Preparation of hydrogenated microcrystalline silicon films with hot-wire-assisted MWECR-CVD system

Intrinsic hydrogenated microcrystalline silicon (\muc-Si:H) films have been prepared by hot-wire-assisted microwave electron-cyclotron-resonance chemical vapour deposition (HW-MWECR-CVD) under different deposition conditions. Fourier-transform infrared spectra and Raman spectra were measured. Optical band gap was determined by Tauc plots, and experiments of photo-induced degradation were performed. It was observed that hydrogen dilution plays a more essential role than substrate temperature in microcrystalline transformation at low temperatures. Crystalline volume fraction and mean grain size in the films increase with the dilution ratio (R=H₂/(H₂+SiH₄)). With the rise of crystallinity in the films, the optical band gap tends to become narrower while the hydrogen content and photo-induced degradation decrease dramatically. The samples, were identified as \muc-Si:H films, by calculating the optical band gap. It is considered that hydrogen dilution has an effect on reducing the crystallization activation energy of the material, which promotes the heterogeneous solid-state phase transition characterized by the Johnson--Mehl--Avrami (JMA) equation. The films with the needed structure can be prepared by balancing deposition and crystallization through controlling process parameters.