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.

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.

Improved Efficiency of Single Junction Microcrystalline Silicon n-i-p Solar Cells with an i-Layer Made by Hot-Wire CVD

2007 ◽  
Vol 989 ◽  
Author(s):  
Hongbo Li ◽  
Ronald H.J. Franken ◽  
Robert L. Stolk ◽  
C. H.M. van der Werf ◽  
Jan-Willem A. Schuttauf ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Solar Cells ◽  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Hot Wire ◽  
Microcrystalline Silicon ◽  
Single Junction ◽  
Layer Deposition ◽  
P Cells

AbstractThe influence of the surface roughness of Ag/ZnO coated substrates on the AM1.5 J-V characteristics of microcrystalline silicon (μc-Si:H) solar cells with an i-layer made by the hot-wire chemical vapour deposition (HWCVD) technique is discussed. Cells deposited on substrates with an intermediate rms roughness show the highest efficiency. When using reverse hydrogen profiling during i-layer deposition, an efficiency of 8.5 % was reached for single junction μc-Si:H n-i-p cells, which is the highest for μc-Si:H n-i-p cells with a hot-wire i-layer.

Problem of catalyst ageing during the hot-wire chemical vapour deposition of thin silicon films

2009 ◽  
Vol 517 (11) ◽  
pp. 3370-3377 ◽  
Author(s):  
D. Hrunski ◽  
M. Scheib ◽  
M. Mertz ◽  
B. Schroeder
Keyword(s):  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Silicon Films ◽  
Hot Wire ◽  
Thin Silicon

Photodegradation in a-Si:H Prepared by Hot-Wire CVD as a Function of Substrate and Filament Temperatures

2000 ◽  
Vol 609 ◽  
Author(s):  
Daxing Han ◽  
Guozhen Yue ◽  
Jing Lin ◽  
Hitoe Habuchi ◽  
Eugene Iwaniczko ◽  
...  
Keyword(s):  
Activation Energy ◽  
Substrate Temperature ◽  
Density Of States ◽  
Electron Mobility ◽  
Defect Density ◽  
Degradation Kinetics ◽  
Hot Wire ◽  
Conductivity Activation Energy ◽  
Charged Defects ◽  
Metastable Defect

ABSTRACTWe have studied light-soaking effects, such as photoconductivity (PC) degradation kinetics, the changes of conductivity activation energy, Ea, and the defect density of states (DOS) in a-Si:H films deposited by hot-wire CVD. Films were deposited in a substrate temperature range from 280 to 440 °C for filament temperatures of 1900 and 2100 °C. We find that (a) the photodegradation kinetics does not follow the stretched exponential rule for all of the samples; (b) the Fermi level position moves up after light-soaking for most samples; and (c) the metastable defect DOS deduced from sub-band gap absorption is not consistent with that deduced from the electron mobility-lifetime product. The results are discussed according to the possible mechanism in which charged defects exist in hot-wire a-Si:H films.a

In situ Ellipsometric Studies of the growth of a-Si:H films Prepared by the Hot wire Deposition

1996 ◽  
Vol 420 ◽  
Author(s):  
S. Bauer ◽  
R. O. Dusane ◽  
R. Biehl ◽  
B. Schroder
Keyword(s):  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Defect Density ◽  
Chemical Vapour ◽  
Hot Wire ◽  
Growth Behaviour ◽  
Film Density ◽  
Filament Temperature ◽  
Reactor Geometry

AbstractIn situ ellipsometric studies have been performed during the nucleation and growth of hydrogenated amorphous silicon (a-Si:H) films prepared by the hot wire chemical vapour deposition (HWCVD) method in order to understand the growth mechanism of these films. For a comparison with films deposited by plasma enhanced chemical vapour deposition (PECVD), the hot wire deposition was carried out under similar conditions and reactor geometry as for the PECVD process. It is observed from the kinetic ellipsometry measurements that low filament temperature (TFil) and low gas pressure favour the growth of more dense films, but at lower deposition rates. Moreover, for a given set of conditions an increase in substrate temperature (Ts) leads to a higher final value of the film density with a different growth behaviour in the initial stage. Thus, the filament temperature in the hot wire method seems to have a similar effect on the film density as the rf power has in the PECVD process, which has been observed earlier. Film density and surface roughness obtained from spectroscopic ellipsometry using a tetrahedron model which takes into account the effect of hydrogen on the dielectric function, is used to get information about the film microstructure. A correlation between this microstructure, the growth behaviour and the electronic properties as the defect density or the ambipolar diffusion length in the films is also reported.

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