Photoluminescence of Polycrystalline SiC Sintered from Graphite and Si Melt

Intense wide-band photoluminescence (PL) with high stability to ultraviolet (UV) light irradiation has been observed in a wide temperature range from a polycrystalline SiC sintered from graphite and melt Si at high temperature over 1500°C. X-ray diffraction results showed that the sintered material consists of mainly cubic and 6H-SiC crystallites oriented randomly and a small amount of graphite with (002) preferential orientation. PL spectra of the samples were measured under excitation of the incident UV light beam from an He-Cd laser (325 nm, 10mW) in the temperature range from 10 to 300 K. The PL spectra were found to be a single wide-band centered around 2.2 eV at room temperature and to be divided into a much more intensive blue band and a less intensive red band at low temperature. The low temperature PL bands consist of several luminescence peaks that change in intensities relatively with variation of temperature.