Optical Characteristics of Polycrystalline 3C-SiC for Harsh Environments

Raman spectra of poly (polycrystalline) 3C-SiC thin films, which were deposited on the oxidized Si substrate by APCVD, have been measured. They were used to study the mechanical characteristics of poly 3C-SiC grown in various temperatures. TO and LO modes of 2.0 mum poly 3C-SiC grown at 1180degC occurred at 794.4 and 965.7 cm-1. Their FWHMs (full width half maximum) were used to investigate the stress and the disorder of 3C-SiC. The broad FWHM can explain that the crystallinity of 3C-SiC grown at 1180degC becomes polycrystalline instead of the disordered crystal. The ratio of intensity I(LO)/I(TO) ap 1.0 means that the crystal defect of 3C-SiC/SiO2/Si is small. The biaxial stress of poly 3C-SiC was obtained as 428 MPa. In the interface of 3C-SiC/SiO2, the phonon mode of C-O bonding appeared at 1122.6 cm-1. The phonon modes related to D and G bands of C-C bonding were measured at 1355.8 and 1596.8 cm-1 respectively.