Photoconductive Polycrystalline Silicon Films on Glass Obtained by Hot-Wire CVD

1996 ◽  
Vol 420 ◽  
Author(s):  
A. R. Middya ◽  
J. Guillet ◽  
J. Perrin ◽  
J. E. Bouree
Keyword(s):  
Polycrystalline Silicon ◽  
Chemical Vapour ◽  
Columnar Structure ◽  
Silicon Films ◽  
High Deposition Rate ◽  
Hot Wire ◽  
Si Films ◽  
Polycrystalline Silicon Films ◽  
Deposited Films

AbstractTextured polycrystalline silicon films with columnar structure have been deposited on glass at low temperature (400–550°C) and high deposition rate (10 to 15 Å/s) by hot-wire chemical vapour deposition using SiH4-H2 gases. The homogeneity of the deposited layer is ± 5% on a 8 cm diameter. As deposited films have a poor photoconductivity. However hydrogen confinement in the films during the deposition or after the deposition is found to be the key for obtaining g.tc/poly-Si with a significant diffusion length. Eventually reasonable values of the mobility lifetime product (> 10−7 cm2/V) are obtained by in situ hydrogen passivation of poly-Si films after deposition. Efficient shifting of the Fermi level is achieved by in situ B or P doping. The incorporation of boron in poly-Si network strongly influences the morphology and the crystalline structure. Undoped films have a Hall mobility of 14 ± 5 cm2/V.s which decreases versus the carrier concentration.

Fast Deposition of Polycrystalline Silicon Films by Hot-Wire CVD

1995 ◽  
Vol 377 ◽  
Author(s):  
A. R. Middya ◽  
A. Lloret ◽  
J. Perrin ◽  
J. Huc ◽  
J. L. Moncel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Polycrystalline Silicon ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Hot Wire ◽  
Crystalline Orientation ◽  
Silicon Thin Films ◽  
Hydrogen Dilution ◽  
Si Films ◽  
Polycrystalline Silicon Films

ABSTRACTPolycrystalline silicon thin films have been deposited at fast growth rates (50 Å/s) by hotwire chemical vapour deposition (HW-CVD) from SiH4/H2 gas mixtures at low substrate temperature (400–500°C). The surface morphology of these films consists of 0.5 – 2.0μm dendritic grains as seen by electron microscopy. The films have a columnar morphology with grains starting from the substrate either on glass or c-Si. Even the 150 nm thick initial layer is polycrystalline. The preferential crystalline orientation of the poly-Si film is apparently not governed by the radiative source but strongly depends on the type and orientation of the substrate. A strong hydrogen dilution (>90%) of silane is essential to obtain poly-Si films with optimal crystalline structure.

Electronic Properties and Device Applications of Hot-Wire CVD Polycrystalline Silicon Films

1997 ◽  
Vol 467 ◽  
Author(s):  
A. R. Middya ◽  
J. Guillet ◽  
R. Brenot ◽  
J. Perrin ◽  
J. E. Bouree ◽  
...  
Keyword(s):  
Polycrystalline Silicon ◽  
Broad Band ◽  
Silicon Films ◽  
Crystallographic Structure ◽  
Hydrogen Treatment ◽  
Textured Surface ◽  
Hot Wire ◽  
Glass Substrates ◽  
Polycrystalline Silicon Films

ABSTRACTPolycrystalline silicon films (5 to 30 μm thick) have been deposited on glass substrates at low temperatures (400–550 °C) with a rate of 15 Å/s by hot-wire chemical vapour deposition (HWCVD). The homogeneity of the deposited layer is ±5% on a 8 cm diameter substrate. The films have columnar microstructure and a textured surface. The undoped films (carrier concentration, 1011 cm−3) have a resistivity of 105-106 Ω-cm, activation energy of 0.50 ± 0.05 eV and Hall mobility of 14 ± 4 cm2 /V.s. By in situ gas phase doping, resistivity can be varied by six to seven orders of magnitude. Incorporation of dopant atoms such as boron into the film, strongly influences its morphological and crystallographic structure. The mobility lifetime product of undoped films is low (10−8 cm2/V), possibly due to the presence of a high density of dangling bonds defects and broad band-tails. This product can be improved by a factor of 5 to 10 by using in-situ hydrogen passivation in the same reactor at lower temperature (350–400 °C) within one hour. The results of many complementary experiments suggest that hydrogen treatment mainly improves carrier mobility by a factor of 3 to 4 by passivating extended defects. Preliminary results on application of these types of materials in unoptimized P-I-N solar cells on c-Si and glass substrates are presented.

Low Temperature Deposition of Polycrystalline Silicon Thin Films Prepared by Hot Wire Cell Method

1998 ◽  
Vol 536 ◽  
Author(s):  
M. Ichikawa ◽  
J. Takeshita ◽  
A. Yamada ◽  
M. Konagai
Keyword(s):  
Low Temperature ◽  
Polycrystalline Silicon ◽  
High Growth ◽  
Columnar Structure ◽  
High Growth Rate ◽  
Silicon Films ◽  
Hot Wire ◽  
Cross Sectional ◽  
Cell Method ◽  
Polycrystalline Silicon Films

AbstractHot wire (HW) cell method has been newly developed and successfully applied to grow polycrystalline silicon films at a low temperature with a relatively high growth rate. In the HWcell method, silane is decomposed by reaction with a heated tungsten wire placed near the substrate. It is found that polycrystalline silicon films can be obtained at substrate temperatures of 175-400°C without hydrogen dilution. The film crystallinity is changed from polycrystalline to amorphous with decreasing the total pressure. The X-ray analysis clearly showed that the films grown at the filament temperature of 1700°C have a very strong (220) preferential orientation. The films consist of large grains as well as small grains, and it was found from cross-sectional SEM that the films have columnar structure. These results suggested that the HW-cell method would be a promising candidate to grow device-grade polycrystalline silicon films for photovoltaic application.

Si-H Vibration Only at 2000 CM-1 in Fully Polycrystalline Silicon Films Made by Hwcvd

2000 ◽  
Vol 609 ◽  
Author(s):  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Polycrystalline Silicon ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Amorphous Region ◽  
Hot Wire ◽  
Wire Temperature ◽  
Stretching Vibration ◽  
Closed Structure ◽  
Si Films ◽  
Polycrystalline Silicon Films

ABSTRACTThe Si-H vibration in IR spectra of our device quality poly-Si films grown by hot-wire chemical vapour deposition (HWCVD) made at low wire temperature (Tw=1800 °C) is at 2000 cm−1 whereas in a poly-Si film made at high wire temperature (Tw=1900 °C) both 2000 cm−1 vibrations as well as 2100 cm−1 are observed. On the other hand, the Raman spectra (probing the upper part of the film) of Si-H stretching vibration measured for both these samples show only 2000 cm-1 mode. XTEM micrographs of these films show that whereas the low Tw film has a structure made of closely packed crystalline columns, the high Tw film has conical crystalline structures with amorphous region between them. The crystal cones meet each other towards the top of the film and form a closed structure. This is confirmed by Raman spectrum at 520 cm−1. We attribute the 2100 cm−1 mode to the Si-H bonds at the surface of the cones touching the amorphous regions. The Si-H vibration shifts to 2000 cm-1 when the crystalline cones coalesce with each other, as is the case in the upper part of both types of films.

scholarly journals Polycrystalline silicon films obtained by hot-wire chemical vapour deposition

1994 ◽  
Vol 59 (6) ◽  
pp. 645-651 ◽  
Author(s):  
J. Cifre ◽  
J. Bertomeu ◽  
J. Puigdollers ◽  
M. C. Polo ◽  
J. Andreu ◽  
...  
Keyword(s):  
Chemical Vapour Deposition ◽  
Polycrystalline Silicon ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Silicon Films ◽  
Hot Wire ◽  
Polycrystalline Silicon Films

Piezoresistive Properties of Boron-Doped PECVD Micro- and Polycrystalline Silicon films

1994 ◽  
Vol 343 ◽  
Author(s):  
M. Le Berre ◽  
M. Lemiti ◽  
D. Barbier ◽  
P. Pinard ◽  
J. Cali ◽  
...  
Keyword(s):  
Polycrystalline Silicon ◽  
Grazing Angle ◽  
Amorphous State ◽  
Silicon Films ◽  
Gauge Factor ◽  
X Ray Diffraction ◽  
Boron Doped ◽  
Polycrystalline Silicon Films ◽  
Oriented Material

ABSTRACTThe electrical and piezoresistive properties of in-situ doped PECVD silicon films deposited on oxided silicon wafers have been investigated. One series of films was deposited in the so-called microcrystalline state at 450°C. The other set of samples was deposited in the amorphous state at 320°C and subjected to rapid thermal annealing. Structural properties (grain size, texture, residual stress) were evaluated experimentally through TEM and grazing angle X ray diffraction and related to the measured gauge factor. A maximum longitudinal gauge factor of 28 is measured in the case of advantageously textured microcrystalline material, the magnitude of the gauge factor decreasing sharply for randomly oriented material. For the amorphous deposited and subsequently annealed material, the longitudinal gauge factor is in the range 22–27 depending on dopant concentration. These experimental features are compared to the results of a theoretical approach of piezoresistance in polysilicon. We derive various expressions of the gauge factor according to the assumptions of either constant stress or constant strain within the aggregate. In the case of untextured films, analytical Voigt-Reuss-Hill averages for the elements of piezoresistive and elastoresistive tensors lead to greatly simplified expressions. Theoretical estimates are shown to be in reasonable agreement with the experimental measurements. This confirms the great potential of PECVD microcrystalline and polycrystalline silicon for strain gauges.

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