In-situ characterization of the amorphous to microcrystalline transition in hot wire CVD growth of Si:H using real time spectroscopic ellipsometry

We have used in-situ real-time spectroscopic ellipsometry (RTSE) to characterize the morphology and crystallinity of hot-wire CVD (HWCVD) Si:H films as a function of hydrogen dilution R=[H]/[H+SiH₄], substrate temperature T_s, and film thickness d_b. Transitions from one mode of film growth to another are correlated with changes in the magnitude of the surface roughness during growth. The degree of crystallinity of the film can be determined from the form of the dielectric function. We have studied the growth parameter space for R from 0 to 14, T_s of 250°C and 500°C, and db from 0 to 1 μm. We have mapped out the crystallinity vs. R, T_s, and d_b based on our analysis of the RTSE data. These results have been corroborated using Raman scattering and atomic force microscopy to characterize the crystallinity and surface morphology of the films.