Photoluminescence and photoluminescence excitation from porous silicon carbide

The dependence of photoluminescence (PL) and photoluminescence excitation ( PLE) on preparation conditions and the aging of porous silicon carbide (PSC ) have been investigated. The fiber size of the material prepared under dar k-current mode, labeled DCM, was larger than that of the photoassisted (PA) process. The intensity of the PL spectrum for the PA condition was higher than that of the DCM condition. The PA condition giving small fiber size ex hibited a more prominent high-energy component but the emission bands of bo th conditions observed were rather similar. The origin of the PL may have p layed an important role in the surface defect center introduced by the reac tion conditions of HF at the surface of the silicon carbide. Selective exci tation of the PL bands using different excitation wavelengths has been used to identify distinct components within the PL bandwidth. Two main PL bands with peak wavelength of 494 and 534 nm were clearly resolved. On the other hand, selective emission of the PLE bands using different omission wavelen gths has been used to identify distinct components within the PLE bandwidth . The higher energy band with peak wavelength of 338 nm and the lower energ y bands involving 390, 451 and 500 nm were clearly resolved. According to t he prolonged aging in air, PL spectra appeared as one band. This emission p robably originated from states localized to the band-to-band recombination due to the oxidation on the crystallite surface.