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

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 (Y-c) 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 similar to 3-6 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 (C-o) increases initially with Y-c and afterwards it decreases. Strong room temperature photoluminescence (PL) peak is obtained for the as-deposited films having lower oxygen content (C-o). The origin of room temperature PL spectra and its correlation with C-o can be explained by quantum confinement effect (QCE) theory.

Automated summary

Undoped hydrogenated silicon oxide thin films were prepared using RF PECVD method, and the impact of carbon dioxide dilution on their optoelectronic and structural properties was thoroughly studied. The films were analyzed for surface morphology using various microscopy techniques, revealing the presence of uniformly embedded silicon nanocrystallites. FTIR spectra showed an initial increase followed by a decrease in oxygen content with increasing carbon dioxide dilution, with films having lower oxygen content exhibiting stronger PL peaks.