Optoelectronic and Structural Properties of Plasma Deposited Nanocrystalline Hydrogenated Silicon Oxide Thin Films

Abstract

To develop wide bandgap materials for solar cells and other optoelectronic devices, undoped hydrogenated silicon oxide (SiOx:H) thin films are prepared by conventional radio frequency plasma enhanced chemical vapor deposition (RF PECVD) method. The variation of carbon dioxide dilution ([Formula: see text]) on optoelectronic and structural properties are studied thoroughly by keeping silane and hydrogen gas flow fixed. Surface morphology of the SiOx:H films have been studied by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM). Distinct silicon nanocrystallites of average diameter [Formula: see text] 3–6[Formula: see text]nm embedded uniformly in amorphous SiOx network have been observed in high resolution Transmission Electron Microscopy (HRTEM). From Fourier Transform Infrared spectra (FTIR), it is observed that oxygen content ([Formula: see text]) increases initially with [Formula: see text] and afterwards it decreases. Strong room temperature photoluminescence (PL) peak is obtained for the as-deposited films having lower oxygen content ([Formula: see text]). The origin of room temperature PL spectra and its correlation with [Formula: see text] can be explained by quantum confinement effect (QCE) theory.