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Journal ArticleDOI

Catalytic chemical vapor deposition method to prepare high quality hydro‐fluorinated amorphous silicon

01 Dec 1988-Journal of Applied Physics (American Institute of Physics)-Vol. 64, Iss: 11, pp 6505-6509
TL;DR: In this paper, a new type of chemical vapor deposition method, named "Catalytic-CVD" method, is presented, in which deposition gases are decomposed by catalytic or pyrolytic reaction between deposition gases and a heated catalyzer, and films are thermally grown on a substrate at temperatures lower than 300°C without any help from glow discharge plasma.
Abstract: A new type of chemical vapor deposition method, named ‘‘Catalytic‐CVD’’ method, is presented. In the method, deposition gases are decomposed by catalytic or pyrolytic reaction between deposition gases and a heated catalyzer, and films are thermally grown on a substrate at temperatures lower than 300 °C without any help from glow discharge plasma. Hydro‐fluorinated amorphous silicon (a‐Si:F:H) films are deposited by this method using both a SiF2 and H2 gas mixture and a SiH2F2 and H2 mixture. It is found that a very high quality a‐Si:F:H film can be obtained, and for instance, that the photosensitivity for AM‐1 of 100 mW/cm2 exceeds 106 and the spin density is as low as 6×1015 cm−3.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors present measurements of low temperature internal friction (Q−1) of amorphous silicon (a-Si) films designed to probe how their structure and formation affect low temperature vibrational properties.
Abstract: We present measurements of low temperature internal friction (Q−1) of amorphous silicon (a-Si) films designed to probe how their structure and formation affect low temperature vibrational properties. All a-Si films, whether produced by e-beam evaporation, sputtering, Si self-ion implantation, or chemical vapor deposition (CVD) show the well-known temperature-independent plateau (Q0−1) common to all amorphous solids. For hydrogenated amorphous silicon (a-Si:H) with about 1 at.% H produced by hot wire CVD; however, the internal friction is nearly three orders of magnitude less than any known amorphous material. For this material we find that Q−1 depends on H concentration (CH), and on deposition conditions. For CH>2 at.%, both a peak and a sharp transitional feature appear in Q−1 between 5 and 40 K. We identify the feature as H2, presumably in microvoids, undergoing a phase transition at the freezing point.

12 citations

Journal ArticleDOI
TL;DR: In this paper, structural properties of cat-CVD poly-Si films are studied by Raman spectroscopy and high resolution transmission electron microscopy, along with carrier transport properties measured by the Van der Pauw method.
Abstract: Polycrystalline silicon (poly-Si) films are obtained at temperatures less than 400°C by catalytic chemical vapor deposition (cat-CVD) method, often called `hot-wire CVD' method. Structural properties of the cat-CVD poly-Si films are studied by Raman spectroscopy and high resolution transmission electron microscopy, along with carrier transport properties measured by the Van der Pauw method. It is found that the cat-CVD poly-Si films have a microstructure which consists of columnar crystalline grains with tens of nanometers diameter and a few nm thick amorphous layers surrounding the columnar grains. It is also found that the Hall mobilities of some samples are several-tens cm 2 /V s and the barrier heights at the grain boundaries become the order of 0.01 eV or less. These good carrier transport properties appear dependent on the grain boundary structure of the cat-CVD poly-Si films.

9 citations

Journal ArticleDOI
TL;DR: In this paper, the carrier transport, optical and structural properties of cat-CVD polycrystalline silicon (poly-Si) films are investigated for thin-film transistors and thin film solar cells.
Abstract: Polycrystalline silicon (poly-Si) films are deposited at temperatures lower than 300–400°C by the cat-CVD method. In the method, a SiH 4 and H 2 gas-mixture is decomposed by catalytic cracking reactions with a heated tungsten catalyzer placed near substrates. Carrier transport, optical and structural properties are investigated for this cat-CVD poly-Si. The films show both large carrier mobility and large optical absorption for particular deposition conditions. The cat-CVD poly-Si films are found to be one of the useful materials for thin film transistors and thin film solar cells.

5 citations

Journal ArticleDOI
TL;DR: In this article, the elastic properties of amorphous silicon and germanium thin films produced by either plasma assisted chemical-vapordeposition (PECVD) or hot-wire (cat) CVD (HWCVD) are reviewed.

3 citations

References
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Book
01 Jan 1962

1,204 citations

Journal ArticleDOI
J. Tauc1
TL;DR: In this paper, a simple model based on the existence of internal electric fields is suggested to explain the exponential part of the absorption edge observed in many amorphous semiconductors.

1,150 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that substitutional doping of an amorphous semiconductor is possible and can provide control of the electronic properties over a wide range, which corresponds to a movement of the Fermi level of 1·2 eV.
Abstract: It is shown that substitutional doping of an amorphous semiconductor is possible and can provide control of the electronic properties over a wide range. a-Si and Ge specimens have been prepared by the decomposition of silane (or germane) in a radio-frequency (r.f.) glow discharge. Doping is achieved by adding carefully measured amounts of phosphine or diborane, between 5 × 10−6 and 10−2 parts per volume, to obtain n- or p-type specimens. The room temperature conductivity of doped a-Si specimens can be controlled reproducibly over about 10 orders of magnitude, which corresponds to a movement of the Fermi level of 1·2 eV. Ion probe analysis on phosphorus doped specimens indicates that about half the phosphine molecules in the gaseous mixture introduce a phosphorus atom into the Si random network; it is estimated that 30–40% of these will act as substitutional donors. The results also show that the number of incorporated phosphorus atoms saturates at about 3 × 1019 cm−3, roughly equal to the number ...

624 citations

Journal ArticleDOI
TL;DR: In this article, a new method of producing high quality hydrogenated amorphous silicon (a-Si:H) films was presented, without using any plasmas or photochemical excitation, but using only thermal and catalytic reactions between deposition-gas and heated tungsten catalyzer.
Abstract: A new method of producing high quality hydrogenated amorphous silicon (a-Si:H) films is presented. An SiH4. and H2 gas mixture is decomposed without using any plasmas or photochemical excitation, but using only thermal and catalytic reactions between deposition-gas and a heated tungsten catalyzer. Photoconductivity of films produced by this methodreaches 10-3 (Ωcm)-1 and photosensitivity exceeds 105 for illumination of AM-1 light of 100 mW/cm2.

151 citations

Journal ArticleDOI
TL;DR: Amorphous silicon (a•Si) films are deposited at about 320˚C by a new thermal chemical vapor deposition method as mentioned in this paper, where the gas mixture of intermediate species SiF2 and H2, decomposed thermally by the catalytic reaction, is used as a material gas.
Abstract: Amorphous silicon (a‐Si) films are deposited at about 320 °C by a new thermal chemical vapor deposition method. In this method, the gas mixture of intermediate species SiF2 and H2, decomposed thermally by the catalytic reaction, is used as a material gas. It is found that the photosensitivity of the a‐Si film for AM1 of 100 mW/cm2 exceeds over 106 and that the spin density is as low as 1.5×1016 cm−3 for the film deposited with a rate of several A/s.

114 citations