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

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.

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.


1995 ◽  
Vol 86 (1-4) ◽  
pp. 600-603 ◽  
Author(s):  
J. Puigdollers ◽  
J. Cifre ◽  
M.C. Polo ◽  
J.M. Asensi ◽  
J. Bertomeu ◽  
...  

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.


1984 ◽  
Vol 35 ◽  
Author(s):  
S.J. Krause ◽  
S.R. Wilson ◽  
W.M. Paulson ◽  
R.B. Gregory

ABSTRACTPolycrystalline silicon films of 300 nm thickness were deposited on oxidized wafer surfaces, implanted with As, and annealed on a Varian IA 200 rapid thermal annealer. Transmission electron microscopy was used to study through-thickness and cross sectional views of grain size and morphology of as-deposited and of transient annealed films. A bimoda] distribution of grain sizes was present in as-deposited polycrystalline silicon films. The first population was due to columnar growth of some grains to a final average diameter of 20 rm. The second population of small equiaxed grains of 5 nm average diameter were formed early in the deposition process. During transient annealing grains in the first population grew rapidly up to 280-nm equiaxed grains. After this the growth rate decreased due to the grain size reaching the thickness of the film. Grains in the second population grew rapidly up to a size of 150 nm, after which the growth rate was lowered due to grains impinging upon one another. The grain growth processes for both populations have been described with a modified model for interfacially driven grain growth. This model accounts for diffusion and grain growth which occur with rapidly rising and falling temperatures during short annealing times characteristic of transient annealing processes.


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