-xylene mixture in a horizontal chemical vapor deposition reactor.The deposition rate of CNTs along the axial direction was measured.The morphology of CNTs was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The results showed that the deposition rate of CNTs along the axial direction first increased and later decreased,the position achieving the maximum deposition rate was influenced by the operating conditions.The morphologies of CNTs also changed along the axial direction.

  14. Silicon doping techniques using chemical vapor dopant deposition

    Energy Technology Data Exchange (ETDEWEB)

    Popadic, M.

    2009-11-12

    Ultrashallow junctions are essential for the achievement of superior transistor performance, both in MOSFET and bipolar transistors. The stringent demands require state-of-the-art fabrication techniques. At the same time, in a different context, the accurate fabrication of various n type doping profiles by low-temperature Si epitaxy is a challenge due to autodoping. In this thesis, these two, apparently unrelated, problems are both addressed as the layer of CVD surface-deposited dopant atoms is used as a doping source. It is demonstrated that a layer of dopants deposited on the Si surface can be used as a doping source by either thermal or laser drive-in for the fabrication of both deep and ultrashallow defect-free junctions. In low-temperature CVD epitaxy, autodoping is a consequence of dopant surface segregation and doping from the surface layer. This process has been characterized, and consequently excellent controllability is achieved. In addition, new results related to the CVD of dopants itself are obtained, and two theoretical achievements are made: the analytical model of arbitrarily shallow junctions is derived, and a new C-V profiling technique suitable for the characterization of ultrashallow junctions is developed.

  15. Structure characterization and strain relief analysis in CVD growth of boron phosphide on silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guoliang [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Abbott, Julia K.C.; Brasfield, John D. [Department of Chemistry, The University of Tennessee, Knoxville, TN 37996 (United States); Liu, Peizhi [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Dale, Alexis [Department of Chemistry, The University of Tennessee, Knoxville, TN 37996 (United States); Duscher, Gerd [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Rack, Philip D. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Feigerle, Charles S., E-mail: cfeigerl@tennessee.edu [Department of Chemistry, The University of Tennessee, Knoxville, TN 37996 (United States)

    2015-02-01

    Highlights: • Crystalline boron phosphide was grown on vicinal 4H (0 0 0 1)-SiC surfaces. • The microstructure evolution of defects generated at the interface was characterized by transmission electron microscopy. • The evolution of lattice distortion and strain are determined. - Abstract: Boron phosphide (BP) is a material of interest for development of a high-efficiency solid-state thermal neutron detector. For a thick film-based device, microstructure evolution is key to the engineering of material synthesis. Here, we report epitaxial BP films grown on silicon carbide with vicinal steps and provide a detailed analysis of the microstructure evolution and strain relief. The BP film is epitaxial in the near-interface region but deviates from epitaxial growth as the film develops. Defects such as coherent and incoherent twin boundaries, dislocation loops, stacking faults concentrate in the near-interface region and segment this region into small domains. The formation of defects in this region do not fully release the strain originated from the lattice mismatch. Large grains emerge above the near-interface region and grain boundaries become the main defects in the upper part of the BP film.

  16. Filament poisoning at typical carbon nanotube deposition conditions by hot-filament CVD

    CSIR Research Space (South Africa)

    Oliphant, CJ

    2009-05-01

    Full Text Available This paper reports on the poisoning of tungsten filaments during the hot-filament chemical vapour deposition process at typical carbon nanotube (CNT) deposition conditions and filament temperatures ranging from 1400 to 2000 °C. The morphological...

  17. Field emissions of graphene films deposited on different substrates by CVD system

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Ping; Liu Xiao-Fei; Liu Xin-Xin; Wang Li-Jun; Yang Can; Jing Long-Wei; Li Song-Kun; Pan Xiu-Fang

    2012-01-01

    Graphene films are deposited on copper (Cu) and aluminum (A1) substrates,respectively,by using a microwave plasma chemical vapour deposition technique.Furthermore,these graphene films are characterized by a field emission type scanning electron microscope (FE-SEM),Raman spectra,and field emission (FE) I-V measurements.It is found that the surface morphologies of the films deposited on Cu and Al substrates are different:the field emission property of graphene film deposited on the Cu substrate is better than that on the Al substrate,and the lowest turn-on field of 2.4 V/μm is obtained for graphene film deposited on the Cu substrate.The macroscopic areas of the graphene samples are all above 400 mm2.

  18. Properties of N-rich Silicon Nitride Film Deposited by Plasma-Enhanced Atomic Layer Deposition

    Science.gov (United States)

    Jhang, Pei-Ci; Lu, Chi-Pin; Shieh, Jung-Yu; Yang, Ling-Wu; Yang, Tahone; Chen, Kuang-Chao; Lu, Chih-Yuan

    2017-07-01

    An N-rich silicon nitride film, with a lower refractive index (RI) than the stoichiometric silicon nitride (RI = 2.01), was deposited by alternating the exposure of dichlorosilane (DCS, SiH2Cl2) and that of ammonia (NH3) in a plasma-enhanced atomic layer deposition (PEALD) process. In this process, the plasma ammonia was easily decomposed to reactive radicals by RF power activating so that the N-rich silicon nitride was easily formed by excited ammonia radicals. The growth kinetics of N-rich silicon nitride were examined at various deposition temperatures ranging from 400 °C to 630 °C; the activation energy (Ea) decreased as the deposition temperature decreased below 550 °C. N-rich silicon nitride film with a wide range of values of refractive index (RI) (RI = 1.86-2.00) was obtained by regulating the deposition temperature. At the optimal deposition temperature, the effects of RF power, NH3 flow rate and NH3 flow time were on the characteristics of the N-rich silicon nitride film were evaluated. The results thus reveal that the properties of the N-rich silicon nitride film that was formed by under plasma-enhanced atomic layer deposition (PEALD) are dominated by deposition temperature. In charge trap flash (CTF) study, an N-rich silicon nitride film was applied to MAONOS device as a charge-trapping layer. The films exhibit excellent electron trapping ability and favor a fresh cell data retention performance as the deposition temperature decreased.

  19. Structural and optical characterization of thick and thin polycrystalline diamond films deposited by microwave plasma activated CVD

    Indian Academy of Sciences (India)

    S K Pradhan; B Satpati; B P Bag; T Sharda

    2012-02-01

    Preliminary results of growth of thin diamond film in a recently installed 3 kW capacity microwave plasma activated CVD (MW-PACVD) system are being reported. The films were deposited on Si (100) substrate at 850°C using methane and hydrogen mixture at 1.5 kW MW power. The grown polycrystalline films were characterized by micro-Raman, transmission electron microscope (TEM), spectrophotometer and atomic force microscope (AFM). The results were compared with that of a thicker diamond film grown elsewhere in a same make MWPACVD system at relatively higher power densities. The presence of a sharp Raman peak at 1332 cm-1 confirmed the growth of diamond, and transmission spectra showed typical diamond film characteristics in both the samples. Typical twin bands and also a quintuplet twinned crystal were observed in TEM, further it was found that the twinned region in thin sample composed of very fine platelet like structure.

  20. Development Status of a CVD System to Deposit Tungsten onto UO2 Powder via the WCI6 Process

    Science.gov (United States)

    Mireles, O. R.; Kimberlin, A.; Broadway, J.; Hickman, R.

    2014-01-01

    Nuclear Thermal Propulsion (NTP) is under development for deep space exploration. NTP's high specific impulse (> 850 second) enables a large range of destinations, shorter trip durations, and improved reliability. W-60vol%UO2 CERMET fuel development efforts emphasize fabrication, performance testing and process optimization to meet service life requirements. Fuel elements must be able to survive operation in excess of 2850 K, exposure to flowing hydrogen (H2), vibration, acoustic, and radiation conditions. CTE mismatch between W and UO2 result in high thermal stresses and lead to mechanical failure as a result UO2 reduction by hot hydrogen (H2) [1]. Improved powder metallurgy fabrication process control and mitigated fuel loss can be attained by coating UO2 starting powders within a layer of high density tungsten [2]. This paper discusses the advances of a fluidized bed chemical vapor deposition (CVD) system that utilizes the H2-WCl6 reduction process.

  1. Method of porous diamond deposition on porous silicon

    Science.gov (United States)

    Baranauskas, Vitor; Peterlevitz, Alfredo C.; Chang, Dahge C.; Durrant, Steven F.

    2001-12-01

    In this paper, we discuss the experimental results of the fabrication of porous diamond/porous silicon and porous diamond structures by chemical vapor deposition of diamond over a skeleton of porous silicon, replicating the porous surface geometry around the Si pores and also creating new porous diamond structures. Scanning electron microscopy (SEM) revealed that the diamond nuclei are deposited on the top of the porous silicon skeleton, forming isolated grains in the first nucleation stages, and then growing like the usual structure of most ceramic materials, making a self-sustained porous diamond structure. Raman spectroscopy revealed that the diamond films are of good quality, close to that of diamond films grown on crystalline silicon.

  2. Effect of PbI2 deposition rate on two-step PVD/CVD all-vacuum prepared perovskite

    Science.gov (United States)

    Ioakeimidis, Apostolos; Christodoulou, Christos; Lux-Steiner, Martha; Fostiropoulos, Konstantinos

    2016-12-01

    In this work we fabricate all-vacuum processed methyl ammonium lead halide perovskite by a sequence of physical vapour deposition of PbI2 and chemical vapour deposition (CVD) of CH3NH3I under a static atmosphere. We demonstrate that for higher deposition rate the (001) planes of PbI2 film show a higher degree of alignment parallel to the sample's surface. From X-ray diffraction data of the resulted perovskite film we derive that the intercalation rate of CH3NH3I is fostered for PbI2 films with higher degree of (001) planes alignment. The stoichiometry of the produced perovskite film is also studied by Hard X-ray photoelectron spectroscopy measurements. Complete all-vacuum perovskite solar cells were fabricated on glass/ITO substrates coated by an ultra-thin (5 nm) Zn-phthalocyanine film as hole selective layer. A dependence of residual PbI2 on the solar cells performance is displayed, while photovoltaic devices with efficiency up to η=11.6% were achieved.

  3. Atmospheric Pressure Plasma CVD of Amorphous Hydrogenated Silicon Carbonitride (a-SiCN:H) Films Using Triethylsilane and Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan Guruvenket; Steven Andrie; Mark Simon; Kyle W. Johnson; Robert A. Sailer

    2011-10-04

    Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films are synthesized by atmospheric pressure plasma enhanced chemical vapor (AP-PECVD) deposition using the Surfx Atomflow{trademark} 250D APPJ source with triethylsilane (HSiEt{sub 3}, TES) and nitrogen as the precursor and the reactive gases, respectively. The effect of the substrate temperature (T{sub s}) on the growth characteristics and the properties of a-SiCN:H films was evaluated. The properties of the films were investigated via scanning electron microscopy (SEM), atomic force microscopy (AFM) for surface morphological analyses, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) for chemical and compositional analyses; spectroscopic ellipsometry for optical properties and thickness determination and nanoindentation to determine the mechanical properties of the a-SiCN:H films. Films deposited at low T{sub s} depict organic like features, while the films deposited at high T{sub s} depict ceramic like features. FTIR and XPS studies reveal that an increases in T{sub s} helps in the elimination of organic moieties and incorporation of nitrogen in the film. Films deposited at T{sub s} of 425 C have an index of refraction (n) of 1.84 and hardness (H) of 14.8 GPa. A decrease in the deposition rate between T{sub s} of 25 and 250 C and increase in deposition rate between T{sub s} of 250 and 425 C indicate that the growth of a-SiCN:H films at lower T{sub s} are surface reaction controlled, while at high temperatures film growth is mass-transport controlled. Based on the experimental results, a potential route for film growth is proposed.

  4. The effects of flow multiplicity on GaN deposition in a rotating disk CVD reactor

    Science.gov (United States)

    Gkinis, P. A.; Aviziotis, I. G.; Koronaki, E. D.; Gakis, G. P.; Boudouvis, A. G.

    2017-01-01

    The effect of gas flow multiplicity, i.e. the possibility of two very different flow regimes prevailing at random in a rotating disk metalorganic chemical vapor deposition (MOCVD) reactor, on the deposited GaN film is investigated. A transport model coupled with a system of chemical reactions in the gas phase and on the wafer where the film is formed, is implemented in the parameter regions where multiple flows are possible. In the region of multiplicity where either plug flow, imposed by forced convection, or buoyancy-dominated flow is possible, the results in the latter case indicate high deposition rate and decreased uniformity. In the former case, increasing the pressure and the rotation rate has a favorable effect on the deposition rate without sacrificing uniformity. In the parameter window of multiplicity where either rotation or combined rotation/buoyancy may prevail, the effects of buoyancy lead to higher deposition rate at the center of the wafer and reduced uniformity. The Arrhenius plots in the regions of multiplicity for exactly the same operating conditions reveal that the system operates in a diffusion-limited regime in the plug flow and in the rotation-dominated flow, in the first and second region of multiplicity respectively. In contrast, in the buoyancy-dominated flow and the combined rotation/buoyancy flow (first and second region of multiplicity respectively) the process shifts into the kinetics-limited regime.

  5. Behavior of incorporated nitrogen in plasma-nitrided silicon oxide formed by chemical vapor deposition

    Science.gov (United States)

    Shinoda, Nao; Itokawa, Hiroshi; Fujitsuka, Ryota; Sekine, Katsuyuki; Onoue, Seiji; Tonotani, Junichi

    2016-04-01

    The behavior of nitrogen (N) atoms in plasma-nitrided silicon oxide (SiO2) formed by chemical vapor deposition (CVD) was characterized by physical analysis and from electrical properties. The changes in the chemical bonding and distribution of N in plasma-nitrided SiO2 were investigated for different subsequent processes. N-Si3, N-Si2O, and N2 are formed in a SiO2 film by plasma nitridation. N2 molecules diffuse out during annealing at temperatures higher than 900 °C. NH species are generated from N2 molecules and H in the SiO2 film with subsequent oxide deposition using O3 as an oxidant. The capacitance-voltage (C-V) curves of metal-oxide-semiconductor (MOS) capacitors are obtained. The negative shift of the C-V curve is caused by the increase in the density of positive fix charge traps in CVD-SiO2 induced by plasma nitridation. The C-V curve of plasma-nitrided SiO2 subjected to annealing shifts to the positive direction and that subjected to the subsequent oxide deposition shifts markedly to the negative direction. It is clarified that the density of positive charge fixed traps in plasma-nitrided SiO2 films decrease because the amount of N2 molecules is decreased by annealing, and that the density of traps increases because NH species are generated and move to the interface between SiO2 and the Si substrate with the subsequent oxide deposition.

  6. Gettering of interstitial iron in silicon by plasma-enhanced chemical vapour deposited silicon nitride films

    Science.gov (United States)

    Liu, A. Y.; Sun, C.; Markevich, V. P.; Peaker, A. R.; Murphy, J. D.; Macdonald, D.

    2016-11-01

    It is known that the interstitial iron concentration in silicon is reduced after annealing silicon wafers coated with plasma-enhanced chemical vapour deposited (PECVD) silicon nitride films. The underlying mechanism for the significant iron reduction has remained unclear and is investigated in this work. Secondary ion mass spectrometry (SIMS) depth profiling of iron is performed on annealed iron-contaminated single-crystalline silicon wafers passivated with PECVD silicon nitride films. SIMS measurements reveal a high concentration of iron uniformly distributed in the annealed silicon nitride films. This accumulation of iron in the silicon nitride film matches the interstitial iron loss in the silicon bulk. This finding conclusively shows that the interstitial iron is gettered by the silicon nitride films during annealing over a wide temperature range from 250 °C to 900 °C, via a segregation gettering effect. Further experimental evidence is presented to support this finding. Deep-level transient spectroscopy analysis shows that no new electrically active defects are formed in the silicon bulk after annealing iron-containing silicon with silicon nitride films, confirming that the interstitial iron loss is not due to a change in the chemical structure of iron related defects in the silicon bulk. In addition, once the annealed silicon nitride films are removed, subsequent high temperature processes do not result in any reappearance of iron. Finally, the experimentally measured iron decay kinetics are shown to agree with a model of iron diffusion to the surface gettering sites, indicating a diffusion-limited iron gettering process for temperatures below 700 °C. The gettering process is found to become reaction-limited at higher temperatures.

  7. Direct deposition of gold on silicon with focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Nebiker, P.W.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muehle, R. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Irradiation with ions at very low energies (below 500 eV) no longer induces a removal of substrate material, but the ions are directly deposited on the surface. In this way, gold has been deposited on silicon with focused ion beam exposure and the properties of the film have been investigated with atomic force microscopy and Auger electron spectroscopy. (author) 3 figs., 1 ref.

  8. TiAlN and TiAlCN deposition in an industrial PaCVD-plant

    Energy Technology Data Exchange (ETDEWEB)

    Heim, D.; Hochreiter, R. [Ruebig GmbH, Co., Wels (Austria)

    1998-01-01

    An industrial PaCVD-plant was equipped with an AlCl{sub 3}-generator. By using Ar, H{sub 2}, N{sub 2}, CH{sub 4}, TiCl{sub 4} and AlCl{sub 3}, TiAlN- and TiAlCN-films could be deposited on hard metal and steel substrates. The plasma was generated by a DC-pulse power supply with frequencies up to 50 kHz. The reactor size was 350 mm in diameter and 900 mm in height. During one batch 1200 indexable inserts could be coated. The growth rates were about 1-3 {mu}m h{sup -1}. The deposited films show a fine structure and Cl-concentrations below 3%. The measured critical loads were between 30 and 40 N. Wear test results show an increase in tool life up to several 100% compared with uncoated or TiN-coated tools. (orig.) 7 refs.

  9. Diamond like carbon coatings deposited by microwave plasma CVD: XPS and ellipsometric studies

    Indian Academy of Sciences (India)

    R M Dey; M Pandey; D Bhattacharyya; D S Patil; S K Kulkarni

    2007-12-01

    Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposition system using d.c. bias voltage ranging from –100 V to –300 V. These films were characterized by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry techniques for estimating 3/2 ratio. The 3/2 ratio obtained by XPS is found to have an opposite trend to that obtained by spectroscopic ellipsometry. These results are explained using sub-plantation picture of DLC growth. Our results clearly indicate that the film is composed of two different layers, having entirely different properties in terms of void percentage and 3/2 ratio. The upper layer is relatively thinner as compared to the bottom layer.

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

    OpenAIRE

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

    2012-01-01

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

  11. The Formation of Nanocrystalline Diamond Coating on WC Deposited by Microwave Assisted Plasma CVD

    Science.gov (United States)

    Toff, M. R. M.; Hamzah, E.; Purniawan, A.

    2010-03-01

    Diamond is one form of carbon structure. The extreme hardness and high chemical resistant of diamond coatings determined that many works on this area relate to coated materials for tribological applications in biomedicine, as mechanical seals or cutting tools for hard machining operations. In the work, nanocrystalline diamond (NCD) coated tungsten carbide (WC) have been deposited by microwave assisted plasma chemical vapor deposition (MAPCVD) from CH4/H2 mixtures. Morphology of NCD was investigated by using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The quality of NCD is defined as ratio between diamond and non diamond and also full width at half maximum (FWHM) was determined using Raman spectra. The result found that the NCD structure can be deposited on WC surface using CH4/H2 gas mixture with grain size ˜20 nm to 100 nm. Increase %CH4 concentration due to increase the nucleation of NCD whereas decrease the quality of diamond. Based on Raman spectra, the quality of NCD is in the range ˜98.82-99.01% and 99.56-99.75% for NCD and microcrystalline (MCD), respectively. In addition, FWHM of NCD is high than MCD in the range of 8.664-62.24 cm-1 and 4.24-5.05 cm-1 for NCD and MCD respectively that indicate the crystallineity of NCD is smaller than MCD.

  12. Plasma deposition of amorphous silicon-based materials

    CERN Document Server

    Bruno, Giovanni; Madan, Arun

    1995-01-01

    Semiconductors made from amorphous silicon have recently become important for their commercial applications in optical and electronic devices including FAX machines, solar cells, and liquid crystal displays. Plasma Deposition of Amorphous Silicon-Based Materials is a timely, comprehensive reference book written by leading authorities in the field. This volume links the fundamental growth kinetics involving complex plasma chemistry with the resulting semiconductor film properties and the subsequent effect on the performance of the electronic devices produced. Key Features * Focuses on the plasma chemistry of amorphous silicon-based materials * Links fundamental growth kinetics with the resulting semiconductor film properties and performance of electronic devices produced * Features an international group of contributors * Provides the first comprehensive coverage of the subject, from deposition technology to materials characterization to applications and implementation in state-of-the-art devices.

  13. RF Reactive Magnetron Sputter Deposition of Silicon Sub-Oxides

    NARCIS (Netherlands)

    Hattum, E.D. van

    2007-01-01

    RF reactive magnetron plasma sputter deposition of silicon sub oxide E.D. van Hattum Department of Physics and Astronomy, Faculty of Sciences, Utrecht University The work described in the thesis has been inspired and stimulated by the use of SiOx layers in the direct inductive printing technology, w

  14. 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.

  15. Structural and optical properties of tellurium films obtained by chemical vapor deposition(CVD)

    Institute of Scientific and Technical Information of China (English)

    MA Yu-tian; GONG Zhu-Qing; XU Wei-Hong; HUANG Jian

    2006-01-01

    Tellurium thin films were prepared by the chemical vapor deposition method. The structure, surface morphology and optical properties of the Te thin films were analyzed by powder X-ray diffraction, scanning electron microscopy, FTIR transmission,UV/VIS/NIR transmission and reflectance. The results show that the films structural and optical properties are influenced by many factors such as film thickness, crystallite size and substrate temperature. The films as thick as 111-133 nm have high IR transmission across the full 8-13 μm band and highly blocking in the solar spectral region elsewhere, which indicates that Te films thickness in this region can be used as good solar radiation shields in radiative cooling devices.

  16. Nanosecond laser ablation and deposition of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Siew, Wee Ong; Tou, Teck Yong [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Yap, Seong Shan; Reenaas, Turid Worren [Norwegian University of Science and Technology, Department of Physics, Trondheim (Norway); Ladam, Cecile; Dahl, Oeystein [SINTEF Materials and Chemistry, Trondheim (Norway)

    2011-09-15

    Nanosecond-pulsed KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) lasers were used to ablate a polycrystalline Si target in a background pressure of <10{sup -4} Pa. Si films were deposited on Si and GaAs substrates at room temperature. The surface morphology of the films was characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Round droplets from 20 nm to 5 {mu}m were detected on the deposited films. Raman Spectroscopy indicated that the micron-sized droplets were crystalline and the films were amorphous. The dependence of the properties of the films on laser wavelengths and fluence is discussed. (orig.)

  17. The effectiveness of Ti implants as barriers to carbon diffusion in Ti implanted steel under CVD diamond deposition conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weiser, P.S.; Prawer, S. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Hoffman, A. [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Chemistry; Evan, P.J. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Paterson, P.J.K. [Royal Melbourne Inst. of Tech., VIC (Australia)

    1993-12-31

    The growth of chemical vapour deposited (CVD) diamond onto iron based substrates complicated by preferential soot formation and carbon diffusion into the substrate [1], leading to poor quality films and poor adhesion. In the initial stages of exposure to a microwave plasma, a layer of graphite is rapidly formed on an untreated Fe based substrate. Once this graphite layer reaches a certain thickness, reasonable quality diamond nucleates and grows upon it. However, the diamond film easily delaminates from the substrate, the weak link being the graphitic layer. Following an initial success in using a TiN barrier layer to inhibit the formation of such a graphitic layer the authors report on attempts to use an implanted Ti layer for the same purpose. This work was prompted by observation that, although the TiN proved to be an extremely effective diffusion barrier, adhesion may be further enhanced by the formation of a TiC interface layer between the diamond film and the Fe substrate. 3 refs., 6 figs.

  18. Investigation of phonon modes in gallium nitride nanowires deposited by thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Rizal, Umesh, E-mail: umeshrizal680@gmail.com; Swain, Bibhu P., E-mail: bibhu.s@smit.smu.edu.in [Nano Processing Laboratory, Centre for Material Science and Nanotechnology, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East Sikkim, India-737136 (India); Swain, Bhabani S., E-mail: bsswain@kookmin.ac.kr [School of Advanced Materials Engineering, Kookmin University, Sungbuk-gu, Jeongnung-dong, Seoul (Korea, Republic of)

    2016-04-13

    Gallium nitride nanowires (GaN-NWs) of diameters ranging from 20 to 80 nm were grown on the p-type Si substrate by Thermal Chemical Vapor Deposition (TCVD) using Iron (Fe) catalyst via VLS mechanism. Raman and FTIR spectra reveal the presence of broad transverse optic (TO) and longitudinal optic (LO) phonon peak spreads over 500-600 cm{sup −1} and 720 cm{sup −1} respectively. The detail deconvolution of integrated transverse and longitudinal phonon analysis reveals phonon confinement brought out by incorporation of hydrogen atom. The red shifts of TO and LO phonon peak position indicates nanosized effect. I{sub A1(LO)}/I{sub A1(TO)} increases from 0.073 to 1.0 and their respective fwhm{sub A1(LO)}/fwhm{sub A1(TO)} also increases from 0.71 to 1.31 with increasing H{sub 2} flow rate. E{sub 1}(LO) - E{sub 1}(TO) and A{sub 1}(LO) - A{sub 1}(TO) increases from 173.83 to 190.73 and 184.89 to 193.22 respectively. Apart from this usual TO and LO phonon, we have found Surface Optic (SO) phonon at 671 cm{sup −1} in FTIR spectra. The intensity of PL peak increases with increasing H{sub 2} dilution reveals efficient passivation of defect centre at surface of GaN-NWs.

  19. The deposition characteristics of copper(I) compounds for CVD by FT-IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hardcastle, F.D.; Peden, C.H.F.; Omstead, T.R.; Blewer, R.S. [Sandia National Labs., Albuquerque, NM (United States); Farkas, J.; Hampden-Smith, M.J.; Kodas, T.T. [New Mexico Univ., Albuquerque, NM (United States)

    1991-12-31

    Fourier transform-infrared spectroscopy (FT-IR) was used to investigate the adsorption and thermally-induced decomposition of copper (I) {beta}-diketonate precursors of the type (hfac)CuL, where hfac is the hexafluoroacetylacetonate bidentate ligand and L is trimethylphosphine or 1,5-cyclooctadiene. The (hfac)CuPMe{sub 3} precursor desorbs from the surface at very low temperatures whereas the (hfac)Cu(1,5-COD) dissociates on adsorption, liberating 1,5-COD and leaving a surface(hfac)Cu complex which can subsequently disproportionate. Evidence is provided for hydrogen-bonding between the hfac ligand and the surface silanols for (hfac)CuPMe{sub 3}, but not for (hfac)Cu(1,5-COD). These results are consistent with the selective behavior of these precursors for copper deposition and suggest that the selectivity of the (hfac)CuPMe{sub 3} and (hfac)Cu(1, 5-COD) precursors may be due to the ability of the hfac ligand to hydrogen bond to the surface silanol groups.

  20. The deposition characteristics of copper(I) compounds for CVD by FT-IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hardcastle, F.D.; Peden, C.H.F.; Omstead, T.R.; Blewer, R.S. (Sandia National Labs., Albuquerque, NM (United States)); Farkas, J.; Hampden-Smith, M.J.; Kodas, T.T. (New Mexico Univ., Albuquerque, NM (United States))

    1991-01-01

    Fourier transform-infrared spectroscopy (FT-IR) was used to investigate the adsorption and thermally-induced decomposition of copper (I) {beta}-diketonate precursors of the type (hfac)CuL, where hfac is the hexafluoroacetylacetonate bidentate ligand and L is trimethylphosphine or 1,5-cyclooctadiene. The (hfac)CuPMe{sub 3} precursor desorbs from the surface at very low temperatures whereas the (hfac)Cu(1,5-COD) dissociates on adsorption, liberating 1,5-COD and leaving a surface(hfac)Cu complex which can subsequently disproportionate. Evidence is provided for hydrogen-bonding between the hfac ligand and the surface silanols for (hfac)CuPMe{sub 3}, but not for (hfac)Cu(1,5-COD). These results are consistent with the selective behavior of these precursors for copper deposition and suggest that the selectivity of the (hfac)CuPMe{sub 3} and (hfac)Cu(1, 5-COD) precursors may be due to the ability of the hfac ligand to hydrogen bond to the surface silanol groups.

  1. Enhancement of porous silicon photoluminescence by electroless deposition of nickel

    Energy Technology Data Exchange (ETDEWEB)

    Amdouni, S. [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia); Rahmani, M., E-mail: rahmanimehdi79@yahoo.com [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia); Zaïbi, M.-A [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia); Ecole Nationale Supérieure des Ingénieurs de Tunis, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia); Oueslati, M. [Unité de nanomatériaux et photonique, Université El Manar, Faculté des Sciences de Tunis, Département de Physique, 2092 El Manar, Tunis Tunisia (Tunisia)

    2015-01-15

    Nickel-porous silicon nanocomposites (PS/Ni) are elaborated by an electroless deposition method using NiCl{sub 2} aqueous solution. The presence of nickel ions in the porous layer is confirmed by Fourier Transformed InfraRed spectroscopy (FTIR) and Raman spectroscopy. The photoluminescence (PL) spectra of PS/Ni, prepared at different electroless durations (t{sub edp}), are analyzed. A remarkable enhancement in the integrated PL intensity of PS containing nickel was observed. The lower t{sub edp} favor the deposition of nickel in PS, hence the silicon dangling bonds at the porous surface are quenched and this was increased the PL intensity. However, for the longer t{sub edp}, the PL intensity has been considerably decreased due to the destruction of some Si nanocrystallites. The PL spectra of PS/Ni, for t{sub edp} less than 8 min, show a multiband profile indicating the creation of new luminescent centers by Ni elements which induces a strong modification in the emission mechanisms. - Highlights: • Deposition of Ni ions into porous silicon (PS) layer using the electroless method. • Formation of Ni–O bonds on the porous layer. • The photoluminescence (PL) intensity of PS is enhanced after Ni deposition. • The increase of the PL is due to the contribution of radiative centers related to Ni.

  2. Simulation and experimental verification of silicon dioxide deposition by PECVD

    Science.gov (United States)

    Xu, Qing; Li, Yu-Xing; Li, Xiao-Ning; Wang, Jia-Bin; Yang, Fan; Yang, Yi; Ren, Tian-Ling

    2017-02-01

    Deposition of silicon dioxide in high-density plasma is an important process in integrated circuit manufacturing. A software named CFD-ACE was used to simulate the mechanism of plasma in the chamber of plasma enhanced chemical vapor deposition (PECVD) system, and the evolution of the feature profile was simulated based on CFD-TOPO. Simulation and experiment of silicon dioxide that deposited in SiH4/N2O mixture by PECVD system was researched. The particle density, energy and angular distribution in the chamber were simulated and discussed. We also studied how the depth/width ratio affected the step coverage of the trench and analyzed the deposition rate of silicon dioxide on the feature scale. X-ray photoelectron spectroscopy (XPS) was used to analyze the elemental composition of thin films. Images of the feature profiles were taken by scanning electron microscope (SEM). The simulation results were in good agreement with experimental, which could guide the semiconductor device manufacture.

  3. Excellent Silicon Surface Passivation Achieved by Industrial Inductively Coupled Plasma Deposited Hydrogenated Intrinsic Amorphous Silicon Suboxide

    Directory of Open Access Journals (Sweden)

    Jia Ge

    2014-01-01

    Full Text Available We present an alternative method of depositing a high-quality passivation film for heterojunction silicon wafer solar cells, in this paper. The deposition of hydrogenated intrinsic amorphous silicon suboxide is accomplished by decomposing hydrogen, silane, and carbon dioxide in an industrial remote inductively coupled plasma platform. Through the investigation on CO2 partial pressure and process temperature, excellent surface passivation quality and optical properties are achieved. It is found that the hydrogen content in the film is much higher than what is commonly reported in intrinsic amorphous silicon due to oxygen incorporation. The observed slow depletion of hydrogen with increasing temperature greatly enhances its process window as well. The effective lifetime of symmetrically passivated samples under the optimal condition exceeds 4.7 ms on planar n-type Czochralski silicon wafers with a resistivity of 1 Ωcm, which is equivalent to an effective surface recombination velocity of less than 1.7 cms−1 and an implied open-circuit voltage (Voc of 741 mV. A comparison with several high quality passivation schemes for solar cells reveals that the developed inductively coupled plasma deposited films show excellent passivation quality. The excellent optical property and resistance to degradation make it an excellent substitute for industrial heterojunction silicon solar cell production.

  4. Processing Research on Chemically Vapor Deposited Silicon Nitride.

    Science.gov (United States)

    1979-12-01

    7 A-A79 328 GENERAL ELECTR IC Co PHILADELPH IA PA RE-ENTRY AND ENV--ETC F/S 3/ PROCESING RESEARCH ON CHEMICALLY VAPR DEPOSITED SILICON HITRI ETCIU) I...NH)2] x-- .Si3N 4 as well as NH 3 2) 3SiCI + 6H --- 3i + 6 HC - Si N 4 2 (V,l1) 3 4 pressure may play a part in shifting the deposition sequence from...hot-wall reactor should be further refined with em- phasis on the formation of figured geometries (hemispherical and ogive shells). As part of this

  5. The structural characterisation of HWCVD-deposited nanocrystalline silicon films

    Directory of Open Access Journals (Sweden)

    Bibhu P. Swain

    2009-12-01

    Full Text Available Nanocrystalline silicon (nc-Si films were deposited by hot-wire chemical vapour deposition (HWCVD in the presence of varying H2 concentrations and their structural and interfacial character investigated by X-ray diffraction, small-angle X-ray scattering (SAXS and Raman spectroscopy. The crystalline fraction was around 30–50% and the nc-Si crystallite size was in the range 20–35 nm. The SAXS results were analysed by Guinier plot, scaling factor, and correlation distance. The nc-Si grains displayed a mass fractal appearance, and the interfacial inhomogeneity distance was ~2 nm.

  6. Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD

    Directory of Open Access Journals (Sweden)

    Muller TFG

    2009-01-01

    Full Text Available Abstract We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200–700 °C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as ≡Si–H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures ≥400 °C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.

  7. Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD.

    Science.gov (United States)

    Arendse, C J; Malgas, G F; Muller, T F G; Knoesen, D; Oliphant, C J; Motaung, D E; Halindintwali, S; Mwakikunga, B W

    2009-01-21

    We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200-700 degrees C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as identical withSi-H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures >/=400 degrees C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.

  8. Advanced optical modelling of dynamically deposited silicon nitride layers

    Science.gov (United States)

    Borojevic, N.; Hameiri, Z.; Winderbaum, S.

    2016-07-01

    Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition systems results in non-uniform structure of the dielectric layer. Appropriate analysis of such layers requires the optical characterization to be performed as a function of the layer's depth. This work presents a method to characterize dynamically deposited silicon nitride layers. The method is based on the fitting of experimental spectroscopic ellipsometry data via grading of Tauc-Lorentz optical parameters through the depth of the layer. When compared with the standard Tauc-Lorentz fitting procedure, used in previous studies, the improved method is demonstrating better quality fits to the experimental data and revealing more accurate optical properties of the dielectric layers. The most significant advantage of the method is the ability to extract the depth profile of the optical properties along the direction of the layer normal. This is enabling a better understanding of layers deposited using dynamic plasma enhanced chemical vapor deposition systems frequently used in the photovoltaic industry.

  9. N-type crystalline silicon films free of amorphous silicon deposited on glass by HCl addition using hot wire chemical vapour deposition.

    Science.gov (United States)

    Chung, Yung-Bin; Park, Hyung-Ki; Lee, Sang-Hoon; Song, Jean-Ho; Hwang, Nong-Moon

    2011-09-01

    Since n-type crystalline silicon films have the electric property much better than those of hydrogenated amorphous and microcrystalline silicon films, they can enhance the performance of advanced electronic devices such as solar cells and thin film transistors (TFTs). Since the formation of amorphous silicon is unavoidable in the low temperature deposition of microcrystalline silicon on a glass substrate at temperatures less than 550 degrees C in the plasma-enhanced chemical vapour deposition and hot wire chemical vapour deposition (HWCVD), crystalline silicon films have not been deposited directly on a glass substrate but fabricated by the post treatment of amorphous silicon films. In this work, by adding the HCl gas, amorphous silicon-free n-type crystalline silicon films could be deposited directly on a glass substrate by HWCVD. The resistivity of the n-type crystalline silicon film for the flow rate ratio of [HCl]/[SiH4] = 7.5 and [PH3]/[SiH4] = 0.042 was 5.31 x 10(-4) ohms cm, which is comparable to the resistivity 1.23 x 10(-3) ohms cm of films prepared by thermal annealing of amorphous silicon films. The absence of amorphous silicon in the film could be confirmed by high resolution transmission electron microscopy.

  10. An assessment of radiotherapy dosimeters based on CVD grown diamond

    CERN Document Server

    Ramkumar, S; Conway, J; Whitehead, A J; Sussman, R S; Hill, G; Walker, S

    2001-01-01

    Diamond is potentially a very suitable material for use as a dosimeter for radiotherapy. Its radiation hardness, the near tissue equivalence and chemical inertness are some of the characteristics of diamond, which make it well suited for its application as a dosimeter. Recent advances in the synthesis of diamond by chemical vapour deposition (CVD) technology have resulted in the improvement in the quality of material and increased its suitability for radiotherapy applications. We report in this paper, the response of prototype dosimeters based on two different types (CVD1 and CVD2) of CVD diamond to X-rays. The diamond devices were assessed for sensitivity, dependence of response on dose and dose rate, and compared with a Scanditronix silicon photon diode and a PTW natural diamond dosimeter. The diamond devices of CVD1 type showed an initial increase in response with dose, which saturates after approx 6 Gy. The diamond devices of CVD2 type had a response at low fields (1162.8 V/cm), the CVD2-type devices show...

  11. Plasma enhanced atomic layer deposition of silicon nitride using neopentasilane

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, Stephen, E-mail: Stephen.Weeks@intermolecular.com; Nowling, Greg; Fuchigami, Nobi; Bowes, Michael; Littau, Karl [Intermolecular, 3011 North 1st Street, San Jose, California 95134 (United States)

    2016-01-15

    Progress in transistor scaling has increased the demands on the material properties of silicon nitride (SiN{sub x}) thin films used in device fabrication and at the same time placed stringent restrictions on the deposition conditions employed. Recently, low temperature plasma enhanced atomic layer deposition has emerged as a viable technique for depositing these films with a thermal budget compatible with semiconductor processing at sub-32 nm technology nodes. For these depositions, it is desirable to use precursors that are free from carbon and halogens that can incorporate into the film. Beyond this, it is necessary to develop processing schemes that minimize the wet etch rate of the film as it will be subjected to wet chemical processing in subsequent fabrication steps. In this work, the authors introduce low temperature deposition of SiN{sub x} using neopentasilane [NPS, (SiH{sub 3}){sub 4}Si] in a plasma enhanced atomic layer deposition process with a direct N{sub 2} plasma. The growth with NPS is compared to a more common precursor, trisilylamine [TSA, (SiH{sub 3}){sub 3 }N] at identical process conditions. The wet etch rates of the films deposited with NPS are characterized at different plasma conditions and the impact of ion energy is discussed.

  12. Tip-based chemical vapor deposition with a scanning nano-heater

    NARCIS (Netherlands)

    Gaitas, A.

    2013-01-01

    In this preliminary effort, a moving nano-heater directs a chemical vapor deposition reaction (nano-CVD) demonstrating a tip-based nanofabrication (TBN) method. Localized nano-CVD of copper (Cu) and copper oxide (CuO) on a silicon (Si) and silicon oxide (SiO2) substrate from gasses, namely sublimate

  13. Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) yields better Hydrolytical Stability of Biocompatible SiOx Thin Films on Implant Alumina Ceramics compared to Rapid Thermal Evaporation Physical Vapor Deposition (PVD).

    Science.gov (United States)

    Böke, Frederik; Giner, Ignacio; Keller, Adrian; Grundmeier, Guido; Fischer, Horst

    2016-07-20

    Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous

  14. Deposition of silicon films in presence of nitrogen plasma—A feasibility study

    Indian Academy of Sciences (India)

    Sheetal J Patil; Dhananjay S Bodas; G J Phatak; S A Gangal

    2002-10-01

    A design, development and validation work of plasma based ‘activated reactive evaporation (ARE) system’ is implemented for the deposition of the silicon films in presence of nitrogen plasma on substrate maintained at room temperature. This plasma based deposition system involves evaporation of pure silicon by e-beam gun in presence of nitrogen plasma, excited by inductively coupled RF source (13.56 MHz). The activated silicon reacts with the ionized nitrogen and the films get deposited on silicon substrate. Different physical and process related parameters are changed. The grown films are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and ellipsometry. The results indicate that the film contains silicon nitride and a phase of silicon oxy nitride deposited even at room temperature. This shows the feasibility of using the ARE technique for the deposition of silicon films in nitrogen plasma.

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

    Science.gov (United States)

    Okoshi, Masayuki; Kuramatsu, Masaaki; Inoue, Narumi

    2002-06-01

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

  16. Multilayered silicone oil droplets of narrow size distribution: preparation and improved deposition on hair.

    Science.gov (United States)

    Nazir, Habiba; Wang, Lianyan; Lian, Guoping; Zhu, Shiping; Zhang, Yueling; Liu, Yuan; Ma, Guanghui

    2012-12-01

    Silicone oil droplets have limited deposition on hair due to electrostatic repulsion with negative surface charge of hair substrates. Aiming to improve silicone deposition on hair substrates, surface properties of uniform-sized silicone oil droplets (produced by membrane emulsification) were modified using layer-by-layer electrostatic deposition. By using this method, silicone oil droplets were coated with large molecular weight polymers, i.e. quaternized chitosan and alginate, and low molecular weight compounds, i.e. diallyl dimethyl ammonium chloride and glycerol to obtain six alternate layers of different surface charges. It was found that the dispersion of coated silicone oil droplets of narrow size distribution exhibited much improved mechanical strength and increased viscosity against shear compared to uncoated droplets. These multilayered silicone oil droplets were then added into model shampoos and conditioners to study the effect of charge and molecular weight of coating materials on silicone oil deposition on hair. The results clearly demonstrated that surface charge and charge density have significant influence on silicone oil deposition. Droplets with higher positive charge density resulted in increased deposition of silicone on hair due to electrostatic attraction. Characterization of the hair surface potential, wetting properties and friction certified the results further, showing reduced friction, decreased wetting angle and positive surface potential of high density positively charged silicone oil droplets. Therefore, LBL surface modification combined with membrane emulsification is a promising method for preparing multilayered silicone oil droplets of increased mechanical strength, viscosity and deposition on hair.

  17. Quenching of porous silicon photoluminescence by deposition of metal adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Andsager, D.; Hilliard, J.; Hetrick, J.M.; AbuHassan, L.H.; Plisch, M.; Nayfeh, M.H. (Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States))

    1993-10-01

    Various metals were deposited on luminescent porous silicon (PS) by immersion in metal ion solutions and by evaporation. The photoluminescence (PL) was quenched upon immersion in ionic solutions of Cu, Ag, and Au but not noticeably quenched in other ionic solutions. Evaporation of 100 A of Cu or 110 A of Au was not observed to quench PL. Auger electron spectroscopy performed on samples quenched and then immediately removed from solution showed a metallic concentration in the PS layer of order 10 at.%, but persisting to a depth of order 3000 A.

  18. THz-conductivity of CVD graphene on different substrates

    OpenAIRE

    Gabriel Cortés, Daniel; Sempere, Bernat; Colominas, Carles; Ferrer Anglada, Núria

    2015-01-01

    Optoelectronic properties of CVD graphene are charac-terized over a wide frequency range: THz, IR, visible and near-UV. We used Raman spectroscopy to characterize the synthesized graphene films. All graphene layers were deposited on various substrates, some ones transparent or flexible, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), quartz and silicon. Transmission Terahertz time-domain spectroscopy (THz-TDS) method, in the range from 100 GHz to 3 THz, is used to an...

  19. Fabrication and Characterization of a Porous Silicon Drug Delivery System with an Initiated Chemical Vapor Deposition Temperature-Responsive Coating.

    Science.gov (United States)

    McInnes, Steven J P; Szili, Endre J; Al-Bataineh, Sameer A; Vasani, Roshan B; Xu, Jingjing; Alf, Mahriah E; Gleason, Karen K; Short, Robert D; Voelcker, Nicolas H

    2016-01-12

    This paper reports on the fabrication of a pSi-based drug delivery system, functionalized with an initiated chemical vapor deposition (iCVD) polymer film, for the sustainable and temperature-dependent delivery of drugs. The devices were prepared by loading biodegradable porous silicon (pSi) with a fluorescent anticancer drug camptothecin (CPT) and coating the surface with temperature-responsive poly(N-isopropylacrylamide-co-diethylene glycol divinyl ether) (pNIPAM-co-DEGDVE) or non-stimulus-responsive poly(aminostyrene) (pAS) via iCVD. CPT released from the uncoated oxidized pSi control with a burst release fashion (∼21 nmol/(cm(2) h)), and this was almost identical at temperatures both above (37 °C) and below (25 °C) the lower critical solution temperature (LCST) of the switchable polymer used, pNIPAM-co-DEGDVE (28.5 °C). In comparison, the burst release rate from the pSi-pNIPAM-co-DEGDVE sample was substantially slower at 6.12 and 9.19 nmol/(cm(2) h) at 25 and 37 °C, respectively. The final amount of CPT released over 16 h was 10% higher at 37 °C compared to 25 °C for pSi coated with pNIPAM-co-DEGDVE (46.29% vs 35.67%), indicating that this material can be used to deliver drugs on-demand at elevated temperatures. pSi coated with pAS also displayed sustainable drug delivery profiles, but these were independent of the release temperature. These data show that sustainable and temperature-responsive delivery systems can be produced by functionalization of pSi with iCVD polymer films. Benefits of the iCVD approach include the application of the iCVD coating after drug loading without causing degradation of the drug commonly caused by exposure to factors such as solvents or high temperatures. Importantly, the iCVD process is applicable to a wide array of surfaces as the process is independent of the surface chemistry and pore size of the nanoporous matrix being coated.

  20. Study of the deposition process of vinpocetine on the surface of porous silicon

    Science.gov (United States)

    Lenshin, A. S.; Polkovnikova, Yu. A.; Seredin, P. V.

    Currently the most prospective way in pharmacotherapy is the obtaining of nanoparticles involving pharmaceutical substances. Application of porous inorganic materials on the basis of silicon is among the main features in solving of this problem. The present work is concerned with the problem of the deposition of pharmaceutical drug with nootropic activity - vinpocetine - into porous silicon. Silicon nanoparticles were obtained by electrochemical anodic etching of Si plates. The process of vinpocetine deposition was studied in dependence of the deposition time. As a result of the investigations it was found that infrared transmission spectra of porous silicon with the deposited vinpocetine revealed the absorption bands characteristic of vinpocetine substance.

  1. Selective palladium electrochemical deposition onto AFM-scratched silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Santinacci, L.; Djenizian, T.; Hildebrand, H.; Ecoffey, S.; Mokdad, H.; Campanella, T.; Schmuki, P

    2003-09-30

    The present work investigates the selective electrochemical deposition of palladium nano-structures into scratches produced through thin oxide layers covering p-Si (1 0 0) surfaces. Using an atomic force microscope equipped with a single-crystalline diamond tip scratches in the 100 nm range were produced through a 10 nm thick dry oxide layer. Pd deposition was carried out in PdCl{sub 2} (0.01 g l{sup -1})+HCl (0.1 M) by cathodic potential steps. Investigation of the palladium nucleation and growth processes onto silicon surfaces is presented. Under optimized conditions sub-100 nm palladium structures can be obtained with a very high selectivity.

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

    Science.gov (United States)

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

    2016-11-01

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

  3. 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.

  4. Diagnosis of gas phase near the substrate surface in diamond film deposition by high-power DC arc plasma jet CVD

    Institute of Scientific and Technical Information of China (English)

    Zuyuan Zhou; Guangchao Chen; Bin Li; Weizhong Tang; Fanxiu Lv

    2007-01-01

    Optical emission spectroscopy (OES) was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition (CVD). C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments (DOE). An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination,or are consumed on the substrate surface where chemical reactions occur.

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

    Directory of Open Access Journals (Sweden)

    Yaser Abdulraheem

    2014-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-15

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

  7. Hydrogen plasma treatment of silicon dioxide for improved silane deposition.

    Science.gov (United States)

    Gupta, Vipul; Madaan, Nitesh; Jensen, David S; Kunzler, Shawn C; Linford, Matthew R

    2013-03-19

    We describe a method for plasma cleaning silicon surfaces in a commercial tool that removes adventitious organic contamination and enhances silane deposition. As shown by wetting, ellipsometry, and XPS, hydrogen, oxygen, and argon plasmas effectively clean Si/SiO2 surfaces. However, only hydrogen plasmas appear to enhance subsequent low-pressure chemical vapor deposition of silanes. Chemical differences between the surfaces were confirmed via (i) deposition of two different silanes: octyldimethylmethoxysilane and butyldimethylmethoxysilane, as evidenced by spectroscopic ellipsometry and wetting, and (ii) a principal components analysis (PCA) of TOF-SIMS data taken from the different plasma-treated surfaces. AFM shows no increase in surface roughness after H2 or O2 plasma treatment of Si/SiO2. The effects of surface treatment with H2/O2 plasmas in different gas ratios, which should allow greater control of surface chemistry, and the duration of the H2 plasma (complete surface treatment appeared to take place quickly) are also presented. We believe that this work is significant because of the importance of silanes as surface functionalization reagents, and in particular because of the increasing importance of gas phase silane deposition.

  8. High deposition rate nanocrystalline silicon with enhanced homogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Verkerk, Arjan; Rath, Jatindra K.; Schropp, Ruud [Section Nanophotonics-Physics of Devices, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands)

    2010-03-15

    High rate growth of hydrogenated nanocrystalline silicon (nc-Si:H) brings additional challenges for the homogeneity in the growth direction, since the start-up effects affect a larger portion of the film, and the very high degree of depletion increases the influence of back diffusion from the inactive region into the plasma zone. It was calculated that back diffusion plays a role in the regime for high deposition rate (4.5 nm/s) via the residence time for particles in the plasma and the corresponding diffusion length for silane from outside the plasma. The stabilization time for back diffusion was derived and found to be on the order of tens of seconds. Experiment showed that the incubation layer for nc-Si:H is very thick in films deposited at a high rate compared to films deposited in a regime of lower deposition rate. The use of a hydrogen plasma start greatly reduced this incubation layer. Further control of the crystalline fraction could be achieved via slight reduction of the degree of depletion via the silane flow. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  9. Synthesis of few-layer graphene on a Ni substrate by using DC plasma enhanced chemical vapor deposition (PE-CVD)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Hyuk; Castro, Edward Joseph; Hwang, Yong Gyoo; Lee, Choong Hun [Wonkwang University, Iksan (Korea, Republic of)

    2011-01-15

    In this work, few-layer graphene (FLG) was successfully grown on polycrystalline Ni a large scale by using DC plasma enhanced chemical vapor deposition (DC PE-CVD), which may serve as an alternative route in large-scale graphene synthesis. The synthesis time had an effect on the quality of the graphene produced. The applied DC voltage, on the other hand, influenced the minimization of the defect densities in the graphene grown. We also present a method of producing a free-standing polymethyl methacrylate (PMMA)/graphene membrane on a FeCl{sub 3(aq)} solution, which could then be transferred to the desired substrate.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-15

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

  11. Hot Wire CVD for thin film triple junction cells and for ultrafast deposition of the SiN passivation layer on polycrystalline Si solar cells

    NARCIS (Netherlands)

    Schropp, R.E.I.; Franken, R.H.; Goldbach, H.D.; Houweling, Z.S.; Li, H. B. T.; Rath, J.K.; Schuttauf, J.A.; Stolk, R.L.; Verlaan, V.; van der Werf, C.H.M.

    2008-01-01

    We present recent progress on hot-wire deposited thin film solar cells and applications of silicon nitride. The cell efficiency reached for μc-Si:H n–i–p solar cells on textured Ag/ZnO presently is 8.5%, in line with the state-of-the-art level for μc-Si:H n–i–p's for any method of deposition. Such c

  12. Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Li, Dong-ling; Feng, Xiao-fei; Wen, Zhi-yu; Shang, Zheng-guo; She, Yin

    2016-07-01

    Stress controllable silicon nitride (SiNx) films deposited by plasma enhanced chemical vapor deposition (PECVD) are reported. Low stress SiNx films were deposited in both high frequency (HF) mode and dual frequency (HF/LF) mode. By optimizing process parameters, stress free (-0.27 MPa) SiNx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited SiNx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit (IC), micro-electro-mechanical systems (MEMS) and bio-MEMS.

  13. The Affordable Pre-Finishing of Silicon Carbide for Optical Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Creare proposes to develop a novel, laser-assisted, pre-finishing process for chemical vapor deposition (CVD) coated silicon-carbide ceramics. Our innovation will...

  14. Enhancement of R6G fluorescence by N-type porous silicon deposited with gold nanoparticles

    Science.gov (United States)

    Mo, Jia-qing; Jiang, Jing; Zhai, Zhen-gang; Shi, Fu-gui; Jia, Zhen-hong

    2017-01-01

    By the electrochemical anodization method, we achieve the single-layer macroporous silicon on the N-type silicon, and prepare gold nanoparticles with sodium citrate reduction method. Through injecting the gold nanoparticles into the porous silicon by immersion, the fluorescence quenching mechanism of porous silicon influenced by gold nanoparticles is analyzed. Then the macroporous silicon deposited with gold nanoparticles is utilized to enhance the fluorescence of rhodamine 6G (R6G). It is found that when the macroporous silicon is deposited with gold nanoparticles for 6 h, the maximum fluorescence enhancement of R6G (about ten times) can be realized. The N-type porous silicon deposited with gold nanoparticles can be an excellent substrate for fluorescence detection.

  15. Novel Silicon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Novel silicon nanotubes with inner-diameter of 60-80 nm was prepared using hydrogen-added dechlorination of SiCl4 followed by chemical vapor deposition (CVD) on a NixMgyO catalyst. The TEM observation showed that the suitable reaction temperature is 973 K for the formation of silicon nanotubes. Most of silicon nanotubes have one open end and some have two closed ends. The shape ofnanoscale silicon, however, is a micro-crystal type at 873 K, a rod or needle type at 993 K and an onion-type at 1023 K, respectively.

  16. Hot wire deposited hydrogenated amorphous silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mahan, A.H.; Iwaniczko, E.; Nelson, B.P.; Reedy, R.C. Jr.; Crandall, R.S. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    This paper details the results of a study in which low H content, high deposition rate hot wire (HW) deposited amorphous silicon (a-Si:H) has been incorporated into a substrate solar cell. The authors find that the treatment of the top surface of the HW i layer while it is being cooled from its high deposition temperature is crucial to device performance. They present data concerning these surface treatments, and correlate these treatments with Schottky device performance. The authors also present first generation HW n-i-p solar cell efficiency data, where a glow discharge (GD) {mu}c-Si(p) layer was added to complete the partial devices. No light trapping layer was used to increase the device Jsc. Their preliminary investigations have yielded efficiencies of up to 6.8% for a cell with a 4000 {Angstrom} thick HW i-layer, which degrade less than 10% after a 900 hour light soak. The authors suggest avenues for further improvement of their devices.

  17. Optical emission spectroscopy study on deposition process of microcrystalline silicon

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

    This paper reports that the optical emission spectroscopy (OES) is used to monitor the plasma during the deposition process of hydrogenated microcrystalline silicon films in a very high frequency plasma enhanced chemical vapour deposition system. The OES intensities (SiH*, H*α and H*β) are investigated by varying the deposition parameters. The result shows that the discharge power, silane concentrations and substrate temperature affect the OES intensities. When the discharge power at silane concentration of 4% increases, the OES intensities increase first and then are constant, the intensities increase with the discharge power monotonously at silane concentration of 6%. The SiH* intensity increases with silane concentration, while the intensities of H*α and H*β increase first and then decrease. When the substrate temperature increases, the SiH* intensity decreases and the intensities of H*α and H*β are constant. The correlation between the intensity ratio of IH*α/ISiH* and the crystalline volume fraction (Xc) of films is confirmed.

  18. Annealing and deposition effects of the chemical composition of silicon rich nitride

    DEFF Research Database (Denmark)

    Andersen, Karin Nordström; Svendsen, Winnie Edith; Stimpel-Lindner, T.;

    2005-01-01

    Silicon-rich nitride, deposited by LPCVD, is a low stress amorphous material with a high refractive index. After deposition the silicon-rich nitride thin film is annealed at temperatures above 1100 oC to break N-H bonds, which have absorption peaks in the wavelength band important for optical tel...

  19. Silicon nitride at high growth rate using hot wire chemical vapor deposition

    NARCIS (Netherlands)

    Verlaan, V.

    2008-01-01

    Amorphous silicon nitride (SiNx) is a widely studied alloy with many commercial applications. This thesis describes the application of SiNx deposited at high deposition rate using hot wire chemical vapor deposition (HWCVD) for solar cells and thin film transistors (TFTs). The deposition process of H

  20. Silicon nitride at high growth rate using hot wire chemical vapor deposition

    NARCIS (Netherlands)

    Verlaan, V.

    2008-01-01

    Amorphous silicon nitride (SiNx) is a widely studied alloy with many commercial applications. This thesis describes the application of SiNx deposited at high deposition rate using hot wire chemical vapor deposition (HWCVD) for solar cells and thin film transistors (TFTs). The deposition process of H

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

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  2. Optical and passivating properties of hydrogenated amorphous silicon nitride deposited by plasma enhanced chemical vapour deposition for application on silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wight, Daniel Nilsen

    2008-07-01

    Within this thesis, several important subjects related to the use of amorphous silicon nitride made by plasma enhanced chemical vapour deposition as an anti-reflective coating on silicon solar cells are presented. The first part of the thesis covers optical simulations to optimise single and double layer anti-reflective coatings with respect to optical performance when situated on a silicon solar cell. The second part investigates the relationship between important physical properties of silicon nitride films when deposited under different conditions. The optical simulations were either based on minimising the reflectance off a silicon nitride/silicon wafer stack or maximising the transmittance through the silicon nitride into the silicon wafer. The former method allowed consideration of the reflectance off the back surface of the wafer, which occurs typically at wavelengths above 1000 nm due to the transparency of silicon at these wavelengths. However, this method does not take into consideration the absorption occurring in the silicon nitride, which is negligible at low refractive indexes but quite significant when the refractive index increases above 2.1. For high-index silicon nitride films, the latter method is more accurate as it considers both reflectance and absorbance in the film to calculate the transmittance into the Si wafer. Both methods reach similar values for film thickness and refractive index for optimised single layer anti-reflective coatings, due to the negligible absorption occurring in these films. For double layer coatings, though, the reflectance based simulations overestimated the optimum refractive index for the bottom layer, which would have lead to excessive absorption if applied to real anti-reflective coatings. The experimental study on physical properties for silicon nitride films deposited under varying conditions concentrated on the estimation of properties important for its applications, such as optical properties, passivation

  3. CVD of pure copper films from amidinate precursor

    OpenAIRE

    2009-01-01

    Copper(I) amidinate [Cu(i-Pr-Me-AMD)]2 was investigated to produce copper films in conventional low pressure chemical vapor deposition (CVD) using hydrogen as reducing gas-reagent. Copper films were deposited on steel, silicon, and SiO2/Si substrates in the temperature range 200–350°C at a total pressure of 1333 Pa. The growth rate on steel follows the surface reaction between atomic hydrogen and the entire precursor molecule up to 240°C. A significant increase of the growth rate at tempera...

  4. Effects of post-deposition argon implantation on the memory properties of plasma-deposited silicon nitride films

    Science.gov (United States)

    Shams, Q. A.; Brown, W. D.

    1989-10-01

    Post-deposition ion implantation has been used to introduce argon into plasma-enhanced chemically vapor deposited silicon nitride films in an attempt to influence the transfer, trapping, and emission of charge during write/erase exercising of the metal-silicon nitride-silicon oxide-silicon structure. Argon was implanted into the SiH4 -NH3 -N2 deposited films at energies ranging from 25 to 75 keV, current densities ranging from 0.1 to 75 μA/cm2 and fluences ranging from 1×1012 to 1×1016 ions/cm2. Physical properties of the films were studied by ellipsometry and infrared spectroscopy, while high frequency capacitance-voltage (C-V) curves were used to obtain programming, retention, and endurance characteristics.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-30

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

  6. Deposition of low stress, high transmittance SiC as an x-ray mask membrane using ECR plasma CVD

    CERN Document Server

    Lee, S Y; Lim, S T; Ahn, J H

    1998-01-01

    SiC for x-ray mask membrane is deposited by Electron Cyclotron Resonance plasma Chemical Vapor Deposition from SiH sub 4 /CH sub 4 Ar mixtures. Stoichiometric SiC is deposited at SiH sub 4 /CH sub 4 ratio of 0.4, deposition temperature of 600.deg.C and microwave power of 500 W with +- 5% thickness uniformity, As-deposited film has compressive residual stress, very smooth surface (31 A rms) and high optical transmittance of 90% at 633 nm wavelength. The microstructure of this film consists of the nanocrystalline particle (100 A approx 200A) embedded in amorphous matrix. Residual stress can be turned to tensile stress via Rapid Thermal Annealing in N sub 2 atmosphere, while suppressing structural change during annealing, As a result, smooth (37 A rms) SiC film with moderate tensile stress and high optical transmittance (85% at 633 nm wavelength) is obtained.

  7. Formation of silicon nanoislands on crystalline silicon substrates by thermal annealing of silicon rich oxide deposited by low pressure chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yu Zhenrui [Department of Electronics, INAOE, Apartado 51, Puebla, Puebla 72000 (Mexico); Aceves-Mijares, Mariano [Department of Electronics, INAOE, Apartado 51, Puebla, Puebla 72000 (Mexico); Luna-Lopez, A [Department of Electronics, INAOE, Apartado 51, Puebla, Puebla 72000 (Mexico); Du Jinhui [College of Material Science and Chemistry Engineering, Tianjin Polytechnical University (China); Bian Dongcai [College of Material Science and Chemistry Engineering, Tianjin Polytechnical University (China)

    2006-10-14

    We report the preparation and characterization of Si nanoislands grown on a c-Si substrate by thermal annealing of silicon-rich oxide (SRO) films deposited using a conventional low pressure chemical vapour deposition (LPCVD) technique. Transmission electron microscopy revealed that a high density of Si nanoislands was formed on the surface of the c-Si substrate during thermal annealing. The nanoislands are nanocrystallites with the same crystal orientation as the substrate. The strain at the c-Si/SRO interface is probably the main reason for the nucleation of the self-assembled Si nanoislands that epitaxially grow on the c-Si substrate. The proposed method is very simple and compatible with Si integrated circuit technology.

  8. Optical and structural properties of nanocrystalline silicon potential well structure fabricated by cat-chemical vapor deposition at 200 degrees C.

    Science.gov (United States)

    Kang, Sin-Young; Keum, Ki-Su; Song, Tae-Ho; Hong, Wan-Shick

    2013-11-01

    We attempted to fabricate multi-layer, thin film structures by catalytic chemical vapor deposition (Cat-CVD) at a low temperature (200 degrees C). A 5-10-nm-thick nanocrystalline silicon (nc-Si) layer was positioned asymmetrically between two silicon nitride (SINx) layers. The compositions of the SiNx layers were varied between silicon-rich and nitrogen-rich. Each layer was deposited continuously in the Cat-CVD chamber without post-annealing. High-resolution transmission electron microscopy (HRTEM) revealed that the nc-Si layer grew in columns on the surface of the bottom SiNx layer, and the columnar structure extended up to a few nanometers of the top SiNx layer. In photoluminescence (PL) spectra, the overall intensity increased with the thickness of the nc-Si layer, but the primary peak position changed more sensitively relative to the composition of the SiNx layers. Capacitance-voltage (C-V) hysteresis was observed only when 10-nm-thick nc-Si layers were inserted between the nitrogen-rich silicon nitride (NRSN) layers. Under a bias voltage of 5 V, the current in the sample with a 10-nm-thick nc-Si layer was higher by at least two orders of magnitude than that in the sample with a 5-nm-thick nc-Si layer. The I-V curve was fitted well using both the Fowler-Nordheim and the Poole-Frenkel models for electric fields of magnitudes greater than 1.1 MV/cm, thereby implying that both mechanisms contribute to the increase in the leakage current.

  9. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  10. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  11. Effect of mixture ratios and nitrogen carrier gas flow rates on the morphology of carbon nanotube structures grown by CVD

    CSIR Research Space (South Africa)

    Malgas, GF

    2008-02-01

    Full Text Available This paper reports on the growth of carbon nanotubes (CNTs) by thermal Chemical Vapour Deposition (CVD) and investigates the effects of nitrogen carrier gas flow rates and mixture ratios on the morphology of CNTs on a silicon substrate by vaporizing...

  12. Initiated Chemical Vapor Deposition (iCVD) of Highly Cross-Linked Polymer Films for Advanced Lithium-Ion Battery Separators.

    Science.gov (United States)

    Yoo, Youngmin; Kim, Byung Gon; Pak, Kwanyong; Han, Sung Jae; Song, Heon-Sik; Choi, Jang Wook; Im, Sung Gap

    2015-08-26

    We report an initiated chemical vapor deposition (iCVD) process to coat polyethylene (PE) separators in Li-ion batteries with a highly cross-linked, mechanically strong polymer, namely, polyhexavinyldisiloxane (pHVDS). The highly cross-linked but ultrathin pHVDS films can only be obtained by a vapor-phase process, because the pHVDS is insoluble in most solvents and thus infeasible with conventional solution-based methods. Moreover, even after the pHVDS coating, the initial porous structure of the separator is well preserved owing to the conformal vapor-phase deposition. The coating thickness is delicately controlled by deposition time to the level that the pore size decreases to below 7% compared to the original dimension. The pHVDS-coated PE shows substantially improved thermal stability and electrolyte wettability. After incubation at 140 °C for 30 min, the pHVDS-coated PE causes only a 12% areal shrinkage (versus 90% of the pristine separator). The superior wettability results in increased electrolyte uptake and ionic conductivity, leading to significantly improved rate performance. The current approach is applicable to a wide range of porous polymeric separators that suffer from thermal shrinkage and poor electrolyte wetting.

  13. Electrochemical deposition of zinc selenide and cadmium selenide onto porous silicon from aqueous acidic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Chubenko, E.B., E-mail: eugene.chubenko@gmail.co [Department of Micro and Nanoelectronics, Belarusian State University of Informatics and Radioelectronics, Minsk 220013 (Belarus); Klyshko, A.A.; Petrovich, V.A.; Bondarenko, V.P. [Department of Micro and Nanoelectronics, Belarusian State University of Informatics and Radioelectronics, Minsk 220013 (Belarus)

    2009-09-01

    An electrochemical deposition process of ZnSe and CdSe compound semiconductors from aqueous acidic solutions onto silicon substrates with porous silicon layers formed on their surfaces was studied by the voltammetry method. The experimental data obtained were compared with the deposition data onto metal and silicon substrates, and the optimal conditions for the binary compound deposition onto porous silicon were determined. Semiconductor films deposited were studied by scanning electron microscopy, X-ray diffractometry, and X-ray microanalysis. The films are shown to have the crystalline structure and a nearly stoichiometric composition with a minor Se excess. Further annealing in air for 15 min allowed the Se concentration to be decreased.

  14. Charging effects during focused electron beam induced deposition of silicon oxide

    NARCIS (Netherlands)

    de Boer, Sanne K.; van Dorp, Willem F.; De Hosson, Jeff Th. M.

    2011-01-01

    This paper concentrates on focused electron beam induced deposition of silicon oxide. Silicon oxide pillars are written using 2, 4, 6, 8, 10-pentamethyl-cyclopenta-siloxane (PMCPS) as precursor. It is observed that branching of the pillar occurs above a minimum pillar height. The branching is attrib

  15. Direct chemical vapour deposited grapheme synthesis on silicon oxide by controlled copper dewettting

    NARCIS (Netherlands)

    van den Beld, Wesley Theodorus Eduardus; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    In this paper we present a novel method for direct uniform graphene synthesis onto silicon oxide in a controlled manner. On a grooved silicon oxide wafer is copper deposited under a slight angle and subsequently the substrate is treated by a typical graphene synthesis process. During this process

  16. Direct chemical vapour deposited grapheme synthesis on silicon oxide by controlled copper dewettting

    NARCIS (Netherlands)

    Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.

    2015-01-01

    In this paper we present a novel method for direct uniform graphene synthesis onto silicon oxide in a controlled manner. On a grooved silicon oxide wafer is copper deposited under a slight angle and subsequently the substrate is treated by a typical graphene synthesis process. During this process di

  17. Growth and microstructure properties of microcrystalline silicon films deposited using jet-ICPCVD

    Institute of Scientific and Technical Information of China (English)

    Zuo Zewen; Guan Wentian; Xin Yu; Lü Jin; Wang Junzhuan; Pu Lin; Shi Yi; Zheng Youdou

    2011-01-01

    Microcrystalline silicon films were deposited at a high rate and low temperature using jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD).An investigation into the deposition rate and microstructure properties of the deposited films showed that a high deposition rate of over 20 nm/s can be achieved while maintaining reasonable material quality.The deposition rate can be controlled by regulating the generation rate and transport of film growth precursors.The film with high crystallinity deposited at low temperature could principally result from hydrogen-induced chemical annealing.

  18. High collection efficiency CVD diamond alpha detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bergonzo, P.; Foulon, F.; Marshall, R.D.; Jany, C.; Brambilla, A. [CEA/Saclay, Gif-sur-Yvette (France); McKeag, R.D.; Jackman, R.B. [University College London (United Kingdom). Electronic and Electrical Engineering Dept.

    1998-06-01

    Advances in Chemical Vapor Deposited (CVD) diamond have enabled the routine use of this material for sensor device fabrication, allowing exploitation of its unique combination of physical properties (low temperature susceptibility (> 500 C), high resistance to radiation damage (> 100 Mrad) and to corrosive media). A consequence of CVD diamond growth on silicon is the formation of polycrystalline films which has a profound influence on the physical and electronic properties with respect to those measured on monocrystalline diamond. The authors report the optimization of physical and geometrical device parameters for radiation detection in the counting mode. Sandwich and co-planar electrode geometries are tested and their performances evaluated with regard to the nature of the field profile and drift distances inherent in such devices. The carrier drift length before trapping was measured under alpha particles and values as high as 40% of the overall film thickness are reported. Further, by optimizing the device geometry, they show that a gain in collection efficiency, defined as the induced charge divided by the deposited charge within the material, can be achieved even though lower bias values are used.

  19. Preparation of high-quality hydrogenated amorphous silicon film with a new microwave electron cyclotron resonance chemical vapour deposition system assisted with hot wire

    Institute of Scientific and Technical Information of China (English)

    Zhu Xiu-Hong; Chen Guang-Hua; Yin Sheng-Yi; Rong Yan-Dong; Zhang Wen-Li; Hu Yue-Hui

    2005-01-01

    The preparation of high-quality hydrogenated amorphous silicon (a-Si:H) film with a new microwave electron cyclotron resonance-chemical vapour deposition (MWECR-CVD) system assisted with hot wire is presented. In this system the hot wire plays an important role in perfecting the microstructure as well as improving the stability and the optoelectronic properties of the a-Si:H film. The experimental results indicate that in the microstructure of the a-Si:H film, the concentration of dihydride is decreased and a trace of microcrystalline occurs, which is useful to improve its stability, and that in the optoelectronic properties of the a-Si:H film, the deposition rate reaches above 2.0nm/s and the photosensitivity increases up to 4.71× 105.

  20. Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

    Science.gov (United States)

    Ballinger, Jared

    . Surface boriding was implemented using the novel method of microwave plasma CVD with a mixture of hydrogen and diborane gases. On 440C bearings, dual phase boride layers of Fe2B and FeB were formed which supported adhered nanostructured diamond films. Continuity of the films was not seamless with limited regions remaining uncoated potentially corresponding to delamination of the film as evidenced by the presence of tubular structures presumably composed of sp2 bonded carbon. Surface boriding of 316 stainless steel discs was conducted at various powers and pressures to achieve temperatures ranging from 550-800 °C. The substrate boriding temperature was found to substantially influence the resultant interlayer by altering the metal boride(s) present. The lowest temperatures produced an interlayer where CrB was the single detected phase, higher temperatures yielded the presence of only Fe2B, and a combination of the two phases resulted from an intermediate boriding temperature. Compared with the more common, commercialized boriding methods, this a profound result given the problems posed by the FeB phase in addition to other advantages offered by CVD processes and microwave generated plasmas in general. Indentation testing of the boride layers revealed excellent adhesion strength for all borided interlayers, and above all, no evidence of cracking was observed for a sole Fe2B phase. As with boriding of 440C bearings, subsequent diamond deposition was achieved on these interlayers with substantially improved adhesion strength relative to diamond coated TiN interlayers. Both XRD and Raman spectroscopy confirmed a nanostructured diamond film with interfacial chromium carbides responsible for enhanced adhesion strength. Interlayers consisting solely of Fe2B have displayed an ability to support fully continuous nanostructured diamond films, yet additional study is required for consistent reproduction. This is in good agreement with initial work on pack borided high alloy steels

  1. Finite Element Analysis Modeling of Chemical Vapor Deposition of Silicon Carbide

    Science.gov (United States)

    2014-06-19

    Engineering Physics Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training...deposited by chemical reaction of gas-phase precursors. Chemical reactions, often endothermic , occur in the gas phase as well as on the surfaces in the...rates in CVD are temperature dependent and are endothermic , changing the temperature of the system further [29]. The beauty of the Heat Equation is

  2. A Comparison between Thin-Film Transistors Deposited by Hot-Wire Chemical Vapor Deposition and PECVD

    Directory of Open Access Journals (Sweden)

    Meysam Zarchi

    2015-03-01

    Full Text Available The effect of new growth techniques on the mobility and stability of amorphous silicon (a-Si:H thin film transistors (TFTs has been studied. It was suggested that the key parameter controlling the field-effect mobility and stability is the intrinsic stress in the a-Si:H layer. Amorphous and microcrystalline silicon films were deposited by radiofrequency plasma enhanced chemical vapor deposition (RF-PECVD and hot-wire chemical vapor deposition (HW-CVD at 100 ºC and 25 ºC. Structural properties of these films were measured by Raman Spectroscopy. Electronic properties were measured by dark conductivity, σd, and photoconductivity, σph. For amorphous silicon films deposited by RF-PECVD on PET, photosensitivity's of >105 were obtained at both 100 º C and 25 ºC. For amorphous silicon films deposited by HW-CVD, a photosensitivity of > 105 was obtained at 100 ºC. Microcrystalline silicon films deposited by HW-CVD at 95% hydrogen dilution show σph~ 10-4 Ω-1cm-1, while maintaining a photosensitivity of ~102 at both 100 ºC and 25 ºC. Microcrystalline silicon films with a large crystalline fraction (> 50% can be deposited by HW-CVD all the way down to room temperature.

  3. Optical spectroscopic analyses of CVD plasmas used in the deposition of transparent and conductive ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.; Espinos, J.P.; Yubero, F.; Barranco, A.; Gonzalez-Elipe, A.R. [Instituto de Ciencias de Materiales de Sevilla, CSIC-Universidad de Sevilla (Spain); Cotrino, J. [Universidad de Sevilla, Facultad de Fisica, Dept. de Fisica Atomica, Molecular y Nuclear, Sevilla (Spain)

    2001-07-01

    Transparent conducting ZnO:A1 thin films have been prepared by remote plasma enhanced chemical vapor deposition. Emission line profiles were recorded as a function of different plasma gas composition (oxygen and hydrogen mixtures) and different rates of precursors (Zn(C{sub 2}H{sub 5}){sub 2} and A1(CH{sub 3}){sub 3}) in the downstream zone of the plasma reactor. Optical emission spectroscopy were used to characterize the oxygen/hydrogen plasma as a function of hydrogen flow rate. The variation of plasma hydrogen content has an important influence in the resistivity of the films. (authors)

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

    Science.gov (United States)

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

    2014-01-01

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

  5. Optoelectronic properties of hot-wire silicon layers deposited at 100 °C

    NARCIS (Netherlands)

    Brinza, M.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2008-01-01

    Hot-wire chemical vapor deposition is employed for the deposition of amorphous and microcrystalline silicon layers at substrate temperature kept below 100 °C with the aid of active cooling of the substrate holder. The hydrogen dilution is varied in order to investigate films at the amorphous-to-micr

  6. Characterization and modeling of atomic layer deposited high-density trench capacitors in silicon

    NARCIS (Netherlands)

    Matters-Kammerer, M.K.; Jinesh, K.B.; Rijks, T.G.S.M.; Roozeboom, F.; Klootwijk, J.H.

    2012-01-01

    A detailed electrical analysis of multiple layer trench capacitors fabricated in silicon with atomic-layer-deposited Al 2O 3 and TiN is presented. It is shown that in situ ozone annealing of the Al 2O 3 layers prior to the TiN electrode deposition significantly improves the electric properties of th

  7. Uniform-sized silicone oil microemulsions: preparation, investigation of stability and deposition on hair surface.

    Science.gov (United States)

    Nazir, Habiba; Lv, Piping; Wang, Lianyan; Lian, Guoping; Zhu, Shiping; Ma, Guanghui

    2011-12-01

    Emulsions are commonly used in foods, pharmaceuticals and home-personal-care products. For emulsion based products, it is highly desirable to control the droplet size distribution to improve storage stability, appearance and in-use property. We report preparation of uniform-sized silicone oil microemulsions with different droplets diameters (1.4-40.0 μm) using SPG membrane emulsification technique. These microemulsions were then added into model shampoos and conditioners to investigate the effects of size, uniformity, and storage stability on silicone oil deposition on hair surface. We observed much improved storage stability of uniform-sized microemulsions when the droplets diameter was ≤22.7 μm. The uniform-sized microemulsion of 40.0 μm was less stable but still more stable than non-uniform sized microemulsions prepared by conventional homogenizer. The results clearly indicated that uniform-sized droplets enhanced the deposition of silicone oil on hair and deposition increased with decreasing droplet size. Hair switches washed with small uniform-sized droplets had lower values of coefficient of friction compared with those washed with larger uniform and non-uniform droplets. Moreover the addition of alginate thickener in the shampoos and conditioners further enhanced the deposition of silicone oil on hair. The good correlation between silicone oil droplets stability, deposition on hair and resultant friction of hair support that droplet size and uniformity are important factors for controlling the stability and deposition property of emulsion based products such as shampoo and conditioner.

  8. Electroless deposition, post annealing and characterization of nickel films on silicon

    Indian Academy of Sciences (India)

    Subir Sabharwal; Siddharth Palit; R B Tokas; A K Poswal; Sangeeta

    2008-10-01

    Electroless deposition of nickel (EN) films on -type silicon has been investigated under different process conditions. The interface between the film and substrate has been characterized for electrical properties by probing the contact resistances. X-ray diffraction and atomic force microscopy have been performed to obtain information about the structural and morphological details of the films. As a comparative study, nickel films have also been sputter deposited on silicon substrates. An as-deposited electroless film is observed to form non-ohmic contact while in a sputtered film prepared without the application of substrate heating, the formation of metal–insulating–semiconductor type junction is seen.

  9. Pulse-height defect in single-crystal CVD diamond detectors

    Energy Technology Data Exchange (ETDEWEB)

    Beliuskina, O.; Imai, N. [The University of Tokyo, Center for Nuclear Study, Wako, Saitama (Japan); Strekalovsky, A.O.; Aleksandrov, A.A.; Aleksandrova, I.A.; Ilich, S.; Kamanin, D.V.; Knyazheva, G.N.; Kuznetsova, E.A.; Mishinsky, G.V.; Pyatkov, Yu.V.; Strekalovsky, O.V.; Zhuchko, V.E. [JINR, Flerov Laboratory of Nuclear Reactions, Dubna, Moscow Region (Russian Federation); Devaraja, H.M. [Manipal University, Manipal Centre for Natural Sciences, Manipal, Karnataka (India); Heinz, C. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Giessen (Germany); Heinz, S. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Giessen (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Hofmann, S.; Kis, M.; Kozhuharov, C.; Maurer, J.; Traeger, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Pomorski, M. [CEA, LIST, Diamond Sensor Laboratory, CEA/Saclay, Gif-sur-Yvette (France)

    2017-02-15

    The pulse-height versus deposited energy response of a single-crystal chemical vapor deposition (scCVD) diamond detector was measured for ions of Ti, Cu, Nb, Ag, Xe, Au, and of fission fragments of {sup 252} Cf at different energies. For the fission fragments, data were also measured at different electric field strengths of the detector. Heavy ions have a significant pulse-height defect in CVD diamond material, which increases with increasing energy of the ions. It also depends on the electrical field strength applied at the detector. The measured pulse-height defects were explained in the framework of recombination models. Calibration methods known from silicon detectors were modified and applied. A comparison with data for the pulse-height defect in silicon detectors was performed. (orig.)

  10. High rate deposition of microcrystalline silicon films by high-pressure radio frequency plasma enhanced chemical vapor deposition (PECVD)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared by high- pressure radio-frequency (13.56 MHz) plasma enhanced chemical vapor deposition (rf-PECVD) with a screened plasma. The deposition rate and crystallinity varying with the deposition pressure, rf power, hydrogen dilution ratio and electrodes distance were systematically studied. By optimizing the deposition parameters the device quality μc-Si:H films have been achieved with a high deposition rate of 7.8 /s at a high pressure. The Voc of 560 mV and the FF of 0.70 have been achieved for a single-junction μc-Si:H p-i-n solar cell at a deposition rate of 7.8 /s.

  11. Influence of deposition temperature of thermal ALD deposited Al2O3 films on silicon surface passivation

    Science.gov (United States)

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

    2015-06-01

    The effect of deposition temperature (Tdep) and subsequent annealing time (tanl) of atomic layer deposited aluminum oxide (Al2O3) films on silicon surface passivation (in terms of surface recombination velocity, SRV) is investigated. The pristine samples (as-deposited) show presence of positive fixed charges, QF. The interface defect density (Dit) decreases with increase in Tdep which further decreases with tanl up to 100s. An effective surface passivation (SRV<8 cm/s) is realized for Tdep ≥ 200 °C. The present investigation suggests that low thermal budget processing provides the same quality of passivation as realized by high thermal budget process (tanl between 10 to 30 min).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  13. Molecular fouling resistance of zwitterionic and amphiphilic initiated chemically vapor-deposited (iCVD) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R; Goktekin, E; Wang, MH; Gleason, KK

    2014-08-08

    Biofouling is a universal problem in various applications ranging from water purification to implantable biomedical devices. Recent advances in surface modification have created a rich library of antifouling surface chemistries, many of which can be categorized into one of the two groups: hydrophilic surfaces or amphiphilic surfaces. We report the straightforward preparation of antifouling thin film coatings in both categories via initiated chemical vapor deposition. A molecular force spectroscopy-based method is demonstrated as a rapid and quantitative assessment tool for comparing the differences in antifouling characteristics. The fouling propensity of single molecules, as opposed to bulk protein solution or bacterial culture, is assessed. This method allows for the interrogation of molecular interaction without the complication resulted from protein conformational change or micro-organism group interactions. The molecular interaction follows the same trend as bacterial adhesion results obtained previously, demonstrating that molecular force probe is a valid method for the quantification and mechanistic examination of fouling. In addition, the molecular force spectroscopy-based method is able to distinguish differences in antifouling capability that is not resolvable by traditional static protein adsorption tests. To lend further insight into the intrinsic fouling resistance of zwitterionic and amphiphilic surface chemistries, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, advancing and receding water contact angles, and atomic force microscopy are used to elucidate the film properties that are relevant to their antifouling capabilities.

  14. Directed deposition of silicon nanowires using neopentasilane as precursor and gold as catalyst

    Directory of Open Access Journals (Sweden)

    Britta Kämpken

    2012-07-01

    Full Text Available In this work the applicability of neopentasilane (Si(SiH34 as a precursor for the formation of silicon nanowires by using gold nanoparticles as a catalyst has been explored. The growth proceeds via the formation of liquid gold/silicon alloy droplets, which excrete the silicon nanowires upon continued decomposition of the precursor. This mechanism determines the diameter of the Si nanowires. Different sources for the gold nanoparticles have been tested: the spontaneous dewetting of gold films, thermally annealed gold films, deposition of preformed gold nanoparticles, and the use of “liquid bright gold”, a material historically used for the gilding of porcelain and glass. The latter does not only form gold nanoparticles when deposited as a thin film and thermally annealed, but can also be patterned by using UV irradiation, providing access to laterally structured layers of silicon nanowires.

  15. Effect of argon ion energy on the performance of silicon nitride multilayer permeation barriers grown by hot-wire CVD on polymers

    Energy Technology Data Exchange (ETDEWEB)

    Alpuim, P. [Centro de Física, Universidade do Minho, 4710-057 Braga (Portugal); INL, International Iberian Nanotechnology Laboratory, 4715-330 Braga (Portugal); Majee, S. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France); Cerqueira, M.F. [INL, International Iberian Nanotechnology Laboratory, 4715-330 Braga (Portugal); Tondelier, D. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France); Geffroy, B. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France); Laboratoire d' Innovation de Chimie des Surfaces et des Nanomatériaux, IRAMIS/NIMBE, CNRS UMR 3685, CEA Saclay, 91191 Gif-sur-Yvette (France); Bonnassieux, Y. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France); Bourée, J.E., E-mail: jean-eric.bouree@polytechnique.edu [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, Université Paris-Saclay, 91128 Palaiseau (France)

    2015-11-30

    Permeation barriers for organic electronic devices on polymer flexible substrates were realized by combining stacked silicon nitride (SiN{sub x}) single layers (50 nm thick) deposited by hot-wire chemical vapor deposition process at low-temperature (~ 100°°C) with a specific argon plasma treatment between two successive layers. Several plasma parameters (RF power density, pressure, treatment duration) as well as the number of single layers have been explored in order to improve the quality of permeation barriers deposited on polyethylene terephthalate. In this work, maximum ion energy was highlighted as the crucial parameter making it possible to minimize water vapor transmission rate (WVTR), as determined by the electrical calcium test method, all the other parameters being kept fixed. Thus fixing the plasma treatment duration at 8 min for a stack of two SiN{sub x} single layers, a minimum WVTR of 5 × 10{sup −4} g/(m{sup 2} day), measured at room temperature, was found for a maximum ion energy of ~ 30 eV. This minimum WVTR value was reduced to 7 × 10{sup −5} g/(m{sup 2} day) for a stack of five SiN{sub x} single layers. The reduction in the permeability is interpreted as due to the rearrangement of atoms at the interfaces when average transferred ion energy to target atoms exceeds threshold displacement energy. - Highlights: • Αn original way to achieve permeation barriers on polymer substrates is developed. • It combines SiN{sub x} multilayers grown by HWCVD with an intermediate Ar plasma treatment. • A minimum of water vapor transmission rate is found related to maximum Ar ion energy. • This minimum is due to atomic rearrangement in SiN{sub x} interfaces under the impact of ions. • The average Ar ion energy must exceed atomic threshold displacement energy for Si.

  16. Radiation induced changes in electrical conductivity of chemical vapor deposited silicon carbides under fast neutron and gamma-ray irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Bun, E-mail: btsuchiya@meijo-u.ac.jp [Department of General Education, Faculty of Science and Technology, Meijo University, 1-501, Shiogamaguchi, Tempaku-ku, Nagoya 468-8502 (Japan); Shikama, Tatsuo; Nagata, Shinji; Saito, Kesami [Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamamoto, Syunya [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233, Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Ohnishi, Seiki [Tokai Research and Development Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Nozawa, Takashi [Aomori Research and Development Center, Japan Atomic Energy Agency, 2-166, Omotedate, Obuchi, Rokkasho, Aomori 039-3212 (Japan)

    2011-10-15

    The radiation-induced changes in the volume electrical conductivities of chemical vapor deposited silicon carbides (CVD-SiCs) were in-site investigated by performing irradiation using 1.17 and 1.33-MeV gamma-ray and 14-MeV fast neutron beams in air and vacuum. Under gamma-ray irradiation at ionization dose rates of 3.6 and 5.9 Gy/s and irradiation temperature of approximately 300 K, the initial rapid increase in electrical conductivity; this is indicative of radiation-induced conductivity (RIC), occurred due to electronic excitation, and a more gradual increase followed up to a dose of approximately 10-50 kGy corresponding to the results in base conductivity without radiation; this is indicative of radiation-induced electrical degradation (RIED). However, the radiation-induced phenomena were not observed at irradiation temperatures above 373 K. Under neutron irradiation at a further low dose rate below approximately 2.1 Gy/s, a fast neutron flux of 9.2 x 10{sup 14} n/m{sup 2} s, and 300 K, the RIED-like behavior according to radiation-induced modification of the electrical property occurred with essentially no displacement damage, but ionizing effects (radiolysis).

  17. The Effect of High Temperature Annealing on the Grain Characteristics of a Thin Chemical Vapor Deposition Silicon Carbide Layer.

    Energy Technology Data Exchange (ETDEWEB)

    Isabella J van Rooyen; Philippus M van Rooyen; Mary Lou Dunzik-Gougar

    2013-08-01

    The unique combination of thermo-mechanical and physiochemical properties of silicon carbide (SiC) provides interest and opportunity for its use in nuclear applications. One of the applications of SiC is as a very thin layer in the TRi-ISOtropic (TRISO) coated fuel particles for high temperature gas reactors (HTGRs). This SiC layer, produced by chemical vapor deposition (CVD), is designed to withstand the pressures of fission and transmutation product gases in a high temperature, radiation environment. Various researchers have demonstrated that macroscopic properties can be affected by changes in the distribution of grain boundary plane orientations and misorientations [1 - 3]. Additionally, various researchers have attributed the release behavior of Ag through the SiC layer as a grain boundary diffusion phenomenon [4 - 6]; further highlighting the importance of understanding the actual grain characteristics of the SiC layer. Both historic HTGR fission product release studies and recent experiments at Idaho National Laboratory (INL) [7] have shown that the release of Ag-110m is strongly temperature dependent. Although the maximum normal operating fuel temperature of a HTGR design is in the range of 1000-1250°C, the temperature may reach 1600°C under postulated accident conditions. The aim of this specific study is therefore to determine the magnitude of temperature dependence on SiC grain characteristics, expanding upon initial studies by Van Rooyen et al, [8; 9].

  18. 边界层对三氯氢硅-氢气系统中多晶硅化学气相沉积的影响%Effect of Boundary Layers on Polycrystalline Silicon Chemical Vapor Deposition in a Trichlorosilane and Hydrogen System

    Institute of Scientific and Technical Information of China (English)

    张攀; 王伟文; 陈光辉; 李建隆

    2011-01-01

    This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three chemical vapor deposition (CVD) reactor. A two-dimensional model for the gas flow, heat transfer, and mass transfer was coupled to the gas-phase reaction and surface reaction mechanism for the deposition of polycrystalline silicon from trichlorosilane (TCS)-hydrogen system. The model was verified by comparing the simulated growth rate with the experimental and numerical data in the open literature. Computed results in the reactors indicate that the deposition characteristics are closely related to the momentum, thermal and mass boundary layer thickness. To yield higher deposition rate, there should be higher concentration of TCS gas on the substrate, and there should also be thinner boundary layer of HCI gas so that HCI gas could be pushed away from the surface of the substrate immediately.

  19. Deposition of gold and silver on porous silicon and inside the pores

    Energy Technology Data Exchange (ETDEWEB)

    Nativ-Roth, Einat [Ilse Katz Institute of Nanoscale Science and Technology, Ben-Gurion University of the Negev, Be' er Sheva 84105 (Israel); Rechav, Katya [Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100 (Israel); Porat, Ze' ev, E-mail: poratze@post.bgu.ac.il [Division of Chemistry, Nuclear Research Center–Negev, Be' er Sheva 84190 (Israel); Institutes of Applied research, Ben-Gurion University of the Negev, Be' er Sheva 84105 (Israel)

    2016-03-31

    Silver and gold were spontaneously deposited on porous silicon (PSi) by immersion-plating. Each metal formed crystallites of typical shapes on top of the PSi layer. Deposition of these metals inside the pores could be achieved by performing the immersion-plating in an ultrasonic bath. Top view and cross-section scanning electron microscope images show slight penetration of silver into the pores but massive filling of gold, to depth of several hundreds of nanometers. - Highlights: • Spontaneous reduction of Ag and Au ions occurs on porous silicon (immersion plating). • Such deposition inside the pores is prevented by entrapped hydrogen bubbles. • Immersion plating under sonication releases the gas and enhances ions diffusion. • Silver and gold were deposited within the pores by ultrasonic-aided deposition.

  20. Mechanical and piezoresistive properties of thin silicon films deposited by plasma-enhanced chemical vapor deposition and hot-wire chemical vapor deposition at low substrate temperatures

    Science.gov (United States)

    Gaspar, J.; Gualdino, A.; Lemke, B.; Paul, O.; Chu, V.; Conde, J. P.

    2012-07-01

    This paper reports on the mechanical and piezoresistance characterization of hydrogenated amorphous and nanocrystalline silicon thin films deposited by hot-wire chemical vapor deposition (HWCVD) and radio-frequency plasma-enhanced chemical vapor deposition (PECVD) using substrate temperatures between 100 and 250 °C. The microtensile technique is used to determine film properties such as Young's modulus, fracture strength and Weibull parameters, and linear and quadratic piezoresistance coefficients obtained at large applied stresses. The 95%-confidence interval for the elastic constant of the films characterized, 85.9 ± 0.3 GPa, does not depend significantly on the deposition method or on film structure. In contrast, mean fracture strength values range between 256 ± 8 MPa and 600 ± 32 MPa: nanocrystalline layers are slightly stronger than their amorphous counterparts and a pronounced increase in strength is observed for films deposited using HWCVD when compared to those grown by PECVD. Extracted Weibull moduli are below 10. In terms of piezoresistance, n-doped radio-frequency nanocrystalline silicon films deposited at 250 °C present longitudinal piezoresistive coefficients as large as -(2.57 ± 0.03) × 10-10 Pa-1 with marginally nonlinear response. Such values approach those of crystalline silicon and of polysilicon layers deposited at much higher temperatures.

  1. Liquid-phase-deposited siloxane-based capping layers for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Veith-Wolf, Boris [Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany); Wang, Jianhui; Hannu-Kuure, Milja; Chen, Ning; Hadzic, Admir; Williams, Paul; Leivo, Jarkko; Karkkainen, Ari [Optitune International Pte. Ltd., 20 Maxwell Road, #05-08 Maxwell House, Singapore 069113 (Singapore); Schmidt, Jan [Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal (Germany); Department of Solar Energy, Institute of Solid-State Physics, Leibniz University Hanover, Appelstrasse 2, 30167 Hanover (Germany)

    2015-02-02

    We apply non-vacuum processing to deposit dielectric capping layers on top of ultrathin atomic-layer-deposited aluminum oxide (AlO{sub x}) films, used for the rear surface passivation of high-efficiency crystalline silicon solar cells. We examine various siloxane-based liquid-phase-deposited (LPD) materials. Our optimized AlO{sub x}/LPD stacks show an excellent thermal and chemical stability against aluminum metal paste, as demonstrated by measured surface recombination velocities below 10 cm/s on 1.3 Ωcm p-type silicon wafers after firing in a belt-line furnace with screen-printed aluminum paste on top. Implementation of the optimized LPD layers into an industrial-type screen-printing solar cell process results in energy conversion efficiencies of up to 19.8% on p-type Czochralski silicon.

  2. Ion assisted deposition of SiO2 film from silicon

    Science.gov (United States)

    Pham, Tuan. H.; Dang, Cu. X.

    2005-09-01

    Silicon dioxide, SiO2, is one of the preferred low index materials for optical thin film technology. It is often deposited by electron beam evaporation source with less porosity and scattering, relatively durable and can have a good laser damage threshold. Beside these advantages the deposition of critical optical thin film stacks with silicon dioxide from an E-gun was severely limited by the stability of the evaporation pattern or angular distribution of the material. The even surface of SiO2 granules in crucible will tend to develop into groove and become deeper with the evaporation process. As the results, angular distribution of the evaporation vapor changes in non-predicted manner. This report presents our experiments to apply Ion Assisted Deposition process to evaporate silicon in a molten liquid form. By choosing appropriate process parameters we can get SiO2 film with good and stable property.

  3. Si Passivation and Chemical Vapor Deposition of Silicon Nitride: Final Technical Report, March 18, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Atwater, H. A.

    2007-11-01

    This report investigated chemical and physical methods for Si surface passivation for application in crystalline Si and thin Si film photovoltaic devices. Overall, our efforts during the project were focused in three areas: i) synthesis of silicon nitride thin films with high hydrogen content by hot-wire chemical vapor deposition; ii) investigation of the role of hydrogen passivation of defects in crystalline Si and Si solar cells by out diffusion from hydrogenated silicon nitride films; iii) investigation of the growth kinetics and passivation of hydrogenated polycrystalline. Silicon nitride films were grown by hot-wire chemical vapor deposition and film properties have been characterized as a function of SiH4/NH3 flow ratio. It was demonstrated that hot-wire chemical vapor deposition leads to growth of SiNx films with controllable stoichiometry and hydrogen.

  4. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography

    Science.gov (United States)

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-01

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga+ ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90–210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  5. On the origin of self-organization of SiO2 nanodots deposited by CVD enhanced by atmospheric pressure remote microplasma

    Science.gov (United States)

    Arnoult, G.; Belmonte, T.; Kosior, F.; Dossot, M.; Henrion, G.

    2011-05-01

    The origin of organization of nanostructured silica coatings deposited on stainless steel substrates by remote microplasma at atmospheric pressure is investigated. We show by resorting to thermal camera measurements coupled with modelling that deposition, limited to a few seconds in time, occurs at low temperature (~below 420 K) although the gas temperature may reach 1400 K. Raman analyses of deposited films with thicknesses below 1 µm show the presence of oxidized silicon bonded to the metallic surface. The origin of nanodots is explained as follows. Close to the microplasma nozzle, the concentration of oxidizing species and/or the temperature being high enough, a silica thin film is obtained, leading to ceramic-metallic oxide interface that leads to a Volmer-Weber growth mode and to the synthesis of 3D structures over long treatment times. Far from the nozzle, the reactivity decreasing, thin films get a plasma-polymer like behaviour which leads to a Franck-Van der Merwe growth mode and films with a higher density. Other nanostructures, made of hexagonal cells, are observed but remain unexplained.

  6. On the origin of self-organization of SiO{sub 2} nanodots deposited by CVD enhanced by atmospheric pressure remote microplasma

    Energy Technology Data Exchange (ETDEWEB)

    Arnoult, G; Belmonte, T; Kosior, F; Henrion, G [Institut Jean Lamour, Department of Physics and Chemistry of Solids and Surfaces, UMR 7198 CNRS, Nancy-Universite, Parc de Saurupt, CS 14234, F-54042 Nancy Cedex (France); Dossot, M, E-mail: thierry.belmonte@mines.inpl-nancy.fr [Laboratoire de Chimie Physique et Microbiologie pour l' Environnement, UMR 7564 CNRS - Universite Henri Poincare, Nancy-Universite, 405, rue de Vandoeuvre, F-54600 Villers-les-Nancy (France)

    2011-05-04

    The origin of organization of nanostructured silica coatings deposited on stainless steel substrates by remote microplasma at atmospheric pressure is investigated. We show by resorting to thermal camera measurements coupled with modelling that deposition, limited to a few seconds in time, occurs at low temperature ({approx}below 420 K) although the gas temperature may reach 1400 K. Raman analyses of deposited films with thicknesses below 1 {mu}m show the presence of oxidized silicon bonded to the metallic surface. The origin of nanodots is explained as follows. Close to the microplasma nozzle, the concentration of oxidizing species and/or the temperature being high enough, a silica thin film is obtained, leading to ceramic-metallic oxide interface that leads to a Volmer-Weber growth mode and to the synthesis of 3D structures over long treatment times. Far from the nozzle, the reactivity decreasing, thin films get a plasma-polymer like behaviour which leads to a Franck-Van der Merwe growth mode and films with a higher density. Other nanostructures, made of hexagonal cells, are observed but remain unexplained.

  7. Methods of depositing an alpha-silicon-carbide-containing film at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Habermehl, Scott D.

    2017-01-17

    Described methods are useful for depositing a silicon carbide film including Alpha-SiC at low temperatures (e.g., below about 1400.degree. C.), and resulting multi-layer structures and devices. A method includes introducing a chlorinated hydrocarbon gas and a chlorosilicon gas into a reaction chamber, and reacting the chlorinated hydrocarbon gas with the chlorosilicon gas at a temperature of less than about 1400.degree. C. to grow the silicon carbide film. The silicon carbide film so-formed includes Alpha-SiC.

  8. Plasma deposition of microcrystalline silicon solar cells. Looking beyond the glass

    Energy Technology Data Exchange (ETDEWEB)

    Donker, M.N. van den

    2006-07-01

    Microcrystalline silicon emerged in the past decade as highly interesting material for application in efficient and stable thin film silicon solar cells. It consists of nanometer-sized crystallites embedded in a micrometer-sized columnar structure, which gradually evolves during the SiH{sub 4} based deposition process starting from an amorphous incubation layer. Understanding of and control over this transient and multi-scale growth process is essential in the route towards low-cost microcrystalline silicon solar cells. This thesis presents an experimental study on the technologically relevant high rate (5-10 Aa s{sup -1}) parallel plate plasma deposition process of state-of-the-art microcrystalline silicon solar cells. The objective of the work was to explore and understand the physical limits of the plasma deposition process as well as to develop diagnostics suitable for process control in eventual solar cell production. Among the developed non-invasive process diagnostics were a pyrometer, an optical spectrometer, a mass spectrometer and a voltage probe. Complete thin film silicon solar cells and modules were deposited and characterized. (orig.)

  9. High deposition rate nanocrystalline silicon with enhanced homogeneity

    NARCIS (Netherlands)

    Verkerk, A.; Rath, J.K.; Schropp, R.E.I.

    2010-01-01

    High rate growth of hydrogenated nanocrystalline silicon (nc-Si:H) brings additional challenges for the homogeneity in the growth direction, since the start-up effects affect a larger portion of the film, and the very high degree of depletion increases the influence of back diffusion from the inacti

  10. Nano-scratch study of molecular deposition (MD) films on silicon wafer using nanoindentation~1

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Experiment of the molecular deposition (MD) films with and without alkyl terminal de-posited on the silicon wafer were conducted by using nanoindentation. It was found that MD filmsand alkyl terminated MD films exhibit higher critical load (scratch resistance or adhesive strength)and lower coefficient of friction compared with the silicon substrate. Critical load (scratch resis-tance) increases with the number of layers, and coefficients of friction of those MD film with alkylterminal are still best for the same layer of MD film.

  11. Strain Release Induced Novel Fluorescence Variation in CVD-Grown Monolayer WS2 Crystals.

    Science.gov (United States)

    Feng, Shanghuai; Yang, Ruilong; Jia, Zhiyan; Xiang, Jianyong; Wen, Fusheng; Mu, Congpu; Nie, Anmin; Zhao, Zhisheng; Xu, Bo; Tao, Chenggang; Tian, Yongjun; Liu, Zhongyuan

    2017-10-04

    Tensile strain is intrinsic to monolayer crystals of transition metal disulfides such as Mo(W)S2 grown on oxidized silicon substrates by chemical vapor deposition (CVD) owing to the much larger thermal expansion coefficient of Mo(W)S2 than that of silica. Here we report fascinating fluorescent variation in intensity with aging time in CVD-grown triangular monolayer WS2 crystals on SiO2 (300 nm)/Si substrates and formation of interesting concentric triangular fluorescence patterns in monolayer crystals of large size. The novel fluorescence aging behavior is recognized to be induced by the partial release of intrinsic tensile strain after CVD growth and the induced localized variations or gradients of strain in the monolayer crystals. The results demonstrate that strain has a dramatic impact on the fluorescence and photoluminescence of monolayer WS2 crystals and thus could potentially be utilized to tune electronic and optoelectronic properties of monolayer transition metal disulfides.

  12. Silicon epitaxy using tetrasilane at low temperatures in ultra-high vacuum chemical vapor deposition

    Science.gov (United States)

    Hazbun, Ramsey; Hart, John; Hickey, Ryan; Ghosh, Ayana; Fernando, Nalin; Zollner, Stefan; Adam, Thomas N.; Kolodzey, James

    2016-06-01

    The deposition of silicon using tetrasilane as a vapor precursor is described for an ultra-high vacuum chemical vapor deposition tool. The growth rates and morphology of the Si epitaxial layers over a range of temperatures and pressures are presented. The layers were characterized using transmission electron microscopy, x-ray diffraction, spectroscopic ellipsometry, Atomic Force Microscopy, and secondary ion mass spectrometry. Based on this characterization, high quality single crystal silicon epitaxy was observed. Tetrasilane was found to produce higher growth rates relative to lower order silanes, with the ability to deposit crystalline Si at low temperatures (T=400 °C), with significant amorphous growth and reactivity measured as low as 325 °C, indicating the suitability of tetrasilane for low temperature chemical vapor deposition such as for SiGeSn alloys.

  13. High quality plasma-enhanced chemical vapor deposited silicon nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Cotler, T.J.; Chapple-Sokol, J. (IBM General Technology Division, Hopewell Junction, NY (United States))

    1993-07-01

    The qualities of plasma-enhanced chemical vapor deposited (PECVD) silicon nitride films can be improved by increasing the deposition temperature. This report compares PECVD silicon nitride films to low pressure chemical vapor deposited (LPCVD) films. The dependence of the film properties on process parameters, specifically power and temperature, are investigated. The stress is shown to shift from tensile to compressive with increasing temperature and power. The deposition rate, uniformity, wet etch rate, index of refraction, composition, stress, hydrogen content, and conformality are considered to evaluate the film properties. Temperature affects the hydrogen content in the films by causing decreased incorporation of N-H containing species whereas the dependence on power is due to changes in the gas-phase precursors. All PECVD film properties, with the exception of conformality, are comparable to those of LPCVD films.

  14. Dispersion engineered high-Q silicon Nitride Ring-Resonators via Atomic Layer Deposition

    CERN Document Server

    Riemensberger, Johann; Herr, Tobias; Brasch, Victor; Holzwarth, Ronald; Kippenberg, Tobias J

    2012-01-01

    We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition (ALD). Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. All results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

  15. INFLUENCE OF THE SILICON INTERLAYER ON DIAMOND-LIKE CARBON FILMS DEPOSITED ON GLASS SUBSTRATES

    Directory of Open Access Journals (Sweden)

    Deiler Antonio Lima Oliveira

    2012-06-01

    Full Text Available Diamond-like carbon (DLC films as a hard protective coating have achieved great success in a diversity of technological applications. However, adhesion of DLC films to substrates can restrict their applications. The influence of a silicon interlayer in order to improve DLC adhesion on glass substrates was investigated. Amorphous silicon interlayer and DLC films were deposited using plasma enhanced chemical vapor deposition from silane and methane, respectively. The bonding structure, transmittance, refraction index, and adherence of the films were also evaluated regarding the thickness of the silicon interlayer. Raman scattering spectroscopy did not show any substantial difference in DLC structure due to the interlayer thickness of the silicon. Optical measurements showed a sharp decrease of transmittance in the ultra-violet region caused by the fundamental absorption of the light. In addition, the absorption edge of transmittance shifted toward longer wavelength side in the ultra-violet region as the thickness of the silicon interlayer increased. The tribological results showed an increase of DLC adherence as the silicon interlayer increased, which was characterized by less cracks around the grooves.

  16. Effect of the initial structure on the electrical property of crystalline silicon films deposited on glass by hot-wire chemical vapor deposition.

    Science.gov (United States)

    Chung, Yung-Bin; Lee, Sang-Hoon; Bae, Sung-Hwan; Park, Hyung-Ki; Jung, Jae-Soo; Hwang, Nong-Moon

    2012-07-01

    Crystalline silicon films on an inexpensive glass substrate are currently prepared by depositing an amorphous silicon film and then crystallizing it by excimer laser annealing, rapid thermal annealing, or metal-induced crystallization because crystalline silicon films cannot be directly deposited on glass at a low temperature. It was recently shown that by adding HCI gas in the hot-wire chemical vapor deposition (HWCVD) process, the crystalline silicon film can be directly deposited on a glass substrate without additional annealing. The electrical properties of silicon films prepared using a gas mixture of SiH4 and HCl in the HWCVD process could be further improved by controlling the initial structure, which was achieved by adjusting the delay time in deposition. The size of the silicon particles in the initial structure increased with increasing delay time, which increased the mobility and decreased the resistivity of the deposited films. The 0 and 5 min delay times produced the silicon particle sizes of approximately 10 and approximately 28 nm, respectively, in the initial microstructure, which produced the final films, after deposition for 300 sec, of resistivities of 0.32 and 0.13 Omega-cm, mobilities of 1.06 and 1.48 cm2 V(-1) S(-1), and relative densities of 0.87 and 0.92, respectively.

  17. In situ transmission infrared spectroscopy of high-kappa oxide atomic layer deposition onto silicon surfaces

    Science.gov (United States)

    Ho, Ming-Tsung

    Ultra-thin aluminum oxide (Al2O3) and hafnium oxide (HfO2) layers have been grown by atomic layer deposition (ALD) using tri-methyl-aluminum (TMA) and tetrakis-ethyl-methyl-amino-hafnium (TEMAH) respectively with heavy water (D2O) as the oxidizing agent. Several different silicon surfaces were used as substrates such as hydrogen terminated silicon (H/Si), SC2 (or RCA 2) cleaned native silicon oxide (SiO 2/Si), and silicon (oxy)nitride. In-situ transmission Fourier transform infrared spectroscopy (FTIR) has been adopted for the study of the growth mechanisms during ALD of these films. The vibrational spectra of gas phase TEMAH and its reaction byproducts with oxidants have also been investigated. Density functional theory (DFT) normal mode calculations show a good agreement with the experimental data when it is combined with linear wave-number scaling method and Fermi resonance mechanism. Ether (-C-O-C-) and tertiary alkylamine (N(R1R 2R3)) compounds are the two most dominant products of TEMAH reacting with oxygen gas and water. When ozone is used as the oxidant, gas phase CH2O, CH3NO2, CH3-N=C=O and other compounds containing -(C=O)- and --C-O-C- (or --O-C-) segments are observed. With substrate temperatures less than 400°C and 300°C for TMA and TEMAH respectively, Al oxide and Hf oxide ALD can be appropriately performed on silicon surfaces. Thin silicon (oxy)nitride thermally grown in ammonia on silicon substrate can significantly reduce silicon oxide interlayer formation during ALD and post-deposition annealing. The crystallization temperature of amorphous ALD grown HfO2 on nitridized silicon is 600°C, which is 100°C higher than on the other silicon surfaces. When HfO2 is grown on H/Si(111) at 100°C deposition temperature, minimum 5--10 ALD cycles are required for the full surface coverage. The steric effect can be seen by the evolution of the H-Si stretching mode at 2083 cm-1. The observed red shift of H-Si stretching to ˜ 2060 cm-1 can be caused by Si

  18. Surface Characteristics and Catalytic Activity of Copper Deposited Porous Silicon Powder

    Directory of Open Access Journals (Sweden)

    Muhammad Yusri Abdul Halim

    2014-12-01

    Full Text Available Porous structured silicon or porous silicon (PS powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO3: H2O (1:3:5 v/v. An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO4 in the presence of HF. Scanning electron microscopy (SEM analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H2-temperature programmed reduction (H2-TPR profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings.

  19. 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.

  20. Electrical properties of plasma-deposited silicon oxide clarified by chemical modeling

    NARCIS (Netherlands)

    Kovalgin, A.Y.; Boogaard, A.; Brunets, I.; Aarnink, A.A.I.; Wolters, R.A.M.

    2009-01-01

    Our study is focused on Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon dioxide films at low temperatures (< 150 oC) using Inductively Coupled (IC) High-Density (HD) plasma source. We recently fabricated Thin Film Transistors (TFTs) with high-quality ICPECVD gate oxides, which exhibited

  1. Photoselective Metal Deposition on Amorphous Silicon p-i-n Solar Cells

    NARCIS (Netherlands)

    Kooij, E.S.; Hamoumi, M.; Kelly, J.J.; Schropp, R.E.I.

    1997-01-01

    A novel method is described for the patternwise metallization of amorphous silicon solar cells, based on photocathodic deposition. The electric field of the p-i-n structure is used for the separation of photogenerated charge carriers. The electrons are driven to the interface of the n+-layer with th

  2. Preparation of lanthanum fluoride nanolayers by depositing ionic layers on silicon surface

    Energy Technology Data Exchange (ETDEWEB)

    Zhuchkov, B.S.; Tolstoi, V.P.; Murin, I.V.; Kirillov, S.N. [St. Petersburg State Univ. (Russian Federation)

    1995-11-10

    The kinetics of growth of LaF{sub 3} nanolayers on silicon surface was studied. Influences due to preparation conditions (the concentration and the pH values of the solution, the time of surface treatment, the number of cycles of ionic layer deposition) were evaluated.

  3. On the intrinsic moisture permeation rate of remote microwave plasma-deposited silicon nitride layers

    NARCIS (Netherlands)

    Assche, F.J.H. Van; Unnikrishnan, S.; Michels, J.J.; Mol, A.M.B. van; Weijer, P. van de; Sanden, M.C.M. van de; Creatore, M.

    2014-01-01

    We report on a low substrate temperature (110°C) remote microwave plasma-enhanced chemical vapor deposition (PECVD) process of silicon nitride barrier layers against moisture permeation for organic light emitting diodes (OLEDs) and other moisture sensitive devices such as organic photovoltaic cells

  4. Controlled deposition and combing of DNA across lithographically defined patterns on silicon

    DEFF Research Database (Denmark)

    Nazari, Zeniab Esmail; Gurevich, Leonid

    2013-01-01

    We have developed a new procedure for efficient combing of DNA on a silicon substrate, which allows reproducible deposition and alignment of DNA molecules across lithographically defined patterns. The technique involves surface modification of Si/SiO2 substrates with a hydrophobic silane by using...

  5. Spatial control of direct chemical vapor deposition of graphene on silicon dioxide by directional copper dewetting

    NARCIS (Netherlands)

    van den Beld, Wesley Theodorus Eduardus; van den Berg, Albert; Eijkel, Jan C.T.

    2016-01-01

    In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated

  6. A mathematical model and simulation results of plasma enhanced chemical vapor deposition of silicon nitride films

    NARCIS (Netherlands)

    Konakov, S.A.; Krzhizhanovskaya, V.V.

    2015-01-01

    We developed a mathematical model of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride thin films from SiH4-NH3-N2-Ar mixture, an important application in modern materials science. Our multiphysics model describes gas dynamics, chemical physics, plasma physics and electrodynamics.

  7. Metal Nanoparticles Deposited on Porous Silicon Templates as Novel Substrates for SERS

    Directory of Open Access Journals (Sweden)

    Lara Mikac

    2015-12-01

    Full Text Available In this paper, results on preparation of stable and uniform SERS solid substrates using macroporous silicon (pSi with deposited silver and gold are presented. Macroporous silicon is produced by anodisation of p-type silicon in hydrofluoric acid. The as prepared pSi is then used as a template for Ag and Au depositions. The noble metals were deposited in three different ways: by immersion in silver nitrate solution, by drop-casting silver colloidal solution and by pulsed laser ablation (PLA. Substrates obtained by different deposition processes were evaluated for SERS efficiency using methylene blue (MB and rhodamine 6G (R6G at 514.5, 633 and 785 nm. Using 514.5 nm excitation and R6G the limits of detection (LOD for macroporous Si samples with noble metal nanostructures obtained by immersion of pSi sample in silver nitrate solution and by applying silver colloidal solution to pSi template were 10–9 M and 10–8 M respectively. Using 633 nm laser and MB the most noticeable SERS activity gave pSi samples ablated with 30000 and 45000 laser pulses where the LODs of 10–10 M were obtained. The detection limit of 10–10 M was also reached for 4 mA cm–2-15 min pSi sample, silver ablated with 30000 pulses. Macroporous silicon proved to be a good base for the preparation of SERS substrates.

  8. Hydrogenated Silicon Layers and Solar Cells Deposited at Very Low Substrate Temperature

    NARCIS (Netherlands)

    Bronsveld, P.C.P.

    2013-01-01

    For direct production of solar cells on cheap plastics, the quality of VHF-PECVD deposited intrinsic and doped silicon layers made at substrate temperatures ≤ 100 °C was optimized. The investigation showed that at lower substrate temperatures, higher hydrogen dilution of the source gas silane was re

  9. Spatial control of direct chemical vapor deposition of graphene on silicon dioxide by directional copper dewetting

    NARCIS (Netherlands)

    Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.

    2016-01-01

    In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated usin

  10. Low Hydrogen Content Silicon Nitride Films Deposited at Room Temperature with an ECR Plasma Source

    NARCIS (Netherlands)

    Isai, Gratiela I.; Holleman, Jisk; Wallinga, Hans; Woerlee, Pierre H.

    2004-01-01

    Silicon nitride layers with very low hydrogen content (less than 1 atomic percent) were deposited at near room temperature, from N2 and SiH4, with a multipolar electron cyclotron resonance plasma. The influences of pressure and nitrogen flow rate on physical and electrical properties were studied in

  11. Silicon protected with atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Seger, Brian; Tilley, David S.; Pedersen, Thomas

    2013-01-01

    dioxide (TiO2) overlayers on silicon-based photocathodes generate extremely stable electrodes. These electrodes can produce an onset potential of +0.510 V vs. RHE and a hydrogen evolution saturation current of 22 mA cm−2 using the red part of the AM1.5 solar spectrum (λ > 635 nm, 38.6 mW cm−2). A PEC...... chronoamperometry experiment was carried out for 2 weeks under constant illumination at +0.300 V vs. RHE with negligible degradation (TiO2 overlayers may have...

  12. The potential of nano-structured silicon oxide type coatings deposited by PACVD for control of aquatic biofouling

    NARCIS (Netherlands)

    Akesso, L.; Pettitt, M.E.; Callow, J.A.; Callow, M.E.; Stallard, J.; Teer, D.; Liu, C.; Wang, S.; Zhao, Q.; D'Souza, F.; Willemsen, P.R.; Donnelly, G.T.; Donik, C.; Kocijan, A.; Jenko, M.; Jones, L.A.; Guinaldo, P.C.

    2009-01-01

    SiOx-like coatings were deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD (PACVD). Surface energies (23.1-45.7 mJ m-1) were correlated with the degree of surface oxidation and hydrocarbon contents. Tapping mode AFM revealed a range of surface topologies with Ra val

  13. Formation of aluminum films on silicon by ion beam deposition: A comparison with ionized cluster beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zuhr, R.A.; Haynes, T.E.; Galloway, M.D. (Oak Ridge National Lab., TN (USA)); Tanaka, S.; Yamada, A.; Yamada, I. (Kyoto Univ. (Japan). Ion Beam Engineering Lab.)

    1990-01-01

    The direct ion beam deposition (IBD) technique has been used to study the formation of oriented aluminum films on single crystal silicon substrates. In the IBD process, thin film growth is accomplished by decelerating a magnetically-analyzed ion beam to low energies (10--200 eV) for direct deposition onto the substrate under UHV conditions. The energy of the incident ions can be selected to provide the desired growth conditions, and the mass analysis ensures good beam purity. The aluminum on silicon system is one which has been studied extensively by ionized cluster beam (ICB) deposition. In this work, we have studied the formation of such films by IBD with emphasis on the effects of ion energy, substrate temperature, and surface cleanliness. Oriented films have been grown on Si(111) at temperatures from 40{degree} to 300{degree}C and with ion energies from 30 to 120 eV per ion. Completed films were analyzed by ion scattering, x-ray diffraction, scanning electron microscopy, and optical microscopy. Results achieved for thin films grown by IBD are compared with results for similar films grown by ICB deposition. 15 refs., 3 figs.

  14. Improvement of the Crystallinity of Silicon Films Deposited by Hot-Wire Chemical Vapor Deposition with Negative Substrate Bias

    Science.gov (United States)

    Zhang, Lei; Shen, Honglie; You, Jiayi

    2013-08-01

    We have investigated the effect of negative substrate bias on microcrystalline silicon films deposited on glass and stainless steel by hot-wire chemical vapor deposition (HWCVD) to gain insight into the effect of negative substrate bias on crystallization. Structural characterization of the silicon films was performed by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. It was found that the crystallinity of the films is obviously improved by applying the substrate bias, especially for films on stainless steel. At hot-wire temperature of 1800°C and negative substrate bias of -800 V, grain size as large as 200 nm was obtained on stainless-steel substrate with crystalline fraction 9% higher than that of films deposited on glass and 15% higher than that of films deposited without substrate bias. It is deduced that the improvement of the crystallinity is mainly related to the accelerated electrons emitted from the hot wires. The differences in this improvement between different substrates are caused by the different electrical potential of the substrates. A solar cell fabricated by HWCVD with -800 V substrate bias is demonstrated, showing an obviously higher conversion efficiency than that without substrate bias.

  15. Femtosecond and nanosecond pulsed laser deposition of silicon and germanium

    Energy Technology Data Exchange (ETDEWEB)

    Reenaas, Turid Worren [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Lee, Yen Sian [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Chowdhury, Fatema Rezwana; Gupta, Manisha; Tsui, Ying Yin [Department of Electrical and Computer Engineering, University of Alberta (Canada); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Ling [Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Kok, Soon Yie [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Shan, E-mail: seongshan@gmail.com [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-11-01

    Highlights: • Ge and Si were deposited by fs and ns laser at room temperature and at vacuum. • Ion of 10{sup 4} ms{sup −1} and 30–200 eV was obtained for ns ablation for Ge and Si. • Highly energetic ions of 10{sup 5} ms{sup −1} with 2–7 KeV were produced in fs laser ablation. • Nanocrystalline Si and Ge were deposited by using fs laser. • Nanoparticles < 10 nm haven been obtained by fs laser. - Abstract: 150 fs Ti:Sapphire laser pulsed laser deposition of Si and Ge were compared to a nanosecond KrF laser (25 ns). The ablation thresholds for ns lasers were about 2.5 J cm{sup −2} for Si and 2.1 J cm{sup −2} for Ge. The values were about 5–10 times lower when fs laser were used. The power densities were 10{sup 8}–10{sup 9} W cm{sup −2} for ns but 10{sup 12} W cm{sup −2} for fs. By using an ion probe, the ions emission at different fluence were measured where the emitting ions achieving the velocity in the range of 7–40 km s{sup −1} and kinetic energy in the range of 30–200 eV for ns laser. The ion produced by fs laser was measured to be highly energetic, 90–200 km s{sup −1}, 2–10 KeV. Two ion peaks were detected above specific laser fluence for both ns and fs laser ablation. Under fs laser ablation, the films were dominated by nano-sized crystalline particles, drastically different from nanosecond pulsed laser deposition where amorphous films were obtained. The ions characteristics and effects of pulse length on the properties of the deposited films were discussed.

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

  18. Structure of silicon oxide films prepared by vacuum deposition

    Science.gov (United States)

    Saito, Yoshio; Kaito, Chihiro; Nishio, Kenzo; Naiki, Toshio

    1985-05-01

    The structure of thin silicon oxide films 5 nm in thickness, which were prepared by electron beam evaporation of SiO 2 glass onto a NaCl substrate, has been examined by high resolution electron microscopy and diffraction. Although the films which were prepared with substrate temperatures ranging from room up to 400°C gave rise to amorphous haloes, lattice fringes in areas 1-2 nm in extent were, however, seen in the micrographs. It is shown that the film is composed of α-quartz micro-crystallites. Crystals of α-cristobalite with sizes of several tens of nanometers appeared at a substrate temperature of 500°C. At a substrate temperature of 600°C, β-cristobalite crystals with sizes of several tens of nanometers appeared. The structural changes due to the substrate temperature were attributed to incorporation of sodium atoms from the substrate into the SiO 2 film.

  19. Optical properties of silicon clusters deposited on the basal plane of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L.N.; Chase, L.L.; Balooch, M.; Terminello, L.J.; Tench, R.J.; Wooten, F.

    1994-04-01

    Laser ablation was used to deposit of silicon on highly oriented pyrolytic graphite surfaces in an ultra high-vacuum environment equipped with Auger electron spectroscopy (AES), scanning tunneling microscopy (STM) and luminescence spectroscopy. For deposition of up to several monolayers, post annealing produced silicon clusters, whose size distribution was determined vs annealing time and temperature using STM. Pure silicon clusters ranging from 1 to 10 nm showed no detectable photoluminescence in visible range. Exposure to oxygen at 10{sup {minus}6} Torr and for up to 8 hours showed adsorption on the surface of the clusters without silicon oxide formation and no detectable luminescence. Hydrogen termination of these clusters was accomplished by exposing them to atomic hydrogen beam but did not result in any photoluminescence. Prolonged exposure of these clusters to ambient air, however, resulted in strong photoluminescence spectra with color ranging from red to greenish-blue depending on average cluster size. Auger electron spectra revealed the existence of partially oxidized silicon clusters. This luminescence could be due to either an oxide phase or to changes in electronic structure of the clusters as a result of quantum confinement effect.

  20. Optical properties of silicon clusters deposited on the basal plane of graphite

    Science.gov (United States)

    Dinh, L. N.; Chase, L. L.; Balooch, M.; Terminello, L. J.; Tench, R. J.; Wooten, F.

    1994-04-01

    Laser ablation was used to deposit of silicon on highly oriented pyrolytic graphite surfaces in an ultra high-vacuum environment equipped with Auger electron spectroscopy (AES), scanning tunneling microscopy (STM) and luminescence spectroscopy. For deposition of up to several monolayers, post annealing produced silicon clusters, whose size distribution was determined vs annealing time and temperature using STM. Pure silicon clusters ranging from 1 to 10 nm showed no detectable photoluminescence in visible range. Exposure to oxygen at 10(exp -6) Torr and for up to 8 hours showed adsorption on the surface of the clusters without silicon oxide formation and no detectable luminescence. Hydrogen termination of these clusters was accomplished by exposing them to atomic hydrogen beam but did not result in any photoluminescence. Prolonged exposure of these clusters to ambient air, however, resulted in strong photoluminescence spectra with color ranging from red to greenish-blue depending on average cluster size. Auger electron spectra revealed the existence of partially oxidized silicon clusters. This luminescence could be due to either an oxide phase or to changes in electronic structure of the clusters as a result of quantum confinement effect.

  1. Surface-enhanced Raman scattering dendritic substrates fabricated by deposition of gold and silver on silicon.

    Science.gov (United States)

    Cheng, Mingfei; Fang, Jinghuai; Cao, Min; Jin, Yonglong

    2010-11-01

    This paper reports a study on the preparation of gold nanoparticles and silver dendrites on silicon substrates by immersion plating. Firstly, gold was deposited onto silicon wafer from HF aqueous solution containing HAuCl4. Then, the silicon wafer deposited gold was dipped into HF aqueous solution of AgNO3 to form silver coating gold film. Scanning electron microscopy reveals a uniform gold film consisted of gold nanoparticles and rough silver coating gold film containing uniform dendritic structures on silicon surface. By SERS (surface-enhanced Raman scattering) measurements, the fabricated gold and silver coating gold substrates activity toward SERS is assessed. The SERS spectra of crystal violet on the fabricated substrates reflect the different SERS activities on gold nanoparticles film and silver coating gold dendrites film. Compared with pure gold film on silicon, the film of silver coating gold dendrites film significantly increased the SERS intensity. As the fabrication process is very simple, cost-effective and reproducible, and the fabricated silver coating gold substrate is of excellent enhancement ability, spatial uniformity and good stability.

  2. Surface passivation of efficient nanotextured black silicon solar cells using thermal atomic layer deposition.

    Science.gov (United States)

    Wang, Wei-Cheng; Lin, Che-Wei; Chen, Hsin-Jui; Chang, Che-Wei; Huang, Jhih-Jie; Yang, Ming-Jui; Tjahjono, Budi; Huang, Jian-Jia; Hsu, Wen-Ching; Chen, Miin-Jang

    2013-10-09

    Efficient nanotextured black silicon solar cells passivated by an Al2O3 layer are demonstrated. The broadband antireflection of the nanotextured black silicon solar cells was provided by fabricating vertically aligned silicon nanowire (SiNW) arrays on the n(+) emitter. A highly conformal Al2O3 layer was deposited upon the SiNW arrays by the thermal atomic layer deposition (ALD) based on the multiple pulses scheme. The nanotextured black silicon wafer covered with the Al2O3 layer exhibited a low total reflectance of ∼1.5% in a broad spectrum from 400 to 800 nm. The Al2O3 passivation layer also contributes to the suppressed surface recombination, which was explored in terms of the chemical and field-effect passivation effects. An 8% increment of short-circuit current density and 10.3% enhancement of efficiency were achieved due to the ALD Al2O3 surface passivation and forming gas annealing. A high efficiency up to 18.2% was realized in the ALD Al2O3-passivated nanotextured black silicon solar cells.

  3. FTIR monitoring of industrial scale CVD processes

    Science.gov (United States)

    Hopfe, V.; Mosebach, H.; Meyer, M.; Sheel, D.; Grählert, W.; Throl, O.; Dresler, B.

    1998-06-01

    The goal is to improve chemical vapour deposition (CVD) and infiltration (CVI) process control by a multipurpose, knowledge based feedback system. For monitoring the CVD/CVI process in-situ FTIR spectroscopic data has been identified as input information. In the presentation, three commonly used, and distinctly different, types of industrial CVD/CVI processes are taken as test cases: (i) a thermal high capacity CVI batch process for manufacturing carbon fibre reinforced SiC composites for high temperature applications, (ii) a continuously driven CVD thermal process for coating float glass for energy protection, and (iii) a laser stimulated CVD process for continuously coating bundles of thin ceramic fibers. The feasibility of the concept with FTIR in-situ monitoring as a core technology has been demonstrated. FTIR monitoring sensibly reflects process conditions.

  4. Amorphous silicon solar cells on natively textured ZnO grown by PECVD

    NARCIS (Netherlands)

    Löffler, J.; Groenen, R.; Linden, J.L.; Sanden, M.C.M. van de; Schropp, R.E.I.

    2001-01-01

    Natively textured ZnO layers deposited by the expanding thermal plasma CVD technique between 150 and 350°C at a deposition rate between 0.65 and 0.75 nm/s have been investigated with respect to their suitability as front electrode material for amorphous silicon pin solar cells in comparison to refer

  5. Photoelectronic properties of hydrogenated amorphous silicon films deposited by R. F sputtering and glow discharge methods

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Rahman, M.; Madkour, H. (Faculty of Science, Aswan (Egypt)); Hassan, H.H.; El-Desouki, S. (Cairo Univ., Giza (Egypt))

    1989-09-01

    Hydrogenated amorphous silicon films a-Si:H were deposited by both R.F. sputtering in a planar magnetron configuration and glow discharge methods on Corning glass substrates at different substrate temperatures. The dc and ac photoconductivities of the deposited films were extensively studied as a function of temperature, photon energy and photo-excitation intensity. The results showed that, the dark and photoconductivities have different dependency regions on temperature with different activation energies in the range of 0.08-0.20 eV. It has been also found that the photoconductivity is influenced by the method of deposition and the deposition parameters, indicating that the density of gap states is sensitive to the deposition conditions. The photoconductivity ({sigma}{sub ph}) has a power dependence on the illumination intensity (I) of the form {sigma}{sub ph} {alpha} I {sup {nu}}, where {nu} is a constant and was found also to be increase with temperature.

  6. CVD elaboration of nanostructured TiO2-Ag thin films with efficient antibacterial properties

    OpenAIRE

    Mungkalasiri, Jitti; Bedel, Laurent; Emieux, Fabrice; Dore, Jeanne; Renaud, François N. R.; Sarantopoulos, Christos; Maury, Francis

    2010-01-01

    Nanostructured TiO2-Ag composite coatings are deposited by direct liquid injection metal-organic (DLI-MO) CVD at 683K in a one-step process. Silver pivalate (AgPiv) and titanium tetra-iso-propoxide (TTIP) are used as Ag and Ti molecular precursors, respectively. Metallic silver nanoparticles are co-deposited with anatase TiO2 on stainless steel, glass, and silicon wafers. The silver particles are uniformly embedded in the oxide matrix through the entire film thickness. The influence of the gr...

  7. Ultrafast triggered transient energy storage by atomic layer deposition into porous silicon for integrated transient electronics

    Science.gov (United States)

    Douglas, Anna; Muralidharan, Nitin; Carter, Rachel; Share, Keith; Pint, Cary L.

    2016-03-01

    Here we demonstrate the first on-chip silicon-integrated rechargeable transient power source based on atomic layer deposition (ALD) coating of vanadium oxide (VOx) into porous silicon. A stable specific capacitance above 20 F g-1 is achieved until the device is triggered with alkaline solutions. Due to the rational design of the active VOx coating enabled by ALD, transience occurs through a rapid disabling step that occurs within seconds, followed by full dissolution of all active materials within 30 minutes of the initial trigger. This work demonstrates how engineered materials for energy storage can provide a basis for next-generation transient systems and highlights porous silicon as a versatile scaffold to integrate transient energy storage into transient electronics.Here we demonstrate the first on-chip silicon-integrated rechargeable transient power source based on atomic layer deposition (ALD) coating of vanadium oxide (VOx) into porous silicon. A stable specific capacitance above 20 F g-1 is achieved until the device is triggered with alkaline solutions. Due to the rational design of the active VOx coating enabled by ALD, transience occurs through a rapid disabling step that occurs within seconds, followed by full dissolution of all active materials within 30 minutes of the initial trigger. This work demonstrates how engineered materials for energy storage can provide a basis for next-generation transient systems and highlights porous silicon as a versatile scaffold to integrate transient energy storage into transient electronics. Electronic supplementary information (ESI) available: (i) Experimental details for ALD and material fabrication, ellipsometry film thickness, preparation of gel electrolyte and separator, details for electrochemical measurements, HRTEM image of VOx coated porous silicon, Raman spectroscopy for VOx as-deposited as well as annealed in air for 1 hour at 450 °C, SEM and transient behavior dissolution tests of uniformly coated VOx on

  8. PE-CVD fabrication of germanium nanoclusters for memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Duerkop, T. [Institut fuer Materialien und Bauelemente der Elektronik, Leibniz Universitaet Hannover, Appelstrasse 11a, 30167 Hannover (Germany)], E-mail: duerkop@mbe.uni-hannover.de; Bugiel, E. [Institut fuer Materialien und Bauelemente der Elektronik, Leibniz Universitaet Hannover, Appelstrasse 11a, 30167 Hannover (Germany); Costina, I. [IHP GmbH, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Ott, A.; Peibst, R.; Hofmann, K.R. [Institut fuer Materialien und Bauelemente der Elektronik, Leibniz Universitaet Hannover, Appelstrasse 11a, 30167 Hannover (Germany)

    2008-02-15

    We have investigated Ge nanoclusters (Ge-NC) embedded in silicon dioxide, whose fundamental properties promise improved characteristics in NC flash memory devices as compared to Si nanoclusters. We present a simple new method, based on plasma-enhanced CVD (PE-CVD) deposition of amorphous Ge (a-Ge) onto SiO{sub 2}, to create gate stacks with embedded Ge-NC at vertically well-controlled positions suitable for use in flash memory devices. This process minimizes the exposure of Ge to environmental influences by depositing a-Ge as well as a SiO{sub 2} cap layer in situ within the same deposition chamber. Subsequent high-temperature anneals compatible with the temperature budget of CMOS processing are used for the actual cluster formation. Variation of annealing temperature and duration of this step as well as the thickness of the initial Ge layer controls the average cluster radius and density, as determined by transmission electron microscopy (TEM). Measurements of electrical properties show the capability of samples with NC to store charge.

  9. SUBSTRATE EFFECT ON HYDROGENATED MICROCRYSTALLINE SILICON FILMS DEPOSITED WITH VHF-PECVD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    H.D. Yang

    2006-01-01

    Raman spectra and scanning electron microscope (SEM) techniques were used to determine the structural properties of microcrystalline silicon (μc-Si:H) films deposited on different substrates with the very high frequency plasma-enhanced chemical vapor deposition ( VHF-PECVD )technique. Using the Raman spectra, the values of crystalline volume fraction Xc and average grain size d are 86%, 12.3nm; 65%, 5.45nm; and 38%, 4.05nm, for single crystalline silicon wafer,corning 7059 glass, and general optical glass substrates, respectively. The SEM images further demonstrate the substrate effect on the film surface roughness. For the single crystalline silicon wafer and Corning 7059 glass, the surfaces of the μc-Si:H films are fairly smooth because of the homogenous growth or little lattice mismatch. But for general optical glass, the surface of the μc-Si:H film is very rough, thus the growing surface roughness affects the crystallization process and determines the average grain size of the deposited material. Moreover, with the measurements of thickness, photo and dark conductivity, photosensitivity and activation energy, the substrate effect on the deposition rate, optical and electrical properties of the μc-Si:H thin films have also been investigated. On the basis of the above results, it can be concluded that the substrates affect the initial growing layers acting as a seed for the formation of a crystalline-like material, and then the deposition rates, optical and electrical properties are also strongly influenced, hence,deposition parameter optimization is the key method that can be used to obtain a good initial growing layer, to realize the deposition of μc-Si:H films with device-grade quality on cheap substrates such as general glass.

  10. Ion beam assisted deposition of hydrogenated amorphous silicon nitride

    Science.gov (United States)

    Hubler, G. K.; Donovan, E. P.; Gossett, C. R.

    1994-06-01

    Hydrogenated silicon nitride films were produced near room temperature by electron beam evaporation of Si and simultaneous bombardment with a 500 eV ammonia ion beam from a Kaufman ion source and for a variety of ratios of incident charge to evaporant fluxes. The composition of N, Si and H in the films as a function of ion current density was measured by means of Rutherford backscattering and elastic recoil detection analyses. Reflection and transmission spectroscopy in the wavelength range 400 nm to 3125 nm were employed to measure optical thickness and refractive index. From the data we extracted the number of nitrogen atoms in the ammonia beam per unit charge collected, the sputtering coefficient for ammonia incident on Si, and the refractive index versus composition of the alloys. At the highest N composition, the films were clear in the visible with the UV cut-off less than 400 nm, the index was 1.80 which is lower than that of pure Si3N4 and the H content was as high as 27 at.%.

  11. Growth of doped silicon nanowires by pulsed laser deposition and their analysis by electron beam induced current imaging

    Energy Technology Data Exchange (ETDEWEB)

    Eisenhawer, B; Berger, A; Christiansen, S [Institute of Photonic Technology, Albert-Einstein-Strasse 9, 07745 Jena (Germany); Zhang, D; Clavel, R [Laboratory of Robotic Systems, Ecole Polytechnique Federale de Lausanne (EPFL), Station 9, CH-1015 Lausanne (Switzerland); Michler, J, E-mail: bjoern.eisenhawer@ipht-jena.de [Mechanics of Materials and Nanostructures Laboratory, EMPA-Materials Science and Technology, Feuerwerkstrasse 39, CH-3602 Thun (Switzerland)

    2011-02-18

    Doped silicon nanowires (NWs) were epitaxially grown on silicon substrates by pulsed laser deposition following a vapour-liquid-solid process, in which dopants together with silicon atoms were introduced into the gas phase by laser ablation of lightly and highly doped silicon target material. p-n or p{sup ++}-p junctions located at the NW-silicon substrate interfaces were thus realized. To detect these junctions and visualize them the electron beam induced current technique and two-point probe current-voltage measurements were used, based on nanoprobing individual silicon NWs in a scanning electron microscope. Successful silicon NW doping by pulsed laser deposition of doped target material could experimentally be demonstrated. This doping strategy compared to the commonly used doping from the gas phase during chemical vapour deposition is evaluated essentially with a view to potentially overcoming the limitations of chemical vapour deposition doping, which shows doping inhomogeneities between the top and bottom of the NW as well as between the core and shell of NWs and structural lattice defects, especially when high doping levels are envisaged. The pulsed laser deposition doping technique yields homogeneously doped NWs and the doping level can be controlled by the choice of the target material. As a further benefit, this doping procedure does not require the use of poisonous gases and may be applied to grow not only silicon NWs but also other kinds of doped semiconductor NWs, e.g. group III nitrides or arsenides.

  12. Electrochemically deposited gallium oxide nanostructures on silicon substrates.

    Science.gov (United States)

    Ghazali, Norizzawati Mohd; Mahmood, Mohamad Rusop; Yasui, Kanji; Hashim, Abdul Manaf

    2014-03-17

    We report a synthesis of β-Ga2O3 nanostructures on Si substrate by electrochemical deposition using a mixture of Ga2O3, HCl, NH4OH, and H2O. The presence of Ga3+ ions contributed to the deposition of Ga2O3 nanostructures on the Si surface with the assistance of applied potentials. The morphologies of the grown structures strongly depended on the molarity of Ga2O3 and pH level of electrolyte. β-Ga2O3 nanodot-like structures were grown on Si substrate at a condition with low molarity of Ga2O3. However, Ga2O3 nanodot structures covered with nanorods on top of their surfaces were obtained at higher molarity, and the densities of nanorods seem to increase with the decrease of pH level. High concentration of Ga3+ and OH- ions may promote the reaction of each other to produce Ga2O3 nanorods in the electrolyte. Such similar nature of Ga2O3 nanorods was also obtained by using hydrothermal process. The grown structures seem to be interesting for application in electronic and optoelectronic devices as well as to be used as a seed structure for subsequent chemical synthesis of GaN by thermal transformation method.

  13. Electrochemically deposited gallium oxide nanostructures on silicon substrates

    Science.gov (United States)

    Ghazali, Norizzawati Mohd; Mahmood, Mohamad Rusop; Yasui, Kanji; Hashim, Abdul Manaf

    2014-03-01

    We report a synthesis of β-Ga2O3 nanostructures on Si substrate by electrochemical deposition using a mixture of Ga2O3, HCl, NH4OH, and H2O. The presence of Ga3+ ions contributed to the deposition of Ga2O3 nanostructures on the Si surface with the assistance of applied potentials. The morphologies of the grown structures strongly depended on the molarity of Ga2O3 and pH level of electrolyte. β-Ga2O3 nanodot-like structures were grown on Si substrate at a condition with low molarity of Ga2O3. However, Ga2O3 nanodot structures covered with nanorods on top of their surfaces were obtained at higher molarity, and the densities of nanorods seem to increase with the decrease of pH level. High concentration of Ga3+ and OH- ions may promote the reaction of each other to produce Ga2O3 nanorods in the electrolyte. Such similar nature of Ga2O3 nanorods was also obtained by using hydrothermal process. The grown structures seem to be interesting for application in electronic and optoelectronic devices as well as to be used as a seed structure for subsequent chemical synthesis of GaN by thermal transformation method.

  14. Silicon protected with atomic layer deposited TiO2

    DEFF Research Database (Denmark)

    Seger, Brian; Tilley, S. David; Pedersen, Thomas

    2013-01-01

    The present work demonstrates that tuning the donor density of protective TiO2 layers on a photocathode has dramatic consequences for electronic conduction through TiO2 with implications for the stabilization of oxidation-sensitive catalysts on the surface. Vacuum annealing at 400 °C for 1 hour...... of atomic layer deposited TiO2 increased the donor density from an as-deposited value of 1.3 × 1019 cm -3 to 2.2 × 1020 cm-3 following the annealing step. Using an Fe(ii)/Fe(iii) redox couple it was shown that the lower dopant density only allows electron transfer through TiO2 under conditions of weak band...... bending. However it was shown that increasing the dopant density to 2.2 × 1020 cm-3 allows tunneling through the surface region of TiO2 to occur at significant band bending. An important implication of this result is that the less doped material is unsuitable for electron transfer across the TiO2...

  15. ENHANCED GROWTH RATE AND SILANE UTILIZATION IN AMORPHOUS SILICON AND NANOCRYSTALLINE-SILICON SOLAR CELL DEPOSITION VIA GAS PHASE ADDITIVES

    Energy Technology Data Exchange (ETDEWEB)

    Ridgeway, R G; Hegedus, S S; Podraza, N J

    2012-08-31

    Air Products set out to investigate the impact of additives on the deposition rate of both CSi and Si-H films. One criterion for additives was that they could be used in conventional PECVD processing, which would require sufficient vapor pressure to deliver material to the process chamber at the required flow rates. The flow rate required would depend on the size of the substrate onto which silicon films were being deposited, potentially ranging from 200 mm diameter wafers to the 5.7 m2 glass substrates used in GEN 8.5 flat-panel display tools. In choosing higher-order silanes, both disilane and trisilane had sufficient vapor pressure to withdraw gas at the required flow rates of up to 120 sccm. This report presents results obtained from testing at Air Products electronic technology laboratories, located in Allentown, PA, which focused on developing processes on a commercial IC reactor using silane and mixtures of silane plus additives. These processes were deployed to compare deposition rates and film properties with and without additives, with a goal of maximizing the deposition rate while maintaining or improving film properties.

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

    Science.gov (United States)

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

    2016-12-01

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

  17. Nanocrystalline silicon and silicon quantum dots formation within amorphous silicon carbide by plasma enhanced chemical vapour deposition method controlling the Argon dilution of the process gases

    Energy Technology Data Exchange (ETDEWEB)

    Kole, Arindam; Chaudhuri, Partha, E-mail: erpc@iacs.res.in

    2012-11-01

    Structural and optical properties of the amorphous silicon carbide (a-SiC:H) thin films deposited by radio frequency plasma enhanced chemical vapour deposition method from a mixture of silane (SiH{sub 4}) and methane (CH{sub 4}) diluted in argon (Ar) have been studied with variation of Ar dilution from 94% to 98.4%. It is observed that nanocrystalline silicon starts to form within the a-SiC:H matrix by increasing the dilution to 96%. With further increase in Ar dilution to 98% formation of the silicon nanocrystals (nc-Si) with variable size is enhanced. The optical band gap (E{sub g}) of the a-SiC:H film decreases from 2.0 eV to 1.9 eV with increase in Ar dilution from 96% to 98% as the a-SiC:H films gradually become Si rich. On increasing the Ar dilution further to 98.4% leads to the appearance of crystalline silicon quantum dots (c-Si q-dots) of nearly uniform size of 3.5 nm. The quantum confinement effect is apparent from the sharp increase in the E{sub g} value to 2.6 eV. The phase transformation phenomenon from nc-Si within the a-SiC:H films to Si q-dot were further studied by high resolution transmission electron microscopy and the grazing angle X-ray diffraction spectra. A relaxation in the lattice strain has been observed with the formation of Si q-dots.

  18. Cold Spray Deposition of Copper Electrodes on Silicon and Glass Substrates

    Science.gov (United States)

    Kim, Do-Yeon; Park, Jung-Jae; Lee, Jong-Gun; Kim, Donghwan; Tark, Sung Ju; Ahn, Sejin; Yun, Jae Ho; Gwak, Jihye; Yoon, Kyung Hoon; Chandra, Sanjeev; Yoon, Sam S.

    2013-10-01

    Copper lines with widths varying from 150 to 1500 μm were deposited onto crystalline silicon wafers and soda-lime glass plates by cold spraying copper particles with 1 μm average diameter through a mask. This direct deposition method yielded high-aspect-ratio electrodes with minimum shadowing effects and maximum electrode-to-silicon contact area. The copper lines had triangular cross sections with aspect ratios (height/width) ranging from 0.1 to 1.1, depending on the number of spray gun passes. Copper particles were densely packed with increasing the width of the masking slit. This study presents the potential use of the cold spray technology in printing lines as front electrodes in solar cell applications.

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

    Directory of Open Access Journals (Sweden)

    Jagannath Panigrahi

    2017-03-01

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

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

    KAUST Repository

    Hussain, Aftab M.

    2013-08-16

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

  1. Laser annealing study of PECVD deposited hydrogenated amorphous silicon carbon alloy films

    Science.gov (United States)

    Coscia, U.; Ambrosone, G.; Gesuele, F.; Grossi, V.; Parisi, V.; Schutzmann, S.; Basa, D. K.

    2007-12-01

    The influence of carbon content on the crystallization process has been investigated for the excimer laser annealed hydrogenated amorphous silicon carbon alloy films deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD) technique, using silane methane gas mixture diluted in helium, as well as for the hydrogenated microcrystalline silicon carbon alloy films prepared by PECVD from silane methane gas mixture highly diluted in hydrogen, for comparison. The study demonstrates clearly that the increase in the carbon content prevents the crystallization process in the hydrogen diluted samples while the crystallization process is enhanced in the laser annealing of amorphous samples because of the increase in the absorbed laser energy density that occurs for the amorphous films with the higher carbon content. This, in turn, facilitates the crystallization for the laser annealed samples with higher carbon content, resulting in the formation of SiC crystallites along with Si crystallites.

  2. Silicon Dioxide Coating Deposited by PDPs on PET Films and Influence on Oxygen Transmission Rate

    Institute of Scientific and Technical Information of China (English)

    SUN Yun-Jin; FU Ya-Bo; CHEN Qiang; ZHANG Chun-Mei; SANG Li-Jun; ZHANG Yue-Fei

    2008-01-01

    A silicon dioxide film is deposited on the polyethyleneterephtalate (PET) by a penning discharge plasma source at ambient temperature in a high vacuum chamber.Hexamethyldisiloxane and oxygen are adopted as precursor and reactive reagent to grow a nano-scale silicon dioxide layer on polymer surfaces.For the chemical structure analysis x-ray photoelectron spectroscopy is performed to demonstrate the content of Si,0 and C elements.It is noticed that a higher silicon concentration is contained if Ar plasma is used for pretreatment.X-ray diffraction analysis shows that a micro-crystal silicon dioxide is formed by peak patterns at 25.84° and 21.8°.The barrier properties examined by oxygen transmission rate show that the permeation parameter of the 12-μm-thick PET film drastically decreases from 135 cc/m2 per day for the control one to 0.713 cc/m2 per day for the as-deposited one after Ar plasma treatment.The surface morphology related to the barrier properties of SiOx-coated polymers os also investigated by scanning electron microscopy and atomic force microscopy.

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

    Science.gov (United States)

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

    2017-09-01

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

  4. Cathode encapsulation of OLEDs by atomic layer deposited Al2O3 films and Al2O3/a-SiNx:H stacks

    NARCIS (Netherlands)

    Keuning, W.; Van de Weijer, P.; Lifka, H.; Kessels, W.M.M.; Creatore, M.

    2011-01-01

    Al2O3 thin films synthesized by plasma-enhanced atomic layer deposition(ALD) at room temperature (25 ºC) have been tested as water vapor per-meation barriers for OLED devices. Silicon nitride films (a-SiNx:H)deposited by plasma-enhanced chemical vapor deposition (PE-CVD) servedas reference and were

  5. Control of the optical properties of silicon and chromium mixed oxides deposited by reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Vergara, L., E-mail: vergara@icmm.csic.e [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Galindo, R. Escobar [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Martinez, R. [AIN, Centro de Ingenieria Avanzada de Superficies, 31191 Cordovilla, Pamplona (Spain); Sanchez, O. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Palacio, C. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Albella, J.M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)

    2011-03-31

    The development of mixed-oxide thin films allows obtaining materials with better properties than those of the different binary oxides, which makes them suitable for a great number of applications in different fields, such as tribology, optics or microelectronics. In this paper we investigate the deposition of mixed chromium and silicon oxides deposited by reactive magnetron sputtering with a view to use them as optical coatings with an adjustable refractive index. These films have been characterized by means of Rutherford backscattering spectrometry, Auger electron spectroscopy, X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy and spectroscopic ellipsometry so as to determine how the deposition conditions influence the characteristics of the material. We have found that the deposition parameter whose influence determines the properties of the films to a greater extent is the amount of oxygen in the reactive sputtering gas.

  6. Silver nanoparticles deposited on porous silicon as a surface-enhanced Raman scattering (SERS) active substrate.

    Science.gov (United States)

    Zeiri, Leila; Rechav, Katya; Porat, Ze'ev; Zeiri, Yehuda

    2012-03-01

    Silver nanoparticles were deposited spontaneously from their aqueous solution on a porous silicon (PS) layer. The PS acts both as a reducing agent and as the substrate on which the nanoparticles nucleate. At higher silver ion concentrations, layers of nanoparticle aggregates were formed on the PS surface. The morphology of the metallic layers and their SERS activity were influenced by the concentrations of the silver ion solutions used for deposition. Raman measurements of rhodamine 6G (R6G) and crystal violet (CV) adsorbed on these surfaces showed remarkable enhancement of up to about 10 orders of magnitude.

  7. The role of defects in electroless metal deposition on silicon (100)

    Energy Technology Data Exchange (ETDEWEB)

    Gorostiza, P.; Servat, J.; Morante, J.R. [Universitat de Barcelona (Spain)

    1996-12-01

    The first stages of platinum electroless deposition on p-Si (100) from hydrogenfluoride solutions are studied using several techniques. Platinum nuclei are deposited on a silicon substrate by immersion in an aqueous HF solution containing a platinum salt. Tapping Mode AFM and TEM have been used to characterize the samples morphologically, and EDS and XPS to identify the chemical nature of the main features. Platinum silicide is formed in the interphase between nuclei and substrate. The influence of crystal defects is analyzed from a qualitative point of view.

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

    CERN Document Server

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

    1999-01-01

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

  9. Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride Using a Novel Silylamine Precursor.

    Science.gov (United States)

    Park, Jae-Min; Jang, Se Jin; Yusup, Luchana L; Lee, Won-Jun; Lee, Sang-Ick

    2016-08-17

    We report the plasma-enhanced atomic layer deposition (PEALD) of silicon nitride thin film using a silylamine compound as the silicon precursor. A series of silylamine compounds were designed by replacing SiH3 groups in trisilylamine by dimethylaminomethylsilyl or trimethylsilyl groups to obtain sufficient thermal stability. The silylamine compounds were synthesized through redistribution, amino-substitution, lithiation, and silylation reactions. Among them, bis(dimethylaminomethylsilyl)trimethylsilyl amine (C9H29N3Si3, DTDN2-H2) was selected as the silicon precursor because of the lowest bond dissociation energy and sufficient vapor pressures. The energies for adsorption and reaction of DTDN2-H2 with the silicon nitride surface were also calculated by density functional theory. PEALD silicon nitride thin films were prepared using DTDN2-H2 and N2 plasma. The PEALD process window was between 250 and 400 °C with a growth rate of 0.36 Å/cycle. The best film quality was obtained at 400 °C with a RF power of 100 W. The PEALD film prepared showed good bottom and sidewall coverages of ∼80% and ∼73%, respectively, on a trench-patterned wafer with an aspect ratio of 5.5.

  10. Electrophoretic Deposition of Carbon Nanotubes on 3-Amino-Propyl-Triethoxysilane (APTES Surface Functionalized Silicon Substrates

    Directory of Open Access Journals (Sweden)

    Theda Daniels-Race

    2013-05-01

    Full Text Available Fabrication of uniform thin coatings of multi-walled carbon nanotubes (MWCNTs by electrophoretic deposition (EPD on semiconductor (silicon substrates with 3-aminopropyl-triethoxysilane (APTES surface functionalization has been studied extensively in this report. The gradual deposition and eventual film formation of the carbon nanotubes (CNTs is greatly assisted by the Coulombic force of attraction existing between the positively charged –NH2 surface groups of APTES and the acid treated, negatively charged nanotubes migrating towards the deposition surfaces. The remarkable deposition characteristics of the CNT coatings by EPD in comparison to the dip coating method and the influence of isopropyl (IPA-based CNT suspension in the fabricated film quality has also been revealed in this study. The effect of varying APTES concentration (5%–100% on the Raman spectroscopy and thickness of the deposited CNT film has been discussed in details, as well. The deposition approach has eliminated the need of metal deposition in the electrophoretic deposition approach and, therefore, establishes a cost-effective, fast and entirely room temperature-based fabrication strategy of CNT thin films for a wide range of next generation electronic applications.

  11. Feasibility of Electrochemical Deposition of Nickel/Silicon Carbide Fibers Composites over Nickel Superalloys

    Science.gov (United States)

    Ambrosio, E. P.; Abdul Karim, M. R.; Pavese, M.; Biamino, S.; Badini, C.; Fino, P.

    2017-02-01

    Nickel superalloys are typical materials used for the hot parts of engines in aircraft and space vehicles. They are very important in this field as they offer high-temperature mechanical strength together with a good resistance to oxidation and corrosion. Due to high-temperature buckling phenomena, reinforcement of the nickel superalloy might be needed to increase stiffness. For this reason, it was thought to investigate the possibility of producing composite materials that might improve properties of the metal at high temperature. The composite material was produced by using electrochemical deposition method in which a composite with nickel matrix and long silicon carbide fibers was deposited over the nickel superalloy. The substrate was Inconel 718, and monofilament continuous silicon carbide fibers were chosen as reinforcement. Chemical compatibility was studied between Inconel 718 and the reinforcing fibers, with fibers both in an uncoated condition, and coated with carbon or carbon/titanium diboride. Both theoretical calculations and experiments were conducted, which suggested the use of a carbon coating over the fibers and a buffer layer of nickel to avoid unwanted reactions between the substrate and silicon carbide. Deposition was then performed, and this demonstrated the practical feasibility of the process. Yield strength was measured to detect the onset of interface debonding between the substrate and the composite layer.

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

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

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

  13. Synthesis of nanocrystalline silicon thin films using the increase of the deposition pressure in the hot-wire chemical vapour deposition technique

    Directory of Open Access Journals (Sweden)

    J.K. Rath

    2010-01-01

    Full Text Available Nanostructured thin silicon-based films have been deposited using the hot-wire chemical vapour deposition (HWCVD technique at the University of the Western Cape. A variety of techniques including optical and infrared spectroscopy, Raman scattering spectroscopy, X-rays diffraction (XRD and transmission electron microscopy (TEM have been used for characterisation of the films. The electrical measurements show that the films have good values of photoresponse, and the photocurrent remains stable after several hours of light soaking. This contribution will discuss the characteristics of the hydrogenated nanocrystalline silicon thin films deposited using increased process chamber pressure at a fixed hydrogen dilution ratio in monosilane gas.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-09-15

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

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

    Science.gov (United States)

    Liu, Y.

    2010-02-01

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

  16. Controlled deposition and combing of DNA across lithographically defined patterns on silicon

    DEFF Research Database (Denmark)

    Nazari, Zeniab Esmail; Gurevich, Leonid

    2013-01-01

    We have developed a new procedure for efficient combing of DNA on a silicon substrate, which allows reproducible deposition and alignment of DNA molecules across lithographically defined patterns. The technique involves surface modification of Si/SiO2 substrates with a hydrophobic silane by using...... gas-phase deposition. Thereafter, DNA molecules are aligned by dragging the droplet on the hydrophobic substrate with a pipette tip. Using this procedure, DNA molecules were stretched to an average value of 122% of their contour length. Furthermore, we demonstrated combing of ca. 900 nm long stretches...... of genomic DNA across nanofabricated electrodes, which was not possible by using other available combing methods. Similar results were also obtained for DNA–peptide conjugates. We suggest this method as a simple yet reliable technique for depositing and aligning DNA and DNA derivatives across nanofabricated...

  17. STRUCTURAL PROPERTIES INVESTIGATION ON MICROCRYSTALLINE SILICON FILMS DEPOSITED WITH VHF-PECVD TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    H.D. Yang

    2005-01-01

    Raman scattering spectroscopy and scanning electron microscopy (SEM) techniques were used to determine the structural properties of two typical series of microcrystalline silicon(μc-Si:H) films deposited at different VHF plasma power and different working gas pressure by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. Raman spectra measurements show that both crystalline volume fraction Xc and average grain size d of μc-Si: H films are strongly affected by the two deposition conditions and are more sensitive to working gas pressure than VHF plasma power. SEM characterizations have further confirmed that VHF plasma power and working gas pressure could clearly enhance the surface roughness of μc-Si: H films ascribing to polymerization reactions, which is also more sensitive to working gas pressure than VHF plasma power.

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

    Science.gov (United States)

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

    1997-01-01

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

  19. High-rate deposition of silicon films in a magnetron discharge with liquid target

    Science.gov (United States)

    Tumarkin, A.; Zibrov, M.; Khodachenko, G.; Tumarkina, D.

    2016-10-01

    Silicon coatings have been deposited on substrates made of low-carbon and high- carbon steels and tungsten in a magnetron discharge with liquid target at substrate bias voltages ranging from +100 V to -600 V. The structure of obtained coatings was examined by a scanning electron microscopy. The strong influence of substrate bias voltage on the coating structure was observed. The corrosion resistance of coated steel samples was examined in concentrated sulphuric, hydrochloric and nitric acids and their solutions. The resistance of coated tungsten samples against high-temperature oxidation was examined by their exposure to O2 gas at a pressure of 0.2 Pa and a temperature of 1073 K. The coatings deposited under bias voltages of+100 V and -600 V had dense structures and showed the best protective properties among all deposited coatings.

  20. LDA and molecular dynamics determination of Ag deposition onto (1 0 0) surfaces in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mazzone, A.M

    2003-03-20

    This study analyzes the effects of the surface morphology on the deposition of Ag onto Si using LDA and isothermal molecular dynamics. The (1 0 0) silicon surface has either a bulk termination or the dimerization pattern experimentally observed. Small clusters representing a section of these surfaces have been used in LDA calculations to find preferred adsorption sites. Isothermal molecular dynamics describe the motions of the diffusing adatoms in a temperature range from T=10 to 1000 K. Both calculations indicate that Ag and Si do not mix and the deposited structure is formed by linear chains located in the trench between surface atoms. However, MD calculations show that, due to the relaxation of the surface and to thermal lattice vibrations, the stable state of the deposited atoms may considerably differ from the one calculated from LDA. This result has both a practical and a methodological significance.

  1. Calcium-phosphate deposits on a hydrophilic acrylic intraocular lens after silicon oil tamponade

    Directory of Open Access Journals (Sweden)

    Rashid Alsaeidi

    2008-01-01

    Full Text Available We report a 52-year-old man who underwent uncomplicated cataract operation and posterior chamber lens implantation (hydrophilic acrylic lens in his left eye 5 years prior to presentation. Two years after surgery he developed pseudophakic retinal detachment which was successfully treated with pars plana vitrectomy and silicon oil tamponade. The silicon oil was removed one year after surgery. A year later he complained of increasing blurred vision in the left eye. Clinical examination revealed vesicular alterations located superficially on the intraocular lens (IOL, which could not be removed by perflourocarbon-perflourohexloctane lavage. As the patient complained about increasing visual impairment, the IOL was removed. The IOL was investigated by electronmicroscopy and biochemical analysis. During electron microscopy and following biochemical analysis the observed alterations were identified as calcium-phosphate particles located on the superficial aspect of the IOL. The occurrence of calcium-phosphate deposits on a posterior chamber IOL after silicon oil tamponade is a rare complication and has not been described so far. As these deposits interfere with visual acuity, removal of the lens has to be considered.

  2. Thermal conductivity of titanium aluminum silicon nitride coatings deposited by lateral rotating cathode arc

    Energy Technology Data Exchange (ETDEWEB)

    Samani, M.K., E-mail: majid1@e.ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore); Ding, X.Z. [Surface Technology Group, Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore); Amini, S. [School of Materials Science and Engineering. Nanyang Technological University, 50 Nanyang Avenue, Singapore (Singapore); Khosravian, N.; Cheong, J.Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Chen, G. [BC Photonics Technological Company, 5255 Woodwards Rd., Richmond, BC V7E 1G9 (Canada); Tay, B.K. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); CINTRA-CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, Singapore 637553 (Singapore)

    2013-06-30

    A series of physical vapour deposition titanium aluminum silicon nitride nanocomposite coating with a different (Al + Si)/Ti atomic ratio, with a thickness of around 2.5 μm were deposited on stainless steel substrate by a lateral rotating cathode arc process in a flowing nitrogen atmosphere. The composition and microstructure of the as-deposited coatings were analyzed by energy dispersive X-ray spectroscopy, and X-ray diffraction, and cross-sectional scanning electron microscopy observation. The titanium nitride (TiN) coating shows a clear columnar structure with a predominant (111) preferential orientation. With the incorporation of Al and Si, the crystallite size in the coatings decreased gradually, and the columnar structure and (111) preferred orientation disappeared. Thermal conductivity of the as-deposited coating samples at room temperature was measured by using pulsed photothermal reflectance technique. Thermal conductivity of the pure TiN coating is about 11.9 W/mK. With increasing the (Al + Si)/Ti atomic ratio, the coatings' thermal conductivity decreased monotonously. This reduction of thermal conductivity could be ascribed to the variation of coatings' microstructure, including the decrease of grain size and the resultant increase of grain boundaries, the disruption of columnar structure, and the reduced preferential orientation. - Highlights: • A series of titanium aluminum silicon nitride with different (Al + Si)/Ti atomic ratio were deposited on Fe304. • The composition and microstructure of the as-deposited coatings were analyzed. • Thermal conductivity of the samples was measured by pulsed photothermal reflectance. • With increasing the (Al + Si)/Ti atomic ratio, thermal conductivity decreased. • Reduction of thermal conductivity is ascribed to the variation of its microstructure.

  3. Low-loss silicon slot waveguides and couplers fabricated with optical lithography and atomic layer deposition.

    Science.gov (United States)

    Säynätjoki, A; Karvonen, L; Alasaarela, T; Tu, X; Liow, T Y; Hiltunen, M; Tervonen, A; Lo, G Q; Honkanen, S

    2011-12-19

    We demonstrate low-loss silicon slot waveguides patterned with 248 nm deep-UV lithography and filled with atomic layer deposited aluminum oxide. Propagation losses less than 5 dB/cm are achieved with the waveguides. The devices are fabricated using low-temperature CMOS compatible processes. We also demonstrate simple, compact and efficient strip-to-slot waveguide couplers. With a coupler as short as 10 µm, coupling loss is less than 0.15 dB. The low-index and low-nonlinearity filling material allows nonlinearities nearly two orders of magnitude smaller than in silicon waveguides. Therefore, these waveguides are a good candidate for linear photonic devices on the silicon platform, and for distortion-free signal transmission channels between different parts of a silicon all-optical chip. The low-nonlinearity slot waveguides and robust couplers also facilitate a 50-fold local change of the waveguide nonlinearity within the chip by a simple mask design.

  4. High-rate deposition of nano-crystalline silicon thin films on plastics

    Energy Technology Data Exchange (ETDEWEB)

    Marins, E.; Guduru, V.; Cerqueira, F.; Alpuim, P. [Centro de Fisica, Universidade do Minho, 4800-058 Guimaraes, 4710-057 Braga (Portugal); Ribeiro, M. [Centro de Nanotecnologia e Materiais Tecnicos, Funcionais e Inteligentes (CeNTI), 4760-034 Vila Nova de Famalicao (Portugal); Bouattour, A. [Institut fuer Physikalische Elektronik (ipe), Universitaet Stuttgart, 70569 Stuttgart (Germany)

    2011-03-15

    Nanocrystalline silicon (nc-Si:H) is commonly used in the bottom cell of tandem solar cells. With an indirect bandgap, nc-Si:H requires thicker ({proportional_to}1 {mu}m) films for efficient light harvesting than amorphous Si (a-Si:H) does. Therefore, thin-film high deposition rates are crucial for further cost reduction of highly efficient a-Si:H based photovoltaic technology. Plastic substrates allow for further cost reduction by enabling roll-to-roll inline deposition. In this work, high nc-Si:H deposition rates on plastic were achieved at low substrate temperature (150 C) by standard Radio-frequency (13.56 MHz) Plasma Enhanced Chemical Vapor Deposition. Focus was on the influence of deposition pressure, inter-electrode distance (1.2 cm) and high power coupled to the plasma, on the hydrogen-to-silane dilution ratios (HD) necessary to achieve the amorphous-to-nanocrystalline phase transition and on the resulting film deposition rate. For each pressure and rf-power, there is a value of HD for which the films start to exhibit a certain amount of crystalline fraction. For constant rf-power, this value increases with pressure. Within the parameter range studied the deposition rate was highest (0.38 nm/s) for nc-Si:H films deposited at 6 Torr, 700 mW/cm{sup 2} using HD of 98.5%. Decreasing the pressure to 3 Torr (1.5 Torr) and rf-power to 350 mW/cm{sup 2} using HD - 98.5% deposition rate is 0.12 nm/s (0.076 nm/s). Raman crystalline fraction of these films is 72, 62 and 53% for the 6, 3 and 1.5 Torr films, respectively (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Microcrystalline Silicon Films and Solar Cells Prepared by Photochemical Vapor Deposition on Textured SnO2 with High Haze Factors

    Science.gov (United States)

    Zhao, Ying; Miyajima, Shinsuke; Ide, Yoshinori; Yamada, Akira; Konagai, Makoto

    2002-11-01

    Microcrystalline silicon (μc-Si) films and solar cells were prepared by mercury-sensitized photochemical vapor deposition (photo-CVD). The changes in the structural properties of a series of μc-Si films grown under various H2 dilution and deposition pressure conditions were discussed. The results indicated that the properties of μc-Si films depend strongly on the atomic hydrogen. The microstructures of μc-Si films on textured SnO2 with different haze factors (from 13% to 65%) were observed with a scanning electron microscope and a transmission electron microscope. The observations revealed that the μc-Si layers grew from the initial stage of deposition with columnar grains and that they were conformal to the surface of textured SnO2. The grain boundary density of μc-Si film on SnO2 with higher haze factors was lower than that on SnO2 with lower haze factors. The effect of textured SnO2 with different haze ratios on p-i-n μc-Si cell characteristics was discussed and it was found that the higher haze factors showed a higher degree of light trapping in our μc-Si cells. We deposited μc-Si cells with an intrinsic μc-Si layer thickness of 430 nm on a textured SnO2 sample with a haze factor of 42% and achieved a conversion efficiency of 6.55%.

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

    NARCIS (Netherlands)

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

    2008-01-01

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  8. Comparison of tungsten films grown by CVD and hot-wire assisted atomic layer deposition in a cold-wall reactor

    NARCIS (Netherlands)

    Yang, Mengdi; Aarnink, Antonius A.I.; Kovalgin, Alexeij Y.; Gravesteijn, Dirk J; Wolters, Robertus A.M.; Schmitz, Jurriaan

    In this work, the authors developed hot-wire assisted atomic layer deposition (HWALD) to deposit tungsten (W) with a tungsten filament heated up to 1700–2000 C. Atomic hydrogen (at-H) was generated by dissociation of molecular hydrogen (H2), which reacted with WF6 at the substrate to deposit W. The

  9. Intermittent Very High Frequency Plasma Deposition on Microcrystalline Silicon Solar Cells Enabling High Conversion Efficiency

    Directory of Open Access Journals (Sweden)

    Mitsuoki Hishida

    2016-01-01

    Full Text Available Stopping the plasma-enhanced chemical vapor deposition (PECVD once and maintaining the film in a vacuum for 30 s were performed. This was done several times during the formation of a film of i-layer microcrystalline silicon (μc-Si:H used in thin-film silicon tandem solar cells. This process aimed to reduce defect regions which occur due to collision with neighboring grains as the film becomes thicker. As a result, high crystallinity (Xc of μc-Si:H was obtained. Eventually, a solar cell using this process improved the conversion efficiency by 1.3% (0.14 points, compared with a normal-condition cell. In this paper, we propose an easy method to improve the conversion efficiency with PECVD.

  10. Deposition of silicon oxynitride films by low energy ion beam assisted nitridation at room temperature

    Science.gov (United States)

    Youroukov, S.; Kitova, S.; Danev, G.

    2008-05-01

    The possibility is studied of growing thin silicon oxynitride films by e-gun evaporation of SiO and SiO2 together with concurrent bombardment with low energy N2+ ions from a cyclotron resonance (ECR) source at room temperature of substrates. The degree of nitridation and oxidation of the films is investigated by means of X-ray spectroscopy. The optical characteristics of the films, their environmental stability and adhesion to different substrates are examined. The results obtained show than the films deposited are transparent. It is found that in the case of SiO evaporation with concurrent N2+ ion bombardment, reactive implantation of nitrogen within the films takes place at room temperature of the substrate with the formation of a new silicon oxynitride compound even at low ion energy (150-200 eV).

  11. Characterization of highly hydrophobic coatings deposited onto pre-oxidized silicon from water dispersible organosilanes

    Energy Technology Data Exchange (ETDEWEB)

    Almanza-Workman, A. Marcia; Raghavan, Srini; Petrovic, Slobodan; Gogoi, Bishnu; Deymier, Pierre; Monk, David J.; Roop, Ray

    2003-01-01

    The formation and quality of highly hydrophobic coatings deposited from water dispersible organosilanes onto pre-oxidized single crystal silicon were studied using atomic force microscopy, ellipsometry, dynamic contact angle measurements and electrochemical impedance spectroscopy (EIS). Highly hydrophobic films of a commercially available water dispersible silane and two different cationic alkoxysilanes were prepared by dip coating. It was found using atomic force microscopy that, in general, the structure of these highly hydrophobic films is a continuous film with some particulates attributed to bulk polymerization of the precursor molecule in water. Film defects were quantified using EIS by the value of charge transfer resistance at the hydrofluoric acid/silicon interface. Potential applications of this type of coatings include reduction/elimination of stiction in micro-electromechanical systems, contact printing in materials microfabrication, inhibition of corrosion and oxidation, prevention of water wetting, lubrication and protein adsorption.

  12. Properties of silicon nitride thin overlays deposited on optical fibers — Effect of fiber suspension in radio frequency plasma-enhanced chemical vapor deposition reactor

    Energy Technology Data Exchange (ETDEWEB)

    Śmietana, M., E-mail: M.Smietana@elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, Warsaw 00-662 (Poland); Dominik, M.; Myśliwiec, M.; Kwietniewski, N. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, Warsaw 00-662 (Poland); Mikulic, P. [Centre de Recherche en Photonique, Université du Québec en Outaouais, 101 rue Saint-Jean-Bosco, Gatineau, J8X 3X7, Québec (Canada); Witkowski, B.S. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, Warsaw 02-666 (Poland); Bock, W.J. [Centre de Recherche en Photonique, Université du Québec en Outaouais, 101 rue Saint-Jean-Bosco, Gatineau, J8X 3X7, Québec (Canada)

    2016-03-31

    This work discusses the effect of sample suspension in radio frequency plasma-enhanced chemical vapor deposition process on properties of the obtained overlays. Silicon nitride (SiN{sub x}) overlays were deposited on flat silicon wafers and cylindrical fused silica optical fibers. The influence of the suspension height and fiber diameter on SiN{sub x} deposition rate is investigated. It has been found that thickness of the SiN{sub x} overlay significantly increases with suspension height, and the deposition rate depends on fiber dimensions. Moreover, the SiN{sub x} overlays were also deposited on long-period gratings (LPGs) induced in optical fiber. Measurements of the LPG spectral response combined with its numerical simulations allowed for a discussion on properties of the deposited overlay. The measurements have proven higher overlay deposition rate on the suspended fiber than on flat Si wafer placed on the electrode. Results of this work are essential for precise tuning of the functional properties of new generations of optical devices such as optical sensors, filters and resonators, which typically are based on optical fibers and require the overlays with well defined properties. - Highlights: • The effect of optical fiber suspension in plasma process is discussed. • The deposition rate of silicon nitride (SiN{sub x}) overlay depends on fiber dimensions. • Thickness of the SiN{sub x} overlay strongly increases with suspension height. • Measurements and simulations of long-period grating confirms experimental results.

  13. Using Py-GC/MS to detect and measure silicone defoamers in pulp fibres and mill deposits

    CSIR Research Space (South Africa)

    Sithole, Bruce

    2013-09-01

    Full Text Available cause pitch deposition in pulp and paper making operations. Please cite this article in press as: B. Sithole, C. Watanabe, Using Py-GC/MS to detect and measure silicone defoamers in pulp fibres and mill deposits, J. Anal. Appl. Pyrol. (2012), http... cite this article in press as: B. Sithole, C. Watanabe, Using Py-GC/MS to detect and measure silicone defoamers in pulp fibres and mill deposits, J. Anal. Appl. Pyrol. (2012), http://dx.doi.org/10.1016/j.jaap.2012.08.013 ARTICLE IN PRESSG ModelJAAP 2804...

  14. Characteristics of Amorphous Silicon Nitride Films Deposited by LF-PECVD from SiH4/N2

    Institute of Scientific and Technical Information of China (English)

    ZHONG Zhi-qin; ZHANG Yi; YU Zhi-wei; DAI Li-ping; ZHANG Guo-jun; WANG Yu-mei; WANG Gang; WANG Shu-ya

    2009-01-01

    Amorphous silicon nitride films were deposited by low-frequency plasma-enhanced chemical vapor deposition(LF-PECVD) using silane and nitrogen as precursors. Characteristics such as deposition rate,surface morphology,and chemical composition were measured by spectroscopic ellipsometry(SE),atomic force microscope(AFM) and x-ray photoelectron spectroscopy(XPS).It was shown that amorphous silicon nitride film could be prepared by LF-PECVD with good uniformity and even surface.The XPS result indicated that a small quantity of oxygen was involved in the sample,which was discussed in this paper.

  15. Application of silver nanodendrites deposited on silicon in SERS technique for the trace analysis of paraquat

    Science.gov (United States)

    Cao Dao, Tran; Quynh Ngan Luong, Truc; Cao, Tuan Anh; Kieu, Ngoc Minh; Le, Van Vu

    2016-03-01

    In order to detect trace concentrations of organic or biological molecules by surface-enhanced Raman scattering (SERS) technique, the SERS-active substrates with high enhancement factor are required. The silver nanodendrites (AgNDs) are a growing class of such SERS-active substrates. This report presents the preliminary results of the trace detection of paraquat (PQ), a commonly used herbicide, with the use of SERS-active substrates, which have been made from AgNDs deposited on silicon. The AgNDs were produced either by electroless deposition, or by electrodeposition onto a silicon wafer, using aqueous solution of HF and AgNO3. It was observed that the silver dendrites are formed only when AgNO3 concentration is high enough. Next, it was found that with the additional assistance of an electric potential in the electrodeposition, the dendrites have grown up with the more perfect ramification. The AgNDs with more perfect branching gave the Raman spectrum of PQ with higher enhancement factor. More specifically, while the SERS-active substrates prepared from electrodeposited AgNDs were able to detect PQ with concentration as low as 0.01 ppm, the ones made from electroless deposited AgNDs could only detect PQ at concentration of hundreds times higher.

  16. Aluminium-induced crystallization of amorphous silicon films deposited by DC magnetron sputtering on glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kezzoula, F., E-mail: kezzoula@usa.com [UDTS 2Bd Frantz Fanon 7 merveilles Algiers (Algeria); Laboratory of Materials, Mineral and Composite (LMMC), Boumerdes University (Algeria); Hammouda, A. [UPR CNRS 3079 CEMHTI - 1D Avenue de la Recherche Scientifique, 45071 Orleans Cedex 2 (France); Equipe Couches Minces, Laboratoire de Physique des Materiaux, Faculte de Physique, USTHB, Algiers (Algeria); Universite d' Orleans, 45067 Orleans Cedex 2 (France); Kechouane, M. [Equipe Couches Minces, Laboratoire de Physique des Materiaux, Faculte de Physique, USTHB, Algiers (Algeria); Simon, P. [UPR CNRS 3079 CEMHTI - 1D Avenue de la Recherche Scientifique, 45071 Orleans Cedex 2 (France); Universite d' Orleans, 45067 Orleans Cedex 2 (France); Abaidia, S.E.H. [Laboratory of Materials, Mineral and Composite (LMMC), Boumerdes University (Algeria); Keffous, A. [UDTS 2Bd Frantz Fanon 7 merveilles Algiers (Algeria); Cherfi, R. [Equipe Couches Minces, Laboratoire de Physique des Materiaux, Faculte de Physique, USTHB, Algiers (Algeria); Menari, H.; Manseri, A. [UDTS 2Bd Frantz Fanon 7 merveilles Algiers (Algeria)

    2011-09-15

    Amorphous silicon (a-Si) and hydrogenated amorphous silicon (a-Si:H) films were deposited by DC magnetron sputtering technique with argon and hydrogen plasma mixture on Al deposited by thermal evaporation on glass substrates. The a-Si/Al and a-Si:H/Al thin films were annealed at different temperatures ranging from 250 to 550 deg. C during 4 h in vacuum-sealed bulb. The effects of annealing temperature on optical, structural and morphological properties of as-grown as well as the vacuum-annealed a-Si/Al and a-Si:H/Al thin films are presented in this contribution. The averaged transmittance of a-Si:H/Al film increases upon increasing the annealing temperature. XRD measurements clearly evidence that crystallization is initiated at 450 deg. C. The number and intensity of diffraction peaks appearing in the diffraction patterns are more important in a-Si:H/Al than that in a-Si/Al layers. Results show that a-Si:H films deposited on Al/glass crystallize above 450 deg. C and present better crystallization than the a-Si layers. The presence of hydrogen induces an improvement of structural properties of poly-Si prepared by aluminium-induced crystallization (AIC).

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

    Institute of Scientific and Technical Information of China (English)

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

    2000-01-01

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

  18. Monitoring of the morphologic reconstruction of deposited ablation products in laser irradiation of silicon

    Directory of Open Access Journals (Sweden)

    Vlasova M.

    2008-01-01

    Full Text Available Using electron microscopy, atomic force microscopy, X-ray microanalysis, and IR spectroscopy, it was established that, in the regime of continuous laser irradiation of silicon at P = 170 W in different gaseous atmospheres with an oxygen impurity, SiOx composite films with a complex morphology form. The main components of ablation products are clusters that form during flight of ablation products and as a result of separation of SiOx-clusters from the zone of the irradiation channel. The roughness and density of the films depend on the heating temperature of the target surface and the type of deposited clusters.

  19. Dimer and String Formation during Low Temperature Silicon Deposition on Si(100)

    DEFF Research Database (Denmark)

    Smith, A. P.; Jonsson, Hannes

    1996-01-01

    We present theoretical results based on density functional theory and kinetic Monte Carlo simulations of silicon deposition and address observations made in recently reported low temperature scanning tunneling microscopy studies. A mechanism is presented which explains dimer formation on top...... of the substrate's dimer rows at 160 K and up to room temperature, while between-row dimers and longer strings of adatoms (''diluted dimer rows'') form at higher temperature. A crossover occurs at around room temperature between two different mechanisms for adatom diffusion in our model....

  20. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    Science.gov (United States)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  1. Directly-deposited blocking filters for high-performance silicon x-ray detectors

    Science.gov (United States)

    Bautz, M.; Kissel, S.; Masterson, R.; Ryu, K.; Suntharalingam, V.

    2016-07-01

    Silicon X-ray detectors often require blocking filters to mitigate noise and out-of-band signal from UV and visible backgrounds. Such filters must be thin to minimize X-ray absorption, so direct deposition of filter material on the detector entrance surface is an attractive approach to fabrication of robust filters. On the other hand, the soft (E X-ray spectral resolution of the detector is sensitive to the charge collection efficiency in the immediate vicinity of its entrance surface, so it is important that any filter layer is deposited without disturbing the electric field distribution there. We have successfully deposited aluminum blocking filters, ranging in thickness from 70 to 220nm, on back-illuminated CCD X-ray detectors passivated by means of molecular beam epitaxy. Here we report measurements showing that directly deposited filters have little or no effect on soft X-ray spectral resolution. We also find that in applications requiring very large optical density (> OD 6) care must be taken to prevent light from entering the sides and mounting surfaces of the detector. Our methods have been used to deposit filters on the detectors of the REXIS instrument scheduled to fly on OSIRIS-ReX later this year.

  2. Brittleness of 6.5wt% Si Silicon Steel Prepared by Chemical Vapor Deposition Method%化学气相沉积法制备硅质量分数6.5%硅钢的脆性

    Institute of Scientific and Technical Information of China (English)

    高超; 苏芳臣; 相颖杰; 孙权; 陈建钧

    2015-01-01

    6.5wt% Si silicon steel was prepared by chemical vapor deposition (CVD)method and the effects of reaction temperature,oxygen content in atmosphere and SiCl4 content on the brittleness of 6.5wt%Si silicon steel were studied using SEM,EDS and self-developed three-point bending machine.The results show that the grain size of the silicon steel increased with the reaction temperature rising,and the brittleness of the silicon steel increased with the increase of the grain size.Grain boundary oxidation was observed in the silicon steel when oxygen content in atmosphere was 100 mg·kg-1 ,which increased the brittleness of the silicon steel.Kirkendall voids were found in the silicon steel with a relatively high SiCl4 content of 35vol%,which increased the brittleness of the steel.%采用化学气相沉积(CVD)法制备了硅质量分数为6.5%的硅钢,利用扫描电镜、能谱仪和自主设计研发的三点压弯机研究了反应温度、气氛含氧量和 SiCl4含量对硅钢脆性的影响.结果表明:硅钢的晶粒尺寸随反应温度的升高而长大,硅钢的脆性随着晶粒尺寸的增加而增大;气氛含氧量在100 mg·kg-1时所制备的硅钢产生了晶界氧化现象,使硅钢脆性增加;SiCl4含量较大时(体积分数35%)所制备的硅钢产生了 Kirkendall 空洞,导致其脆性加剧.

  3. Development of open air silicon deposition technology by silane-free atmospheric pressure plasma enhanced chemical transport under local ambient gas control

    Science.gov (United States)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2016-07-01

    Open air silicon deposition was performed by combining silane-free atmospheric pressure plasma-enhanced chemical transport and a newly developed local ambient gas control technology. The effect of air contamination on silicon deposition was investigated using a vacuum chamber, and the allowable air contamination level was confirmed to be 3 ppm. The capability of the local ambient gas control head was investigated numerically and experimentally. A safe and clean process environment with air contamination less than 1 ppm was achieved. Combining these technologies, a microcrystalline silicon film was deposited in open air, the properties of which were comparable to those of silicon films deposited in a vacuum chamber.

  4. Immersion Deposition of Pt Nanoparticles on Porous Silicon for Methanol Oxidation

    Institute of Scientific and Technical Information of China (English)

    SU Xu; LU Kangle; CHANG Yanlong; ZHANG Yan; WANG Chunming

    2009-01-01

    Porous silicon(PS)was chosen as the substrate for supporting the Pt particles because of great surface area,good conductivity and stability.Pt nanoparticles have been successfully prepared on the substrate by immersion deposition,which is convenient.The component and morphological properties of the films have been investigated by means of X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDX)and scanning electron microscopy(SEM),which shows that the Pt particles have small size and big specific surface.Cyclic voltammetry(CV)research showed that the Pt nanoparticles had novel catalytic activity for methanol when the immersion deposition time was past 24 min.

  5. Investigation of droplet formation in pulsed Nd:YAG laser deposition of metals and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Siew, Wee-Ong; Lee, Wai-Keat; Wong, Hin-Yong; Tou, Teck-Yong [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Yong, Thian-Khok [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Universiti Tunku Abdul Rahman, Faculty of Engineering and Science, Kuala Lumpur (Malaysia); Yap, Seong-Shan [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Norwegian University of Science and Technology, Institute of Physics, Trondheim (Norway)

    2010-12-15

    In the process of pulsed laser deposition of nickel (Ni) and ruthenium (Ru) thin films, the occurrence of phase explosion in ablation was found to affect the deposition rate and enhance the optical emissions from the plasma plume. Faster thin-film growth rates coincide with the onset of phase explosion as a result of superheating and/or sub-surface boiling which also increased the particulates found on the thin-film surface. These particulates were predominantly droplets which may not be round but flattened and also debris for the case of silicon (Si) ablation. The droplets from Ni and Ru thin films were compared in terms of size distribution and number density for different laser fluences. The origins of these particulates were correlated to the bubble and ripple formations on the targets while the transfer to the thin film surface was attributed to the laser-induced ejection from the targets. (orig.)

  6. Electrowetting properties of atomic layer deposited Al{sub 2}O{sub 3} decorated silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Rajkumar, K.; Rajavel, K. [Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu (India); Cameron, D. C. [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); current address Miktech Oy, Mikkeli (Finland); Mangalaraj, D. [Department of NanoScience and Technology, Bharathiar University, Coimbatore, Tamil Nadu (India); Rajendrakumar, R. T., E-mail: buc@edu.in [Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu (India); Department of NanoScience and Technology, Bharathiar University, Coimbatore, Tamil Nadu (India)

    2015-06-24

    This paper reports the electrowetting properties of liquid droplet on superhydrophobic silicon nanowires with Atomic layer deposited (ALD) Al{sub 2}O{sub 3} as dielectric layer. Silicon wafer were etched by metal assisted wet chemical etching with silver as catalyst. ALD Al{sub 2}O{sub 3} films of 10nm thickness were conformally deposited over silicon nanowires. Al{sub 2}O{sub 3} dielectric film coated silicon nanowires was chemically modified with Trichloro (1H, 1H, 2H, 2H-perfluorooctyl) silane to make it superhydrophobic(SHP). The contact angle was measured and all the samples exhibited superhydrophobic nature with maximum contact angles of 163° and a minimum contact angle hysteresis of 6°. Electrowetting induced a maximum reversible decrease of the contact angle of 20°at 150V in air.

  7. CVD silicon carbide monofilament reinforced SrO-Al2O3-2SiO2 (SAS) glass-ceramic composites

    Science.gov (United States)

    Bansal, Narottam P.

    1995-01-01

    Unidirectional CVD SiC fiber-reinforced SrO.Al2O3.2SiO2 (SAS) glass-ceramic matrix composites have been fabricated by hot pressing at various combinations of temperature, pressure and time. Both carbon-rich surface coated SCS-6 and uncoated SCS-0 fibers were used as reinforcements. Almost fully dense composites have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix from x-ray diffraction. During three point flexure testing of composites, a test span to thickness ratio of approximately 25 or greater was necessary to avoid sample delamination. Strong and tough SCS-6/SAS composites having a first matrix crack stress of approximately 300 MPa and an ultimate bend strength of approximately 825 MPa were fabricated. No chemical reaction between the SCS-6 fibers and the SAS matrix was observed after high temperature processing. The uncoated SCS-0 fiber-reinforced SAS composites showed only limited improvement in strength over SAS monolithic. The SCS-0/SAS composite having a fiber volume fraction of 0.24 and hot pressed at 1400 deg C exhibited a first matrix cracking stress of approximately 231 +/- 20 MPa and ultimate strength of 265 +/- 17 MPa. From fiber push-out tests, the fiber/matrix interfacial debonding strength (tau(sub debond)) and frictional sliding stress (tau(sub friction)) in the SCS-6/SAS system were evaluated to be approximately 6.7 +/- 2.3 MPa and 4.3 +/- 0.6 MPa, respectively, indicating a weak interface. However, for the SCS-0/SAS composite, much higher values of approximately 17.5 +/- 2.7 MPa for tau(sub debond) and 11.3 +/- 1.6 MPa for tau(sub friction) respectively, were observed; some of the fibers were so strongly bonded to the matrix that they could not be pushed out. Examination of fracture surfaces revealed limited short pull-out length of SCS-0 fibers. The applicability of various micromechanical models for predicting the values of first matrix cracking stress and ultimate strength of these

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

    OpenAIRE

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

    2016-01-01

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

  9. A mathematical model and simulation results of plasma enhanced chemical vapor deposition of silicon nitride films

    Science.gov (United States)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a mathematical model of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride thin films from SiH4-NH3-N2-Ar mixture, an important application in modern materials science. Our multiphysics model describes gas dynamics, chemical physics, plasma physics and electrodynamics. The PECVD technology is inherently multiscale, from macroscale processes in the chemical reactor to atomic-scale surface chemistry. Our macroscale model is based on Navier-Stokes equations for a transient laminar flow of a compressible chemically reacting gas mixture, together with the mass transfer and energy balance equations, Poisson equation for electric potential, electrons and ions balance equations. The chemical kinetics model includes 24 species and 58 reactions: 37 in the gas phase and 21 on the surface. A deposition model consists of three stages: adsorption to the surface, diffusion along the surface and embedding of products into the substrate. A new model has been validated on experimental results obtained with the "Plasmalab System 100" reactor. We present the mathematical model and simulation results investigating the influence of flow rate and source gas proportion on silicon nitride film growth rate and chemical composition.

  10. Chemical-vapour-deposition growth and electrical characterization of intrinsic silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Salem, B. [Laboratoire des Technologies de la Microelectronique (LTM)-UMR 5129 CNRS, CEA-Grenoble, 17 Rue des Martyrs, F-38054 Grenoble (France)], E-mail: bassem.salem@cea.fr; Dhalluin, F.; Baron, T. [Laboratoire des Technologies de la Microelectronique (LTM)-UMR 5129 CNRS, CEA-Grenoble, 17 Rue des Martyrs, F-38054 Grenoble (France); Jamgotchian, H.; Bedu, F.; Dallaporta, H. [CRMC-N, Faculte des Sciences de Luminy, Case 913, 13288 Marseille Cedex 09 (France); Gentile, P.; Pauc, N. [CEA-DRFMC/SiNaPS, 17 Rue des Martyrs, F-38054 Grenoble (France); Hertog, M.I. den; Rouviere, J.L. [CEA-DRFMC/SP2M/LEMMA GEM-minatec, 17 Rue des Martyrs, F-38054 Grenoble (France); Ferret, P. [CEA-Leti, DOPT, 17 Rue des Martyrs, F-38054 Grenoble (France)

    2009-03-15

    In this work, we present the elaboration and the electrical characterisation of undoped silicon nanowires (SiNWs) which are grown via vapour-liquid-solid mechanism using Au nucleation catalyst and SiH{sub 4} as the silicon source. The nanowires were investigated by high-resolution transmission electron microscopy. An electrical test structure was realized by a dispersion of the nanowires on SiO{sub 2}/Si substrate with photolithography pre-patterned Au/Ti microelectrodes. The connexion is made on a single nanowire using a cross beam plate form allowing scanning electron microscopy imaging and the deposition of tungsten wiring by focussed ion beam deposition. The current-voltage characteristics of the nanowires are linear which indicates an ohmic contact between tungsten allow and SiNWs. The total resistance of the nanowires increases from 135 M{omega} to 5 G{omega} when the diameter decreases from 190 to 130 nm. This effect is may be due to the reduction of the conductive inner volume of the nanowires and to charged defects at the Si-SiO{sub 2} interface if we assume that the contact resistance is constant. Moreover, gate-dependent current versus bias voltage measurement show that the nanowires exhibit a field effect response characteristic of a p-type semiconductor.

  11. Heat transfer model of an iCVD reactor

    NARCIS (Netherlands)

    Bakker, R.; Verlaan, V.; Verkerk, A.D.; van der Werf, C.H.M.; van Dijk, L.; Rudolph, H.; Rath, J.K.; Schropp, R.E.I.

    2009-01-01

    Contrary to conventional HWCVD, the power consumption in the iCVD process is dominated by heat conduction rather than radiation. This is due to the fact that while the typical wire temperature for HWCVD is about 1750–2200 °C, for iCVD the temperature is only 250–500 °C. Typical deposition pressures

  12. Thickness-dependent stress in plasma-deposited silicon dioxide films

    Science.gov (United States)

    Au, V.; Charles, C.; Bulla, D. A. P.; Love, J. D.; Boswell, R. W.

    2005-04-01

    Thick silicon dioxide (SiO2) films up to 5 μm have been deposited by helicon activated reactive evaporation (plasma assisted deposition with electron beam evaporation source) as both bilayer and trilayer structures, and the film stress was investigated in the context of optical waveguide fabrication. A model for stress in the SiO2-Si bilayer as a function of film thickness is formulated and interpreted in terms of Volmer-Weber film growth mechanisms. We find that island coalescence begins at a film thickness of less than 165 nm and continues until about 700 nm. Above approximately 1 μm thickness, the film continues growth as a continuous film. The stress in a deposited SiO2 film in an SiO2-Si-SiO2 trilayer structure was investigated by adapting the established Stoney's equation for a trilayer system, and comparing it with a thermally grown SiO2 trilayer. A constant value of stress is obtained for the deposited SiO2 film for film thickness >1μm which was consistently less than both measured and previously reported values of stress in thermally grown SiO2.

  13. Titanium dioxide antireflection coating for silicon solar cells by spray deposition

    Science.gov (United States)

    Kern, W.; Tracy, E.

    1980-01-01

    A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

  14. Laser cleaning of silicon surface with deposition of different liquid films

    Science.gov (United States)

    Lu, Y. F.; Zhang, Y.; Wan, Y. H.; Song, W. D.

    1999-01-01

    Laser cleaning can efficiently remove tiny particles from a silicon surface on which a liquid film has been previously deposited when the laser fluence is large enough. The cleaning force is due to the high pressure of stress wave generated through the rapid growth of vapor bubbles inside the superheated liquid. The behaviors of this type of laser cleaning are theoretically described with deposition of two kinds of liquid film: acetone and ethanol. The cleaning threshold of laser fluence is different for these two kinds of liquids for some differences in their thermodynamic properties. For removal of alumina particles with a size of 1 μm, the lower cleaning threshold of laser fluence is obtained with deposition of acetone because of its lower boiling point and volume heat capacity. The theoretical result also indicates that the cleaning force with deposition of ethanol increases more quickly along with laser fluence than with acetone. This phenomenon is much useful for removal of smaller particles and can lead to high cleaning efficiency.

  15. Titanium dioxide antireflection coating for silicon solar cells by spray deposition

    Science.gov (United States)

    Kern, W.; Tracy, E.

    1980-01-01

    A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

  16. Practical silicon deposition rules derived from silane monitoring during plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Bartlome, Richard, E-mail: richard.bartlome@alumni.ethz.ch; De Wolf, Stefaan; Demaurex, Bénédicte; Ballif, Christophe [Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory, Rue de la Maladière 71b, 2000 Neuchâtel (Switzerland); Amanatides, Eleftherios; Mataras, Dimitrios [University of Patras, Department of Chemical Engineering, Plasma Technology Laboratory, P.O. Box 1407, 26504 Patras (Greece)

    2015-05-28

    We clarify the difference between the SiH{sub 4} consumption efficiency η and the SiH{sub 4} depletion fraction D, as measured in the pumping line and the actual reactor of an industrial plasma-enhanced chemical vapor deposition system. In the absence of significant polysilane and powder formation, η is proportional to the film growth rate. Above a certain powder formation threshold, any additional amount of SiH{sub 4} consumed translates into increased powder formation rather than into a faster growing Si film. In order to discuss a zero-dimensional analytical model and a two-dimensional numerical model, we measure η as a function of the radio frequency (RF) power density coupled into the plasma, the total gas flow rate, the input SiH{sub 4} concentration, and the reactor pressure. The adjunction of a small trimethylboron flow rate increases η and reduces the formation of powder, while the adjunction of a small disilane flow rate decreases η and favors the formation of powder. Unlike η, D is a location-dependent quantity. It is related to the SiH{sub 4} concentration in the plasma c{sub p}, and to the phase of the growing Si film, whether the substrate is glass or a c-Si wafer. In order to investigate transient effects due to the RF matching, the precoating of reactor walls, or the introduction of a purifier in the gas line, we measure the gas residence time and acquire time-resolved SiH{sub 4} density measurements throughout the ignition and the termination of a plasma.

  17. Atmospheric pressure plasma-initiated chemical vapor deposition (AP-PiCVD) of poly(diethylallylphosphate) coating: a char-forming protective coating for cellulosic textile.

    Science.gov (United States)

    Hilt, Florian; Boscher, Nicolas D; Duday, David; Desbenoit, Nicolas; Levalois-Grützmacher, Joëlle; Choquet, Patrick

    2014-01-01

    An innovative atmospheric pressure chemical vapor deposition method toward the deposition of polymeric layers has been developed. This latter involves the use of a nanopulsed plasma discharge to initiate the free-radical polymerization of an allyl monomer containing phosphorus (diethylallylphosphate, DEAP) at atmospheric pressure. The polymeric structure of the film is evidence by mass spectrometry. The method, highly suitable for the treatment of natural biopolymer substrate, has been carried out on cotton textile to perform the deposition of an efficient and conformal protective coating.

  18. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrakellis, P.; Amanatides, E., E-mail: lef@plasmatech.gr; Mataras, D. [Department of Chemical Engineering, Plasma Technology Laboratory, University of Patras, P.O. Box 140, 26504 Patras (Greece); Kalampounias, A. G. [University of Ioannina, Dep. of Chemistry, 45110, Ioannina (Greece); Spiliopoulos, N. [Department of Physics, University of Patras, P.O. Box 140, 26504 Patras (Greece); Lahootun, V.; Coeuret, F.; Madec, A. [Air Liquide CRCD,1 chemin de la porte des Loges, Les Loges en Josas, 78354 Jouy en Josas (France)

    2016-07-15

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  19. Thermal Conductivity of Amorphous and Nanocrystalline Silicon Films Prepared by Hot-Wire Chemical-Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Nemeth, William M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jugdersuren, B. [Sotera Defense Solutions, Inc.; Kearney, B. T. [Naval Research Laboratory; Queen, D. R. [Naval Research Laboratory; Metcalf, T. H. [Naval Research Laboratory; Culbertson, J. C. [Naval Research Laboratory; Chervin, C. N. [Naval Research Laboratory; Stroud, R. M. [Naval Research Laboratory; Wang, Q. [Formerly NREL; Liu, Xiao [Naval Research Laboratory

    2017-07-31

    We report 3..omega.. thermal conductivity measurements of amorphous and nanocrystalline silicon thin films from 85 to 300 K prepared by hot-wire chemical-vapor deposition, where the crystallinity of the films is controlled by the hydrogen dilution during growth. The thermal conductivity of the amorphous silicon film is in agreement with several previous reports of amorphous silicon prepared by a variety of deposition techniques. The thermal conductivity of the as-grown nanocrystalline silicon film is 70% higher and increases 35% more after an anneal at 600 degrees C. They all have similarly weak temperature dependence. Structural analysis shows that the as-grown nanocrystalline silicon is approximately 60% crystalline, nanograins and grain boundaries included. The nanograins, averaging 9.1 nm in diameter in the as-grown film, are embedded in an amorphous matrix. The grain size increases to 9.7 nm upon annealing, accompanied by the disappearance of the amorphous phase. We extend the models of grain boundary scattering of phonons with two different non-Debye dispersion relations to explain our result of nanocrystalline silicon, confirming the strong grain size dependence of heat transport for nanocrystalline materials. However, the similarity in thermal conductivity between amorphous and nanocrystalline silicon suggests the heat transport mechanisms in both structures may not be as dissimilar as we currently understand.

  20. Thermal conductivity of amorphous and nanocrystalline silicon films prepared by hot-wire chemical-vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jugdersuren, B.; Kearney, B. T.; Queen, D. R.; Metcalf, T. H.; Culbertson, J. C.; Chervin, C. N.; Stroud, R. M.; Nemeth, W.; Wang, Q.; Liu, Xiao

    2017-07-01

    We report 3..omega.. thermal conductivity measurements of amorphous and nanocrystalline silicon thin films from 85 to 300 K prepared by hot-wire chemical-vapor deposition, where the crystallinity of the films is controlled by the hydrogen dilution during growth. The thermal conductivity of the amorphous silicon film is in agreement with several previous reports of amorphous silicon prepared by a variety of deposition techniques. The thermal conductivity of the as-grown nanocrystalline silicon film is 70% higher and increases 35% more after an anneal at 600 degrees C. They all have similarly weak temperature dependence. Structural analysis shows that the as-grown nanocrystalline silicon is approximately 60% crystalline, nanograins and grain boundaries included. The nanograins, averaging 9.1 nm in diameter in the as-grown film, are embedded in an amorphous matrix. The grain size increases to 9.7 nm upon annealing, accompanied by the disappearance of the amorphous phase. We extend the models of grain boundary scattering of phonons with two different non-Debye dispersion relations to explain our result of nanocrystalline silicon, confirming the strong grain size dependence of heat transport for nanocrystalline materials. However, the similarity in thermal conductivity between amorphous and nanocrystalline silicon suggests the heat transport mechanisms in both structures may not be as dissimilar as we currently understand.

  1. Thermal conductivity of amorphous and nanocrystalline silicon films prepared by hot-wire chemical-vapor deposition

    Science.gov (United States)

    Jugdersuren, B.; Kearney, B. T.; Queen, D. R.; Metcalf, T. H.; Culbertson, J. C.; Chervin, C. N.; Stroud, R. M.; Nemeth, W.; Wang, Q.; Liu, Xiao

    2017-07-01

    We report 3 ω thermal conductivity measurements of amorphous and nanocrystalline silicon thin films from 85 to 300 K prepared by hot-wire chemical-vapor deposition, where the crystallinity of the films is controlled by the hydrogen dilution during growth. The thermal conductivity of the amorphous silicon film is in agreement with several previous reports of amorphous silicon prepared by a variety of deposition techniques. The thermal conductivity of the as-grown nanocrystalline silicon film is 70% higher and increases 35% more after an anneal at 600 ∘C . They all have similarly weak temperature dependence. Structural analysis shows that the as-grown nanocrystalline silicon is approximately 60 % crystalline, nanograins and grain boundaries included. The nanograins, averaging 9.1 nm in diameter in the as-grown film, are embedded in an amorphous matrix. The grain size increases to 9.7 nm upon annealing, accompanied by the disappearance of the amorphous phase. We extend the models of grain boundary scattering of phonons with two different non-Debye dispersion relations to explain our result of nanocrystalline silicon, confirming the strong grain size dependence of heat transport for nanocrystalline materials. However, the similarity in thermal conductivity between amorphous and nanocrystalline silicon suggests the heat transport mechanisms in both structures may not be as dissimilar as we currently understand.

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

    Science.gov (United States)

    Ebil, Ozgenc

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

  3. X-Ray structural and gas phase studies of silver(i) perfluorinated carboxylate complexes with 2,2'-bipyridyl as potential precursors for chemical vapour deposition (CVD).

    Science.gov (United States)

    Szłyk, Edward; Szczesny, Robert; Wojtczak, Andrzej

    2010-02-21

    [Ag(CF(3)COO)(bpy)] (), [Ag(2)(C(2)F(5)COO)(2)(bpy)] () and [Ag(2)(C(3)F(7)COO)(2)(bpy)] () were prepared and characterized by MS-EI, (1)H, (13)C NMR, variable-temperature IR (VT-IR) spectroscopy (solid sample and evolved volatile species) and thermal analysis. Single-crystal X-ray diffraction data revealed the polymeric structure for [Ag(2)(C(2)F(5)COO)(2)(bpy)] and [Ag(6)(C(3)F(7)COO)(6)(bpy)(4)], with bridging bpy ligand, whereas for [Ag(CF(3)COO)(bpy)] the dimeric system with monodentately linked carboxylate was noted. Mass spectra analysis of () over 30-300 degrees C indicates the presence of binuclear ions [(RCOO)Ag(2)](+) as a main volatile particles, which can be transported in CVD process. VT-IR studies of gases evolved during the thermal decomposition process, demonstrate the presence of fluorocarbon species and CO(2) as the most abundant molecules. Thermal analysis of () revealed a multi-stage decomposition mechanism resulting in Ag(0) formation below 290 degrees C. Compounds were tested for silver metal spray pyrolysis and obtained layers were characterized by scanning electron microscopy (SEM-EDX) and XRD.

  4. Thin film silicon deposited at 100 C by VHF PECVD: optoelectronic properties and incorporation in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Brinza, Monica; Rath, Jatindra K.; Schropp, Ruud E.I. [Nanophotonics - Physics of Devices, Debye Institute for Nanomaterials Science, Faculty of Science, Utrecht University, PO Box 80000, 3508 TA Utrecht (Netherlands)

    2010-04-15

    This paper explores the possibility of producing amorphous and nanocrystalline silicon using very high frequency PECVD at a low substrate temperature of 123 C at high deposition rate of 0.4-0.7 nm/s. The quality of these amorphous layers remains similar to that obtained in layers deposited at low deposition rate of 0.1 nm/s. The amorphous-to-nanocrystalline transition is sensitive to deposition chamber history. The microstructure parameter of the best nanocrystalline layers amounts to 0.4. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Structural characterisation of BaTiO{sub 3} thin films deposited on SrRuO{sub 3}/YSZ buffered silicon substrates and silicon microcantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Colder, H.; Jorel, C., E-mail: corentin.jorel@unicaen.fr; Méchin, L. [GREYC, UMR 6072, CNRS, ENSICAEN, UCBN, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Domengès, B. [LAMIPS, CRISMAT-NXP Semiconductors-Presto Engineering laboratory, CNRS-UMR 6508, ENSICAEN, UCBN, 2 rue de la Girafe, 14 000 Caen (France); Marie, P.; Boisserie, M. [CIMAP, UMR 6252, CNRS, ENSICAEN, UCBN, CEA, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Guillon, S.; Nicu, L. [LAAS, CNRS, Univ de Toulouse, 7 avenue du Colonel Roche, 31400 Toulouse (France); Galdi, A. [GREYC, UMR 6072, CNRS, ENSICAEN, UCBN, 6 bd du Maréchal Juin, 14050 Caen Cedex (France); Department of Industrial Engineering, CNR-SPIN Salerno, Università di Salerno, 84084 Fisciano, Salerno (Italy)

    2014-02-07

    We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO{sub 3} (BTO) thin films were deposited at two different oxygen pressures, 5.10{sup −2} mbar and 5.10{sup −3} mbar, on SrRuO{sub 3}/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO{sub 3} electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10{sup −2} mbar strain was mostly localized inside the BTO grains whereas at 5.10{sup −3} mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O{sub 2} pressure of 5.10{sup −3} mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission electron microscopy (TEM) was used to investigate the epitaxial quality of the layers and their epitaxial relationship on plain silicon wafers as well as on released microcantilevers, thanks to Focused-Ion-Beam TEM lamella preparation.

  6. Surface Characteristics of Silicon Nanowires/Nanowalls Subjected to Octadecyltrichlorosilane Deposition and n-octadecane Coating.

    Science.gov (United States)

    Yilbas, Bekir Sami; Salhi, Billel; Yousaf, Muhammad Rizwan; Al-Sulaiman, Fahad; Ali, Haider; Al-Aqeeli, Nasser

    2016-12-09

    In this study, nanowires/nanowalls were generated on a silicon wafer through a chemical etching method. Octadecyltrichlorosilane (OTS) was deposited onto the nanowire/nanowall surfaces to alter their hydrophobicity. The hydrophobic characteristics of the surfaces were further modified via a 1.5-μm-thick layer of n-octadecane coating on the OTS-deposited surface. The hydrophobic characteristics of the resulting surfaces were assessed using the sessile water droplet method. Scratch and ultraviolet (UV)-visible reflectivity tests were conducted to measure the friction coefficient and reflectivity of the surfaces. The nanowires formed were normal to the surface and uniformly extended 10.5 μm to the wafer surface. The OTS coating enhanced the hydrophobic state of the surface, and the water contact angle increased from 27° to 165°. The n-octadecane coating formed on the OTS-deposited nanowires/nanowalls altered the hydrophobic state of the surface. This study provides the first demonstration that the surface wetting characteristics change from hydrophobic to hydrophilic after melting of the n-octadecane coating. In addition, this change is reversible; i.e., the hydrophilic surface becomes hydrophobic after the n-octadecane coating solidifies at the surface, and the process again occurs in the opposite direction after the n-octadecane coating melts.

  7. Surface modification of silicon-containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Jin, Yoonyoung; Desta, Yohannes; Goettert, Jost; Lee, G. S.; Ajmera, P. K.

    2005-07-01

    Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°+/-2° before treatment to 32°+/-2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4 kJ/cm3, the contact angle of the sessile water drop changed from 95°+/-2° before radiation to 39°+/-3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applicability of the surface modified films. The x-ray irradiation method offers a unique advantage in making possible surface modification in a localized area of high-aspect-ratio microstructures. Fabrication of a Ti-membrane x-ray mask is introduced here for selective surface modification using x-ray irradiation.

  8. Structural and electrical properties of an Au film system deposited on silicone oil surfaces

    CERN Document Server

    Yang Bo; Jin Jin Sheng; Ye Quan Lin; Lao Yan Feng; Jiao Zheng Kuan; Ye Gao Xiang

    2002-01-01

    An Au thin film system, deposited on silicone oil surfaces by the thermal deposition method, has been fabricated and its structure as well as electrical properties has been studied. A web-shaped characteristic surface morphology of the films is observed. The dc sheet resistance R of the metal films on the liquid surfaces is measured during and after deposition in situ by the four-probe method. The time dependence of the sheet resistance can be explained in terms of the film growth mechanism on the oil surface. The anomalous I-V characteristics of the film system can be interpreted as a competition among the local Joule heating, hopping and tunnelling effects. It is found that the dc third-harmonic coefficient B sub 0 and the zero-power resistance R sub 0 satisfy the power-law relation B sub 0 propor to R sub 0 sup 2 sup + sup w and the exponent w is close to zero. This result indicates that the hopping and tunnelling effects in the samples are much stronger than those of the other film systems. We also find I...

  9. Hydrogenated Amorphous Silicon Sensor Deposited on Integrated Circuit for Radiation Detection

    CERN Document Server

    Despeisse, M; Jarron, P; Kaplon, J; Moraes, D; Nardulli, A; Powolny, F; Wyrsch, N

    2008-01-01

    Radiation detectors based on the deposition of a 10 to 30 mum thick hydrogenated amorphous silicon (a-Si:H) sensor directly on top of integrated circuits have been developed. The performance of this detector technology has been assessed for the first time in the context of particle detectors. Three different circuits were designed in a quarter micron CMOS technology for these studies. The so-called TFA (Thin-Film on ASIC) detectors obtained after deposition of a-Si:H sensors on the developed circuits are presented. High internal electric fields (104 to 105 V/cm) can be built in the a-Si:H sensor and overcome the low mobility of electrons and holes in this amorphous material. However, the deposited sensor's leakage current at such fields turns out to be an important parameter which limits the performance of a TFA detector. Its detailed study is presented as well as the detector's pixel segmentation. Signal induction by generated free carrier motion in the a-Si:H sensor has been characterized using a 660 nm pul...

  10. Atomic Layer Deposition of Silicon Nitride from Bis(tert-butylamino)silane and N2 Plasma.

    Science.gov (United States)

    Knoops, Harm C M; Braeken, Eline M J; de Peuter, Koen; Potts, Stephen E; Haukka, Suvi; Pore, Viljami; Kessels, Wilhelmus M M

    2015-09-01

    Atomic layer deposition (ALD) of silicon nitride (SiNx) is deemed essential for a variety of applications in nanoelectronics, such as gate spacer layers in transistors. In this work an ALD process using bis(tert-butylamino)silane (BTBAS) and N2 plasma was developed and studied. The process exhibited a wide temperature window starting from room temperature up to 500 °C. The material properties and wet-etch rates were investigated as a function of plasma exposure time, plasma pressure, and substrate table temperature. Table temperatures of 300-500 °C yielded a high material quality and a composition close to Si3N4 was obtained at 500 °C (N/Si=1.4±0.1, mass density=2.9±0.1 g/cm3, refractive index=1.96±0.03). Low wet-etch rates of ∼1 nm/min were obtained for films deposited at table temperatures of 400 °C and higher, similar to that achieved in the literature using low-pressure chemical vapor deposition of SiNx at >700 °C. For novel applications requiring significantly lower temperatures, the temperature window from room temperature to 200 °C can be a solution, where relatively high material quality was obtained when operating at low plasma pressures or long plasma exposure times.

  11. 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.

  12. Thermal and plasma enhanced atomic layer deposition of SiO{sub 2} using commercial silicon precursors

    Energy Technology Data Exchange (ETDEWEB)

    Putkonen, Matti, E-mail: matti.putkonen@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, Espoo (Finland); Laboratory of Inorganic Chemistry, Aalto University School of Chemical Technology, P.O. Box 16100, FI-00076, Espoo (Finland); Bosund, Markus [Beneq Oy, Ensimmäinen savu, FI-01510, Vantaa (Finland); Ylivaara, Oili M.E.; Puurunen, Riikka L.; Kilpi, Lauri; Ronkainen, Helena [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, Espoo (Finland); Sintonen, Sakari; Ali, Saima; Lipsanen, Harri [Aalto University School of Electrical Engineering, Department of Micro- and Nanosciences, P.O. Box 13500, FI-00076 Espoo (Finland); Liu, Xuwen; Haimi, Eero; Hannula, Simo-Pekka [Aalto University School of Chemical Technology, Department of Materials Science and Engineering, P.O. Box 16200, FI-00076 Espoo (Finland); Sajavaara, Timo [University of Jyväskylä, Department of Physics, P.O. Box 35, FI-40014 Jyväskylä (Finland); Buchanan, Iain; Karwacki, Eugene [Air Products and Chemicals Inc., 7201 Hamilton Blvd., Allentown, PA 18195 (United States); Vähä-Nissi, Mika [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, Espoo (Finland)

    2014-05-02

    In this paper, we report ALD deposition of silicon dioxide using either thermal or plasma enhanced atomic layer deposition (PEALD). Several aminosilanes with differing structures and reactivity were used as silicon precursors in R and D single wafer ALD tools. One of the precursors was also tested on pilot scale batch ALD using O{sub 3} as oxidant and with substrates measuring 150 × 400 mm. The SiO{sub 2} film deposition rate was greatly dependent on the precursors used, highest values being 1.5–2.0 Å/cycle at 30–200 °C for one precursor with an O{sub 2} plasma. According to time-of-flight-elastic recoil detection analysis measurements carbon and nitrogen impurities were relatively low, but hydrogen content increased at low deposition temperatures. - Highlights: • SiO{sub 2} thin film is deposited by thermal and plasma enhanced atomic layer deposition (PEALD). • We report low-temperature deposition of SiO{sub 2} even at 30 °C by PEALD. • Scaling up of the atomic layer deposition processes to industrial batch is reported. • Deposited films had low low compressive residual stress and good conformality.

  13. Plasma-enhanced atomic-layer-deposited MoO{sub x} emitters for silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Johannes; Schneider, Thomas; Sprafke, Alexander N. [Martin-Luther-University Halle-Wittenberg, mu-MD Group, Institute of Physics, Halle (Germany); Mews, Mathias; Korte, Lars [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Silicon-Photovoltaics, Berlin (Germany); Kaufmann, Kai [Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Germany); University of Applied Sciences, Hochschule Anhalt Koethen, Koethen (Germany); Wehrspohn, Ralf B. [Martin-Luther-University Halle-Wittenberg, mu-MD Group, Institute of Physics, Halle (Germany); Fraunhofer Institute for Mechanics of Materials IWM Halle, Halle (Germany)

    2015-09-15

    A method for the deposition of molybdenum oxide (MoO{sub x}) with high growth rates at temperatures below 200 C based on plasma-enhanced atomic layer deposition is presented. The stoichiometry of the over-stoichiometric MoO{sub x} films can be adjusted by the plasma parameters. First results of these layers acting as hole-selective contacts in silicon heterojunction solar cells are presented and discussed. (orig.)

  14. Compensation of decreased ion energy by increased hydrogen dilution in plasma deposition of thin film silicon solar cells at low substrate temperatures

    NARCIS (Netherlands)

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

    2008-01-01

    In order to deposit thin film silicon solar cells on plastics and papers, the deposition process needs to be adapted for low deposition temperatures. In a very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) process, both the gas phase and the surface processes are affected by l

  15. Metallic Tungsten Nanostructures and Highly Nanostructured Thin Films by Deposition of Tungsten Oxide and Subsequent Reduction in a Single Hot-Wire CVD Process

    NARCIS (Netherlands)

    Harks, P.P.R.M.L.; Houweling, Z.S.; de Jong, M.M.; Kuang, Y; Geus, J.W.; Schropp, R.E.I.

    2012-01-01

    The synthesis of metallic tungsten nanostructures and highly nanostructured thin films is presented. Crystalline tungsten oxide nanostructures are deposited on glassy carbon substrates kept at 700 100 8C by oxidizing resistively heated tungsten filaments in an air flow under subatmospheric pressures

  16. Large-Scale Graphene Film Deposition for Monolithic Device Fabrication

    Science.gov (United States)

    Al-shurman, Khaled

    Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors. The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an urgent need for a new platform material to replace Si. Graphene is considered a promising material with enormous potential applications in many electronic and optoelectronics devices due to its superior properties. There are several techniques to produce graphene films. Among these techniques, chemical vapor deposition (CVD) offers a very convenient method to fabricate films for large-scale graphene films. Though CVD method is suitable for large area growth of graphene, the need for transferring a graphene film to silicon-based substrates is required. Furthermore, the graphene films thus achieved are, in fact, not single crystalline. Also, graphene fabrication utilizing Cu and Ni at high growth temperature contaminates the substrate that holds Si CMOS circuitry and CVD chamber as well. So, lowering the deposition temperature is another technological milestone for the successful adoption of graphene in integrated circuits fabrication. In this research, direct large-scale graphene film fabrication on silicon based platform (i.e. SiO2 and Si3N4) at low temperature was achieved. With a focus on low-temperature graphene growth, hot-filament chemical vapor deposition (HF-CVD) was utilized to synthesize graphene film using 200 nm thick nickel film. Raman spectroscopy was utilized to examine graphene formation on the bottom side of the Ni film

  17. Low-pressure Chemical Vapour Deposition of Silicon Nanoparticles:Synthesis and Characterisation

    Directory of Open Access Journals (Sweden)

    A. Kumar

    2008-07-01

    Full Text Available emiconductor nanostructures such as quantum wells, quantum wires or quantum dots exhibit superior properties in comparison to their bulk forms. Quantum dots are described aszero-dimensional electron gas system, as carriers are confined in all the three directions. Densityof states is discrete function of energy. Allowed energy spectrum is discrete like in an atom.Energy band gap is broadened due to carriers confinement. Semiconductor quantum dots exhibittypical coulomb blockade characteristic which is exploited for development of new generationof nanoelectronic devices namely single-electron transistor, memories, etc, whose operationdepends on quantum mechanical tunneling of carriers through energy barriers. Thesesemiconductor nanostructures emit light in visible range upon excitation by optical means. Inrecent years,  research  has been focused on different nano-scale materials; metals (Au, Ag, Fe,Mn, Ni, metal oxides (SnO2, ZnO2, compound semiconductors (GaAs, GaAlAs, CdSe, CdS,GaN, and elemental semiconductors (silicon and germanium. As silicon is the most favouredmaterial in the established integrated circuits manufacturing technology, research is being donefor controlled synthesis and characterisation of Si nanoparticles. The Si nanoparticles havebeen synthesised on oxide and nitride layers over  Si substrate by IC technology compatiblelow-pressure chemical vapour deposition technique. Atomic force microscopy (AFMcharacterisation has been extensively carried out on the samples. It is shown that the tip radiusand shape of tip lead to less accurate estimate of the actual size. The AFM images have been evaluated based on the real surface topography and shape of the tip. Photolumine scence (PL studies have been performed to characterise the samples. The PL measurements showed visiblelight emission from synthesised silicon nanoparticles.Defence Science Journal, 2008, 58(4, pp.550-558, DOI:http://dx.doi.org/10.14429/dsj.58.1676

  18. Deposition of thin layers of boron nitrides and hydrogenated microcrystalline silicon assisted by high current direct current arc plasma; Deposition assistee par un plasma a arc a haut courant continu de couches minces de Nitrure de Bore et de Silicium microcristallin hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Franz, D. [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    1999-09-01

    In the frame of this thesis, a high current direct current arc (HCDCA) used for the industrial deposition of diamond, has been adapted to study the deposition of two types of coatings: a) boron nitride, whose cubic phase is similar to diamond, for tribological applications, b) hydrogenated microcrystalline silicon, for applications in the semiconductor fields (flat panel displays, solar cells,...). For the deposition of these coatings, the substrates were placed in the diffusion region of the arc. The substrate heating is mainly due to atomic species recombining on its surface. The deposition temperature, varying from 300 to 900 {sup o}C according to the films deposited, is determined by the substrate position, the arc power and the injected gas fluxes, without the use of any external heating or cooling system. Measurements performed on the arc plasma show that the electronic temperature is around 2 eV (23'000 K) while the gas temperature is lower than 5500 K. Typical electronic densities are in the range of 10{sup 12}-10{sup 1'}3 cm{sup -3}. For the deposition of boron nitride films, different boron precursors were used and a wide parameter range was investigated. The extreme difficulty of synthesising cubic boron nitride films by chemical vapour deposition (CVD) did not allow to stabilize the cubic phase of boron nitride in HCDCA. Coatings resulted in hexagonal or amorphous boron nitride with a chemical composition close to stoichiometric. The presence of hydrogen leads to the deposition of rough and porous films. Negative biasing of the samples, for positive ion bombardment, is commonly used to stabilize the cubic phase. In HCDCA and in our biasing range, only a densification of the films could be observed. A boron nitride deposition plasma study by infrared absorption spectroscopy in a capacitive radio frequency reactor has demonstrated the usefulness of this diagnostic for the understanding of the various chemical reactions which occur in this kind

  19. Photoluminescence of oxidized silicon nanoclusters deposited on the basal plane of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L.N. (Chemistry and Materials Science Department, and Department of Applied Science, University of California, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)); Chase, L.L.; Balooch, M.; Terminello, L.J. (Chemistry and Materials Science Department, University of California, Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)); Wooten, F. (Department of Applied Science, University of California, Davis/Livermore, California 94551 (United States))

    1994-12-12

    Silicon (Si) nanoclusters, with an average size of 3--5 nm in diameter, have been deposited on the basal plane of highly oriented pyrolytic graphite in an ultrahigh vacuum chamber, and investigated by scanning tunneling microscopy. Clusters passivated [ital in] [ital situ] with hydrogen or oxygen showed no detectable visible photoluminescence (PL). Prolonged exposure of the clusters to ambient air, however, resulted in strong stable red to green-blue PL spectra. Further study of these clusters by x-ray photoelectron spectroscopy and Auger electron spectroscopy revealed the existence of only SiO[sub 2] for the prolonged air-exposed samples, and the existence of SiO[sub [ital x

  20. Photoluminescence of oxidized silicon nanoclusters deposited on the basal plane of graphite

    Science.gov (United States)

    Dinh, L. N.; Chase, L. L.; Balooch, M.; Terminello, L. J.; Wooten, F.

    1994-12-01

    Silicon (Si) nanoclusters, with an average size of 3-5 nm in diameter, have been deposited on the basal plane of highly oriented pyrolytic graphite in an ultrahigh vacuum chamber, and investigated by scanning tunneling microscopy. Clusters passivated in situ with hydrogen or oxygen showed no detectable visible photoluminescence (PL). Prolonged exposure of the clusters to ambient air, however, resulted in strong stable red to green-blue PL spectra. Further study of these clusters by x-ray photoelectron spectroscopy and Auger electron spectroscopy revealed the existence of only SiO2 for the prolonged air-exposed samples, and the existence of SiOx (x ranged from 0 to 2) for the in situ oxidized samples which did not exhibit any detectable visible PL. We believe that the observed visible PL originated from defects in SiO2.

  1. Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen

    Science.gov (United States)

    Opila, Elizabeth J.

    1994-01-01

    The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

  2. Depositing nanoparticles on a silicon substrate using a freeze drying technique

    Science.gov (United States)

    Sigehuzi, Tomoo

    2017-08-01

    For the microscopic observation of nanoparticles, an adequate sample preparation is an essential part of this task. Much research has been performed for usable preparation methods that will yield aggregate-free samples. A freeze drying technique, which only requires a -80 °C freezer and a freeze dryer, is shown to provide an on-substrate dispersion of mostly isolated nanoparticles. The particle density could be made sufficiently high for efficient observations using atomic force microscopy. Since this sandwich method is purely physical, it could be applied to deposit various nanoparticles independent of their surface chemical properties. Suspension film thickness, or the dimensionality of the suspension film, was shown to be crucial for the isolation of the particles. Silica nanoparticles were dispersed on a silicon substrate using this method and the sample properties were examined using atomic force microscopy.

  3. Characterization of doped hydrogenated nanocrystalline silicon films prepared by plasma enhanced chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Wang Jin-Liang; Wu Er-Xing

    2007-01-01

    The B-and P-doped hydrogenated nanocrystalline silicon films (nc-Si:H) are prepared by plasma-enhanced chemical vapour deposition (PECVD) .The microstructures of doped nc-Si:H films are carefully and systematically char acterized by using high resolution electron microscopy (HREM) ,Raman scattering,x-ray diffraction (XRD) ,Auger electron spectroscopy (AES) ,and resonant nucleus reaction (RNR) .The results show that as the doping concentration of PH3 increases,the average grain size (d) tends to decrease and the crystalline volume percentage (Xc) increases simultaneously.For the B-doped samples,as the doping concentration of B2H6 increases,no obvious change in the value of d is observed,but the value of Xc is found to decrease.This is especially apparent in the case of heavy B2H6 doped samples,where the films change from nanocrystalline to amorphous.

  4. Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition.

    Science.gov (United States)

    Carretero-Genevrier, Adrián; Gich, Martí

    2015-12-21

    This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol. However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr(2+) act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.

  5. Highly efficient shrinkage of inverted-pyramid silicon nanopores by plasma-enhanced chemical vapor deposition technology

    Science.gov (United States)

    Wang, Yifan; Deng, Tao; Chen, Qi; Liang, Feng; Liu, Zewen

    2016-06-01

    Solid-state nanopore-based analysis systems are currently one of the most attractive and promising platforms in sensing fields. This work presents a highly efficient method to shrink inverted-pyramid silicon nanopores using plasma-enhanced chemical vapor deposition (PECVD) technology by the deposition of SiN x onto the surface of the nanopore. The contraction of the inverted-pyramid silicon nanopores when subjected to the PECVD process has been modeled and carefully analyzed, and the modeling data are in good agreement with the experimental results within a specific PECVD shrinkage period (˜0-600 s). Silicon nanopores within a 50-400 nm size range contract to sub-10 nm dimensions. Additionally, the inner structure of the nanopores after the PECVD process has been analyzed by focused ion beam cutting process. The results show an inner structure morphology change from inverted-pyramid to hourglass, which may enhance the spatial resolution of sensing devices.

  6. Highly efficient shrinkage of inverted-pyramid silicon nanopores by plasma-enhanced chemical vapor deposition technology.

    Science.gov (United States)

    Wang, Yifan; Deng, Tao; Chen, Qi; Liang, Feng; Liu, Zewen

    2016-06-24

    Solid-state nanopore-based analysis systems are currently one of the most attractive and promising platforms in sensing fields. This work presents a highly efficient method to shrink inverted-pyramid silicon nanopores using plasma-enhanced chemical vapor deposition (PECVD) technology by the deposition of SiN x onto the surface of the nanopore. The contraction of the inverted-pyramid silicon nanopores when subjected to the PECVD process has been modeled and carefully analyzed, and the modeling data are in good agreement with the experimental results within a specific PECVD shrinkage period (∼0-600 s). Silicon nanopores within a 50-400 nm size range contract to sub-10 nm dimensions. Additionally, the inner structure of the nanopores after the PECVD process has been analyzed by focused ion beam cutting process. The results show an inner structure morphology change from inverted-pyramid to hourglass, which may enhance the spatial resolution of sensing devices.

  7. Extraction of Kinetic Parameters for the Chemical Vapor Deposition of Polycrystalline Silicon at Medium and Low Pressures

    NARCIS (Netherlands)

    Holleman, J.; Verweij, J.F.; Verweij, Jan F.

    1993-01-01

    The deposition of silicon (Si) from silane (SiH4) was studied in the silane pressure range from 0.5 to 100 Pa (0.005 to1 mbar) and total pressure range from 10 to 1000 Pa using N2 or He as carrier gases. The two reaction paths, namely,heterogeneous and homogeneous decomposition could be separated by

  8. Plasma-enhanced chemical vapor deposited silicon oxynitride films for optical waveguide bridges for use in mechanical sensors

    DEFF Research Database (Denmark)

    Storgaard-Larsen, Torben; Leistiko, Otto

    1997-01-01

    In this paper the influence of RF power, ammonia flow, annealing temperature, and annealing time on the optical and mechanical properties of plasma-enhanced chemically vapor deposited silicon oxynitride films, is presented. A low refractive index (1.47 to 1.48) film having tensile stress has been...

  9. High Throughput Nanofabrication of Silicon Nanowire and Carbon Nanotube Tips on AFM Probes by Stencil-Deposited Catalysts

    DEFF Research Database (Denmark)

    Engstrøm, Daniel Southcott; Savu, Veronica; Zhu, Xueni;

    2011-01-01

    A new and versatile technique for the wafer scale nanofabrication of silicon nanowire (SiNW) and multiwalled carbon nanotube (MWNT) tips on atomic force microscope (AFM) probes is presented. Catalyst material for the SiNW and MWNT growth was deposited on prefabricated AFM probes using aligned wafer...

  10. Extraction of Kinetic Parameters for the Chemical Vapor Deposition of Polycrystalline Silicon at Medium and Low Pressures

    NARCIS (Netherlands)

    Holleman, Jisk; Verweij, Jan F.

    1993-01-01

    The deposition of silicon (Si) from silane (SiH4) was studied in the silane pressure range from 0.5 to 100 Pa (0.005 to1 mbar) and total pressure range from 10 to 1000 Pa using N2 or He as carrier gases. The two reaction paths, namely,heterogeneous and homogeneous decomposition could be separated by

  11. Thin film silicon n–i–p solar cells deposited by VHF PECVD at 100 °C substrate temperature

    NARCIS (Netherlands)

    Brinza, M.; Rath, J.K.; Schropp, R.E.I.

    2009-01-01

    The applicability of the very high frequency (VHF) plasma-enhanced chemical vapor deposition (PECVD) technique to the fabrication of solar cells in an n–i–p configuration at 100 °C substrate temperature is being investigated. Amorphous and microcrystalline silicon cells are made with the absorber la

  12. Efficient solar photocatalytic activity of TiO2 coated nano-porous silicon by atomic layer deposition

    Science.gov (United States)

    Sampath, Sridhar; Maydannik, Philipp; Ivanova, Tatiana; Shestakova, Marina; Homola, Tomáš; Bryukvin, Anton; Sillanpää, Mika; Nagumothu, Rameshbabu; Alagan, Viswanathan

    2016-09-01

    In the present study, TiO2 coated nano-porous silicon (TiO2/PS) was prepared by atomic layer deposition (ALD) whereas porous silicon was prepared by stain etching method for efficient solar photocatalytic activity. TiO2/PS was characterized by FESEM, AFM, XRD, XPS and DRS UV-vis spectrophotometer. Absorbance spectrum revealed that TiO2/PS absorbs complete solar light with wave length range of 300 nm-800 nm and most importantly, it absorbs stronger visible light than UV light. The reason for efficient solar light absorption of TiO2/PS is that nanostructured TiO2 layer absorbs UV light and nano-porous silicon layer absorbs visible light which is transparent to TiO2 layer. The amount of visible light absorption of TiO2/PS directly increases with increase of silicon etching time. The effect of silicon etching time of TiO2/PS on solar photocatalytic activity was investigated towards methylene blue dye degradation. Layer by layer solar absorption mechanism was used to explain the enhanced photocatalytic activity of TiO2/PS solar absorber. According to this, the photo-generated electrons of porous silicon will be effectively injected into TiO2 via hetero junction interface which leads to efficient charge separation even though porous silicon is not participating in any redox reactions in direct.

  13. High growth rate of a-SiC:H films using ethane carbon source by HW-CVD method

    Indian Academy of Sciences (India)

    Mahesh M Kamble; Vaishali S Waman; Sanjay S Ghosh; Azam Mayabadi; Vasant G Sathe; T Shripathi; Habib M Pathan; Sandesh R Jadkar

    2013-12-01

    Hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared using pure silane (SiH4) and ethane (C2H6), a novel carbon source, without hydrogen dilution using hot wire chemical vapour deposition (HW-CVD) method at low substrate temperature (200 °C) and at reasonably higher deposition rate (19.5 Å/s < d < 35.2 Å/s). Formation of a-SiC:H films has been confirmed from FTIR, Raman and XPS analysis. Influence of deposition pressure on compositional, structural, optical and electrical properties has been investigated. FTIR spectroscopy analysis revealed that there is decrease in C–H and Si–H bond densities while, Si–C bond density increases with increase in deposition pressure. Total hydrogen content drops from 22.6 to 14.4 at.% when deposition pressure is increased. Raman spectra show increase in structural disorder with increase in deposition pressure. It also confirms the formation of nearly stoichiometric a-SiC:H films. Bandgap calculated using both Tauc’s formulation and absorption at 104 cm-1 shows decreasing trend with increase in deposition pressure. Decrease in refractive index and increase in Urbach energy suggests increase in structural disorder and microvoid density in the films. Finally, it has been concluded that C2H6 can be used as an effective carbon source in HW-CVD method to prepare stoichiometric a-SiC:H films.

  14. Electrochemically assisted deposition of hydroxyapatite on Ti6Al4V substrates covered by CVD diamond films — Coating characterization and first cell biological results

    Energy Technology Data Exchange (ETDEWEB)

    Strąkowska, Paulina [Gdańsk University of Technology, Mechanical Engineering Faculty (Poland); Gdańsk University of Technology, Faculty of Electronics, Telecommunications, and Informatics (Poland); Beutner, René [Max Bergmann Center, Technische Universität Dresden (Germany); Gnyba, Marcin [Gdańsk University of Technology, Faculty of Electronics, Telecommunications, and Informatics (Poland); Zielinski, Andrzej [Gdańsk University of Technology, Mechanical Engineering Faculty (Poland); Scharnweber, Dieter, E-mail: Dieter.Scharnweber@tu-dresden.de [Max Bergmann Center, Technische Universität Dresden (Germany)

    2016-02-01

    Although titanium and its alloys are widely used as implant material for orthopedic and dental applications they show only limited corrosion stability and osseointegration in different cases. The aim of the presented research was to develop and characterize a novel surface modification system from a thin diamond base layer and a hydroxyapatite (HAp) top coating deposited on the alloy Ti6Al4V widely used for implants in contact with bone. This coating system is expected to improve both the long-term corrosion behavior and the biocompatibility and bioactivity of respective surfaces. The diamond base films were obtained by Microwave Plasma Assisted Chemical Vapor Deposition (MW-PACVD); the HAp coatings were formed in aqueous solutions by electrochemically assisted deposition (ECAD) at varying polarization parameters. Scanning electron microscopy (SEM), Raman microscopy, and electrical conductivity measurements were applied to characterize the generated surface states; the calcium phosphate coatings were additionally chemically analyzed for their composition. The biological properties of the coating system were assessed using hMSC cells analyzing for cell adhesion, proliferation, and osteogenic differentiation. Varying MW-PACVD process conditions resulted in composite coatings containing microcrystalline diamond (MCD/Ti-C), nanocrystalline diamond (NCD), and boron-doped nanocrystalline diamond (B-NCD) with the NCD coatings being dense and homogeneous and the B-NCD coatings showing increased electrical conductivity. The ECAD process resulted in calcium phosphate coatings from stoichiometric and non-stoichiometric HAp. The deposition of HAp on the B-NCD films run at lower cathodic potentials and resulted both in the highest coating mass and the most homogenous appearance. Initial cell biological investigations showed an improved cell adhesion in the order B-NCD > HAp/B-NCD > uncoated substrate. Cell proliferation was improved for both investigated coatings whereas ALP

  15. Use of statistical modeling to predict the effect of formulation composition on coacervation, silicone deposition, and conditioning sensory performance of cationic cassia polymers.

    Science.gov (United States)

    Lepilleur, Carole; Mullay, John; Kyer, Carol; McCalister, Pam; Clifford, Ted

    2011-01-01

    Formulation composition has a dramatic influence on coacervate formation in conditioning shampoo. The purpose of this study is to correlate the amount of coacervate formation of novel cationic cassia polymers to the corresponding conditioning profiles on European brown hair using silicone deposition, cationic polymer deposition and sensory evaluation. A design of experiments was conducted by varying the levels of three surfactants (sodium lauryl ether sulfate, sodium lauryl sulfate, and cocamidopropyl betaine) in formulations containing cationic cassia polymers of different cationic charge density (1.7 and 3.0m Eq/g). The results show formulation composition dramatically affects physical properties, coacervation, silicone deposition, cationic polymer deposition and hair sensory attributes. Particularly, three parameters are of importance in determining silicone deposition: polymer charge, surfactant (micelle) charge and total amount of surfactant (micelle aspect ratio). Both sensory panel testing and silicone deposition results can be predicted with a high confidence level using statistical models that incorporate these parameters.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kilpi, Lauri, E-mail: Lauri.Kilpi@vtt.fi; Ylivaara, Oili M. E.; Vaajoki, Antti; Puurunen, Riikka L.; Ronkainen, Helena [VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT (Finland); Malm, Jari [Department of Physics, University of Jyväskylä, P.O. Box 35, Jyväskylä 40014 (Finland); Sintonen, Sakari [Department of Micro- and Nanosciences, Aalto University School of Electrical Engineering, P.O. Box 13500, FI-00076 AALTO (Finland); Tuominen, Marko [ASM Microchemistry Oy, Pietari Kalmin katu 1 F 2, FIN-00560 Helsinki (Finland)

    2016-01-15

    The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as L{sub CSi1}, L{sub CSi2}, L{sub CALD1}, and L{sub CALD2}, representing the failure points of the silicon substrate and the coating delamination points of the ALD coating. The adhesion performance of the ALD Al{sub 2}O{sub 3}, TiO{sub 2}, TiN, and TaCN+Ru coatings with a thickness range between 20 and 600 nm and deposition temperature between 30 and 410 °C on silicon wafers was investigated. In addition, the impact of the annealing process after deposition on adhesion was evaluated for selected cases. The tests carried out using scratch and Scotch tape test showed that the coating deposition and annealing temperature, thickness of the coating, and surface pretreatments of the Si wafer had an impact on the adhesion performance of the ALD coatings on the silicon wafer. There was also an improved load carrying capacity due to Al{sub 2}O{sub 3}, the magnitude of which depended on the coating thickness and the deposition temperature. The tape tests were carried out for selected coatings as a comparison. The results show that the scratch test is a useful and applicable tool for adhesion evaluation of ALD coatings, even when carried out for thin (20 nm thick) coatings.

  17. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-12-15

    A rapid thermal anneal (RTA) in an NH/sub 3/ ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 /sup 0/C in NH/sub 3/ and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (greater than or equal to1000 /sup 0/C) RTA in Ar completely converted W into the low resistivity (31 ..mu cap omega.. cm) tetragonal WSi/sub 2/ phase. In contrast, after a prior 900 /sup 0/C RTA in NH/sub 3/, N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi/sub 2/ formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 /sup 0/C NH/sub 3/ anneal. The NH/sub 3/-treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 /sup 0/C, at which point some increase in contact resistance was measured.

  18. Fabrication and characterization of silicon based thermal neutron detector with hot wire chemical vapor deposited boron carbide converter

    Science.gov (United States)

    Chaudhari, Pradip; Singh, Arvind; Topkar, Anita; Dusane, Rajiv

    2015-04-01

    In order to utilize the well established silicon detector technology for neutron detection application, a silicon based thermal neutron detector was fabricated by integrating a thin boron carbide layer as a neutron converter with a silicon PIN detector. Hot wire chemical vapor deposition (HWCVD), which is a low cost, low temperature process for deposition of thin films with precise thickness was explored as a technique for direct deposition of a boron carbide layer over the metalized front surface of the detector chip. The presence of B-C bonding and 10B isotope in the boron carbide film were confirmed by Fourier transform infrared spectroscopy and secondary ion mass spectrometry respectively. The deposition of HWCVD boron carbide layer being a low temperature process was observed not to cause degradation of the PIN detector. The response of the detector with 0.2 μm and 0.5 μm thick boron carbide layer was examined in a nuclear reactor. The pulse height spectrum shows evidence of thermal neutron response with signature of (n, α) reaction. The results presented in this article indicate that HWCVD boron carbide deposition technique would be suitable for low cost industrial fabrication of PIN based single element or 1D/2D position sensitive thermal neutron detectors.

  19. Fabrication and characterization of silicon based thermal neutron detector with hot wire chemical vapor deposited boron carbide converter

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhari, Pradip, E-mail: pradipcha@gmail.com [Semiconductor Thin Films and Plasma Processing Laboratory, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai – 400076 (India); Singh, Arvind, E-mail: arvindsingh1884@gmail.com [Electronics Division, Bhabha Atomic Research Centre, Trombay, Mumbai – 400085 (India); Topkar, Anita, E-mail: anita.topkar@gmail.com [Electronics Division, Bhabha Atomic Research Centre, Trombay, Mumbai – 400085 (India); Dusane, Rajiv, E-mail: rodusane@iitb.ac.in [Semiconductor Thin Films and Plasma Processing Laboratory, Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Powai, Mumbai – 400076 (India)

    2015-04-11

    In order to utilize the well established silicon detector technology for neutron detection application, a silicon based thermal neutron detector was fabricated by integrating a thin boron carbide layer as a neutron converter with a silicon PIN detector. Hot wire chemical vapor deposition (HWCVD), which is a low cost, low temperature process for deposition of thin films with precise thickness was explored as a technique for direct deposition of a boron carbide layer over the metalized front surface of the detector chip. The presence of B-C bonding and {sup 10}B isotope in the boron carbide film were confirmed by Fourier transform infrared spectroscopy and secondary ion mass spectrometry respectively. The deposition of HWCVD boron carbide layer being a low temperature process was observed not to cause degradation of the PIN detector. The response of the detector with 0.2 µm and 0.5 µm thick boron carbide layer was examined in a nuclear reactor. The pulse height spectrum shows evidence of thermal neutron response with signature of (n, α) reaction. The results presented in this article indicate that HWCVD boron carbide deposition technique would be suitable for low cost industrial fabrication of PIN based single element or 1D/2D position sensitive thermal neutron detectors.

  20. Vacuum deposited polycrystalline silicon films for solar cell applications. Second quarterly technical progress report. January 1-March 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Feldman, C.; Arlington, III, C. H.; Blum, N. A.; Satkiewicz, F. G.

    1980-05-01

    A careful study of a specially formed thin silicon layer on TiB/sub 2/-coated sapphire reveals that the interaction layer of TiSi/sub 2/ is composed of larger grains. Processing steps were developed which lead closer to the goal of fabricating polycrystalline silicon photovoltaic devices completely by vacuum deposition. Both n-type and p-type silicon are now being deposited. New deposition masks were made for depositing the n-regions upon the p-layers. New electrode deposition masks were also made for a direct electroding process to replace the photolithographic process used previously. The TiB/sub 2/ bottom electrode fabrication has been achieved in a single vacuum chamber. Reaction constants and activation energy for TiB/sub 2/ layer formation were determined to be less than those reported by other authors for bulk material. Studies of crystallite growth and interfacial interactions have continued. Major sources of undesirable impurities have been identified and removed from the vacuum chambers. The changes made this quarter have not been incorporated into a completed photovoltaic device.

  1. Microwave Plasma Chemical Vapor Deposition of Diamond Films on Silicon From Ethanol and Hydrogen

    Institute of Scientific and Technical Information of China (English)

    马志斌; 汪建华; 王传新; 满卫东

    2003-01-01

    Diamond films with very smooth surface and good optical quality have been deposited onto silicon substrate using microwave plasma chemical vapor deposition (MPCVD) from a gas mixture of ethanol and hydrogen at a low substrate temperature of 450 ℃. The effects of the substrate temperature on the diamond nucleation and the morphology of the diamond film have been investigated and observed with scanning electron microscopy (SEM). The microstructure and the phase of the film have been characterized using Raman spectroscopy and X-ray diffraction (XRD). The diamond nucleation density significantly decreases with the increasing of the substrate temperature. There are only sparse nuclei when the substrate temperature is higher than 800 ℃ although the ethanol concentration in hydrogen is very high. That the characteristic diamond peak in the Raman spectrum of a diamond film prepared at a low substrate temperature of 450 ℃ extends into broadband indicates that the film is of nanophase. No graphite peak appeared in the XRD pattern confirms that the film is mainly composed of SP3 carbon. The diamond peak in the XRD pattern also broadens due to the nanocrystalline of the film.

  2. Development and characterization of Undoped Silicon Glass (USG using chemical vapour deposition

    Directory of Open Access Journals (Sweden)

    Jagadeesha T

    2011-02-01

    Full Text Available Sub atmospheric chemical vapour deposition (SACVD is a widely used technique in semiconductor integrated circuit (IC manufacturing, especially to form inter-metal silicon (IMD dioxide thin films. It was designed for commercially available tools in order to satisfy the gap filling requirements necessary for 0.18 and 0.15 lm technology ICs, but it has been successfully extended also for 0.13 lm technological node and over. SACVD technique has a potential impact on device electrical characteristics and metallurgy compatibility, according to process conditions, such as mass flow rate of TEOS, Gasflows, RF power. Present work focuses on development and characterisation of undoped silicate glass that can be used for Flash memory and Logic devices. It is shown that new process yield deposition rate improvement of 51% and throughput improvement of 13%.. Qualitative yield comparison and wafer map to map comparison work is also presented for various technology nodes. Device parameters comparison with the standard process is also included in the present work.

  3. Highly conductive boron doped micro/nanocrystalline silicon thin films deposited by VHF-PECVD for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Juneja, Sucheta; Sudhakar, S., E-mail: sudhakars@nplindia.org; Gope, Jhuma; Lodhi, Kalpana; Sharma, Mansi; Kumar, Sushil

    2015-09-15

    Graphical abstract: AFM images of boron doped micro/nanocrystalline silicon films at different diborane gas flow. - Highlights: • High deposition rate of 10 Å/s was achieved for boron doped silicon films. • Wide range of optical band gap from 1.32 eV to 1.84 eV observed for the deposited films. - Abstract: Boron doped hydrogenated micro/nanocrystalline silicon (μc/nc-Si:H) thin films have been deposited by plasma enhanced chemical vapor deposition technique (PECVD) using silane (SiH{sub 4}) diluted in argon. Diborane (B{sub 2}H{sub 6}) was used as the dopant gas and deposition was carried out at substrate temperature of 200 °C. The diborane flow (F{sub B}) varied in the range 0.00–0.30. Here, we report the effects of B{sub 2}H{sub 6} doping on electronic, optical and structural properties of hydrogenated micro/nanocrystalline silicon films. The structural properties were analyzed by atomic force microscopy (AFM) and X-ray diffraction (XRD). The doped micro/nano crystalline silicon films presented a crystallographic orientation preferentially in the (1 1 1) and (2 2 0) plane. We resolve the deposition parameters that lead to the formation of p-type micro/nanocrystalline silicon thin films with very high value of conductivity and lower optical band gap. Correlations between structural and electrical properties were also studied. Based on temperature dependent conductivity measurements, it has been observed that the room temperature dark conductivity varies in the range 1.45 × 10{sup −4} Ω{sup −1} cm{sup −1} to 2.02 Ω{sup −1} cm{sup −1} for the B-doped films. Meanwhile, the corresponding value of activation energies decreased to 0.06 eV for the B-doped films, which indicates the doped μc/nc-Si films with high conductivity can be achieved and these films prove to be a very good candidate for application in amorphous and micro/nano crystalline silicon solar cells as a p-type window layer.

  4. High-quality AlN films grown on chemical vapor-deposited graphene films

    Directory of Open Access Journals (Sweden)

    Chen Bin-Hao

    2016-01-01

    Full Text Available We report the growth of high-quality AlN films on graphene. The graphene films were synthesized by CVD and then transferred onto silicon substrates. Epitaxial aluminum nitride films were deposited by DC magnetron sputtering on both graphene as an intermediate layer and silicon as a substrate. The structural characteristics of the AlN films and graphene were investigated. Highly c-axis-oriented AlN crystal structures are investigated based on the XRDpatterns observations.

  5. Effects of pressure and inter-electrode distance on deposition of nanocrystalline silicon under high pressure conditions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanchao; Verkerk, Arjan D.; Rath, Jatindra K.; Schropp, Ruud E.I. [Debye Institute for Nanomaterials Science, Section Nanophotonics - Physics of Devices, Faculty of Science, Utrecht University (Netherlands); Goedheer, Wim J. [FOM-Institute for Plasma Physics, Nieuwegein (Netherlands)

    2010-04-15

    Pressure (p) and inter-electrode distance (d) are important parameters in the process of depositing hydrogenated nanocrystalline silicon (nc-Si:H) by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD). High quality nc-Si:H materials are normally deposited at high pressure (1 mbar < p < 7 mbar). However, systematic research on the combined effects of p and d is rare. In order to optimize nc-Si:H for solar cells, such effects are investigated for a silane-hydrogen discharge at high pressure conditions. All nc-Si:H layers were deposited at fixed hydrogen dilution ratio (H{sub 2}/SiH{sub 4}), power and frequency. With optical emission spectroscopy, direct images taken by a photo camera and by 1D SiH{sub 4}/H{sub 2} plasma simulation, three different series were analyzed to study the combined effects of p and d at high pressure. The effects on the crystalline ratio and the porosity of the deposited silicon layers were also investigated. When the p .d product is constant, the plasma sheath becomes relatively thinner when d increases. When p or d increases independently, the electron density decreases. All the above modifications can increase the deposition rate, but by different mechanisms. When nc-Si:H is deposited at a p.d product of 30 mbar.mm, compact material with high crystalline ratio is obtained (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: spin coating vs electrochemical activation.

    Science.gov (United States)

    Hernandez-Montelongo, J; Gallach, D; Naveas, N; Torres-Costa, V; Climent-Font, A; García-Ruiz, J P; Manso-Silvan, M

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering.

  7. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: Spin coating vs electrochemical activation

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Montelongo, J., E-mail: jacobo.hernandez@uam.es [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Gallach, D.; Naveas, N.; Torres-Costa, V. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Climent-Font, A. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Centro de Microanálisis de Materiales (CMAM), Universidad Autónoma de Madrid, Madrid 28049 (Spain); García-Ruiz, J.P. [Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049 (Spain); Manso-Silvan, M. [Departamento de Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering. - Highlights: • Proposed cyclic methods produce specific morphologies and CaP phases in biocomposites. • The brushite phase is favored in the biocomposite produced by Cyclic Spin Coating. • The hydroxyapatite phase is favored in the biocomposite produced by Cyclic Electrochemical Activation. • The Ca/P atomic ratio of hydroxyapatite was validated by elastic backscattering spectroscopy. • Cells grown showed morphological and

  8. Atomic layer deposition TiO{sub 2} coated porous silicon surface: Structural characterization and morphological features

    Energy Technology Data Exchange (ETDEWEB)

    Iatsunskyi, Igor, E-mail: igoyat@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan (Poland); Department of Experimental Physics, Odessa National I.I. Mechnikov University, 42, Pastera str., 65023 Odessa (Ukraine); Jancelewicz, Mariusz; Nowaczyk, Grzegorz [NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan (Poland); Kempiński, Mateusz [NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan (Poland); Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poland (Poland); Peplińska, Barbara [NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan (Poland); Department of Macromolecular Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland); Jarek, Marcin; Załęski, Karol [NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan (Poland); Jurga, Stefan [NanoBioMedical Centre, Adam Mickiewicz University, 85 Umultowska str., 61-614, Poznan (Poland); Department of Macromolecular Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland); Smyntyna, Valentyn [Department of Experimental Physics, Odessa National I.I. Mechnikov University, 42, Pastera str., 65023 Odessa (Ukraine)

    2015-08-31

    TiO{sub 2} thin films were grown on highly-doped p-Si (100) macro- and mesoporous structures by atomic layer deposition (ALD) using TiCl{sub 4} and deionized water as precursors at 300 °C. The crystalline structure, chemical composition, and morphology of the deposited films and initial silicon nanostructures were investigated by scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy and X-ray diffraction (XRD). The mean size of TiO{sub 2} crystallites was determined by TEM, XRD and Raman spectroscopy. It was shown that the mean crystallite size and the crystallinity of the TiO{sub 2} are influenced dramatically by the morphology of the porous silicon, with the mesoporous silicon resulting in a much finer grain size and amorphous structure than the macroporous silicon having a partially crystal anatase phase. A simple model of the ALD layer growth inside the pores was presented. - Highlights: • The morphology and chemical composition of TiO{sub 2} and porous Si were established. • The approximate size of TiO{sub 2} nanocrystals was estimated. • The model of the atomic layer deposition coating in the porous Si was presented.

  9. Developing the Beijing CVD

    Institute of Scientific and Technical Information of China (English)

    LU JINGXIAN

    2006-01-01

    @@ Slowly but surely, the high-end villa property in Beijing is gaining new momentum. Limited amounts of new properties, rising prices and increasing demand will be the trend in the villa market in 2006, real estate experts predict. Among them, the exclusive Central Villa District(CVD), a top-tier villa area along the Wenyu River in northeast Beijing, has emerged as a hot spot of the market.

  10. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, V., E-mail: V.Mohammadi@tudelft.nl; Nihtianov, S. [Department of Microelectronics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft (Netherlands)

    2016-02-15

    The lateral gas phase diffusion length of boron atoms, L{sub B}, along silicon and boron surfaces during chemical vapor deposition (CVD) using diborane (B{sub 2}H{sub 6}) is reported. The value of L{sub B} is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and confirmed analytically in the boron deposition temperature range from 700 °C down to 400 °C. For this temperature range the local loading effect of the boron deposition is investigated on the micro scale. A L{sub B} = 2.2 mm was determined for boron deposition at 700 °C, while a L{sub B} of less than 1 mm was observed at temperatures lower than 500 °C.

  11. Thermal chemistry of copper acetamidinate atomic layer deposition precursors on silicon oxide surfaces studied by XPS

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Yunxi; Zaera, Francisco, E-mail: zaera@ucr.edu [Department of Chemistry, University of California, Riverside, California 92521 (United States)

    2016-01-15

    The thermal surface chemistry of copper(I)-N,N′-di-sec-butylacetamidinate, [Cu({sup s}Bu-amd)]{sub 2}, a metalorganic complex recently proposed for the chemical-based deposition of copper films, has been characterized on SiO{sub 2} films under ultrahigh vacuum conditions by x-ray photoelectron spectroscopy (XPS). Initial adsorption at cryogenic temperatures results in the oxidation of the copper centers with Cu 2p{sub 3/2} XPS binding energies close to those seen for a +2 oxidation state, an observation that the authors interpret as the result of the additional coordination of oxygen atoms from the surface to the Cu atoms of the molecular acetamidinate dimer. Either heating to 300 K or dosing the precursor directly at that temperature leads to the loss of one of its two ligands, presumably via hydrogenation/protonation with a hydrogen/proton from a silanol group, or following a similar reaction on a defect site. By approximately 500 K the Cu 2p{sub 3/2}, C 1s, and N 1s XPS data suggest that the remaining acetamidinate ligand is displaced from the copper center and bonds to the silicon oxide directly, after which temperatures above 900 K need to be reached to promote further (and only partial) decomposition of those organic moieties. It was also shown that the uptake of the Cu precursor is self-limiting at either 300 or 500 K, although the initial chemistry is somewhat different at the two temperatures, and that the nature of the substrate also defines reactivity, with the thin native silicon oxide layer always present on Si(100) surfaces being less reactive than thicker films grown by evaporation, presumably because of the lower density of surface nucleation sites.

  12. In-Situ Cleaning, Passivation, Functionalization, and Atomic Layer Deposition on Germanium and Silicon-Germanium

    Science.gov (United States)

    Kaufman-Osborn, Tobin Adar

    In recent years, germanium (Ge) and silicon-germanium (SiGe) have drawn significant interest as replacements of conventional silicon in the search for alternative materials for use in complementary metal-oxide-semiconductor (CMOS) devices due to their high electron and hole mobilities. In order to effectively implement Ge or SiGe as a replacement for silicon, two major challenges must be overcome: non-disruptive cleaning and surface passivation/functionalization. As electrical devices are increasingly scaled, it becomes especially crucial to effectively clean each unit cell on the Ge/SiGe surface without causing major disruption or damage to the surface. If air-induced defects or contaminants persist on the surface after cleaning, these defect sites may be un-reactive for functionalization and thereby will hinder device performance and/or the ability to aggressively scale device size. If a cleaning method is too aggressive leaving a rough or disordered surface, this can lower the mobility at the interface which will worsen device performance. For these reasons, it is necessary to develop a non-disruptive cleaning process that cleans each unit cell leaving a flat, ordered, and reactive surface. Once the Ge or SiGe surface is cleaned, in order to achieve a good electrical quality interface and a high nucleation density on the surface, all surface atoms must be passivated and functionalized allowing for aggressive device scaling. The interface must remain electrically passive in order to not inhibit electrical performance of the device. This study uses scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and x-ray photoelectron spectroscopy (XPS) to develop and analyze a completely in-situ non-disruptive cleaning method of the Ge surface using H2O2(g) and atomic hydrogen. After cleaning, the Ge or SiGe surface is passivated and functionalized using H2O2(g) as a method to improve upon the conventional H2O(g) passivation method by more than

  13. Correlation between optical emission spectra and the process parameters of a 915 MHz microwave plasma CVD reactor used for depositing polycrystalline diamond coatings

    Indian Academy of Sciences (India)

    Awadesh Kumar Mallik; Sandip Bysakh; Someswar Dutta; Debabrata Basu

    2014-08-01

    In this paper, the hydrogen and hydrogen-methane mixed plasma have been generated inside a 33 cm diameter quartz bell jar with a low power (9 KW) and lower frequency 915 MHz microwave plasma chemical vapor deposition system. The reactor is being used for growing polycrystalline diamond (PCD) over large area (100 mm). The generated plasma is diagnosed by in situ optical emission spectroscopy method with wave length ranging from 200 to 900 nm. The effects of microwave power, chamber pressure and gas concentration on plasma characteristics have been studied in this work. Within the optical range, Balmer H, H, C2swan band and CH lines have been detected at the wavelengths of 655.95, 485.7, 515.82 and 430.17 nm, respectively. It has been observed that for hydrogen plasma, the amount of transition from hydrogen atom inner shell 3 to 2 (H) is almost constant with increasing microwave (MW) power (from 2000 to 2800 W) and pressure (from 15 to 30 Torr) initially, after that it increases with further increase of MW power and pressure, whereas, the transition from 4 to 2 (H) is slowly increased with increasing MW power and pressure. For hydrogen-methane plasma, intensities of C2 swan band, i.e., the transitions from D$^3\\Pi_\\text{g}$ to A$^3\\Pi_{\\mu}$ energy levels, are also increased with the increasing microwave power and reactor pressure. It has been observed that the radicals present in the plasma are affected by variation of different reactor parameters like pressure, MW power, CH4 concentration, etc.

  14. On the Origin of Light Emission in Silicon Rich Oxide Obtained by Low-Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. Aceves-Mijares

    2012-01-01

    Full Text Available Silicon Rich Oxide (SRO has been considered as a material to overcome the drawbacks of silicon to achieve optical functions. Various techniques can be used to produce it, including Low-Pressure Chemical Vapor Deposition (LPCVD. In this paper, a brief description of the studies carried out and discussions of the results obtained on electro-, cathode-, and photoluminescence properties of SRO prepared by LPCVD and annealed at 1,100°C are presented. The experimental results lead us to accept that SRO emission properties are due to oxidation state nanoagglomerates rather than to nanocrystals. The emission mechanism is similar to Donor-Acceptor decay in semiconductors, and a wide emission spectrum, from 450 to 850 nm, has been observed. The results show that emission is a function of both silicon excess in the film and excitation energy. As a result different color emissions can be obtained by selecting the suitable excitation energy.

  15. Spatial resolution in thin film deposition on silicon surfaces by combining silylation and UV/ozonolysis

    Science.gov (United States)

    Guo, Lei; Zaera, Francisco

    2014-12-01

    A simple procedure has been developed for the processing of silicon wafers in order to facilitate the spatially resolved growth of thin solid films on their surfaces. Specifically, a combination of silylation and UV/ozonolysis was tested as a way to control the concentration of the surface hydroxo groups required for subsequent atomic layer deposition (ALD) of metals or oxides. Water contact angle measurements were used to evaluate the hydrophilicity/hydrophobicity of the surface, a proxy for OH surface coverage, and to optimize the UV/ozonolysis treatment. Silylation with hexamethyldisilazane, trichloro(octadecyl)silane, or trimethylchlorosilane was found to be an efficient way to block the hydroxo sites and to passivate the underlying surface, and UV/O3 treatments were shown to effectively remove the silylation layer and to regain the surface reactivity. Both O3 and 185 nm UV radiation were determined necessary for the removal of the silylation layer, and additional 254 nm radiation was found to enhance the process. Attenuated total reflection-infrared absorption spectroscopy was employed to assess the success of the silylation and UV/O3 removal steps, and atomic force microscopy data provided evidence for the retention of the original smoothness of the surface. Selective growth of HfO2 films via TDMAHf + H2O ALD was seen only on the UV/O3 treated surfaces; total inhibition of the deposition was observed on the untreated silylated surfaces (as determined by x-ray photoelectron spectroscopy and ellipsometry). Residual film growth was still detected on the latter if the ALD was carried out at high temperatures (250 °C), because the silylation layer deteriorates under such harsh conditions and forms surface defects that act as nucleation sites for the growth of oxide grains (as identified by electron microscopy and scanning electron microscopy). We believe that the silylation-UV/O3 procedure advanced here could be easily implemented for the patterning of surfaces

  16. Atomic Layer Deposition of Chemical Passivation Layers and High Performance Anti-Reflection Coatings on Back-Illuminated Detectors

    Science.gov (United States)

    Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Nikzad, Shouleh (Inventor)

    2014-01-01

    A back-illuminated silicon photodetector has a layer of Al2O3 deposited on a silicon oxide surface that receives electromagnetic radiation to be detected. The Al2O3 layer has an antireflection coating deposited thereon. The Al2O3 layer provides a chemically resistant separation layer between the silicon oxide surface and the antireflection coating. The Al2O3 layer is thin enough that it is optically innocuous. Under deep ultraviolet radiation, the silicon oxide layer and the antireflection coating do not interact chemically. In one embodiment, the silicon photodetector has a delta-doped layer near (within a few nanometers of) the silicon oxide surface. The Al2O3 layer is expected to provide similar protection for doped layers fabricated using other methods, such as MBE, ion implantation and CVD deposition.

  17. Piezoelectric ceramic thick films deposited on silicon substrates by screen printing

    Science.gov (United States)

    Yao, Kui; He, Xujiang; Xu, Yuan; Chen, Meima

    2004-07-01

    Screen-printing processes offer advantages in producing directly patterned and integrated piezoelectric elements, and fill an important technological gap between thin film and bulk ceramics. However, several existing problems in the screen-printed piezoelectric thick films, such as the poor reliability and the required high sintering temperature, are significantly limiting their applications. In this work, lead zirconate titanate (PZT) ceramic films of 30 μm in thickness were deposited on Pt-coated silicon substrates by the screen-printing process, in which the ceramic pastes were prepared through a chemical liquid-phase doping approach. Porous thick films with good adhesion were formed on the substrates at a temperature of 925°C. Stable out-of-plane piezoelectric vibration of the thick films was observed with a laser scanning vibrometer (LSV), and the piezoelectric dilatation magnitude was determined accordingly. Our piezoelectric measurements through the areal displacement detection with LSV exhibited distinct advantages for piezoelectric film characterization, including high reliability, high efficiency, and comprehensive information. The longitudinal piezoelectric coefficients of the thick films were calculated from the measured dilatation data through a numerical simulation. High piezoelectric voltage constants were obtained due to the very low dielectric constant of the porous thick films. The application potentials of our screen-printed thick films as integrated piezoelectric sensors are discussed.

  18. Surface morphology and structure of ultra-thin magnesium oxide grown on (100) silicon by atomic layer deposition oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Rochdi, N., E-mail: rochdi.nabil@gmail.com [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS UPR 3118, Aix-Marseille Universite, Case 913, Campus de Luminy, 13288 Marseille cedex 9 (France); Liudvikouskaya, K. [Belarusian State University of Informatics and Radioelectronics, P. Browka 6, 220013 Minsk (Belarus); Descoins, M.; Raissi, M.; Coudreau, C.; Lazzari, J.-L. [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS UPR 3118, Aix-Marseille Universite, Case 913, Campus de Luminy, 13288 Marseille cedex 9 (France); Oughaddou, H. [Commissariat a l' Energie Atomique, DSM-IRAMIS-SPCSI, Bat. 462, Saclay, 91191, Gif-sur-Yvette cedex (France); Universite de Cergy-Pontoise, LAMAp, 95000 Cergy-Pontoise cedex (France); D' Avitaya, F. Arnaud [Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), CNRS UPR 3118, Aix-Marseille Universite, Case 913, Campus de Luminy, 13288 Marseille cedex 9 (France)

    2011-07-29

    Ultra-thin magnesium oxide layers were elaborated by atomic layer deposition and oxidation process on silicon (100) starting from (2 x 1) thermally-reconstructed or hydrogen-terminated Si surfaces. Low-energy electron diffraction experiments show (2 x 3) and (3 x 3) reconstructions while depositing a magnesium monolayer on Si clean surfaces, and a 3-dimentional growth of the oxide as confirmed by ex-situ atomic force microscopy. For hydrogen-terminated or clean surfaces previously physisorbed by oxygen, uniform cobalt/magnesium-oxide/silicon stacks of layers are observed by transmission electron microscopy. Annealing above 150 deg. C leads to MgO dissolution and formation of an interfacial complex compound by inter-diffusion of Si and Co.

  19. Structural and optical studies on hot wire chemical vapour deposited hydrogenated silicon films at low substrate temperature

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, Purabi; Agarwal, Pratima [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam (India)

    2009-02-15

    Thin films of hydrogenated silicon are deposited by hot wire chemical vapour deposition technique, as an alternative of plasma enhanced chemical vapour deposition technique. By varying the hydrogen and silane flow rate, we deposited the films ranging from pure amorphous to nanocrystallite-embedded amorphous in nature. In this paper we report extensively studied structural and optical properties of these films. It is observed that the rms bond angle deviation decreases with increase in hydrogen flow rate, which is an indication of improved order in the films. We discuss this under the light of breaking of weak Si-Si bonds and subsequent formation of strong Si-Si bonds and coverage of the growing surface by atomic hydrogen. (author)

  20. 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...

  1. CVD polymers fabrication of organic surfaces and devices

    CERN Document Server

    Gleason, Karen K

    2015-01-01

    The method of CVD (chemical vapor deposition) is a versatile technique to fabricate high-quality thin films and structured surfaces in the nanometer regime from the vapor phase. Already widely used for the deposition of inorganic materials in the semiconductor industry, CVD has become the method of choice in many applications to process polymers as well. This highly scalable technique allows for synthesizing high-purity, defect-free films and for systematically tuning their chemical, mechanical and physical properties. In addition, vapor phase processing is critical for the deposition of insol

  2. Structural evolution of a Ta-filament during hot-wire chemical vapour deposition of Silicon investigated by electron backscatter diffraction

    CSIR Research Space (South Africa)

    Oliphant, CJ

    2012-03-01

    Full Text Available In this study we investigate the structural changes of a burnt-out tantalum filament that was operated at typical hydrogenated nanocrystalline silicon synthesis conditions in our hot-wire chemical vapour deposition chamber. Scanning electron...

  3. Processing for optically active erbium in silicon by film co-deposition and ion-beam mixing

    Energy Technology Data Exchange (ETDEWEB)

    Abedrabbo, S., E-mail: sxa0215@yahoo.com [Department of Physics, University of Jordan, Amman 11942 (Jordan); Mohammed, Q. [Tadawul Shares and Bonds Mediation L.L.C., Dubai (United Arab Emirates); Fiory, A.T. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07901 (United States)

    2009-02-01

    Techniques of film deposition by co-evaporation, ion-beam assisted mixing, oxygen ion implantation, and thermal annealing were been combined in a novel way to study processing of erbium-in-silicon thin-film materials for optoelectronics applications. Structures with erbium concentrations above atomic solubility in silicon and below that of silicide compounds were prepared by vacuum co-evaporation from two elemental sources to deposit 200-270 nm films on crystalline silicon substrates. Ar{sup +} ions were implanted at 300 keV. Oxygen was incorporated by O{sup +}-ion implantation at 130 keV. Samples were annealed at 600 deg. C in vacuum. Concentration profiles of the constituent elements were obtained by Rutherford backscattering spectrometry. Results show that diffusion induced by ion-beam mixing and activated by thermal annealing depends on the deposited Si-Er profile and reaction with implanted oxygen. Room temperature photoluminescence spectra show Er{sup 3+} transitions in a 1480-1550 nm band and integrated intensities that increase with the oxygen-to-erbium ratio.

  4. Chemical reactivity of CVC and CVD SiC with UO{sub 2} at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Chinthaka M., E-mail: silvagw@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Katoh, Yutai [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Voit, Stewart L. [Fusion and Materials for Nuclear Systems Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Snead, Lance L. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-05-15

    Two types of silicon carbide (SiC) synthesized using two different vapor deposition processes were embedded in UO{sub 2} pellets and evaluated for their potential chemical reaction with UO{sub 2}. While minor reactivity between chemical-vapor-composited (CVC) SiC and UO{sub 2} was observed at comparatively low temperatures of 1100 and 1300 °C, chemical-vapor-deposited (CVD) SiC did not show any such reactivity. However, both CVD and CVC SiCs showed some reaction with UO{sub 2} at a higher temperature (1500 °C). Elemental maps supported by phase maps obtained using electron backscatter diffraction indicated that CVC SiC was more reactive than CVD SiC at 1500 °C. Furthermore, this investigation indicated the formation of uranium carbides and uranium silicide chemical phases such as UC, USi{sub 2}, and U{sub 3}Si{sub 2} as a result of SiC reaction with UO{sub 2}.

  5. Thermal post-deposition treatment effects on nanocrystalline hydrogenated silicon prepared by PECVD under different hydrogen flow rates

    Science.gov (United States)

    Amor, Sana Ben; Meddeb, Hosny; Daik, Ridha; Othman, Afef Ben; Slama, Sonia Ben; Dimassi, Wissem; Ezzaouia, Hatem

    2016-01-01

    In this paper, hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited on mono-crystalline silicon substrate by plasma enhanced chemical vapor deposition (PECVD) under different hydrogen flow rates followed by a thermal treatment in an infrared furnace at different temperature ranging from 300 to 900 °C. The investigated structural, morphological and optoelectronic properties of samples were found to be strongly dependent on the annealing temperature. Raman spectroscopy revealed that nc-Si:H films contain crystalline, amorphous and mixed structures as well. We find that post-deposition thermal treatment may lead to a tendency for structural improvement and a decrease of the disorder in the film network at moderate temperature under 500 °C. As for annealing at higher temperature up to 900 °C induces the recrystallization of the film which is correlated with the grain size and volume fraction in the layer. We demonstrate that high annealing temperature can lead to a decrease of silicon-hydrogen bonds corresponding to a reduction of the amorphous matrix in the layer promoting the formation of covalent Si-Si bonds. The effusion of the hydrogen from the grown film leads to increase its density and therefore induces a decrease in the thickness of the layer. For post-deposition thermal treatment in temperature range under 700 °C, the post-deposition anneal seems to be crucial for obtaining good passivation quality as expressed by a minority carrier lifetime of 17 μs, as it allows a significant reduction in defect states at the layer/substrate interface. While for a temperature higher than 900 °C, the lifetime reduction is obtained because of hydrogen effusion phenomenon, thus a tendency for crystallization in the grown film.

  6. The use of x-ray fluorescent spectroscopy to study the influence of cationic polymers on silicone oil deposition from shampoo.

    Science.gov (United States)

    Gruber, J V; Lamoureux, B R; Joshi, N; Moral, L

    2001-01-01

    In this study, x-ray fluorescent spectroscopy was employed, in a non-destructive way, to analyze the influence that water-soluble, cationic hydroxyethylcellulose (i.e., polyquaternium-10) has on the deposition of silicone oil (dimethicone) onto hair. Virgin brown hair tresses were washed with various model shampoos that contained emulsified dimethicone. The shampoos were modified only by the addition or absence of polyquaternium-10. The results indicate that the cationic polymers do influence silicone oil deposition onto hair during the shampooing process. In the absence of cationic polymer, the silicone oils deposit readily, but appear to show "build-up" phenomena upon repeated washings. When a cationic polymer is present in the continuous phase of the shampoo, the build-up phenomena is significantly diminished, and silicone oil deposition remains relatively constant in repeated washings. In addition, we have noted that the molecular weight of the cationic polymer can have a strong effect on silicone oil deposition. It appears that the higher the molecular weight of the polyquaternium-10, the greater the amount of silicone deposition onto the surface of the hair. To demonstrate that the analysis technique has potential applications in commercial shampoos, we examined a commercial "2-in-1" shampoo that contains dimethicone and polyquaternium-10 and found that the data for our simple model shampoos and the commercial shampoo correlated closely.

  7. Analysis of Residual Thermal Stress in CVD-W Coating as Plasma Facing Material

    Institute of Scientific and Technical Information of China (English)

    朱大焕; 王坤; 王先平; 陈俊凌; 方前锋

    2012-01-01

    Chemical vapor deposition-tungsten (CVD-W) coating covering the surface of the plasma facing component (PFC) is an effective method to implement the tungsten material as plasma facing material (PFM) in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method (ANSYS 10.0 code). The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.

  8. Analysis of Residual Thermal Stress in CVD-W Coating as Plasma Facing Material

    Science.gov (United States)

    Zhu, Dahuan; Wang, Kun; Wang, Xianping; Chen, Junling; Fang, Qianfeng

    2012-07-01

    Chemical vapor deposition-tungsten (CVD-W) coating covering the surface of the plasma facing component (PFC) is an effective method to implement the tungsten material as plasma facing material (PFM) in fusion devices. Residual thermal stress in CVD-W coating due to thermal mismatch between coating and substrate was successfully simulated by using a finite element method (ANSYS 10.0 code). The deposition parametric effects, i.e., coating thickness and deposition temperature, and interlayer were investigated to get a description of the residual thermal stress in the CVD-W coating-substrate system. And the influence of the substrate materials on the generation of residual thermal stress in the CVD-W coating was analyzed with respect to the CVD-W coating application as PFM. This analysis is beneficial for the preparation and application of CVD-W coating.

  9. Modeling for CVD of Solid Oxide Electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.

    2002-09-18

    Because of its low thermal conductivity, high thermal expansion and high oxygen ion conductivity yttria-stabilized zirconia (YSZ) is the material of choice for high temperature electrolyte applications. Current coating fabrication methods have their drawbacks, however. Air plasma spray (APS) is a relatively low-cost process and is suitable for large and relatively complex shapes. it is difficult to produce uniform, relatively thin coatings with this process, however, and the coatings do not exhibit the columnar microstructure that is needed for reliable, long-term performance. The electron-beam physical vapor deposition (EB-PVD) process does produce the desirable microstructure, however, the capital cost of these systems is very high and the line-of-sight nature of the process limits coating uniformity and the ability to coat large and complex shapes. The chemical vapor deposition (CVD) process also produces the desirable columnar microstructure and--under proper conditions--can produce uniform coatings over complex shapes. CVD has been used for many materials but is relatively undeveloped for oxides, in general, and for zirconia, in particular. The overall goal of this project--a joint effort of the University of Louisville and Oak Ridge National Laboratory (ORNL)--is to develop the YSZ CVD process for high temperature electrolyte applications. This report describes the modeling effort at the University of Louisville, which supports the experimental work at ORNL. Early work on CVD of zirconia and yttria used metal chlorides, which react with water vapor to form solid oxide. Because of this rapid gas-phase reaction the water generally is formed in-situ using the reverse water-gas-shift reaction or a microwave plasma. Even with these arrangements gas-phase nucleation and powder formation are problems when using these precursors. Recent efforts on CVD of zirconia and YSZ have focused on use of metal-organic precursors (MOCVD). These are more stable in the gas

  10. Preparation of silicon-substituted hydroxyapatite coatings on Ti–30Nb–xTa alloys using cyclic electrochemical deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Sil [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University (Korea, Republic of); Jeong, Yong-Hoon [Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University (Korea, Republic of); Brantley, William A. [Division of Restorative Science and Prosthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2014-12-01

    Silicon-substituted hydroxyapatite coatings on Ti–30Nb–xTa alloys, prepared using a cyclic electrochemical deposition method, have been investigated using a variety of surface analytical experimental methods. The silicon-substituted hydroxyapatite (Si-HA) coatings were prepared by electrolytic deposition in electrolytes containing Ca{sup 2+}, PO{sub 4}{sup 3−} and SiO{sub 3}{sup 2−} ions. The deposited layers were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and a wettability test. Phase transformation from (α″ + β) to largely β occurred with increasing Ta content in the Ti –30Nb–xTa alloys, yielding larger grain size. The morphology of the Si-HA coatings was changed by increasing the number of deposition cycles, with the initial plate-like structures changing to mixed rod-like and plate-like shapes, and finally to a rod-like structure. From the ATR-FTIR spectra, Si existed in the form of SiO{sub 4}{sup 4−} groups in Si-HA coating layer. The lowest aqueous contact angles and best wettability were found for the Si-HA coatings prepared with 30 deposition cycles. - Highlights: • Electrochemically deposited Si-HA coatings on Ti –30Nb–xTa alloys were investigated. • The Si-HA coatings were initially precipitated along the martensitic structure. • The morphology of the Si-HA coating changed with the deposition cycles. • Si existed in the form of SiO{sub 4}{sup 4−} groups in the Si-HA coating.

  11. Characterization of epitaxial Pb(Zr,Ti)O3 thin films deposited by pulsed laser deposition on silicon cantilevers

    NARCIS (Netherlands)

    Nguyen, M.D.; Nazeer, H.; Karakaya, K.; Pham, S.V.; Steenwelle, R.; Dekkers, M.; Abelmann, L.; Blank, D.H.A.; Rijnders, G.

    2010-01-01

    This paper reports on the piezoelectric-microelectromechanical system micro-fabrication process and the behavior of piezoelectric stacks actuated silicon cantilevers. All oxide layers in the piezoelectric stacks, such as buffer-layer/bottom-electrode/film/top-electrode: YSZ/SrRuO\\3/Pb(Zr, Ti)\\3/SrRu

  12. Characterization of epitaxial Pb(Zr,Ti)O3 thin films deposited by pulsed laser deposition on silicon cantilevers

    NARCIS (Netherlands)

    Nguyen, M.D.; Nazeer, H.; Karakaya, K.; Pham, S.V.; Steenwelle, R.; Dekkers, M.; Abelmann, L.; Blank, D.H.A.

    2010-01-01

    This paper reports on the piezoelectric-microelectromechanical system micro-fabrication process and the behavior of piezoelectric stacks actuated silicon cantilevers. All oxide layers in the piezoelectric stacks, such as buffer-layer/bottom-electrode/film/top-electrode: YSZ/SrRuO3/Pb(Zr,Ti)3/SrRuO3,

  13. Characterization of epitaxial Pb(Zr,Ti)O3 thin films deposited by pulsed laser deposition on silicon cantilevers

    NARCIS (Netherlands)

    Nguyen, M.D.; Nazeer, H.; Karakaya, K.; Pham, S.V.; Steenwelle, R.; Dekkers, M.; Abelmann, L.; Blank, D.H.A.; Rijnders, G.

    2010-01-01

    This paper reports on the piezoelectric-microelectromechanical system micro-fabrication process and the behavior of piezoelectric stacks actuated silicon cantilevers. All oxide layers in the piezoelectric stacks, such as buffer-layer/bottom-electrode/film/top-electrode: YSZ/SrRuO\\3/Pb(Zr,

  14. Cathodic cage plasma deposition of TiN and TiO{sub 2} thin films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Romulo R. M. de [Department of Mechanics, Federal Institute of Education, Science, and Technology of Piaui, Praça da Liberdade, 1597, CEP 64000-040 Teresina, Piaui, Brazil and Department of Mechanical Engineering, Federal University of Piaui, Campus Min. Petronio Portela, Ininga, CEP 64049-550 Teresina, Piaui (Brazil); Sato, Patricia S.; Nascente, Pedro A. P., E-mail: nascente@ufscar.br [Department of Materials Engineering, Federal University of Sao Carlos, Via Washington Luis km 235, CEP 13565-905 Sao Carlos, Sao Paulo (Brazil); Viana, Bartolomeu C. [Department of Physics, Federal University of Piaui, Campus Min. Petronio Portela, Ininga, CEP 64049-550 Teresina, Piaui (Brazil); Alves, Clodomiro [Department of Exact and Natural Sciences, Federal Rural University of Semi Arido, Avenida Francisco Mota, 572, CEP 59625-900 Mossoro, Rio Grande do Norte (Brazil); Nishimoto, Akio [Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2015-07-15

    Cathodic cage plasma deposition (CCPD) was used for growing titanium nitride (TiN) and titanium dioxide (TiO{sub 2}) thin films on silicon substrates. The main advantages of the CCPD technique are the uniformity, tridimensionality, and high rate of the film deposition that occurs at higher pressures, lower temperatures, and lower treatment times than those used in conventional nitriding treatments. In this work, the influence of the temperature and gas atmosphere upon the characteristics of the deposited films was investigated. The TiN and TiO{sub 2} thin films were characterized by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy to analyze their chemical, structural, and morphological characteristics, and the combination of these results indicates that the low-cost CCPD technique can be used to produce even and highly crystalline TiN and TiO{sub 2} films.

  15. The study of the substrate temperature depended growth properties of microcrystalline silicon films deposited by VHF-PECVD method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongsheng, E-mail: chysh2003@zzu.edu.cn [Key Lab of Material Physics, Department of Physics, Zhengzhou University, Zhengzhou 450052 (China); Chen, Xiping; Hao, Xiuli; Lu, Jingxiao; Yang, Shi-e [Key Lab of Material Physics, Department of Physics, Zhengzhou University, Zhengzhou 450052 (China)

    2013-04-01

    In this paper, we have measured the temperature depended growth properties of hydrogenated microcrystalline silicon (μc-Si:H) films, prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) from SiH{sub 4} and H{sub 2} gas mixtures. And, a 1D plasma model coupled with a well-mixed reactor model is used to simulate the growth process, in which concentrations of gas phase species, the crystalline orientation, the hydrogen content and the deposition rate are calculated. It suggests that the increasing surface fraction of the dangling bonds with the increase of substrate temperatures is responsible for the increase in the grain sizes. At the same time, the observed variations of the X-ray-diffraction intensities and the deposition rates of the films with temperature result from the differences in the growth rates of the facets.

  16. CVD technologies used in preparation of low dielectric constant CVD technologies used in preparation of low dielectric constant%ULSI低介电常数材料制备中的CVD技术

    Institute of Scientific and Technical Information of China (English)

    王鹏飞; 丁士进; 张卫; 王季陶; 李伟

    2001-01-01

    Various CVD technologies for preparing low dielectric constantmaterials in ULSI circuits are summarized. The processes of deposition of fluorinated silicon oxide thin films, fluorinated amorphous carbon thin films and polyimide films are discussed in detail. The APCVD and RTCVD methods applied to prepare parylene films and fluorinated silicon oxide thin films are also briefly imroduced.%综述了制备ULSI低介电常数材料的各种CVD技术。详细介绍PCVD技术淀积含氟氧化硅薄膜、含氟无定型碳膜与聚酰亚胺类薄膜的工艺,简要介绍了APCVD技术淀积聚对二甲苯类有机薄膜及RTCVD技术淀积SiOF薄膜的工艺。

  17. Geochemical Trace of Silicon Isotopes of Intrusions and Ore Veins Related to Alkali-rich Porphyry Deposits in Western Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    LIU Xianfan; YANG Zhengxi; LIU Jiaduo; WU Dechao; ZHANG Chenjiang; LI Youguo

    2004-01-01

    Western Yunnan is the well-known polymetallic province in China. It is characterized by copper-gold mineralization related to Cenozoic alkali-rich porphyry. This paper analyzes the silicon isotope data obtained from four typical alkali-rich porphyry deposits based on the dynamic fractionation principle of silicon isotope. The study shows that the ore materials should originate mainly from alkali-rich magmas, together with silicon-rich mineralizing fluids.The process of mineralization was completed by auto-metasomatism, i.e. silicon-rich mineralizing fluids (including alkali-rich porphyry and wall-rock strata) replaced and altered the country rocks and contaminated with crustal rocks during the crystallization of alkali-rich magmas. Such a process is essentially the continuance of the metasomatism of mantle fluids in crust's mineralization. This provides important evidence of silicon isotopic geochemistry for better understanding the mineralization of the Cenozoic alkali-rich porphyry polymetallic deposits

  18. Amorphous silicon carbon films prepared by hybrid plasma enhanced chemical vapor/sputtering deposition system: Effects of r.f. power

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Nur Maisarah Abdul, E-mail: nurmaisarahrashid@gmail.com [Low Dimensional Materials Research Centre, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ritikos, Richard; Othman, Maisara; Khanis, Noor Hamizah; Gani, Siti Meriam Ab. [Low Dimensional Materials Research Centre, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Muhamad, Muhamad Rasat [Chancellery Office, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Rahman, Saadah Abdul, E-mail: saadah@um.edu.my [Low Dimensional Materials Research Centre, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Chancellery Office, Multimedia University, Jalan Multimedia, 63100 Cyberjaya, Selangor (Malaysia)

    2013-02-01

    Silicon carbon films were deposited using a hybrid radio frequency (r.f.) plasma enhanced chemical vapor deposition (PECVD)/sputtering deposition system at different r.f. powers. This deposition system combines the advantages of r.f. PECVD and sputtering techniques for the deposition of silicon carbon films with the added advantage of eliminating the use of highly toxic silane gas in the deposition process. Silicon (Si) atoms were sputtered from a pure amorphous silicon (a-Si) target by argon (Ar) ions and carbon (C) atoms were incorporated into the film from C based growth radicals generated through the discharge of methane (CH{sub 4}) gas. The effects of r.f. powers of 60, 80, 100, 120 and 150 W applied during the deposition process on the structural and optical properties of the films were investigated. Raman spectroscopic studies showed that the silicon carbon films contain amorphous silicon carbide (SiC) and amorphous carbon (a-C) phases. The r.f. power showed significant influence on the C incorporation in the film structure. The a-C phases became more ordered in films with high C incorporation in the film structure. These films also produced high photoluminescence emission intensity at around 600 nm wavelength as a result of quantum confinement effects from the presence of sp{sup 2} C clusters embedded in the a-SiC and a-C phases in the films. - Highlights: ► Effects of radio frequency (r.f.) power on silicon carbon (SiC) films were studied. ► Hybrid plasma enhanced chemical vapor deposition/sputtering technique was used. ► r.f. power influences C incorporation in the film structure. ► High C incorporation results in higher ordering of the amorphous C phase. ► These films produced high photoluminescence emission intensity.

  19. Comparative evaluation of CVD diamond technologies

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, T.R. [General Electric Corporate Research & Development Center, Schenectady, NY (United States)

    1993-01-01

    Chemical vapor deposition (CVD) of diamonds occurs from hydrogen-hydrocarbon gas mixtures in the presence of atomic hydrogen at subatmospheric pressures. Most CVD methods are based on different means of generating and transporting atomic hydrogen in a particular system. Evaluation of these different techniques involves their capital costs, material costs, energy costs, labor costs and the type and quality of diamond that they produce. Currently, there is no universal agreement on which is the best technique and technique selection has been largely driven by the professional background of the user as well as the particular application of interest. This article discusses the criteria for evaluating a process for low-pressure deposition of diamond. Next, a brief history of low-pressure diamond synthesis is reviewed. Several specific processes are addressed, including the hot filament process, hot filament electron-assisted chemical vapor deposition, and plasma generation of atomic hydrogen by glow discharge, microwave discharge, low pressure radio frequency discharge, high pressure DC discharge, high pressure microwave discharge jets, high pressure RF discharge, and high and low pressure flames. Other types of diamond deposition methods are also evaluated. 101 refs., 15 figs.

  20. Approaching Defect-free Amorphous Silicon Nitride by Plasma-assisted Atomic Beam Deposition for High Performance Gate Dielectric

    Science.gov (United States)

    Tsai, Shu-Ju; Wang, Chiang-Lun; Lee, Hung-Chun; Lin, Chun-Yeh; Chen, Jhih-Wei; Shiu, Hong-Wei; Chang, Lo-Yueh; Hsueh, Han-Ting; Chen, Hung-Ying; Tsai, Jyun-Yu; Lu, Ying-Hsin; Chang, Ting-Chang; Tu, Li-Wei; Teng, Hsisheng; Chen, Yi-Chun; Chen, Chia-Hao; Wu, Chung-Lin

    2016-06-01

    In the past few decades, gate insulators with a high dielectric constant (high-k dielectric) enabling a physically thick but dielectrically thin insulating layer, have been used to replace traditional SiOx insulator and to ensure continuous downscaling of Si-based transistor technology. However, due to the non-silicon derivative natures of the high-k metal oxides, transport properties in these dielectrics are still limited by various structural defects on the hetero-interfaces and inside the dielectrics. Here, we show that another insulating silicon compound, amorphous silicon nitride (a-Si3N4), is a promising candidate of effective electrical insulator for use as a high-k dielectric. We have examined a-Si3N4 deposited using the plasma-assisted atomic beam deposition (PA-ABD) technique in an ultra-high vacuum (UHV) environment and demonstrated the absence of defect-related luminescence; it was also found that the electronic structure across the a-Si3N4/Si heterojunction approaches the intrinsic limit, which exhibits large band gap energy and valence band offset. We demonstrate that charge transport properties in the metal/a-Si3N4/Si (MNS) structures approach defect-free limits with a large breakdown field and a low leakage current. Using PA-ABD, our results suggest a general strategy to markedly improve the performance of gate dielectric using a nearly defect-free insulator.

  1. Role of oxygen and nitrogen in n-type microcrystalline silicon carbide grown by hot wire chemical vapor deposition

    Science.gov (United States)

    Pomaska, Manuel; Mock, Jan; Köhler, Florian; Zastrow, Uwe; Perani, Martina; Astakhov, Oleksandr; Cavalcoli, Daniela; Carius, Reinhard; Finger, Friedhelm; Ding, Kaining

    2016-12-01

    N-type microcrystalline silicon carbide (μc-SiC:H(n)) deposited by hot wire chemical vapor deposition provides advantageous opto-electronic properties for window layer material in silicon-based thin-film solar cells and silicon heterojunction solar cells. So far, it is known that the dark conductivity (σd) increases with the increase in the crystallinity of μc-SiC:H(n)films. However, due to the fact that no active doping source is used, the mechanism of electrical transport in these films is still under debate. It is suggested that unintentional doping by atmospheric oxygen (O) or nitrogen (N) contamination plays an important role in the electrical transport. To investigate the impact of O and N, we incorporated O and N in μc-SiC:H(n) films and compared the influence on the microstructural, electronic, and optical properties. We discovered that, in addition to increasing the crystallinity, it is also possible to increase the σd by several orders of magnitude by increasing the O-concentration or the N-concentration in the films. Combining a high concentration of O and N, along with a high crystallinity in the film, we optimized the σd to a maximum of 5 S/cm.

  2. CVD diamond - fundamental phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Yarbrough, W.A. [Pennsylvania State Univ., University Park (United States)

    1993-01-01

    This compilation of figures and diagrams addresses the basic physical processes involved in the chemical vapor deposition of diamond. Different methods of deposition are illustrated. For each method, observations are made of the prominent advantages and disadvantages of the technique. Chemical mechanisms of nucleation are introduced.

  3. Deposition, characterization, and in vivo performance of parylene coating on general-purpose silicone for examining potential biocompatible surface modifications

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Chia-Man [Division of Pediatric Surgery, Department of Surgery, Taichung Veterans General Hospital, 160, Sec. 3, Taichung Port Rd., Taichung 40705, Taiwan, ROC (China); Department of Medicine, National Yang-Ming University, 155, Sec. 2, Linong Street, Taipei 11221, Taiwan, ROC (China); Shiao, Chiao-Ju [Department of Materials Science and Engineering, Feng Chia University, 100, Wen-Hwa Rd., Taichung 40724, Taiwan, ROC (China); Chung, Chi-Jen, E-mail: cjchung@seed.net.tw [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, 666 Buzih Rd., Beitun District, Taichung 40601, Taiwan, ROC (China); He, Ju-Liang [Department of Materials Science and Engineering, Feng Chia University, 100, Wen-Hwa Rd., Taichung 40724, Taiwan, ROC (China)

    2013-12-31

    In this study, a thorough investigation of parylene coatings was conducted, as follows: microstructure (i.e., X-ray diffractometer (XRD) and cold field emission scanning electron microscope (FESEM)), mechanical property (i.e., pencil hardness and cross-cut adhesion test), surface property (i.e., water contact angle measurement, IR, and X-ray photoelectron spectroscopy (XPS)), and biocompatibility tests (i.e., fibroblast cell culture, platelet adhesion, and animal studies). The results revealed that parylene, a crystalline and brittle coating, exhibited satisfactory film adhesion and relative hydrophobicity, thereby contributing to its effective barrier properties. Fibroblast cell culturing on the parylene-deposited specimen demonstrated improved cell proliferation and equivalent to or superior blood compatibility than that of the medical-grade silicone (currently used clinically). In the animal study, parylene coatings exhibited similar subcutaneous inflammatory reactions compared with the medical-grade silicone. Both in vitro and in vivo tests demonstrated the satisfactory biocompatibility of parylene coatings. - Highlights: • A complete investigation to identify the characteristics of parylene coatings on general-purpose silicones. • Microstructures, surface properties and mechanical properties of parylene coatings were examined. • In vitro (Cell culture, platelet adhesion) tests and animal studies revealed satisfactory biocompatibility. • An alternative of medical-grade silicones is expected to be obtained.

  4. Evaluation on residual stresses of silicon-doped CVD diamond films using X-ray diffraction and Raman spectroscopy%CVD掺硅金刚石残余应力的X射线衍射和拉曼光谱分析

    Institute of Scientific and Technical Information of China (English)

    陈苏琳; 沈彬; 张建国; 王亮; 孙方宏

    2012-01-01

    采用X射线衍射(XRD)和拉曼光谱2种方法测量了不同硅碳比的CVD掺硅金刚石薄膜的残余应力.采用偏压增强热丝化学气相沉积装置在硬质合金基底上制备了掺硅金刚石薄膜,将正硅酸乙酯以不同的体积比溶解在丙酮中以使得反应气体中的硅碳比从0.1%变化到1.4%,从而控制掺硅金刚石薄膜的掺杂浓度.SEM和XRD的表征结果显示,随着硅掺杂浓度的增加,金刚石薄膜的晶粒尺寸减小,而金刚石(110)的晶面则逐渐占优.XRD法是测量入射角从0°到45°变化时对应的金刚石(220)面XRD衍射峰,并采用sin2ψ方法计算掺硅金刚石薄膜的残余应力.拉曼谱法则是通过检测金刚石特征峰偏移1332 cm-1位置的偏移量来测量残余应力.2种方法测得的残余应力随着硅掺杂含量的升高显示出良好的一致性,所有的硅掺杂金刚石的残余应力均为压应力,Si/C摩尔比为0.1%的薄膜具有最高的残余应力,为~1.75 GPa(拉曼谱法)或~2.3 GPa(XRD法).随着硅掺杂浓度的进一步升高,薄膜的残余应力则稳定在~1.3 GPa左右.%The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction(XRD)analysis and Raman spectroscopy measurements.The examined Si-doped diamond films are deposited on WC-Co substrates in a home-made bias-enhanced HFCVD apparatus.Ethyl silicate(Si(OC2H5)4)is dissolved in acetone to obtain various Si/C mole ratio ranging from 0.1% to 1.4% in the reaction gas.Characterizations with SEM and XRD indicate increasing silicon concentration may result in grain size decreasing and diamond [110] texture becoming dominant.The residual stress values of as-deposited Si-doped diamond films are evaluated by both sin2ψ method,which measures the(220)diamond Bragg diffraction peaks using XRD,with ψ-values ranging from 0°to 45°,and Raman spectroscopy,which detects the diamond Raman peak shift from the natural diamond line at

  5. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply

    Directory of Open Access Journals (Sweden)

    Sue Elaine Hartley

    2015-02-01

    Full Text Available Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and 3 different grass species (F. ovina, F. rubra and Deschampsia cespitosa differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F.arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species.

  6. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply.

    Science.gov (United States)

    Hartley, Sue E; Fitt, Rob N; McLarnon, Emma L; Wade, Ruth N

    2015-01-01

    Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si) is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and three different grass species (F. ovina, F. rubra, and Deschampsia cespitosa) differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F. arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species.

  7. Optical properties of plasma ion-assisted deposition silicon coatings: application to the manufacture of blocking filters for the near-infrared region.

    Science.gov (United States)

    Bruynooghe, Stephane

    2008-05-01

    I report on the preparation and characterization of optical constants of silicon coatings deposited by an electron beam gun with plasma ion-assisted deposition. With the fabrication of long-wave-pass filters the reliability of the optical constants is assured.

  8. Low Temperature Silicon Nitride by Hot Wire Chemical Vapour Deposition for the Use in Impermeable Thin Film Encapsulation on Flexible Substrates

    NARCIS (Netherlands)

    Spee, D.A.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2011-01-01

    High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si–H peak position of 2180 cm−1

  9. Thermodynamic behaviors of SiCl2 in silicon deposition by gas phase zinc reduction of silicon tetrachloride☆

    Institute of Scientific and Technical Information of China (English)

    Yanqing Hou; Zhifeng Nie; Gang Xie; Rongxing Li; Xiaohua Yu; Plant A Ramachandran

    2015-01-01

    The modified Siemens process, which is the major process of producing polycrystal ine silicon through current technologies, is a high temperature, slow, semi-batch process and the product is expensive primarily due to the large energy consumption. Therefore, the zinc reduction process, which can produce solar-grade silicon in a cost effective manner, should be redeveloped for these conditions. The SiCl2 generation ratio, which stands for the degree of the side reactions, can be decomposed to SiCl4 and ZnCl2 in gas phase zinc atmosphere in the exit where the temperature is very low. Therefore, the lower SiCl2 generation ratio is profitable with lower power consumption. Based on the thermodynamic data for the related pure substances, the relations of the SiCl2 generation ratio and pressure, temperature and the feed molar ratio nZn=nSiCl4 ? ? are investigated and the graphs thereof are plotted. And the diagrams of KpΘ–T at standard atmosphere pressure have been plotted to account for the influence of temperature on the SiCl2 generation ratio. Furthermore, the diagram of KpΘ–T at dif-ferent pressures have also been plotted to give an interpretation of the influence of pressure on the SiCl2 gener-ation ratio. The results show that SiCl2 generation ratio increases with increasing temperature, and the higher pressure and excess gas phase zinc can restrict SiCl2 generation ratio. Finally, suitable operational conditions in the practical process of polycrystalline silicon manufacture by gas phase zinc reduction of SiCl4 have been established with 1200 K, 0.2 MPa and the feed molar ratio nZn=nSiCl4 ? ? of 4 at the entrance. Under these conditions, SiCl2 generation ratio is very low, which indicates that the side reactions can be restricted and the energy consumption is reasonable.

  10. Effect of plasma parameters on characteristics of silicon nitride film deposited by single and dual frequency plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Sahu, B. B.; Yin, Yongyi; Han, Jeon G.

    2016-03-01

    This work investigates the deposition of hydrogenated amorphous silicon nitride films using various low-temperature plasmas. Utilizing radio-frequency (RF, 13.56 MHz) and ultra-high frequency (UHF, 320 MHz) powers, different plasma enhanced chemical vapor deposition processes are conducted in the mixture of reactive N2/NH3/SiH4 gases. The processes are extensively characterized using different plasma diagnostic tools to study their plasma and radical generation capabilities. A typical transition of the electron energy distribution function from single- to bi-Maxwellian type is achieved by combining RF and ultra-high powers. Data analysis revealed that the RF/UHF dual frequency power enhances the plasma surface heating and produces hot electron population with relatively low electron temperature and high plasma density. Using various film analysis methods, we have investigated the role of plasma parameters on the compositional, structural, and optical properties of the deposited films to optimize the process conditions. The presented results show that the dual frequency power is effective for enhancing dissociation and ionization of neutrals, which in turn helps in enabling high deposition rate and improving film properties.

  11. Effect of annealing temperature on optical and electrical properties of metallophthalocyanine thin films deposited on silicon substrate

    Directory of Open Access Journals (Sweden)

    Skonieczny R.

    2016-09-01

    Full Text Available The cobalt phthalocyanine (CoPc thin films (300 nm thick deposited on n-type silicon substrate have been studied using micro-Raman spectroscopy, atomic force spectroscopy (AFM and I-V measurement. The CoPc thin layers have been deposited at room temperature by the quasi-molecular beam evaporation technique. The micro-Raman spectra of CoPc thin films have been recorded in the spectral range of 1000 cm-1 to 1900 cm-1 using 488 nm excitation wavelength. Moreover, using surface Raman mapping it was possible to obtain information about polymorphic forms distribution (before and after annealing of metallophthalocyanine (α and β form from polarized Raman spectra. The I-V characteristics of the Au/CoPc/n-Si/Al Schottky barrier were also investigated. The obtained results showed that influence of the annealing process plays a crucial role in the ordering and electrical conductivity of the molecular structure of CoPc thin films deposited on n-type silicon substrate.

  12. Effects of space exposure on ion-beam-deposited silicon-carbide and boron-carbide coatings.

    Science.gov (United States)

    Keski-Kuha, R A; Blumenstock, G M; Fleetwood, C M; Schmitt, D R

    1998-12-01

    Two recently developed optical coatings, ion-beam-deposited silicon carbide and ion-beam-deposited boron carbide, are very attractive as coatings on optical components for instruments for space astronomy and earth sciences operating in the extreme-UV spectral region because of their high reflectivity, significantly higher than any conventional coating below 105 nm. To take full advantage of these coatings in space applications, it is important to establish their ability to withstand exposure to the residual atomic oxygen and other environmental effects at low-earth-orbit altitudes. The first two flights of the Surface Effects Sample Monitor experiments flown on the ORFEUS-SPAS and the CRISTA-SPAS Shuttle missions provided the opportunity to study the effects of space exposure on these materials. The results indicate a need to protect ion-beam-deposited silicon-carbide-coated optical components from environmental effects in a low-earth orbit. The boron-carbide thin-film coating is a more robust coating able to withstand short-term exposure to atomic oxygen in a low-earth-orbit environment.

  13. Development and evaluation of die materials for use in the growth of silicon ribbons by the inverted ribbon growth process, task 2, LSSA project

    Science.gov (United States)

    Duffy, M. T.; Berkman, S.; Cullen, G. W.; Moss, H. I.

    1977-01-01

    Silicon sessile drop experiments were performed on a variety of commercially available refractory carbides, nitrides, oxides, and borides to examine the potential of these materials for applications involving either direct contact with molten silicon or as substrates for CVD coatings in the fabrication of dies and crucibles for containing molten silicon. Simultaneous experiments were also conducted with CVD layers of SiC, Si3N4, and SiOxNy. Silicon nitride layers, deposited with NH3:SiH4 ratios ranging from 100:1 down to 5:1, were examined in sessile drop experiments to determine if the layers are degraded as a result of using lower reagent ratios. Preliminary experiments were undertaken on the stability of CVD Si3N4 near the melting point of silicon. Silicon ribbon segments were grown from vitreous carbon dies which had been coated with CVD Si3N4. Depending upon the purity of the die materials, ribbon resistivity values up to 40 Omega cm were obtained.

  14. Low temperature silicon nitride by hot wire chemical vapour deposition for the use in impermeable thin film encapsulation on flexible substrates.

    Science.gov (United States)

    Spee, D A; van der Werf, C H M; Rath, J K; Schropp, R E I

    2011-09-01

    High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 degrees C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si-H peak position of 2180 cm(-1) in the Fourier transform infrared absorption spectrum indicates a N/Si ratio around 1.2. Together with a refractive index of 1.97 at a wavelength of 632 nm and an extinction coefficient of 0.002 at 400 nm, this suggests that a transparent high density silicon nitride material has been made below 110 degrees C, which is compatible with polymer films and is expected to have a high impermeability. To confirm the compatibility with polymer films a silicon nitride layer was deposited on poly(glycidyl methacrylate) made by initiated chemical vapour deposition, resulting in a highly transparent double layer.

  15. Tailored Voltage Waveform Deposition of Microcrystalline Silicon Thin Films from Hydrogen-Diluted Silane and Silicon Tetrafluoride: Optoelectronic Properties of Films

    Science.gov (United States)

    Johnson, Erik V.; Pouliquen, Sylvain; Delattre, Pierre-Alexandre; Booth, Jean-Paul

    2012-08-01

    The use of tailored voltage waveforms (TVW's) to excite a plasma for the deposition of thin films of hydrogenated microcrystalline silicon (µc-Si:H) has been shown to be an effective technique to decouple mean ion bombardment energy (IBE) from injected power. In this work, we examine the changes in material properties controlled by this technique through Raman scattering and spectroscopic ellipsometry for films deposited from H2-diluted SiH4, and we examine the electrical properties of such films using temperature dependent conductivity. As the laboratory-scale deposition system used had neither a load lock nor an oxygen filter in the H2 line, accidental O-doping was observed for the µc-Si:H films. We investigated suppression of this doping by adding varying amounts of SiF4, and using an SiF4/Ar pre-etch step to clean the reactor. This technique is shown to be effective in decreasing the accidental doping of the films, and intrinsic µc-Si:H films are produced with an activation energy of up to 0.55 eV. As well, an important difference in the amorphous-to-microcrystalline transition is observed once SiF4 is included in the gas mixture.

  16. Mo-C Multilayered CVD Coatings

    Directory of Open Access Journals (Sweden)

    A. Sagalovych

    2013-12-01

    Full Text Available Production processes of multi-layered Mo-C coatings by the method of chemical vapor deposition (CVD with the use of organometallic compounds were developed. Coatings are applied on technical purpose steel DIN 1.2379 (H12F1 and DIN 1.7709 (25H2MF (ÉI10 heat-treated ball with the high class of surface roughness (> 10. The average deposition rate was 50 μm / h. The optimal conditions of deposition coatings for different technological schemas were defined. Metallographic investigations of the obtained coatings were carried out. Tribological studies of the friction and wear characteristics of sliding friction in conditions of boundary lubrication of Ï-S multilayered CVD coatings shows, that coatings have low friction coefficients (0075-0095 at loads up to 2.0 kN, showed high resistance to wear and are effective in increasing the stability of the pair for precision friction pairs of hydraulical units.

  17. Growth direction of oblique angle electron beam deposited silicon monoxide thin films identified by optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Vejling Andersen, Søren; Lund Trolle, Mads; Pedersen, Kjeld [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Øst (Denmark)

    2013-12-02

    Oblique angle deposited (OAD) silicon monoxide (SiO) thin films forming tilted columnar structures have been characterized by second-harmonic generation. It was found that OAD SiO leads to a rotationally anisotropic second-harmonic response, depending on the optical angle of incidence. A model for the observed dependence of the second-harmonic signal on optical angle of incidence allows extraction of the growth direction of OAD films. The optically determined growth directions show convincing agreement with cross-sectional scanning electron microscopy images. In addition to a powerful characterization tool, these results demonstrate the possibilities for designing nonlinear optical devices through SiO OAD.

  18. Comparative study of solution-phase and vapor-phase deposition of aminosilanes on silicon dioxide surfaces.

    Science.gov (United States)

    Yadav, Amrita R; Sriram, Rashmi; Carter, Jared A; Miller, Benjamin L

    2014-02-01

    The uniformity of aminosilane layers typically used for the modification of hydroxyl bearing surfaces such as silicon dioxide is critical for a wide variety of applications, including biosensors. However, in spite of many studies that have been undertaken on surface silanization, there remains a paucity of easy-to-implement deposition methods reproducibly yielding smooth aminosilane monolayers. In this study, solution- and vapor-phase deposition methods for three aminoalkoxysilanes differing in the number of reactive groups (3-aminopropyl triethoxysilane (APTES), 3-aminopropyl methyl diethoxysilane (APMDES) and 3-aminopropyl dimethyl ethoxysilane (APDMES)) were assessed with the aim of identifying methods that yield highly uniform and reproducible silane layers that are resistant to minor procedural variations. Silane film quality was characterized based on measured thickness, hydrophilicity and surface roughness. Additionally, hydrolytic stability of the films was assessed via these thickness and contact angle values following desorption in water. We found that two simple solution-phase methods, an aqueous deposition of APTES and a toluene based deposition of APDMES, yielded high quality silane layers that exhibit comparable characteristics to those deposited via vapor-phase methods.

  19. Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system

    Science.gov (United States)

    Ficek, M.; Drijkoningen, S.; Karczewski, J.; Bogdanowicz, R.; Haenen, K.

    2016-01-01

    It is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of a linear antenna microwave plasma enhanced chemical vapor deposition system (LA MW CVD) is the fact that it allows to grow the diamond layers at low temperature (below 300°C) [1]. High quality nanocrystalline diamond (NCD) thin films with thicknesses ranging from 70 nm to 150 nm, were deposited on silicon, glass and optical fibre substrates [2]. Substrates pretreatment by dip-coating and spin coating process with a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) has been applied. During the deposition process the continuous mode of operation of the LA MW CVD system was used, which produces a continuous wave at a maximum power of 1.9 kW (in each antenna). Diamond films on optical fibres were obtained at temperatures below 350°C, providing a clear improvement of results compared to our earlier work [3]. The samples were characterized by scanning electron microscopy (SEM) imaging to investigate the morphology of the nanocrystalline diamond films. The film growth rate, film thickness, and optical properties in the VIS-NIR range, i.e. refractive index and extinction coefficient will be discussed based on measurements on reference quartz plates by using spectroscopic ellipsometry (SE).

  20. Low-temperature SiON films deposited by plasma-enhanced atomic layer deposition method using activated silicon precursor

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Sungin; Kim, Jun-Rae; Kim, Seongkyung; Hwang, Cheol Seong; Kim, Hyeong Joon, E-mail: thinfilm@snu.ac.kr [Department of Materials Science and Engineering with Inter-University Semiconductor Research Center (ISRC), Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Ryu, Seung Wook, E-mail: tazryu78@gmail.com [Department of Electrical Engineering, Stanford University, Stanford, California 94305-2311 (United States); Cho, Seongjae [Department of Electronic Engineering and New Technology Component & Material Research Center (NCMRC), Gachon University, Seongnam-si, Gyeonggi-do 13120 (Korea, Republic of)

    2016-01-15

    It has not been an easy task to deposit SiN at low temperature by conventional plasma-enhanced atomic layer deposition (PE-ALD) since Si organic precursors generally have high activation energy for adsorption of the Si atoms on the Si-N networks. In this work, in order to achieve successful deposition of SiN film at low temperature, the plasma processing steps in the PE-ALD have been modified for easier activation of Si precursors. In this modification, the efficiency of chemisorption of Si precursor has been improved by additional plasma steps after purging of the Si precursor. As the result, the SiN films prepared by the modified PE-ALD processes demonstrated higher purity of Si and N atoms with unwanted impurities such as C and O having below 10 at. % and Si-rich films could be formed consequently. Also, a very high step coverage ratio of 97% was obtained. Furthermore, the process-optimized SiN film showed a permissible charge-trapping capability with a wide memory window of 3.1 V when a capacitor structure was fabricated and measured with an insertion of the SiN film as the charge-trap layer. The modified PE-ALD process using the activated Si precursor would be one of the most practical and promising solutions for SiN deposition with lower thermal budget and higher cost-effectiveness.

  1. Effect of time and of precursor molecule on the deposition of hydrophobic nanolayers on ethyelene tetrafluoroethylene-silicon oxide substrates

    Science.gov (United States)

    Rossi, Gabriella; Castellano, Piera; Incarnato, Loredana

    2016-10-01

    A method was developed for generating transparent and hydrophobic nanolayers chemisorbed onto flexible substrates of ethylene tetrafluoroethylene-silicon oxide (ETFE-SiOx). In particular, the effect of the deposition time and of the precursor molecule on the nanocoating process was analyzed with the aim of pursuing an optimization of the above method in an industrial application perspective. It was found that precursor molecule of triethoxysilane allowed to obtain better hydrophobic properties on the SiOx surface in shorter times compared to trichlorosilane, reaching the 92 % of final contact angle (CA) value of 106° after only 1 h of deposition. The optical properties and surface morphology were also assessed in function of time, revealing that an initial transparency reduction is followed by a subsequent transmittance increase during the self assembly of fluoroalkylsilanes on the SiOx surface, coherently with the surface roughness analysis data. Encouraging results were also obtained in terms of oleophobic properties improvement of the nanocoated surfaces.

  2. Low-temperature atomic layer deposition of MoO{sub x} for silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Macco, B.; Vos, M.F.J.; Thissen, N.F.W.; Bol, A.A. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven (Netherlands); Kessels, W.M.M. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven (Netherlands); Solliance Solar Research, Eindhoven (Netherlands)

    2015-07-15

    The preparation of high-quality molybdenum oxide (MoO{sub x}) is demonstrated by plasma-enhanced atomic layer deposition (ALD) at substrate temperatures down to 50 C. The films are amorphous, slightly substoichiometric with respect to MoO{sub 3}, and free of other elements apart from hydrogen (<11 at%). The films have a high transparency in the visible region and their compatibility with a-Si:H passivation schemes is demonstrated. It is discussed that these aspects, in conjunction with the low processing temperature and the ability to deposit very thin conformal films, make this ALD process promising for the future application of MoO{sub x} in hole-selective contacts for silicon heterojunction solar cells. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Amorphous silicon films with high deposition rate prepared using argon and hydrogen diluted silane for stable solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, Purabi; Agarwal, Pratima [Department of Physics, IIT Guwahati, Guwahati 781039 (India); Dixit, P.N. [Plasma Processed Materials Division, National Physical Laboratory, New Delhi 110012 (India)

    2007-08-15

    Hydrogenated amorphous silicon films with high deposition rate (4-5 Aa/s) and reduced Staebler-Wronski effect are prepared using a mixture of silane (SiH{sub 4}), hydrogen and argon. The films show an improvement in short and medium range order. The structural, transport and stability studies on the films are done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman scattering studies, electrical conductivity and diffusion length measurement. Presence of both atomic hydrogen and Ar{sup *} in the plasma causes breaking of weak Si-Si bonds and subsequent reconstruction of strong bonds resulting in improvement of short and medium range order. The improved structural order enhances the stability of these films against light soaking. High deposition rate is due to the lesser etching of growing surface compared to the case of only hydrogen diluted silane. (author)

  4. Plasma diagnostic approach for the low-temperature deposition of silicon quantum dots using dual frequency PECVD

    Science.gov (United States)

    Sahu, B. B.; Yin, Y.; Lee, J. S.; Han, Jeon G.; Shiratani, M.

    2016-10-01

    Although studies of silicon (Si) quantum dots (QDs) were started just a few years ago, progress is noteworthy concerning unique film properties and their potential application for devices. In particular, relating to the Si QD process optimization, it is essential to control the deposition environment by studying the role of plasma parameters and atomic and molecular species in the process plasmas. In this work, we report on advanced material processes for the low-temperature deposition of Si QDs by utilizing radio frequency and ultrahigh frequency dual frequency (DF) plasma enhanced chemical vapor deposition (PECVD) method. DF PECVD can generate a very high plasma density in the range ~9  ×  1010 cm-3 to 3.2  ×  1011 cm-3 at a very low electron temperature (T e) ~ 1.5 to 2.4 eV. The PECVD processes, using a reactive mixture of H2/SiH4/NH3 gases, are carefully studied to investigate the operating regime and to optimize the deposition parameters by utilizing different plasma diagnostic tools. The analysis reveals that a higher ion flux at a higher plasma density on the substrate is conducive to enhancing the overall crystallinity of the deposited film. Along with high-density plasmas, a high concentration of atomic H and N is simultaneously essential for the high growth rate deposition of Si QDs. Numerous plasma diagnostics methods and film analysis tools are used to correlate the effect of plasma- and atomic-radical parameters on the structural and chemical properties of the deposited Si QD films prepared in the reactive mixtures of H2/SiH4/NH3 at various pressures.

  5. Surface morphology, growth rate and quality of diamond films synthesized in hot filament CVD system under various methane concentrations

    Science.gov (United States)

    Ali, M.; Ürgen, M.

    2011-08-01

    Hot filament chemical vapor deposition (CVD) technique has been used to deposit diamond films on silicon substrate. In the present study, diamond films were grown at various vol.% CH 4 in H 2 from 0.5% to 3.5%, at substrate temperature and pressure of 850 °C and 80 torr, respectively. Scanning electron microscopy, X-ray diffraction and Raman spectroscopy were employed to analyze the properties of deposited films. The formation of methyl radicals as a function of vol.% CH 4 not only changes film morphology but also increase film growth rate. At low, intermediate and high vol.% CH 4, cluster, faceted cubes and pyramidal features growth, were dominant. By increasing vol.% CH 4 from 0.5% to 3.5%, as the growth rate improved from ˜0.25 μm/h to ˜2.0 μm/h. Raman studies features revealed high purity diamond films at intermediate range of vol.% CH 4 and grain density increased by increasing CH 4 concentration. The present study represents experimentally surface morphology, growth rate and quality of diamond films grown in hot filament CVD system at various CH 4 concentrations.

  6. Regular growth combined with lateral etching in diamond deposited over silicon substrate by using hot filament chemical vapor deposition technique

    Science.gov (United States)

    Ali, M.; Ürgen, M.

    2013-05-01

    Hot filament chemical vapor deposition has proved to be an attractive method for growing diamond films with good quality and higher growth rate. Diamond films were produced at deposition parameters under which, it is possible to have regular growth combined with lateral etching (RGCLE). Fracture cross-section SEM images showed that RGCLE initiated over polycrystalline diamond film and proceeded by the growth of consecutive steps in each crystallite, which terminated with square/rectangle shaped facets. All the diamond films exhibit RGCLE but with different type of growth behavior. Present work discusses the cyclic formation of the steps in diamond crystallites and RGCLE modes. RGCLE in diamond film may find important applications where heat absorption and dissipation are key issues.

  7. Improved amorphous/crystalline silicon interface passivation for heterojunction solar cells by low-temperature chemical vapor deposition and post-annealing treatment.

    Science.gov (United States)

    Wang, Fengyou; Zhang, Xiaodan; Wang, Liguo; Jiang, Yuanjian; Wei, Changchun; Xu, Shengzhi; Zhao, Ying

    2014-10-07

    In this study, hydrogenated amorphous silicon (a-Si:H) thin films are deposited using a radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) system. The Si-H configuration of the a-Si:H/c-Si interface is regulated by optimizing the deposition temperature and post-annealing duration to improve the minority carrier lifetime (τeff) of a commercial Czochralski (Cz) silicon wafer. The mechanism of this improvement involves saturation of the microstructural defects with hydrogen evolved within the a-Si:H films due to the transformation from SiH2 into SiH during the annealing process. The post-annealing temperature is controlled to ∼180 °C so that silicon heterojunction solar cells (SHJ) could be prepared without an additional annealing step. To achieve better performance of the SHJ solar cells, we also optimize the thickness of the a-Si:H passivation layer. Finally, complete SHJ solar cells are fabricated using different temperatures for the a-Si:H film deposition to study the influence of the deposition temperature on the solar cell parameters. For the optimized a-Si:H deposition conditions, an efficiency of 18.41% is achieved on a textured Cz silicon wafer.

  8. CVD Diamond Sensors In Detectors For High Energy Physics

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00334150; Trischuk, William

    At the end of the next decade an upgrade of the Large Hadron Collider (LHC) to High Luminosity LHC (HL-LHC) is planned which requires the development of new radiation tolerant sensor technology. Diamond is an interesting material for use as a particle detector in high radiation environments. The large band gap ($5.47\\,\\text{eV}$) and the large displacement energy suggest that diamond is a radiation tolerant detector material. In this Thesis the capability of Chemical Vapor Deposition (CVD) diamond as such a sensor technology is investigated. The radiation damage constant for $800\\,\\text{MeV}$ protons is measured using single crystalline CVD (scCVD) and polycrystalline CVD (pCVD) diamonds irradiated to particle fluences up to $12 \\times 10^{15}\\,\\text{p/cm}^2$. In addition the signal response of a pCVD diamond detector after an irradiation to $12 \\times 10^{15}\\,\\text{p/cm}^2$ is investigated to determine if such a detector can be operated efficiently in the expected HL-LHC environment. By using electrodes em...

  9. Chemical vapor deposition coating for micromachines

    Energy Technology Data Exchange (ETDEWEB)

    MANI,SEETHAMBAL S.; FLEMING,JAMES G.; SNIEGOWSKI,JEFFRY J.; DE BOER,MAARTEN P.; IRWIN,LAWRENCE W.; WALRAVEN,JEREMY A.; TANNER,DANELLE M.; DUGGER,MICHAEL T.

    2000-04-21

    Two major problems associated with Si-based MEMS devices are stiction and wear. Surface modifications are needed to reduce both adhesion and friction in micromechanical structures to solve these problems. In this paper, the authors will present a process used to selectively coat MEMS devices with tungsten using a CVD (Chemical Vapor Deposition) process. The selective W deposition process results in a very conformal coating and can potentially solve both stiction and wear problems confronting MEMS processing. The selective deposition of tungsten is accomplished through silicon reduction of WF{sub 6}, which results in a self-limiting reaction. The selective deposition of W only on polysilicon surfaces prevents electrical shorts. Further, the self-limiting nature of this selective W deposition process ensures the consistency necessary for process control. Selective tungsten is deposited after the removal of the sacrificial oxides to minimize process integration problems. This tungsten coating adheres well and is hard and conducting, requirements for device performance. Furthermore, since the deposited tungsten infiltrates under adhered silicon parts and the volume of W deposited is less than the amount of Si consumed, it appears to be possible to release stuck parts that are contacted over small areas such as dimples. Results from tungsten deposition on MEMS structures with dimples will be presented. The effect of wet and vapor phase cleanings prior to the deposition will be discussed along with other process details. The W coating improved wear by orders of magnitude compared to uncoated parts. Tungsten CVD is used in the integrated-circuit industry, which makes this approach manufacturable.

  10. Nanocrystalline ZnO film deposited by ultrasonic spray on textured silicon substrate as an anti-reflection coating layer

    Energy Technology Data Exchange (ETDEWEB)

    Sali, S., E-mail: samira_sali@yahoo.fr [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria); Houari Boumediene University (USTHB), Faculty of Physics, Algiers (Algeria); Boumaour, M. [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria); Kechouane, M. [Houari Boumediene University (USTHB), Faculty of Physics, Algiers (Algeria); Kermadi, S.; Aitamar, F. [Silicon Technology Development Unit (UDTS), 02 Bd, Frantz FANON, B.P. 140, Algiers (Algeria)

    2012-07-01

    A ZnO thin film was successfully synthesized on glass, flat surface and textured silicon substrates by chemical spray deposition. The textured silicon substrate was carried out using two solutions (NaOH/IPA and Na{sub 2}CO{sub 3}). Textured with Na{sub 2}CO{sub 3} solution, the sample surface exhibits uniform pyramids with an average height of 5 {mu}m. The properties and morphology of ZnO films were investigated. X-ray diffraction (XRD) spectra revealed a preferred orientation of the ZnO nanocrystalline film along the c-axis where the low value of the tensile strain 0.26% was obtained. SEM images show that all films display a granular, polycrystalline morphology. The morphology of the ZnO layers depends dramatically on the substrate used and follows the contours of the pyramids on the substrate surface. The average reflectance of the textured surface was found to be around 13% and it decreases dramatically to 2.57% after deposition of a ZnO antireflection coating. FT-IR peaks arising from the bonding between Zn-O are clearly represented using a silicon textured surface. A very intense photoluminescence (PL) emission peak is observed for ZnO/textured Si, revealing the good quality of the layer. The PL peak at 380.5 nm (UV emission) and the high-intensity PL peak at 427.5 nm are observed and a high luminescence occurs when using a textured Si substrate.

  11. Shadow-casted ultrathin surface coatings of titanium and titanium/silicon oxide sol particles via ultrasound-assisted deposition.

    Science.gov (United States)

    Karahan, H Enis; Birer, Özgür; Karakuş, Kerem; Yıldırım, Cansu

    2016-07-01

    Ultrasound-assisted deposition (USAD) of sol nanoparticles enables the formation of uniform and inherently stable thin films. However, the technique still suffers in coating hard substrates and the use of fast-reacting sol-gel precursors still remains challenging. Here, we report on the deposition of ultrathin titanium and titanium/silicon hybrid oxide coatings using hydroxylated silicon wafers as a model hard substrate. We use acetic acid as the catalyst which also suppresses the reactivity of titanium tetraisopropoxide while increasing the reactivity of tetraethyl orthosilicate through chemical modifications. Taking the advantage of this peculiar behavior, we successfully prepared titanium and titanium/silicon hybrid oxide coatings by USAD. Varying the amount of acetic acid in the reaction media, we managed to modulate thickness and surface roughness of the coatings in nanoscale. Field-emission scanning electron microscopy and atomic force microscopy studies showed the formation of conformal coatings having nanoroughness. Quantitative chemical state maps obtained by x-ray photoelectron spectroscopy (XPS) suggested the formation of ultrathin (coatings and thickness measurements by rotating analyzer ellipsometry supported this observation. For the first time, XPS chemical maps revealed the transport effect of ultrasonic waves since coatings were directly cast on rectangular substrates as circular shadows of the horn with clear thickness gradient from the center to the edges. In addition to the progress made in coating hard substrates, employing fast-reacting precursors and achieving hybrid coatings; this report provides the first visual evidence on previously suggested "acceleration and smashing" mechanism as the main driving force of USAD.

  12. Fabrication of silicon inverse woodpile photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hermatschweiler, Martin; Wegener, Martin [DFG-Center for Functional Nanostructures (CFN) and Institut fuer Angewandte Physik, Universitaet Karlsruhe (TH), 76131 Karlsruhe (Germany); Ozin, Geoffrey A. [Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada); Ledermann, Alexandra; Freymann, Georg von [Institut fuer Nanotechnologie, Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, 76021 Karlsruhe (Germany)

    2007-07-01

    We fabricate silicon inverse woodpile structures for the first time. Direct laser writing of polymeric templates and a novel silicon-singleinversion procedure lead to structures with gap/midgap ratios of 14.2% centered at 2.5 {mu}m wavelength. First, polymer templates are fabricated by direct laser writing or other means. Next, we deposit a thin silica coating via atomic layer deposition (ALD) on the polymer and - without removing the polymer - infiltrate the composite structure with Si via Si chemical vapor deposition (CVD). The silica shell provides sufficient and reliable stabilization for the high temperature CVD process. Finally, the silica is etched out and the polymer is calcined in air, leading to a Si inverse woodpile structure. Optical measurements and comparison to bandstructure and scattering-matrix calculations reveal a gap/midgap ratio of 14.2% centered at 2.5 {mu}m. An optimized structure could open a band gap with a gap/midgap ratio of up to 20.5%.

  13. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    Science.gov (United States)

    Knoops, Harm C. M.; de Peuter, K.; Kessels, W. M. M.

    2015-07-01

    The requirements on the material properties and growth control of silicon nitride (SiNx) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiNx by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiNx by plasma-assisted ALD and that this parameter can be linked to a so-called "redeposition effect". This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiNx ALD using SiH2(NHtBu)2 as precursor and N2 plasma as reactant, the gas residence time τ was found to determine both SiNx film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  14. CVD Diamonds in the BaBar Radiation Monitoring System

    CERN Document Server

    Bruinsma, M; Edwards, A J; Kagan, H; Kass, R; Kirkby, D; Petersen, B A

    2006-01-01

    To prevent excessive radiation damage to its Silicon Vertex Tracker, the BaBar experiment at SLAC uses a radiation monitoring and protection system that triggers a beam abort whenever radiation levels are anomalously high. The existing system, which employs large area Si PIN diodes as radiation sensors, has become increasingly difficult to operate due to radiation damage. We have studied CVD diamond sensors as a potential alternative for these silicon sensors. Two diamond sensors have been routinely used since their installation in the Vertex Tracker in August 2002. The experience with these sensors and a variety of tests in the laboratory have shown CVD diamonds to be a viable solution for dosimetry in high radiation environments. However, our studies have also revealed surprising side-effects.

  15. Development of atmospheric pressure CVD processes for highquality transparent conductive oxides

    NARCIS (Netherlands)

    Graaf, A. de; Deelen, J. van; Poodt, P.W.G.; Mol, A.M.B. van; Spee, C.I.M.A.; Grob, F.; Kuypers, A.

    2010-01-01

    For the past decade TNO has been involved in the research and development of atmospheric pressure CVD (APCVD) and plasma enhanced CVD (PECVD) processes for deposition of transparent conductive oxides (TCO), such as tin oxide and zinc oxide. It is shown that by combining precursor development, fundam

  16. Surface analysis of CVD diamond exposed to fusion plasma

    NARCIS (Netherlands)

    Porro, S.; De Temmerman, G.; MacLaren, D. A.; Lisgo, S.; Rudakov, D. L.; Westerhout, J.; Wiora, M.; John, P.; Villalpando, I.; Wilson, J. I. B.

    2010-01-01

    Microcrystalline undoped and heavily boron-doped polycrystalline diamond layers have been deposited on various substrates by hot filament CVD and exposed to hydrogen plasma in a linear plasma reactor (Pilot-PSI, The Netherlands) that simulates the high flux and high density plasma conditions of toka

  17. Atmospheric pressure CVD of SNO2 and ZNO:AL

    NARCIS (Netherlands)

    Deelen, J. van; Kniknie, B.J.; Steijvers, H.L.A.H.; Mannie, G.; Thune, P.; Illiberi, A.

    2012-01-01

    Atmospheric pressure CVD (APCVD) is a highly cost effective method of depositing transparent conductive oxides (TCOs). In this work, insights in alcohol addition in the widely applied SnO2 process are discussed, including high resolution TEM images. Furthermore, the APCVD process of ZnO:Al was demon

  18. Comparative study on microstructure, crystallite size and lattice strain of as-deposited and thermal treatment silver silicon nitride coating on Ti6Al4V alloy

    Science.gov (United States)

    Zalilah, Umi; Mahmoodian, R.

    2017-06-01

    Silver silicon nitride coating were deposited on Ti6Al4V alloy using physical vapor deposition magnetron sputtering technique. Field Emission Spectroscopy (FESEM), Electron Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterize as-deposited and after heat treatment of AgSiN coatings in order to understand the morphology, compositions and structure. Meanwhile, in determining the crystallite size and lattice strain, the simplified Williamson-Hall plot method was utilized. The heat treated coated sample shown to reveal granular surface structure, bigger crystallite size and lattice strain as compared to the as-deposited coated sample.

  19. Molecular layer deposition of APTES on silicon nanowire biosensors: Surface characterization, stability and pH response

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yuchen [Department of Electrical Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Huang, Jie [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Zang, Pengyuan [Department of Electrical Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Kim, Jiyoung [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States); Hu, Walter, E-mail: walter.hu@utdallas.edu [Department of Electrical Engineering, University of Texas at Dallas, Richardson, TX 75080 (United States)

    2014-12-15

    Graphical abstract: - Abstract: We report the use of molecular layer deposition (MLD) for depositing 3-aminopropyltriethoxysilane (APTES) on a silicon dioxide surface. The APTES monolayer was characterized using spectroscopic ellipsometry, contact angle goniometry, and atomic force microscopy. Effects of reaction time of repeating pulses and simultaneous feeding of water vapor with APTES were tested. The results indicate that the synergistic effects of water vapor and reaction time are significant for the formation of a stable monolayer. Additionally, increasing the number of repeating pulses improved the APTES surface coverage but led to saturation after 10 pulses. In comparing MLD with solution-phase deposition, the APTES surface coverage and the surface quality were nearly equivalent. The hydrolytic stability of the resulting films was also studied. The results confirmed that the hydrolysis process was necessary for MLD to obtain stable surface chemistry. Furthermore, we compared the pH sensing results of Si nanowire field effect transistors (Si NWFETs) modified by both the MLD and solution methods. The highly repeatable pH sensing results reflected the stability of APTES monolayers. The results also showed an improved pH response of the sensor prepared by MLD compared to the one prepared by the solution treatment, which indicated higher surface coverage of APTES.

  20. Molecular layer deposition of APTES on silicon nanowire biosensors: Surface characterization, stability and pH response

    Science.gov (United States)

    Liang, Yuchen; Huang, Jie; Zang, Pengyuan; Kim, Jiyoung; Hu, Walter

    2014-12-01

    We report the use of molecular layer deposition (MLD) for depositing 3-aminopropyltriethoxysilane (APTES) on a silicon dioxide surface. The APTES monolayer was characterized using spectroscopic ellipsometry, contact angle goniometry, and atomic force microscopy. Effects of reaction time of repeating pulses and simultaneous feeding of water vapor with APTES were tested. The results indicate that the synergistic effects of water vapor and reaction time are significant for the formation of a stable monolayer. Additionally, increasing the number of repeating pulses improved the APTES surface coverage but led to saturation after 10 pulses. In comparing MLD with solution-phase deposition, the APTES surface coverage and the surface quality were nearly equivalent. The hydrolytic stability of the resulting films was also studied. The results confirmed that the hydrolysis process was necessary for MLD to obtain stable surface chemistry. Furthermore, we compared the pH sensing results of Si nanowire field effect transistors (Si NWFETs) modified by both the MLD and solution methods. The highly repeatable pH sensing results reflected the stability of APTES monolayers. The results also showed an improved pH response of the sensor prepared by MLD compared to the one prepared by the solution treatment, which indicated higher surface coverage of APTES.

  1. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Science.gov (United States)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  2. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Provine, J., E-mail: jprovine@stanford.edu; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Kim, Ki-Hyun [Manufacturing Technology Center, Samsung Electronics, Suwon, Gyeonggi-Do (Korea, Republic of); Prinz, Fritz B. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-06-15

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiN{sub x}), particularly for use a low k dielectric spacer. One of the key material properties needed for SiN{sub x} films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiN{sub x} and evaluate the film’s WER in 100:1 dilutions of HF in H{sub 2}O. The remote plasma capability available in PEALD, enabled controlling the density of the SiN{sub x} film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiN{sub x} of 6.1 Å/min, which is similar to WER of SiN{sub x} from LPCVD reactions at 850 °C.

  3. The effect of composition on the bond structure and refractive index of silicon nitride deposited by HWCVD and PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Verlaan, V.; Verkerk, A.D.; Arnoldbik, W.M.; Van der Werf, C.H.M.; Bakker, R.; Houweling, Z.S.; Schropp, R.E.I. [Utrecht University, Faculty of Science, Debye Institute for Nanomaterials Science, Nanophotonics - Physics of Devices, P.O. Box 80.000, 3508 TA Utrecht (Netherlands); Romijn, I.G.; Borsa, D.M.; Weeber, A.W. [ECN Solar Energy, Petten (Netherlands); Luxembourg, S.L.; Zeman, M. [DIMES, Delft University of Technology, Delf (Netherlands); Dekkers, H.F.W. [IMEC, Leuven (Belgium)

    2009-04-15

    Silicon nitride (SiNx) is a material with many applications and can be deposited with various deposition techniques. Series of SiNx films were deposited with HWCVD, RF PECVD,MWPECVD and LF PECVD. The atomic densities are quantified using RBS and ERD. The influence of the atomic densities on the Si-N and Si-Si bond structure is studied. The density of N-N bonds is found to be negligible. New Si-N FTIR proportionality factors are determined which increase with increasing N/Si ratio from 1.2 x 10{sup 19} cm-1 for Si rich films (N/Si=0.2) to 2.4 x 10{sup 19}cm-1 for N rich films (N/Si=1.5). The peak position of the Si-H stretching mode in the FTIR spectrum is discussed using the chemical induction model. It is shown that especially for Si-rich films the hydrogen content affects the Si-H peak position. The influence of the composition on the refractive index of the films is discussed on the basis of the Lorentz-Lorenz equation and the Kramers-Kronig relation. The decreasing refractive index with increasing N/Si ratio is primarily caused by an increase of the band gap.

  4. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Directory of Open Access Journals (Sweden)

    J. Provine

    2016-06-01

    Full Text Available The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD of silicon nitride (SiNx, particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER in hydrofluoric (HF acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD of SiNx and evaluate the film’s WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  5. Engineered CVD Diamond Coatings for Machining and Tribological Applications

    Science.gov (United States)

    Dumpala, Ravikumar; Chandran, Maneesh; Ramachandra Rao, M. S.

    2015-07-01

    Diamond is an allotropes of carbon and is unique because of its extreme hardness (~100 GPa), low friction coefficient (fracture toughness can be tuned by controlling the grain size of the coatings from a few microns to a few nanometers. In this review, characteristics and performance of the CVD diamond coatings deposited on cemented tungsten carbide (WC-Co) substrates were discussed with an emphasis on WC-Co grade selection, substrate pretreatment, nanocrystallinity and microcrystallinity of the coating, mechanical and tribological characteristics, coating architecture, and interfacial adhesion integrity. Engineered coating substrate architecture is essential for CVD diamond coatings to perform well under harsh and highly abrasive machining and tribological conditions.

  6. Deposition of dielectric films on silicon using a fore-vacuum plasma electron source.

    Science.gov (United States)

    Zolotukhin, D B; Oks, E M; Tyunkov, A V; Yushkov, Yu G

    2016-06-01

    We describe an experiment on the use of a fore-vacuum-pressure, plasma-cathode, electron beam source with current up to 100 mA and beam energy up to 15 keV for deposition of Mg and Al oxide films on Si substrates in an oxygen atmosphere at a pressure of 10 Pa. The metals (Al and Mg) were evaporated and ionized using the electron beam with the formation of a gas-metal beam-plasma. The plasma was deposited on the surface of Si substrates. The elemental composition of the deposited films was analyzed.

  7. Deposition of dielectric films on silicon using a fore-vacuum plasma electron source

    Energy Technology Data Exchange (ETDEWEB)

    Zolotukhin, D. B.; Tyunkov, A. V.; Yushkov, Yu. G., E-mail: yuyushkov@gmail.com [Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Ave., Tomsk 634050 (Russian Federation); Oks, E. M. [Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Ave., Tomsk 634050 (Russian Federation); Institute of High Current Electronics SB RAS, 2/3, Akademichesky Ave., Tomsk 634055 (Russian Federation)

    2016-06-15

    We describe an experiment on the use of a fore-vacuum-pressure, plasma-cathode, electron beam source with current up to 100 mA and beam energy up to 15 keV for deposition of Mg and Al oxide films on Si substrates in an oxygen atmosphere at a pressure of 10 Pa. The metals (Al and Mg) were evaporated and ionized using the electron beam with the formation of a gas-metal beam-plasma. The plasma was deposited on the surface of Si substrates. The elemental composition of the deposited films was analyzed.

  8. Laser-Directed CVD 3D Printing of Refractory Metal Rocket Propulsion Hardware Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project, Ultramet will develop a three-dimensional (3D) laser-directed chemical vapor deposition (CVD) additive manufacturing system to build free-form...

  9. Electrochemical deposition of zinc oxide on a thin nickel buffer layer on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Chubenko, E.B., E-mail: eugene.chubenko@gmail.co [Department of Micro and Nanoelectronics, Belarusian State University of Informatics and Radioelectronics, P. Brovki str, 6, Minsk 220013 (Belarus); Klyshko, A.A.; Bondarenko, V.P. [Department of Micro and Nanoelectronics, Belarusian State University of Informatics and Radioelectronics, P. Brovki str, 6, Minsk 220013 (Belarus); Balucani, M. [Electronics Engineering Department, University of Rome ' La Sapienza' , Rome 00184 (Italy)

    2011-04-15

    Research highlights: {yields} Cyclic voltammograms of ZnO electrochemical deposition. {yields} Parameters of ZnO electrochemical deposition in potentio- and galvanostatic modes. {yields} Crystalline structure of electrochemically deposited continuous ZnO films. {yields} Photoluminescence properties of ZnO films deposition current density dependence. - Abstract: Electrochemical deposition of ZnO from aqueous nitrate solutions on nickel and platinum electrodes was investigated using the voltammetry technique to determine the optimal regimes in both potentiostatic and galvanostatic modes for acquiring polycrystalline ZnO films. Scanning electron microscopy, X-ray diffractometry, and X-ray microanalysis of the formed ZnO films are presented, showing a polycrystalline structure of the ZnO films with a preferable orientation in the (0 0 0 2) direction and an exact stoichiometric composition. The deposited ZnO films demonstrate a strong visible yellow-greenish photoluminescence at room temperature with a maximum at 600 nm that can be referred to crystal lattice oxygen defects. The maximum of the photoluminescence excitation spectrum at 370 nm corresponds to the band gap of ZnO (3.3-3.35 eV) confirming that band-to-band excitation mechanism takes place.

  10. Photocatalytic activity of Cr-doped TiO2 nanoparticles deposited on porous multicrystalline silicon films.

    Science.gov (United States)

    Hajjaji, Anouar; Trabelsi, Khaled; Atyaoui, Atef; Gaidi, Mounir; Bousselmi, Latifa; Bessais, Brahim; El Khakani, My Ali

    2014-01-01

    This work deals with the deposition of Cr-doped TiO2 thin films on porous silicon (PS) prepared from electrochemical anodization of multicrystalline (mc-Si) Si wafers. The effect of Cr doping on the properties of the TiO2-Cr/PS/Si samples has been investigated by means of X-ray diffraction (XRD), atomic force microcopy (AFM), photoluminescence, lifetime, and laser beam-induced current (LBIC) measurements. The photocatalytic activity is carried out on TiO2-Cr/PS/Si samples. It was found that the TiO2-Cr/PS/mc-Si type structure degrades an organic pollutant (amido black) under ultraviolet (UV) light. A noticeable degradation of the pollutant is obtained for a Cr doping of 2 at. %. This result is discussed in light of LBIC and photoluminescence measurements.

  11. Boron- and phosphorus-doped silicon germanium alloy nanocrystals—Nonthermal plasma synthesis and gas-phase thin film deposition

    Directory of Open Access Journals (Sweden)

    David J. Rowe

    2014-02-01

    Full Text Available Alloyed silicon-germanium (SiGe nanostructures are the topic of renewed research due to applications in modern optoelectronics and high-temperature thermoelectric materials. However, common techniques for producing nanostructured SiGe focus on bulk processing; therefore little is known of the physical properties of SiGe nanocrystals (NCs synthesized from molecular precursors. In this letter, we synthesize and deposit thin films of doped SiGe NCs using a single, flow-through nonthermal plasma reactor and inertial impaction. Using x-ray and vibrational analysis, we show that the SiGe NC structure appears truly alloyed for Si1−xGex for 0.16 < x < 0.24, and quantify the atomic dopant incorporation within the SiGe NC films.

  12. Solar Hydrogen Production by Amorphous Silicon Photocathodes Coated with a Magnetron Sputter Deposited Mo2C Catalyst.

    Science.gov (United States)

    Morales-Guio, Carlos G; Thorwarth, Kerstin; Niesen, Bjoern; Liardet, Laurent; Patscheider, Jörg; Ballif, Christophe; Hu, Xile

    2015-06-10

    Coupling of Earth-abundant hydrogen evolution catalysts to photoabsorbers is crucial for the production of hydrogen fuel using sunlight. In this work, we demonstrate the use of magnetron sputtering to deposit Mo2C as an efficient hydrogen evolution reaction catalyst onto surface-protected amorphous silicon (a-Si) photoabsorbers. The a-Si/Mo2C photocathode evolves hydrogen under simulated solar illumination in strongly acidic and alkaline electrolytes. Onsets of photocurrents are observed at potentials as positive as 0.85 V vs RHE. Under AM 1.5G (1 sun) illumination, the photocathodes reach current densities of -11.2 mA cm(-2) at the reversible hydrogen potential in 0.1 M H2SO4 and 1.0 M KOH. The high photovoltage and low-cost of the Mo2C/a-Si assembly make it a promising photocathode for solar hydrogen production.

  13. Growth process and mechanism of a multi-walled carbon nanotube nest deposited on a silicon nanoporous pillar array

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Weifen, E-mail: gingerwfj@yahoo.com.cn [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, No. 36 Beihuan Road, Zhengzhou 450011 (China); Jian Lv; Yang Xiaohui [Department of Mathematics and Information Science, North China Institute of Water Conservancy and Hydroelectric Power, No. 36 Beihuan Road, Zhengzhou 450011 (China); Li Xinjian [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

    2010-03-01

    A large scale nest array of multi-walled carbon nanotubes (NACNTs) was grown on silicon nanoporous pillar array (Si-NPA) by thermal chemical vapor deposition. Through observing its macro/micromorphology and structure, ascertaining the catalyst component and its locations at different growth time by hiring field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and selected area electron diffraction, the growth process was deduced. Its thermal properties were also investigated by using a thermogravimetric analyzer. Our experiments demonstrated that the CNTs growth by means of root-growth mechanism at the initial growth stage, then a continuous growth process with its tip open is suggested, finally, a schematic growth model of NACNT/Si-NPA was presented.

  14. Improving low pressure chemical vapor deposited zinc oxide contacts for thin film silicon solar cells by using rough glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Steinhauser, J., E-mail: jerome.steinhauser@oerlikon.com; Boucher, J.-F.; Omnes, E.; Borrello, D.; Vallat-Sauvain, E.; Monteduro, G.; Marmelo, M.; Orhan, J.-B.; Wolf, B.; Bailat, J.; Benagli, S.; Meier, J.; Kroll, U.

    2011-12-01

    Compared to zinc oxide grown (ZnO) on flat glass, rough etched glass substrates decrease the sheet resistance (R{sub sq}) of zinc oxide layers grown on it. We explain this R{sub sq} reduction from a higher thickness and an improved electron mobility for ZnO layers deposited on rough etched glass substrates. When using this etched glass substrate, we also obtain a large variety of surface texture by changing the thickness of the ZnO layer grown on it. This new combination of etched glass and ZnO layer shows improved light trapping potential compared to ZnO films grown on flat glass. With this new approach, Micromorph thin film silicon tandem solar cells with high total current densities (sum of the top and bottom cell current density) of up to 26.8 mA cm{sup -2} were fabricated.

  15. Trimethyl(phenylsilane — a precursor for gas phase processes of SiCx:H film deposition: Synthesis and characterization

    Directory of Open Access Journals (Sweden)

    Evgeniya N. Ermakova

    2015-12-01

    Full Text Available The technique of synthesis and purification of trimethyl(phenylsilane PhSiMe3, allowing to obtain the product with high yield. Individuality of the product was confirmed by elemental analysis for C, H, Si was developed. IR, UV and 1H NMR-spectroscopic studies were used to define its spectral characteristics. Complex thermal analysis and thermogravimetry defined thermoanalytical behavior of PhSiMe3 in an inert atmosphere. Tensimetric studies have shown that the compound has sufficient volatility and thermal stability for use as a precursor in the process of chemical vapor deposition (CVD. The composition and temperature limits of the possible crystalline phase complexes in equilibrium with the gas phase of different composition has been determined by method of thermodynamic modeling. Calculated CVD diagrams allow us to select the optimal conditions of film deposition. The possibility of using trimethyl(phenylsilane in CVD processes for producing dielectric films of hydrogenated silicon carbide has been demonstrated.

  16. Optimization of conditions for growth of vanadium dioxide thin films on silicon by pulsed-laser deposition

    Directory of Open Access Journals (Sweden)

    Keisuke Shibuya

    2015-10-01

    Full Text Available We systematically examined the effects of the substrate temperature (TS and the oxygen pressure (PO2 on the structural and optical properties polycrystalline V O2 films grown directly on Si(100 substrates by pulsed-laser deposition. A rutile-type V O2 phase was formed at a TS ≥ 450 °C at PO2 values ranging from 5 to 20 mTorr, whereas other structures of vanadium oxides were stabilized at lower temperatures or higher oxygen pressures. The surface roughness of the V O2 films significantly increased at growth temperatures of 550 °C or more due to agglomeration of V O2 on the surface of the silicon substrate. An apparent change in the refractive index across the metal–insulator transition (MIT temperature was observed in V O2 films grown at a TS of 450 °C or more. The difference in the refractive index at a wavelength of 1550 nm above and below the MIT temperature was influenced by both the TS and PO2, and was maximal for a V O2 film grown at 450 °C under 20 mTorr. Based on the results, we derived the PO2 versus 1/TS phase diagram for the films of vanadium oxides, which will provide a guide to optimizing the conditions for growth of V O2 films on silicon platforms.

  17. Sputtering temperature dependent growth kinetics and CO2 sensing properties of ZnO deposited over porous silicon

    Science.gov (United States)

    Martínez, L.; Holguín-Momaca, J. T.; Karthik, T. V. K.; Olive-Méndez, S. F.; Campos-Alvarez, J.; Agarwal, V.

    2016-10-01

    We report the growth kinetics and sensing properties of ZnO deposited over macro-porous silicon substrates at 400 and 600 °C using magnetron-sputtering technique. Scanning electron microscopy was employed to investigate the morphology and the particle size of the ZnO nanoparticles (NPs). The grain growth kinetics was analyzed with the help of the phenomenological equation rn =k0 texp(- Q / RT) finding an activation energy Q = 13.92 kJ/mol. The grain growth exponent (n = 2.85) for the growth at 400 °C corresponds to an Ostwald ripening process, while the growth at 600 °C is described by n = 1.66 implying a higher growth rate attributed to a high surface diffusion of add-atoms contributing to the formation of larger grains. The sensing response of the complete structure has been tested at different temperatures. The highest sensitivity, S ∼10, was obtained at a sensor temperature of 300 °C on the ZnO NPs sputtered on to the porous silicon substrate at 400 °C. The high response is attributed to the infiltration, uniform and homogenous distribution of the ZnO NPs into the pores. ZnO NPs sputtered at 400 °C are found to be smaller than those grown at 600 °C, exhibiting a larger surface-area/volume ratio and hence increasing the oxygen adsorption resulting in an enhanced CO2 sensitivity.

  18. Measurement of cluster-cluster interaction in liquids by deposition and AFM of silicon clusters onto HOPG surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Galinis, Gediminas; Torricelli, Gauthier; Akraiam, Atea; Haeften, Klaus von, E-mail: kvh6@le.ac.uk [University of Leicester, Department of Physics and Astronomy (United Kingdom)

    2012-08-15

    We have investigated the interaction and aggregation of novel fluorescent silicon nanoclusters in liquids by measuring the size distribution of dried clusters on graphite. The clusters were produced by gas aggregation and co-deposition with a beam of water vapour. Drops of the solutions were placed on freshly cleaved highly oriented pyrolitic graphite, subsequently vacuum dried and investigated by atomic force microscopy (AFM) in ultra high vacuum. The AFM images show single clusters and agglomerates. The height distributions are Gaussian-shaped with average heights of 1 nm and widths of 1 nm. The heights never exceed 3 nm. In some regions a second cluster layer is observed. In all samples the separation between first and second layers is larger than the separation between the first layer and the graphite substrate, which we attribute to a stronger interaction between clusters and surface than the cluster self-interaction. We conclude that the separation between first and second layer represents a much better fingerprint of the original size distribution of the clusters in solution than the height of the first layer. The observation of a second cluster layer is important for using silicon clusters as building blocks for cluster-assembled materials.

  19. Present limitations of CVD diamond detectors for IMRT applications

    Energy Technology Data Exchange (ETDEWEB)

    De Angelis, C. [Dipartimento di Tecnologie e Salute, Istituto Superiore di Sanita and INFN, Viale regina Elena 299, 00161 Rome (Italy)], E-mail: cinzia.deangelis@iss.it; Casati, M. [Dipartimento di Fisiopatologia dell' Universita and INFN, Florence (Italy); Bruzzi, M. [Dipartimento di Energetica dell' Universita and INFN, Florence (Italy); Onori, S. [Dipartimento di Tecnologie e Salute, Istituto Superiore di Sanita and INFN, Viale regina Elena 299, 00161 Rome (Italy); Bucciolini, M. [Dipartimento di Fisiopatologia dell' Universita and INFN, Florence (Italy)

    2007-12-11

    The aim of the work was to test the suitability of chemical vapor deposited (CVD) diamond detectors for dosimetry in IMRT fields. We used in-house CVD detectors prepared with state-of-the-art polycrystalline diamond films (Element Six Ltd., UK). The parameters considered were time stability, dynamic response, dose-rate dependence and energy dependence. Output factors and TPR were measured in conventional photon fields and dose measurements were performed in IMRT fields using the step-and-shoot technique. Results prove that CVD diamond detectors are suitable for dosimetry in conventional treatments, but they still do not fit the IMRT dosimetry requirements, mainly because of their slow dynamic response. In particular, the slow dynamics affects linearity at low Monitor Units and renders it impossible to follow the sharp transients of IMRT fields. Time stability and dose-rate dependence as well must be improved to reduce their influence on dose assessment.

  20. Hydrogenated amorphous silicon p-i-n solar cells deposited under well controlled ion bombardment using pulse-shaped substrate biasing

    NARCIS (Netherlands)

    Wank, M. A.; van Swaaij, R.; R. van de Sanden,; Zeman, M.

    2012-01-01

    We applied pulse-shaped biasing (PSB) to the expanding thermal plasma deposition of intrinsic hydrogenated amorphous silicon layers at substrate temperatures of 200 degrees C and growth rates of about 1?nm/s. Fourier transform infrared spectroscopy of intrinsic films showed a densification with incr

  1. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    Energy Technology Data Exchange (ETDEWEB)

    Knoops, Harm C. M., E-mail: h.c.m.knoops@tue.nl, E-mail: w.m.m.kessels@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Oxford Instruments Plasma Technology, North End, Bristol BS49 4AP (United Kingdom); Peuter, K. de; Kessels, W. M. M., E-mail: h.c.m.knoops@tue.nl, E-mail: w.m.m.kessels@tue.nl [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2015-07-06

    The requirements on the material properties and growth control of silicon nitride (SiN{sub x}) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiN{sub x} by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiN{sub x} by plasma-assisted ALD and that this parameter can be linked to a so-called “redeposition effect”. This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiN{sub x} ALD using SiH{sub 2}(NH{sup t}Bu){sub 2} as precursor and N{sub 2} plasma as reactant, the gas residence time τ was found to determine both SiN{sub x} film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  2. Nano-laminate vs. direct deposition of high permittivity gadolinium scandate on silicon by high pressure sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Feijoo, P.C., E-mail: pedronska@fis.ucm.es [Dpto. Física Aplicada III (Electricidad y Electrónica), Universidad Complutense de Madrid, Fac. de CC. Físicas. Av/Complutense S/N, E-28040 Madrid (Spain); Pampillón, M.A.; San Andrés, E. [Dpto. Física Aplicada III (Electricidad y Electrónica), Universidad Complutense de Madrid, Fac. de CC. Físicas. Av/Complutense S/N, E-28040 Madrid (Spain); Fierro, J.L.G. [Instituto de Catálisis y Petroleoquímica, Consejo Superior de Investigaciones Científicas, C/Marie Curie 2, E-28049 Cantoblanco (Spain)

    2015-10-30

    In this work we use the high pressure sputtering technique to deposit the high permittivity dielectric gadolinium scandate on silicon substrates. This nonconventional deposition technique prevents substrate damage and allows for growth of ternary compounds with controlled composition. Two different approaches were assessed: the first one consists of depositing the material directly from a stoichiometric GdScO{sub 3} target; in the second one, we anneal a nano-laminate of < 0.5 nm thick Gd{sub 2}O{sub 3} and Sc{sub 2}O{sub 3} films in order to control the composition of the scandate. Metal–insulator–semiconductor capacitors were fabricated with platinum gates for electrical characterization. Accordingly, we grew a Gd-rich Gd{sub 2−x}Sc{sub x}O{sub 3} film that, in spite of higher leakage currents, presents a better effective relative permittivity of 21 and lower density of defects. - Highlights: • GdScO is deposited on Si as a high permittivity dielectric by two procedures. • Films sputtered from GdScO{sub 3} target are Sc-rich and present thick interface SiO{sub x}. • Gd-rich GdScO is obtained from a nano-laminate sputtered from Sc{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}. • Gd{sub 1.8}Sc{sub 0.2}O{sub 3} shows good effective permittivity and electrical properties.

  3. Atomic layer deposited titanium dioxide coatings on KD-II silicon carbide fibers and their characterization

    Science.gov (United States)

    Cao, Shiyi; Wang, Jun; Wang, Hao

    2016-03-01

    To provide oxidation protection and/or to act as an interfacial coating, titanium oxide (TiO2) coatings were deposited on KD-II SiC fibers by employing atomic layer deposition (ALD) technique with tetrakis(dimethylamido)titanium (TDMAT) and water (H2O) as precursors. The average deposition rate was about 0.08 nm per cycle, and the prepared coatings were smooth, uniform and conformal, shielding the fibers entirely. The as-deposited coatings were amorphous regardless of the coating thickness, and changed to anatase and rutile crystal phase after annealing at 600 °C and 1000 °C, respectively. The oxidation measurement suggests that the TiO2 coating enhanced the oxidation resistance of SiC fibers obviously. SiC fibers coated with a 70-nm-thick TiO2 layer retained a relatively high tensile strength of 1.66 GPa even after exposition to air at 1400 °C for 1 h, and thick silica layer was not observed. In contrast, uncoated SiC fibers were oxidized dramatically through the same oxidation treatment, covered with a macro-cracked thick silica film, and the tensile strength was not measurable due to interfilament adhesion. The above results indicate that TiO2 films deposited by ALD are a promising oxidation resistance coating for SiC fibers.

  4. Bismuth Oxide Thin Films Deposited on Silicon Through Pulsed Laser Ablation, for Infrared Detectors

    Science.gov (United States)

    Condurache-Bota, Simona; Constantinescu, Catalin; Tigau, Nicolae; Praisler, Mirela

    2016-12-01

    Infrared detectors are used in many human activities, from industry to military, telecommunications, environmental studies and even medicine. Bismuth oxide thin films have proved their potential for optoelectronic applications, but their uses as infrared sensors have not been thoroughly studied so far. In this paper, pulsed laser ablation of pure bismuth targets within a controlled oxygen atmosphere is proposed for the deposition of bismuth oxide films on Si (100) substrates. Crystalline films were obtained, whose uniformity depends on the deposition conditions (number of laser pulses and the use of a radio-frequency (RF) discharge of the oxygen inside the deposition chamber). The optical analysis proved that the refractive index of the films is higher than 3 and that their optical bandgap is around 1eV, recommending them for infrared applications.

  5. Synthesis of CVD-graphene on rapidly heated copper foils.

    Science.gov (United States)

    Kim, Sang-Min; Kim, Jae-Hyun; Kim, Kwang-Seop; Hwangbo, Yun; Yoon, Jong-Hyuk; Lee, Eun-Kyu; Ryu, Jaechul; Lee, Hak-Joo; Cho, Seungmin; Lee, Seung-Mo

    2014-05-07

    Most chemical vapor deposition (CVD) systems used for graphene growth mainly employ convection and radiation heat transfer between the heating source and the metal catalyst in order to reach the activation temperature of the reaction, which in general leads to a long synthesis time and poor energy efficiency. Here, we report a highly time- and energy-efficient CVD setup, in which the metal catalyst (Cu) is designed to be physically contacted with a heating source to give quick heat transfer by conduction. The induced conduction heating enabled the usual effects of the pretreatment and annealing of Cu (i.e., annihilation of surface defects, impurities and contaminants) to be achieved in a significantly shorter time compared to conventional CVD. Notably, the rapid heating was observed to lead to larger grains of Cu with high uniformity as compared to the Cu annealed by conventional CVD, which are believed to be beneficial for the growth of high quality graphene. Through this CVD setup, bundles of high quality (∼252 Ω per square) and large area (over 16 inch) graphenes were able to be readily synthesized in 40 min in a significantly efficient way. When considering ease of scalability, high energy effectiveness and considerable productivity, our method is expected to be welcomed by industrialists.

  6. Carbon Nanotubes by CVD and Applications

    Science.gov (United States)

    Cassell, Alan; Delzeit, Lance; Nguyen, Cattien; Stevens, Ramsey; Han, Jie; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    2001-01-01

    Carbon nanotube (CNT) exhibits extraordinary mechanical and unique electronic properties and offers significant potential for structural, sensor, and nanoelectronics applications. An overview of CNT, growth methods, properties and applications is provided. Single-wall, and multi-wall CNTs have been grown by chemical vapor deposition. Catalyst development and optimization has been accomplished using combinatorial optimization methods. CNT has also been grown from the tips of silicon cantilevers for use in atomic force microscopy.

  7. Electrochemical deposition of buried contacts in high-efficiency crystalline silicon photovoltaic cells

    DEFF Research Database (Denmark)

    Jensen, Jens Arne Dahl; Møller, Per; Bruton, Tim

    2003-01-01

    by electrochemical deposition at a rate of up to 10 mm per min. With the newly developed process, void-free, superconformal Cu-filling of the laser-cut grooves was observed by scanning electron microscopy and focused ion beam techniques. The Cu microstructure in grooves showed both bottom and sidewall texture...

  8. Low-Temperature Plasma-Assisted Atomic Layer Deposition of Silicon Nitride Moisture Permeation Barrier Layers.

    Science.gov (United States)

    Andringa, Anne-Marije; Perrotta, Alberto; de Peuter, Koen; Knoops, Harm C M; Kessels, Wilhelmus M M; Creatore, Mariadriana

    2015-10-14

    Encapsulation of organic (opto-)electronic devices, such as organic light-emitting diodes (OLEDs), photovoltaic cells, and field-effect transistors, is required to minimize device degradation induced by moisture and oxygen ingress. SiNx moisture permeation barriers have been fabricated using a very recently developed low-temperature plasma-assisted atomic layer deposition (ALD) approach, consisting of half-reactions of the substrate with the precursor SiH2(NH(t)Bu)2 and with N2-fed plasma. The deposited films have been characterized in terms of their refractive index and chemical composition by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The SiNx thin-film refractive index ranges from 1.80 to 1.90 for films deposited at 80 °C up to 200 °C, respectively, and the C, O, and H impurity levels decrease when the deposition temperature increases. The relative open porosity content of the layers has been studied by means of multisolvent ellipsometric porosimetry (EP), adopting three solvents with different kinetic diameters: water (∼0.3 nm), ethanol (∼0.4 nm), and toluene (∼0.6 nm). Irrespective of the deposition temperature, and hence the impurity content in the SiNx films, no uptake of any adsorptive has been observed, pointing to the absence of open pores larger than 0.3 nm in diameter. Instead, multilayer development has been observed, leading to type II isotherms that, according to the IUPAC classification, are characteristic of nonporous layers. The calcium test has been performed in a climate chamber at 20 °C and 50% relative humidity to determine the intrinsic water vapor transmission rate (WVTR) of SiNx barriers deposited at 120 °C. Intrinsic WVTR values in the range of 10(-6) g/m2/day indicate excellent barrier properties for ALD SiNx layers as thin as 10 nm, competing with that of state-of-the-art plasma-enhanced chemical vapor-deposited SiNx layers of a few hundred

  9. Effect of time and of precursor molecule on the deposition of hydrophobic nanolayers on ethyelene tetrafluoroethylene–silicon oxide substrates

    Directory of Open Access Journals (Sweden)

    Gabriella Rossi

    2016-01-01

    Full Text Available Abstract A method was developed for generating transparent and hydrophobic nanolayers chemisorbed onto flexible substrates of ethylene tetrafluoroethylene–silicon oxide (ETFE–SiOx. In particular, the effect of the deposition time and of the precursor molecule on the nanocoating process was analyzed with the aim of pursuing an optimization of the above method in an industrial application perspective. It was found that precursor molecule of triethoxysilane allowed to obtain better hydrophobic properties on the SiOx surface in shorter times compared to trichlorosilane, reaching the 92 % of final contact angle (CA value of 106° after only 1 h of deposition. The optical properties and surface morphology were also assessed in function of time, revealing that an initial transparency reduction is followed by a subsequent transmittance increase during the self assembly of fluoroalkylsilanes on the SiOx surface, coherently with the surface roughness analysis data. Encouraging results were also obtained in terms of oleophobic properties improvement of the nanocoated surfaces.

  10. STEM-EELS analysis reveals stable high-density He in nanopores of amorphous silicon coatings deposited by magnetron sputtering.

    Science.gov (United States)

    Schierholz, Roland; Lacroix, Bertrand; Godinho, Vanda; Caballero-Hernández, Jaime; Duchamp, Martial; Fernández, Asunción

    2015-02-20

    A broad interest has been showed recently on the study of nanostructuring of thin films and surfaces obtained by low-energy He plasma treatments and He incorporation via magnetron sputtering. In this paper spatially resolved electron energy-loss spectroscopy in a scanning transmission electron microscope is used to locate and characterize the He state in nanoporous amorphous silicon coatings deposited by magnetron sputtering. A dedicated MATLAB program was developed to quantify the helium density inside individual pores based on the energy position shift or peak intensity of the He K-edge. A good agreement was observed between the high density (∼35-60 at nm(-3)) and pressure (0.3-1.0 GPa) values obtained in nanoscale analysis and the values derived from macroscopic measurements (the composition obtained by proton backscattering spectroscopy coupled to the macroscopic porosity estimated from ellipsometry). This work provides new insights into these novel porous coatings, providing evidence of high-density He located inside the pores and validating the methodology applied here to characterize the formation of pores filled with the helium process gas during deposition. A similar stabilization of condensed He bubbles has been previously demonstrated by high-energy He ion implantation in metals and is newly demonstrated here using a widely employed methodology, magnetron sputtering, for achieving coatings with a high density of homogeneously distributed pores and He storage capacities as high as 21 at%.

  11. Nanostructured Hydrogenated Silicon Films by Hot-Wire Chemical Vapor Deposition: the Influence of Substrate Temperature on Material Properties

    Directory of Open Access Journals (Sweden)

    V.S. Waman

    2011-01-01

    Full Text Available Thin films of hydrogenated nanocrystalline silicon are prepared at reasonably higher deposition rates (9-13 Å/s by indigenously fabricated hot-wire chemical vapor deposition system at various substrate temperatures (Ts. In this paper we report extensively studied structural, optical and electrical properties of these films by Fourier transform infrared (FTIR spectroscopy, low angle X-ray diffraction (low angle XRD, micro-Raman spectroscopy and UV-Visible spectroscopy. The low angle XRD and micro-Raman spectroscopy analysis indicate amorphous-to-nanocrystalline transition occurred at Ts = 300 °C. It is observed that volume fraction of crystallites and its size increases with increase in Ts. The low angle XRD study also shows nc-Si:H films with well-identified lattice planes of (111 orientation. In addition, it is observed from the FTIR spectroscopy that the hydrogen is incorporated in the film mainly in Si-H2 and (Si-H2n complexes. The nc-Si:H films with low hydrogen content (< 4 at. % and wide band gap (1.83-1.89 eV and low refractive index (< 3 is useful for various device applications.

  12. Effective optimization of surface passivation on porous silicon carbide using atomic layer deposited Al2O3

    DEFF Research Database (Denmark)

    Lu, Weifang; Iwasa, Yoshimi; Ou, Yiyu

    2017-01-01

    Porous silicon carbide (B–N co-doped SiC) produced by anodic oxidation showed strong photoluminescence (PL) at around 520 nm excited by a 375 nm laser. The porous SiC samples were passivated by atomic layer deposited (ALD) aluminum oxide (Al2O3) films, resulting in a significant enhancement...... of the PL intensity (up to 689%). The effect of thickness, annealing temperature, annealing duration and precursor purge time on the PL intensity of ALD Al2O3 films was investigated. In order to investigate the penetration depth and passivation effect in porous SiC, the samples were characterized by X......-ray photoelectron spectroscopy (XPS) and time-resolved PL. The optimized passivation conditions (20 nm Al2O3 deposited at 160 °C with purge time of 20 s, followed by an annealing for 5 min at 350 °C) for porous SiC were achieved and the results indicate that surface passivation by ALD Al2O3 thin films is a very...

  13. Polymer Layers by Initiated CVD for Thin Film Gas Barrier Encapsulation

    NARCIS (Netherlands)

    Spee, D.A.; Rath, J.K.; Schropp, R.E.I.

    2013-01-01

    In this chapter a thorough description of the initiated chemical vapor deposition (iCVD) process will be given, concentrating on molecular weight and deposition rate of the deposited polymer, which are essential for largescale application in hybrid gas barriers. Practical applications of coatings by

  14. Effect of the carrier gas flow rate on the microstructure evolution and the generation of the charged nanoparticles during silicon chemical vapor deposition.

    Science.gov (United States)

    Youn, Woong-Kyu; Kim, Chan-Soo; Hwang, Nong-Moon

    2013-10-01

    The generation of charged nanoparticles in the gas phase has been continually reported in many chemical vapor deposition processes. Charged silicon nanoparticles in the gas phase were measured using a differential mobility analyzer connected to an atmospheric-pressure chemical vapor deposition reactor at various nitrogen carrier gas flow rates (300-1000 standard cubic centimeter per minute) under typical conditions for silicon deposition at the reactor temperature of 900 degrees C. The carrier gas flow rate affected not only the growth behavior of nanostructures but also the number concentration and size distribution of both negatively and positively charged nanoparticles. As the carrier gas flow rate decreased, the growth behavior changed from films to nanowires, which grew without catalytic metal nanoparticles on a quartz substrate.

  15. Tuning the Photoelectrocatalytic Hydrogen Evolution of Pt-Decorated Silicon Photocathodes by the Temperature and Time of Electroless Pt Deposition.

    Science.gov (United States)

    Fabre, Bruno; Li, Gaozeng; Gouttefangeas, Francis; Joanny, Loic; Loget, Gabriel

    2016-11-15

    The electroless deposition of Pt nanoparticles (NPs) on hydrogen-terminated silicon (H-Si) surfaces is studied as a function of the temperature and the immersion time. It is demonstrated that isolated Pt structures can be produced at all investigated temperatures (between 22 and 75 °C) for short deposition times, typically within 1-10 min if the temperature is 45 °C or less than 5 min at 75 °C. For longer times, dendritic metal structures start to grow, ultimately leading to highly rough interconnected Pt networks. Upon increasing the temperature from 22 to 75 °C and for an immersion time of 5 min, the average size of the observed Pt NPs monotonously increases from 120 to 250 nm, and their number density calculated using scanning electron microscopy decreases from (4.5 ± 1.0) × 10(8) to (2.0 ± 0.5) × 10(8) Pt NPs cm(-2). The impact of both the morphology and the distribution of the Pt NPs on the photoelectrocatalytic activity of the resulting metallized photocathodes is then analyzed. Pt deposited at 45 °C for 5 min yields photocathodes with the best electrocatalytic activity for the hydrogen evolution reaction. Under illumination at 33 mW cm(-2), this optimized photoelectrode shows a fill factor of 45%, an efficiency (η) of 9.7%, and a short-circuit current density (|Jsc|) at 0 V versus a reversible hydrogen electrode of 15.5 mA cm(-2).

  16. A platform for large-scale graphene electronics--CVD growth of single-layer graphene on CVD-grown hexagonal boron nitride.

    Science.gov (United States)

    Wang, Min; Jang, Sung Kyu; Jang, Won-Jun; Kim, Minwoo; Park, Seong-Yong; Kim, Sang-Woo; Kahng, Se-Jong; Choi, Jae-Young; Ruoff, Rodney S; Song, Young Jae; Lee, Sungjoo

    2013-05-21

    Direct chemical vapor deposition (CVD) growth of single-layer graphene on CVD-grown hexagonal boron nitride (h-BN) film can suggest a large-scale and high-quality graphene/h-BN film hybrid structure with a defect-free interface. This sequentially grown graphene/h-BN film shows better electronic properties than that of graphene/SiO2 or graphene transferred on h-BN film, and suggests a new promising template for graphene device fabrication.

  17. Two-dimensional WS2 nanoribbon deposition by conversion of pre-patterned amorphous silicon

    Science.gov (United States)

    Heyne, Markus H.; de Marneffe, Jean-François; Delabie, Annelies; Caymax, Matty; Neyts, Erik C.; Radu, Iuliana; Huyghebaert, Cedric; De Gendt, Stefan

    2017-01-01

    We present a method for area selective deposition of 2D WS2 nanoribbons with tunable thickness on a dielectric substrate. The process is based on a complete conversion of a pre-patterned, H-terminated Si layer to metallic W by WF6, followed by in situ sulfidation by H2S. The reaction process, performed at 450 °C, yields nanoribbons with lateral dimension down to 20 nm and with random basal plane orientation. The thickness of the nanoribbons is accurately controlled by the thickness of the pre-deposited Si layer. Upon rapid thermal annealing at 900 °C under inert gas, the WS2 basal planes align parallel to the substrate.

  18. Nano-cube MgO formed on silicon substrate using pulsed laser deposition.

    Science.gov (United States)

    Kaneko, Satoru; Ito, Takeshi; Akiyama, Kensuke; Yasui, Manabu; Hirabayashi, Yasuo; Soga, Masayasu; Miyake, Yumiko; Yoshimoto, Mamoru

    2012-03-01

    Nano-cube MgO particles were formed on Si substrates by deposition of an MgO target using pulsed laser deposition method. An epitaxial film grows on Si(001) substrate with its contraction of lattice constants. In this study, expecting high quality MgO film, the MgO film prepared in the oxygen pressure ranging from 75-400 mTorr at the high temperature of -750 degrees C. The deposited MgO showed the growth of (001) preferred orientation on the Si(001) substrate. However, X-ray Photoelectron Spectroscopy (XPS) indicated the MgO film did not form a continuous film on the Si surface. Interestingly, the surface morphology observed by an Atomic Force Microscopy (AFM) showed nano-cube MgO particles scattered on the smooth surface of Si substrate. After annealing the nano-cube MgO, the shape of MgO particles were changed from nano-cube to round shaped particles. The AFM image of the surface showed round shaped MgO nanoparticles scattered on rough surface. X-ray Diffraction (XRD) revealed the epitaxial growth of MgO(001) with cubic on cubic arrangement on the Si(001) substrate (MgO[100] parallel to Si[100]).

  19. Gold nanoparticles deposited on linker-free silicon substrate and embedded in aluminum Schottky contact.

    Science.gov (United States)

    Gorji, Mohammad Saleh; Razak, Khairunisak Abdul; Cheong, Kuan Yew

    2013-10-15

    Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current-voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si-OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics.

  20. Flame hydrolysis deposition of glass on silicon for the integration of optical and microfluidic devices

    Science.gov (United States)

    Ruano; Benoit; Aitchison; Cooper

    2000-03-01

    Flame hydrolysis deposition (FHD) of glasses has previously found applications in the telecommunications industry. This paper shows how the technology can be used to deposit silica with different refractive indices and thereby produce low-loss planar waveguides for use in analytical applications. We also show that the glasses can be patterned using a new reactive ion etch and sealed using a modification of anodic bonding, such that the resulting microstructures can be readily incorporated within a lithographically defined "chip", integrating both optical and fluidic circuitry on the same device. In the example described in this paper, waveguides, analytical microtiter chambers and fluidic capillary channels, with the necessary high aspect ratio features (and with depths up to 40 microm) were all produced in glass, using the appropriate deposition and etching technologies. The performance of the chip was assessed in the framework of a low-volume fluorescence assay, using waveguides to address miniaturized microtiter chambers with volumes of 230 and 570 pL. Devices featuring different optical detection configurations, including both in-line and orthogonal waveguide geometries, were fabricated. In the optimal configuration, the experimental detection limit was determined as ca. 20 pM (equivalent to 10 zmol) of a cyanine fluorophore, Cy5. The applicability of the device as a biochip platform was further illustrated by analytical measurements on fluorescently labeled oligodeoxynucleotides.

  1. Microfabrication of Tungsten, Molybdenum and Tungsten Carbide Rods by Laser-Assisted CVD

    OpenAIRE

    Björklund, Kajsa

    2001-01-01

    Thin films of refractory metals and carbides have been studied extensively over many years because of their wide range of application. The two major techniques used are Chemical Vapour Deposition (CVD) and Physical Vapour Deposition (PVD). These can result in the deposition of two-dimensional blanket or patterned thin films. Laser-assisted Chemical Vapour Deposition (LCVD) can provide a maskless alternative for localised deposition in two and three dimensions. This thesis describes LCVD of mi...

  2. Silicon carbide, a semiconductor for space power electronics

    Science.gov (United States)

    Powell, J. A.; Matus, Lawrence G.

    1991-01-01

    After many years of promise as a high temperature semiconductor, silicon carbide (SiC) is finally emerging as a useful electronic material. Recent significant progress that has led to this emergence has been in the area of crystal growth and device fabrication technology. High quality of single-crystal SiC wafers, up to 25 mm in diameter, can now be produced routinely from boules grown by a high temperature (2700 K) sublimation process. Device fabrication processes, including chemical vapor deposition (CVD), in situ doping during CVD, reactive ion etching, oxidation, metallization, etc. have been used to fabricate p-n junction diodes and MOSFETs. The diode was operated to 870 K and the MOSFET to 770 K.

  3. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate

    Science.gov (United States)

    Ghazali, Norizzawati Mohd; Yasui, Kanji; Hashim, Abdul Manaf

    2014-12-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.

  4. Drastically Enhanced High-Rate Performance of Carbon-Coated LiFePO4 Nanorods Using a Green Chemical Vapor Deposition (CVD) Method for Lithium Ion Battery: A Selective Carbon Coating Process.

    Science.gov (United States)

    Tian, Ruiyuan; Liu, Haiqiang; Jiang, Yi; Chen, Jiankun; Tan, Xinghua; Liu, Guangyao; Zhang, Lina; Gu, Xiaohua; Guo, Yanjun; Wang, Hanfu; Sun, Lianfeng; Chu, Weiguo

    2015-06-03

    Application of LiFePO4 (LFP) to large current power supplies is greatly hindered by its poor electrical conductivity (10(-9) S cm(-1)) and sluggish Li+ transport. Carbon coating is considered to be necessary for improving its interparticle electronic conductivity and thus electrochemical performance. Here, we proposed a novel, green, low cost and controllable CVD approach using solid glucose as carbon source which can be extended to most cathode and anode materials in need of carbon coating. Hydrothermally synthesized LFP nanorods with optimized thickness of carbon coated by this recipe are shown to have superb high-rate performance, high energy, and power densities, as well as long high-rate cycle lifetime. For 200 C (18s) charge and discharge, the discharge capacity and voltage are 89.69 mAh g(-1) and 3.030 V, respectively, and the energy and power densities are 271.80 Wh kg(-1) and 54.36 kW kg(-1), respectively. The capacity retention of 93.0%, and the energy and power density retention of 93.6% after 500 cycles at 100 C were achieved. Compared to the conventional carbon coating through direct mixing with glucose (or other organic substances) followed by annealing (DMGA), the carbon phase coated using this CVD recipe is of higher quality and better uniformity. Undoubtedly, this approach enhances significantly the electrochemical performance of high power LFP and thus broadens greatly the prospect of its applications to large current power supplies such as electric and hybrid electric vehicles.

  5. High Growth Rate Deposition of Hydrogenated Amorphous Silicon-Germanium Films and Devices Using ECR-PECVD

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yong [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Hydrogenated amorphous silicon germanium films (a-SiGe:H) and devices have been extensively studied because of the tunable band gap for matching the solar spectrum and mature the fabrication techniques. a-SiGe:H thin film solar cells have great potential for commercial manufacture because of very low cost and adaptability to large-scale manufacturing. Although it has been demonstrated that a-SiGe:H thin films and devices with good quality can be produced successfully, some issues regarding growth chemistry have remained yet unexplored, such as the hydrogen and inert-gas dilution, bombardment effect, and chemical annealing, to name a few. The alloying of the SiGe introduces above an order-of-magnitude higher defect density, which degrades the performance of the a-SiGe:H thin film solar cells. This degradation becomes worse when high growth-rate deposition is required. Preferential attachment of hydrogen to silicon, clustering of Ge and Si, and columnar structure and buried dihydride radicals make the film intolerably bad. The work presented here uses the Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) technique to fabricate a-SiGe:H films and devices with high growth rates. Helium gas, together with a small amount of H2, was used as the plasma species. Thickness, optical band gap, conductivity, Urbach energy, mobility-lifetime product, I-V curve, and quantum efficiency were characterized during the process of pursuing good materials. The microstructure of the a-(Si,Ge):H material was probed by Fourier-Transform Infrared spectroscopy. They found that the advantages of using helium as the main plasma species are: (1) high growth rate--the energetic helium ions break the reactive gas more efficiently than hydrogen ions; (2) homogeneous growth--heavy helium ions impinging on the surface promote the surface mobility of the reactive radicals, so that heteroepitaxy growth as clustering of Ge and Si, columnar structure are

  6. Comparison of hydrolytic and non-hydrolytic atomic layer deposition chemistries: Interfacial electronic properties at alumina-silicon interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Marstell, Roderick J.; Strandwitz, Nicholas C., E-mail: strand@lehigh.edu [Department of Materials Science and Engineering and Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

    2015-11-14

    We report the differences in the passivation and electronic properties of aluminum oxide (Al{sub 2}O{sub 3}) deposited on silicon via traditional hydrolytic atomic layer deposition (ALD) and non-hydrolytic (NH) ALD chemistries. Traditional films were grown using trimethylaluminum (TMA) and water and NHALD films grown using TMA and isopropanol at 300 °C. Hydrolytically grown ALD films contain a smaller amount of fixed charge than NHALD films (oxide fixed charge Q{sub f} {sub Traditional} = −8.1 × 10{sup 11 }cm{sup −2} and Q{sub f} {sub NHALD} = −3.6 × 10{sup 12 }cm{sup −2}), and a larger degree of chemical passivation than NHALD films (density of interface trap states, D{sub it} {sub Traditional} = 5.4 × 10{sup 11 }eV{sup −1 }cm{sup −2} and D{sub it} {sub NHALD} = 2.9 × 10{sup 12 }eV{sup −1 }cm{sup −2}). Oxides grown with both chemistries were found to have a band gap of 7.1 eV. The conduction band offset was 3.21 eV for traditionally grown films and 3.38 eV for NHALD. The increased D{sub it} for NHALD films may stem from carbon impurities in the oxide layer that are at and near the silicon surface, as evidenced by both the larger trap state time constant (τ{sub Traditional} = 2.2 × 10{sup −9} s and τ{sub NHALD} = 1.7 × 10{sup −7} s) and the larger carbon concentration. We have shown that the use of alcohol-based oxygen sources in NHALD chemistry can significantly affect the resulting interfacial electronic behavior presenting an additional parameter for understanding and controlling interfacial electronic properties at semiconductor-dielectric interfaces.

  7. A novel passivation process of silicon nanowires by a low-cost PECVD technique for deposition of hydrogenated silicon nitride using SiH4 and N2 as precursor gases

    Science.gov (United States)

    Bouaziz, Lamia; Dridi, Donia; Karyaoui, Mokhtar; Angelova, Todora; Sanchez Plaza, Guillermo; Chtourou, Radhouane

    2017-03-01

    In this work, a different SiNx passivation process of silicon nanowires has been opted for the deposition of a hydrogenated silicon nitride (SiNx:H) by a low-cost plasma enhanced chemical vapor deposition (PECVD) using silane ( SiH4 and nitrogen ( N2 as reactive gases. This study is focused on the effect of the gas flow ratio on chemical composition, morphological, optical and optoelectronic properties of silicon nanowires. The existence of Si-N and Si-H bonds was proven by the Fourier transmission infrared (FTIR) spectrum. Morphological structures were shown by scanning electron microscopy (SEM), and the roughness was investigated by atomic force microscopy (AFM). A low reflectivity less than 6% in the wavelength range 250-1200nm has been shown by UV-visible spectroscopy. Furthermore, the thickness and the refractive index of the passivation layer is determined by ellipsometry measurements. As a result, an improvement in minority carrier lifetime has been obtained by reducing surface recombination of silicon nanowires.

  8. Catalytic CVD of SWCNTs at Low Temperatures and SWCNT Devices

    Science.gov (United States)

    Seidel, Robert; Liebau, Maik; Unger, Eugen; Graham, Andrew P.; Duesberg, Georg S.; Kreupl, Franz; Hoenlein, Wolfgang; Pompe, Wolfgang

    2004-09-01

    New results on the planar growth of single-walled carbon nanotubes (SWCNTs) by catalytic chemical vapor deposition (CVD) at low temperatures will be reported. Optimizing catalyst, catalyst support, and growth parameters yields SWCNTs at temperatures as low as 600 °C. Growth at such low temperatures largely affects the diameter distribution since coalescence of the catalyst is suppressed. A phenomenological growth model will be suggested for CVD growth at low temperatures. The model takes into account surface diffusion and is an alternative to the bulk diffusion based vapor-liquid-solid (VLS) model. Furthermore, carbon nanotubes field effect transistors based on substrate grown SWCNTs will be presented. In these devices good contact resistances could be achieved by electroless metal deposition or metal evaporation of the contacts.

  9. Amorphous carbon-silicon heterojunctions by pulsed Nd:YAG laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Seong-Shan; Yow, Ho-Kwang [Faculty of Engineering, Multimedia University, Cyberjaya, Selangor 63100 (Malaysia); Tou, Teck-Yong, E-mail: tytou@mmu.edu.m [Faculty of Engineering, Multimedia University, Cyberjaya, Selangor 63100 (Malaysia)

    2009-07-31

    Amorphous carbon (a-C) films were deposited at 10{sup -4} Pa on n-Si (Si-111) and p-Si (Si-100) substrates using a pulsed Nd:YAG laser with fundamental, second- and third-harmonic outputs. These unhydrogenated and undoped a-C films were characterized by visible and UV Raman spectroscopy which indicated the presence of substantial amount of sp{sup 3} hybridized carbon network depending on the laser wavelength. The bulk resistivity in the Au/a-C/indium tin oxide structure varied between (10{sup 9}-10{sup 13}) {Omega} cm - the lowest resistivity was obtained for films deposited by the fundamental laser output at 1064 nm while the highest value was by the third-harmonic laser output at 355 nm. All the a-C/Si heterostructures exhibited a nonlinear current density-voltage characteristic. Under light illumination, by taking into consideration the fill factor of {approx} 0.2 for a-C/n-Si, the conversion efficiency at the highest photovoltage and photocurrent, at an illumination density of 0.175 mW/cm{sup 2} was estimated to be {approx} 0.28%.

  10. Leakage current measurements of a pixelated polycrystalline CVD diamond detector

    OpenAIRE

    Zain, R.M.; Maneuski, D.; O'Shea, V.; Bates, R.; Blue, A.; Cunnigham, L.; Stehl, C.; Berderman, E.; Rahim, R. A.

    2013-01-01

    Diamond has several desirable features when used as a material for radiation detection. With the invention of synthetic growth techniques, it has become feasible to look at developing diamond radiation detectors with reasonable surface areas. Polycrystalline diamond has been grown using a chemical vapour deposition (CVD) technique by the University of Augsburg and detector structures fabricated at the James Watt Nanofabrication Centre (JWNC) in the University of Glasgow in order to produce pi...

  11. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate.

    Science.gov (United States)

    Ghazali, Norizzawati Mohd; Yasui, Kanji; Hashim, Abdul Manaf

    2014-01-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm(2) using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.

  12. Optimization of process parameter for synthesis of silicon quantum dots using low pressure chemical vapour deposition

    Indian Academy of Sciences (India)

    Dipika Barbadikar; Rashmi Gautam; Sanjay Sahare; Rajendra Patrikar; Jatin Bhatt

    2013-06-01

    Si quantum dots-based structures are studied recently for performance enhancement in electronic devices. This paper presents an attempt to get high density quantum dots (QDs) by low pressure chemical vapour deposition (LPCVD) on SiO2 substrate. Surface treatment, annealing and rapid thermal processing (RTP) are performed to study their effect on size and density of QDs. The samples are also studied using Fourier transformation infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence study (PL). The influence of Si–OH bonds formed due to surface treatment on the density of QDs is discussed. Present study also discusses the influence of surface treatment and annealing on QD formation.

  13. Processing of n+/p-/p+ strip detectors with atomic layer deposition (ALD) grown Al2O3 field insulator on magnetic Czochralski silicon (MCz-si) substrates

    Science.gov (United States)

    Härkönen, J.; Tuovinen, E.; Luukka, P.; Gädda, A.; Mäenpää, T.; Tuominen, E.; Arsenovich, T.; Junkes, A.; Wu, X.; Li, Z.

    2016-08-01

    Detectors manufactured on p-type silicon material are known to have significant advantages in very harsh radiation environment over n-type detectors, traditionally used in High Energy Physics experiments for particle tracking. In p-type (n+ segmentation on p substrate) position-sensitive strip detectors, however, the fixed oxide charge in the silicon dioxide is positive and, thus, causes electron accumulation at the Si/SiO2 interface. As a result, unless appropriate interstrip isolation is applied, the n-type strips are short-circuited. Widely adopted methods to terminate surface electron accumulation are segmented p-stop or p-spray field implantations. A different approach to overcome the near-surface electron accumulation at the interface of silicon dioxide and p-type silicon is to deposit a thin film field insulator with negative oxide charge. We have processed silicon strip detectors on p-type Magnetic Czochralski silicon (MCz-Si) substrates with aluminum oxide (Al2O3) thin film insulator, grown with Atomic Layer Deposition (ALD) method. The electrical characterization by current-voltage and capacitance-voltage measurement shows reliable performance of the aluminum oxide. The final proof of concept was obtained at the test beam with 200 GeV/c muons. For the non-irradiated detector the charge collection efficiency (CCE) was nearly 100% with a signal-to-noise ratio (S/N) of about 40, whereas for the 2×1015 neq/cm2 proton irradiated detector the CCE was 35%, when the sensor was biased at 500 V. These results are comparable with the results from p-type detectors with the p-spray and p-stop interstrip isolation techniques. In addition, interestingly, when the aluminum oxide was irradiated with Co-60 gamma-rays, an accumulation of negative fixed oxide charge in the oxide was observed.

  14. Investigation of the Millimeter-Wave Plasma Assisted CVD Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Vikharev, A; Gorbachev, A; Kozlov, A; Litvak, A; Bykov, Y; Caplan, M

    2005-07-21

    A polycrystalline diamond grown by the chemical vapor deposition (CVD) technique is recognized as a unique material for high power electronic devices owing to unrivaled combination of properties such as ultra-low microwave absorption, high thermal conductivity, high mechanical strength and chemical stability. Microwave vacuum windows for modern high power sources and transmission lines operating at the megawatt power level require high quality diamond disks with a diameter of several centimeters and a thickness of a few millimeters. The microwave plasma-assisted CVD technique exploited today to produce such disks has low deposition rate, which limits the availability of large size diamond disk windows. High-electron-density plasma generated by the millimeter-wave power was suggested for enhanced-growth-rate CVD. In this paper a general description of the 30 GHz gyrotron-based facility is presented. The output radiation of the gyrotron is converted into four wave-beams. Free localized plasma in the shape of a disk with diameter much larger than the wavelength of the radiation is formed in the intersection area of the wave-beams. The results of investigation of the plasma parameters, as well as the first results of diamond film deposition are presented. The prospects for commercially producing vacuum window diamond disks for high power microwave devices at much lower costs and processing times than currently available are outlined.

  15. Silver nanocrystals of various morphologies deposited on silicon wafer and their applications in ultrasensitive surface-enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Limiao, E-mail: chenlimiao@csu.edu.cn; Jing, Qifeng; Chen, Jun; Wang, Bodong; Huang, Jianhan; Liu, Younian

    2013-11-15

    Silver nanostructures with dendritic, flower-like and irregular morphologies were controllably deposited on a silicon substrate in an aqueous hydrogen fluoride solution at room temperature. The morphology of the Ag nanostructures changed from dendritic to urchin-like, flowerlike and pinecone-like with increasing the concentration of polyvinyl pyrrolidone (MW = 55,000) from 2 to 10 mM. The Ag nanostructures were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction. Through a series of time-dependent morphological evolution studies, the growth processes of Ag nanostructures have been systematically investigated and the corresponding growth mechanisms have been discussed. In addition, the morphology-dependent surface-enhanced Raman scattering of as-synthesized Ag nanostructures were investigated. The results indicated that flower-like Ag nanostructure had the highest activity than the other Ag nanostructures for Rhodamine 6G probe molecules. Highlights: • A simple method was developed to prepare dendritic and flower-like Ag nanostructures. • The flower-like Ag nanoparticles exhibit highest SERS activity. • The SERS substrate based on flower-like Ag particles can be used to detect melamine.

  16. Effect of hydrogen on low temperature epitaxial growth of polycrystalline silicon by hot wire chemical vapor deposition

    Science.gov (United States)

    Yong, Cao; Hailong, Zhang; Fengzhen, Liu; Meifang, Zhu; Gangqiang, Dong

    2015-02-01

    Polycrystalline silicon (poly-Si) films were prepared by hot-wire chemical vapor deposition (HWCVD) at a low substrate temperature of 525 °C. The influence of hydrogen on the epitaxial growth of ploy-Si films was investigated. Raman spectra show that the poly-Si films are fully crystallized at 525 °C with a different hydrogen dilution ratio (50%-91.7%). X-ray diffraction, grazing incidence X-ray diffraction and SEM images show that the poly-Si thin films present (100) preferred orientation on (100) c-Si substrate in the high hydrogen dilution condition. The P-type poly-Si film prepared with a hydrogen dilution ratio of 91.7% shows a hall mobility of 8.78 cm2/(V·s) with a carrier concentration of 1.3 × 1020 cm-3, which indicates that the epitaxial poly-Si film prepared by HWCVD has the possibility to be used in photovoltaic and TFT devices.

  17. 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.

  18. PECVD-ONO: A New Deposited Firing Stable Rear Surface Passivation Layer System for Crystalline Silicon Solar Cells

    Directory of Open Access Journals (Sweden)

    M. Hofmann

    2008-01-01

    Full Text Available A novel plasma-enhanced chemical vapour deposited (PECVD stack layer system consisting of a-SiOx:H, a-SiNx:H, and a-SiOx:H is presented for silicon solar cell rear side passivation. Surface recombination velocities below 60 cm/s (after firing and below 30 cm/s (after forming gas anneal were achieved. Solar cell precursors without front and rear metallisation showed implied open-circuit voltages Voc values extracted from quasi-steady-state photoconductance (QSSPC measurements above 680 mV. Fully finished solar cells with up to 20.0% energy conversion efficiency are presented. A fit of the cell's internal quantum efficiency using software tool PC1D and a comparison to a full-area aluminium-back surface field (Al-BSF and thermal SiO2 is shown. PECVD-ONO was found to be clearly superior to Al-BSF. A separation of recombination at the metallised and the passivated area at the solar cell's rear is presented using the equations of Fischer and Kray. Nuclear reaction analysis (NRA has been used to evaluate the hydrogen depth profile of the passivation layer system at different stages.

  19. Heat and Mass Transfer in the Chemical Vapor Deposition of Silicon Carbide in a Porous Carbon-Carbon Composite Material for a Heat Shield

    Science.gov (United States)

    Reznik, S. V.; Mikhailovskii, K. V.; Prosuntsov, P. V.

    2017-03-01

    Physical and mathematical simulations of the chemical vapor deposition of silicon carbide in a porous carbon-carbon composite material in a chemical vapor deposition reactor for formation of a matrix of a carbon-ceramic composite material for a heat shield of an aerospace aircraft have been performed. Results of parametric calculations of the heat and mass transfer at the macro- and microlevels in representative elements of the microstructure of carbon-carbon composite materials different in residual porosity at different temperatures in the reaction zone of the reactor are presented. Features of compaction of the pore space of a carbon-carbon composite material by a silicon-carbide matrix depending on the technological parameters of the reaction medium were analyzed.

  20. Chemical Vapor Deposition Growth. Final Report, December 29, 1975 -- August 31, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Ruth, R. P.; Manasevit, H. M.; Campbell, A. G.; Johnson, R. E.; Kenty, J. L.; Moudy, L. A.; Shaw, G. L.; Simpson, W. I.; Yang, J. J.

    1978-10-01

    The objective of this study was to investigate and develop chemical vapor deposition (CVD) techniques for the growth of large areas of Si sheet on inexpensive substrate materials, with resulting sheet properties suitable for fabricating solar cells that would meet the technical goals of the Low Cost Silicon Solar Array (LSSA) Project. The results of 20 months of experimental work are summarized. The program involved six main technical tasks: (1) modification and test of an existing vertical-chamber CVD reactor system; (2) identification and/or development of suitable inexpensive substrate materials; (3) experimental investigation of CVD process parameters using various candidate substrate materials; (4) preparation of Si sheet samples for various special studies, including solar cell fabrication; (5) evaluation of the properties of the Si sheet material produced by the CVD process; and (6) fabrication and evaluation of experimental solar cell structures by OCLI, using impurity diffusion and other standard and near-standard processing techniques, supplemented late in the program by the in situ CVD growth of n exp + /p/p exp + sheet structures subsquently processed into experimental cells. The principal CVD process used was silane (SiH sub 4 ) pyrolysis, although a few experiments were done with the dichlorosilane (SiH sub 2 Cl sub 2 ) process for Si deposition. The evaluation of various possiblesubstrate materials, the CVD parameter investigations, and the experimental solar cell fabrication and characterization are described in considerable detail. Specific conclusions of the work are discussed, and recommendations for continued investigations in certain areas are given.