Purely Intrinsic Poly-Silicon Films by Hot Wire Chemical Vapor Deposition

1996 ◽  
Vol 452 ◽  
Author(s):  
J. K. Rath ◽  
K. F. Feenstra ◽  
D. Ruff ◽  
H. Meiling ◽  
R. E. I. Schropp
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Defect Density ◽  
Chemical Vapor ◽  
Average Crystallite Size ◽  
Silicon Films ◽  
Hot Wire ◽  
Intrinsic Nature ◽  
Poly Silicon

AbstractPoly-silicon films have been prepared by hot-wire chemical vapor deposition (HWCVD) from hydrogen diluted silane gas at a low temperature (430 °C). The optical gap of the poly-silicon films is 1.1 eV, though with a higher optical absorption than c-Si. The grains have a preferential orientation (220) perpendicular to the substrate with an average crystallite size of 70 nm. The crystalline volume fraction is 95% with complete coalescence of grains. Large structures up to 0.5 μm could be observed in the AFM micrograph. The activation energy (0.54 eV) and the low carrier concentration (1011 cm−3) indicate a fully intrinsic nature of the films. The μτ product of carriers is 7.1×10−7 cm2V−1 whereas the ambipolar diffusion length (LD) is 334 nm. The excellent photo-conductive properties are attributed to the low (∼1017 cm−3) defect density. The HWCVD poly-silicon films showed a very small temperature dependence of mobility, indicating negligible trapping of carriers at the grain boundaries. Preliminary n-i-p cells incorporating poly-silicon i-layer yielded 3.15 % efficiency.

Application of Hot Wire Deposited Intrinsic Poly-Silicon Films in N-I-P cells and TFTS

1997 ◽  
Vol 467 ◽  
Author(s):  
J. K. Rath ◽  
A.J.M.M. Van Zutphen ◽  
H. Meiling ◽  
R. E. I. Schropp
Keyword(s):  
Activation Energy ◽  
Volume Fraction ◽  
Defect Density ◽  
Chemical Vapour ◽  
Silicon Films ◽  
Hot Wire ◽  
Intrinsic Nature ◽  
Poly Silicon ◽  
Conducting Path ◽  
P Cells

ABSTRACTPoly-silicon films have been prepared by hot-wire chemical vapour deposition (HWCVD) from hydrogen diluted silane gas at a low temperature (430 °C). The crystalline volume fraction is 95%. The grains have an average size of 70 nm and coalesce completely. The activation energy (0.54 eV) and the low carrier concentration (6.8 × 1010 cm−3) indicate the fully intrinsic nature of the films. The low (<1017 cm−3) defect density, the absence of 2100 cm−1 mode in infrared spectrum, the low activation energy of Hall mobility (0.012 eV) and the ambipolar diffusion length (LD) of 568 nm all indicate that the grain boundaries in the poly-Si:H films are indeed very thin. Preliminary n-i-p cells incorporating a poly-silicon i-layer yielded 3.15% efficiency and a current density of 18.2 mW/cm2 for only a 1.5 μm i-layer. In the solar cell, the conducting path is along the columnar grains ( (220) preferential orientation from XRD) and the carrier transport bypasses the grain boundary defects. This has been confirmed from the c-Si like optical absorption spectrum (measured by Dual Beam Photoconductivity in the cell configuration) at the low energy region. Inverted staggered thin-film transistors incorporating the poly-silicon layers showed transfer and output characteristics similar to those of state of the art a-Si:H TFTs : the saturation mobility is 0.4 cm2/Vs and the off current is approximately 10−11 A. This leads to the conclusion that the silicon near the SiO2 interface (the channel region) is still amorphous. This is illustrated by XTEM.

Properties and Production Mechanism of Low-Temperature Deposited CAT-CVD Poly-Silicon films

1992 ◽  
Vol 283 ◽  
Author(s):  
Hideki Matsumura ◽  
Yoichi Hosoda ◽  
Seijiro Furukawa
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Gas Pressure ◽  
Silicon Films ◽  
Production Mechanism ◽  
Cvd Method ◽  
Poly Silicon ◽  
Deposition Conditions

ABSTRACTPoly-silicon films are obtained at temperatures as low as 400 °C by the catalytic chemical vapor deposition (cat-CVD) method, in which deposition gases are decomposed by the catalytic or pyrolytic reactions with a heated catalyzer near substrates. It is found that there are roughly two modes of deposition conditions such as low gas pressure mode and high gas pressure mode for obtaining poly-silicon films, and also that the Hall mobility of the cat-CVD poly-silicon films of low gas pressure mode sometimes exceeds over 100 cm2/Vs.

Silicon homoepitaxy using tantalum-filament hot-wire chemical vapor deposition

2005 ◽  
Vol 862 ◽  
Author(s):  
Charles W. Teplin ◽  
Eugene Iwaniczko ◽  
Kim M. Jones ◽  
Robert Reedy ◽  
Bobby To ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Vapor ◽  
Silicon Wafers ◽  
Silicon Films ◽  
Hot Wire ◽  
Transmission Electron ◽  
Increasing Temperature

AbstractWe have studied silicon films grown epitaxially on silicon wafers using hot-wire chemical vapor deposition (HWCVD) with a tantalum filament. Silicon films were grown on (100)-oriented hydrogen terminated silicon wafers at temperatures from 175°C to 480°C, using a Ta filament 5 cm from the substrate to decompose pure SiH4 gas. The progression of epitaxy was monitored using real-time spectroscopic ellipsometry (RTSE). Analysis using RTSE, transmission electron microscopy (TEM), and scanning electron microscopy shows that at a characteristic thickness, hepi all of the films break down into a-Si:H cones. Below 380°C, both hepi and the thickness of the transition to pure a-Si:H increase with increasing temperature. Above 380°C, hepi was not observed to increase further but TEM images show fewer defects in the epitaxial regions. Secondary ion-mass spectrometry shows that the oxygen concentration remains nearly constant during growth (<1018 cm-3). The hydrogen concentration is found to increase substantially with film thickness from 5·1018 to 5·1019 cm-3, likely due to the incorporation of hydrogen into the a-Si:H cones that grow after the breakdown of epitaxy.

Roughness, impurities and strain in low-temperature epitaxial silicon films grown by tantalum filament hot-wire chemical vapor deposition

2006 ◽  
Vol 910 ◽  
Author(s):  
Charles W. Teplin ◽  
Matthew Page ◽  
Eugene Iwaniczko ◽  
Kim M. Jones ◽  
Robert M. Ready ◽  
...  
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Epitaxial Films ◽  
Silicon Films ◽  
Epitaxial Silicon ◽  
Hot Wire ◽  
Film Interface

AbstractWe grow epitaxial silicon films onto (100) silicon wafers from pure silane by hot-wire chemical vapor deposition (HWCVD). The films grow epitaxially for a thickness hepi before a Si:H cones nucleate and expand. We study the dependence of hepi on growth rate and the differences between Ta and W filaments. The surface morphology of thin but completely epitaxial films are studied in order to correlate the surface roughness during growth with the eventual epitaxial breakdown thickness. Surface roughness, strain and H at the wafer/film interface are not likely to cause the observed breakdown.

Deposition of amorphous silicon films by hot-wire chemical vapor deposition

1999 ◽  
Vol 85 (9) ◽  
pp. 6843-6852 ◽  
Author(s):  
K. F. Feenstra ◽  
R. E. I. Schropp ◽  
W. F. Van der Weg
Keyword(s):  
Chemical Vapor Deposition ◽  
Amorphous Silicon ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Silicon Films ◽  
Hot Wire

Effect of Hydrogen Radical on Properties of Hydrogen in Hydrogenated Microcrystalline Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
Takashi Itoh ◽  
Noriyuki Yamana ◽  
Hiroki Inouchi ◽  
Norimitsu Yoshida ◽  
Hidekuni Harada ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Volume Fraction ◽  
Chemical Vapor ◽  
Hot Wire ◽  
Crystalline Volume Fraction ◽  
Microcrystalline Silicon ◽  
Integrated Intensity ◽  
Hydrogen Radical ◽  
Integrated Intensities

ABSTRACTHydrogenated microcrystalline silicon (μc-Si:H) films are prepared by hot-wire assisted plasma enhanced chemical vapor deposition, which controls the hydrogen radical density by filament temperatures, Tf, without changing other conditions. The effect of hydrogen radical on the properties of incorporated hydrogen into μc-Si:H films is studied using infrared absorption and gas effusion spectroscopies. The hydrogen concentration decreases with increasing Tf. The crystalline volume fraction, Xc, increases with Tf and shows a peak at Tf of 1850 °C. Integrated intensities of the modes near 2000 and 2100 cm-1 decrease with increasing Tf. Integrated intensity of the mode near 880 cm-1 shows almost same tendency of Xc. The effect of hydrogen radical on the properties of incorporated hydrogen into μc-Si:H films is discussed.

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