The microstructure of hydrogenated microcrystalline silicon thin films studied by small-angle x-ray scattering

Abstract

The microstructures of hydrogenated microcrystalline silicon (μc-Si:H) thin fil ms, prepared by plasma-enhanced chemical vapor deposition (PECVD), hot wire CVD( HWCVD) and plasma assisted HWCVD (PE-HWCVD), have been analyzed by the small ang le x_ray scattering(SAXS) measurement. The SAXS data show that the microstructur es of the μc-Si:H films display different characteristics for different deposit ion techniques. For films deposited by PECVD, the volume fraction of micro-voids and mean size are smaller than those in HWCVD sample. Aided by suitable ion-bom bardment, PE-HWCVD samples show a more compact structure than the HWCVD sample. The microstructure parameters of the μc-Si:H thin films deposited by two-steps HWCVD and PE-HWCVD with Ar ions are evidently improved. The result of 45° tilti ng SAXS measurement indicates that the distribution of micro-voids in the film i s anisotropic. The Fouriertransform infrared spectra confirm the SAXS data.