Microstructure, Stress and Defect Evolution

The purpose of this study is firstly to investigate the relation between microstructure, stress and hydrogen distribution in as deposited hydrogenated amorphous silicon (a-Si:H) layers, and secondly the investigation of the influence of illumination on hydrogen evolution and its relationship with the strain in illuminated layers. A set of a-Si:H layers produced by hot wire chemical vapour deposition, at different temperatures using pure silane, was analyzed using different characterization techniques. UV-Visible absorption spectroscopy was used to investigate the bandgap, refractive index and absorption coefficient. These measurements were also used to determine the film thickness. Hydrogen in the bonded form was investigated using Fourier transform infrared spectroscopy (FTIR), while the total hydrogen was estimated with elastic recoil detection analysis (ERD). Direct diffraction patterns from synchrotron diffraction measurements, and the corresponding pair correlation function, were used to investigate the structure and the strain.