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 ◽  
...  

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.

2000 ◽  
Vol 609 ◽  
Author(s):  
J.K. Rath ◽  
R.E.I. Schropp

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.


1999 ◽  
Vol 557 ◽  
Author(s):  
M. Ichikawa ◽  
J. Takeshita ◽  
A. Yamada ◽  
M. Konagai

AbstractA new process, the Hot Wire Cell method, was developed and successfully used to grow polycrystalline silicon thin films at a low temperature and high growth rate. In the Hot Wire Cell method, reactant gases are decomposed as a result of reacting with a heated tungsten filament placed near to a substrate and polycrystalline silicon films can be deposited at a growth rate of 1.2nm/s without hydrogen dilution and 0.9nm/s with the use hydrogen dilution. The film crystallinity changed from amorphous to polycrystalline due to the addition of hydrogen, thus hydrogen dilution was effective for improving film crystallinity. Furthermore, we obtained (220) oriented polycrystalline silicon thin films with a 90% crystal fraction by the use of hydrogen dilution. These results showed that the Hot Wire Cell method is promising for the deposition of device-grade polycrystalline silicon films for photovoltaic applications.


1996 ◽  
Vol 420 ◽  
Author(s):  
A. R. Middya ◽  
J. Guillet ◽  
J. Perrin ◽  
J. E. Bouree

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.


1994 ◽  
Vol 59 (6) ◽  
pp. 645-651 ◽  
Author(s):  
J. Cifre ◽  
J. Bertomeu ◽  
J. Puigdollers ◽  
M. C. Polo ◽  
J. Andreu ◽  
...  

2006 ◽  
Vol 497 (1-2) ◽  
pp. 157-162 ◽  
Author(s):  
Bin Ai ◽  
Hui Shen ◽  
Zongcun Liang ◽  
Zhi Chen ◽  
Guanglin Kong ◽  
...  

2020 ◽  
Vol 705 ◽  
pp. 137978 ◽  
Author(s):  
Edris Khorani ◽  
Tudor E. Scheul ◽  
Antulio Tarazona ◽  
John Nutter ◽  
Tasmiat Rahman ◽  
...  

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