SiO2 films deposited on Si substrates studied by monoenergetic positron beams

Abstract

Variable‐energy positron beams were utilized to study SiO₂ films grown on Si substrates. Annihilation characteristics of positrons in the SiO₂ films were found to be dominated by the formation probability of positronium (Ps). For the SiO₂ film grown by wet oxidation, a high formation probability of Ps was found by measurements of Doppler broadening profiles of the annihilation radiation and those of lifetime spectra. For SiO₂ films grown by an atmospheric‐pressure chemical vapor deposition technique using tetraethylorthosilicate and ozone, however, the formation probability of Ps drastically decreased. The inhibition of the Ps formation was attributed to interactions between positrons and –OH bonds.