APPEARANCE OF BETA-PHASE CRYSTALLITES IN POROUS LAYERS OF SILICON-CARBIDE

Photoluminescence and vibrational spectroscopy (Raman scattering, infr ared reflection) methods are used to investigate porous SiC samples ob tained from the same crystalline film of n-type 6H-SiC (n(0) = 10(17) cm(-3)). It is shown that efficient photoluminescence in the range 2.5 -2.8 eV arises as a result of interband excitation in the samples in w hich the nanocrystalline phase beta-SiC, which appears on the porous s urface under certain conditions of anodic etching, is clearly observed . It is concluded that the observed photoluminescence is associated wi th the appearance of the beta-SiC phase. The shift of the spectral max imum of the photoluminescence toward higher energies (compared to the crystalline polytype 3C-SIC) is attributed to quantum-well effects. (C ) 1996 American Institute of Physics.