论文部分内容阅读
Intrinsic hydrogenated microcrystalline silicon (μc-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 μc-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 crystaUization through controlling process parameters.