Synthesis and Characterization of a-Si_xC_y Thin Films Prepared by RF Magnetron Co-Sputtering Technique

Abstract

Si-C based alloys have attracted much attention due to their potential applications in electronic and optical devices. In this paper, a-SixCy thin films with different Silicon (Si) content are obtained by sputtering of SiC; co-sputtering of SiC and Si targets at different deposition temperatures (Td) such as 200oC, 350oC and 500oC. It is annealed at various annealing temperature (Ta) using conventional thermal annealing (CTA) and Rapid Thermal Annealing (RTA) techniques. The effect of excess Si incorporation and the unintentional oxidation during various stages of sample preparation are discussed. Their structural and optical properties are investigated using spectroscopic ellipsometry, X-Ray Diffraction spectroscopy (XRD), and Fourier Transform Infrared spectroscopy (FTIR). The refractive index value (n1.95eV) varies between 1.6 to 3.6, suggesting the transition from porous silicon carbide to Si-rich silicon carbide or silicon oxycarbide upon increasing Td and Ta, which is also supported by the FTIR spectra. The emergence of absorption peak between ~950 cm−1 and 1100 cm−1 with the increase of Ta and excess silicon is attributed to Si-O a stretching vibration bond which is an indication of Si richness and unintentional oxidation during annealing. Detailed analysis on the process parameters and the evolution of phase transformations are discussed.