The influence of deposition time on the photoluminescent properties of SiOxCy thin films obtained by Cat-CVD from monomethyl silane precursor

Abstract

In recent years, silicon-related photoluminescent materials have attracted great attention due to their optical properties. This work aims to study the deposited silicon oxycarbide (SiOxCy) thin films by using the Organic Catalytic Chemical Vapor Deposition (O-Cat CVD) technique. Monomethyl Silane gas [MMS; (CH3-SiH3)] was used as an organometallic silicon precursor, and tantalum (Ta) filament was used as a catalyst. The influence of deposition time on the photoluminescent properties, resulting from the Si/C ratio in thin layers, was assessed. The nature of shifted silicon-oxygen stretching bonds from their stoichiometry value was discussed by Fourier Transform Infrared (FTIR) analysis. The chemical composition of the SiOxCy matrix was confirmed by X-ray Photoelectron Spectroscopy (XPS) analysis. Wide and intense photoluminescence (PL) emissions were observed for as-deposited films at substrate temperatures as low as 200 °C and the origin of emissions was explained by different defect mechanisms. Moreover, the shift of PL spectra from the red to the blue band was also explained. This investigation provides further understanding of the SiOxCy thin film properties to improve its optical properties and produce it more safely.