DEFECTS IN SIO2/SI STRUCTURES PROBED BY USING A MONOENERGETIC POSITRON BEAM

Defects in SiO2/Si specimens were probed by using a monoenergetic positron beam. Doppler broadening profiles of the annihilation radiation were measured as a function of incident positron energy for SiO2(100 nm)/Si specimens fabricated by wet, dry and ultradry oxidation. The diffusion of positrons in the Si substrate was found to be enhanced by an electric field caused by positive charges near the SiO2/Si interface. The Doppler broadening profile corresponding to the annihilation of positrons in the Si substrate with the SiO2 film grown by wet oxidation was found to be broader than those in the specimens fabricated by dry or ultradry oxidation. This was attributed to the fact that the concentration of oxygen clusters in the Si substrate for the specimen fabricated by wet oxidation was higher than those for the specimens fabricated by dry or ultradry oxidation.