Optical transmission, photoluminescence, and Raman scattering of porous SiC prepared from p-type 6H SiC

The optical transmission, temperature-dependence of the photoluminescence ( PL), and Raman scattering of porous SiC prepared from p-type 6H-SiC are com pared with those from bulk p-type 6H-SiC. While the transmission spectrum o f bulk SiC at room temperature reveals a relatively sharp edge correspondin g to its band gap at 3.03 eV, the transmission edge of porous SiC (PSC) is too wide to determine its band gap. It is believed that this wide edge migh t be due to surface states in PSC. At room temperature, the PL from PSC is 20 times stronger than that from bulk SIG. The PL PSC spectrum is essential ly independent of temperature. The relative intensities of the Raman scatte ring peaks from PSC are largely independent of the polarization configurati on, in contrast to those from bulk SIG, which suggests that the local order is fairly random.