Characterization of porous SiC by variable-energy positron beams

3C-SiC grown on n-type Si wafers by chemical vapor deposition (CVD) was ano dized in a HF-ethanol solution. Positron annihilation Doppler broadening an d 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 l ong-lived components with lifetimes 5-30 ns have been reported (Suzuki et a l., 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 broade ning spectrum in the high momentum region. (C) 2000 Elsevier Science Ltd. A ll rights reserved.