HW-CVD Deposited Nanocrystalline Silicon Thin Films at Low Substrate Temperature with White-Blue Luminescence

We report the influence of deposition pressure on the morphology and structural properties of the nanocrystalline silicon (nc-Si) particles embedded in amorphous silicon oxide (a-SiOx) using hot wire chemical vapor deposition (HW-CVD). Catalyst material Tantalum (Ta) was employed for the decomposition of source gases in the reaction chamber. X-Ray diffraction (XRD) and Raman spectroscopy techniques were used to understand the thin film phase transition. Different bonds in the films, for example Si-H, were identified using Fourier transform infrared spectroscopy (FTIR) and the role of hydrogen species in inducing crystallization has been discussed. Particular pressure limit has been found to be adequate for the growth of silicon related crystalline particles. The samples deposited at substrate temperature of 200 °C, has shown photoluminescence spectra from blue to red zone, and the parts of the visible spectra has been found to be in correlation with the size of nc-Si and/or defects present in the thin film. This low temperature deposited Si based thin films using HW-CVD could be useful for a visible light emitting device production. Keywords: Blue-white luminescence, deposition pressure, HW-CVD, hydrogen species, nc-Si, Si-H bonding.