Papers by Keyword: nc-Si:H

Abstract: We report for the first time a simple optimization of triple-junction solar cell nc-Si:H/a-Si:H/a-SiGe:H using computer modeling and Robust Design. Firstly we performed a computer modeling of solar cell by wxAMPS software. Subsequently, we investigated the parameters of the solar cell layers and the effect of the solar cell efficiency using Robust Design via Taguchi method, ANOVA and additive model. The results show that the a-Si:H middle absorber cell has the highest contribution of solar cell efficiency at 40.87% and the nc-Si:H n-back layer cell has the second highest contribution of solar cell efficiency at 31.15%. Moreover, the optimum condition for triple-junction solar cell is A₂ B₁ C₂ D₂ with solar cell efficiency at 15.73%. These results indicate that Robust Design succeeded predicting the best condition for optimizing triple-junction solar cell nc-Si:H/a-Si:H/a-SiGe:H.

Abstract: Nanocrystalline silicon (nc-Si:H) grown by hot-wire chemical vapor deposition (HWCVD). We report on the effects of B2H6 doping ratio on the microstructural and optoelectrical properties of the p-type nc-Si:H thin films grown by HWCVD at low substrate temperature of 200 °C. An attempt has been made to elucidate the boron doping mechanism of the p-type nc-Si:H thin films deposited by HWCVD and the correlation between the B2H6 ratio, crystalline volume fraction, optical band gap and dark conductivity. Characterization of these films from Raman spectroscopy revealed that the high conductive film consists of mixed phase of nanocrystalline silicon embedded in an amorphous network. A small increase in B2H6 doping ratio showed marked effect on film microstructure. At the optimal condition, high dark conductivity (8 S/cm) with high optical band gap (~2.0 eV) was obtained.

Abstract: In this work we report synthesis and characterization of hydrogenated nanocrystalline silicon (nc-Si:H) thin films by plasma chemical vapor deposition (P-CVD) method at 200 0C on glass substrates. Film properties are carefully and systematically investigated as a function of argon (Ar) flow rate. Characterization of these films with Raman spectroscopy revealed that the addition of Ar into SiH4-H2 plasma endorses the growth of crystallinity in the films. The Fourier transform infrared (FTIR) spectroscopic analysis showed that with increasing Ar flow rate the hydrogen bonding in the films shifts from mono-hydride (Si-H) to di-hydride (Si-H2) and (Si-H2)n complexes. The hydrogen content in the films was found < 7 at. % over the entire range of studied Ar flow rate. The band gap of nc-Si:H films was found to be higher than hydrogenated amorphous silicon (a-Si:H) films (> 2 eV). The nc-Si:H films with dark conductivity 1.3x10-7 S/cm having deposition rate as high as 2.5 Å/s and of crystalline fraction 98 % have been obtained.