Effect of substrate temperature on silicon Oxycarbide thin films prepared by catalytic chemical vapor deposition

Abstract

Silicon oxycarbide (SiOC) thin films were synthesized using catalytic chemical vapor deposition (Cat-CVD) at substrate temperatures of room temperature, 70 °C, 140 °C, and 210 °C. The impact of substrate temperature on the morphology, composition, and optical properties of the thin films was systematically examined through advanced characterization techniques. Field emission scanning electron microscopy analysis revealed that increased substrate temperatures improved the surface morphology, with reduced surface roughness and enhanced uniformity and continuity. Energy-dispersive spectroscopy and X-ray photoelectron spectroscopy confirmed a compositional shift toward a stoichiometric SiOC ratio at higher temperatures, attributed to more efficient precursor decomposition. Fourier Transform Infrared spectra demonstrated improved structural homogeneity, showing sharper and more intense absorption bands at elevated temperatures, indicative of stronger Si-O-C bonding. Time-resolved photoluminescence measurements revealed a reduction in defect-related non-radiative recombination at higher temperatures, aligning with the increased structural and compositional quality of the films. Ellipsometric analyses indicated a progressive increase in refractive index and film thickness with temperature, correlating with higher film density and fewer structural defects. These findings highlight the role of substrate temperature in controlling the structural, chemical, and optical properties of SiOC thin films.