Characterization of porous SiC by variable-energy positron beams

3C-SiC grown on n-type Si wafers by chemical vapor deposition (CVD) was anodized in a HF-ethanol solution. Positron annihilation Doppler broadening and lifetime measurements were carried out to characterize a porous structure formed in the SiC layer. In contrast to the case of porous Si, for which long- lived components with lifetimes 5-30 ns have been reported (Suzuki et al., 1994), a lifetime longer than 1 ns was not observed for the porous SiC. We discuss chemical effect in the pore surface based on the Doppler broadening spectrum in the high momentum region.