On correlation between visible−near-infrared transmittance spectra and structural properties of plasma deposited nanocrystalline silicon thin films

Abstract

Visible−near-infrared transmittance (T) spectra is correlated with the structural properties of hydrogenated nanocrystalline silicon (nc-Si:H) thin films, produced by plasma enhanced CVD (PECVD) under various RF power densities (100−444 mW/cm2), various substrate temperatures (80−200 °C), at different regions of the PECVD electrode (center/edge). It is found that for the highly crystalline films there is downward deviation of maximum T envelope curve (TM) from the glass substrate T (Tsubstrate) in 650−900 nm region, and it is linearly proportional to grazing angle XRD (GAXRD) (111) peak height. Field emission SEM (FE-SEM) surface reveals conglomerates for these films. TM≈Tsubstrate for the films with low GAXRD (111) peak height or fully amorphous samples, which have partially or fully smooth FE- SEM film surface, respectively. The effect of each film structural property (surface roughness, columns, incubation layer, etc.) on the observed deviation of TM from Tsubstrate is considered.