Effect of thermal annealing on the structural, optical and microstructural properties of a-SiC thin films

Abstract

ABSTRACT)Silicon nanocrystals in a host matrix of silicon carbide SiC are important to high band gap dielectrics for solar cells applications. Forming Si-NC is difficult considering that SiC nano-clusters are easily formed in the host matrix. This analysis focuses on the influence of deposition temperature (Td) and annealing ambience to synthesise SiC film for forming Si-NC in the host matrix. Here Si-NC is obtained by co-sputtering Si and C targets at 350°C and 500°C. Annealing is done at various temperatures using vacuum (VA) or conventional thermal annealing (CTA). Its structural and optical properties are investigated using spectroscopic ellipsometry, Fourier-transform spectroscopy (FTIR) and X-ray spectroscopy (XPS). The findings are its refractive index is between 2.69-4.08, showing Si abundance in the film. FTIR spectra shows change in intensity and position of Si-C bond variations of 620-700 cm−1with change in Td and XPS spectra confirms the presence of Si-C- and Si-Si-related bonds, influenced with increase in Td and VA. CTA samples show increase in Si-O related bonds which indicates increase in oxygen presence. Hence a higher Td=5000Cwith VA appears to be a vital to synthesize Si-NC predominantly for optoelectronic applications.