Influence of the deposition parameters on the microstructure and opto-electrical properties of hydrogenated nanocrystalline silicon films by HW-CVD

Abstract Hydrogenated nanocrystalline silicon (nc-Si:H) films were prepared at high deposition rates (> 13 A/s) from pure silane without hydrogen dilution by hot wire deposition method by varying filament-to-substrate distance (d s–f ). In this study we have systematically and carefully investigated the effect of filament-to-substrate distance on structural, optical and electrical properties of the Si:H films. A variety of characterization techniques, including Raman spectroscopy, low angle X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FE-SEM), UV–Visible-NIR spectroscopy and electrical dark and photoconductivity measurement were used to characterize these films. Films deposited at d s–f  > 5 cm are amorphous while those deposited at d s–f s–f , the crystallinity and crystalline size increases whereas hydrogen bonding shifts from mono-hydride (Si H) to di-hydride (Si H 2 ) and poly-hydride (Si H 2 ) n complexes. The band gaps of nc-Si:H films (~ 1.9–2.0 eV) are high compared to the a-Si:H films, while hydrogen content remains