J. Phys. IV France 03 (1993) C4-177-C4-183
Characterization of SiO2 films grown on Si substrates by monoenergetic positron beamsA. UEDONO1, L. WEI1, S. TANIGAWA1, R. SUZUKI2, H. OHGAKI2 and T. MIKADO2
1 Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305, Japan
2 Electrotechnical Laboratory, 1-1-4, Umezono, Tsukuba, Ibaraki 305, Japan
Variable-energy positron beams were utilized to characterize SiO2 films grown on Si substrates. For a SiO2 film grown by wet oxidation, a high formation probability of positronium (Ps) was found by measurements of Doppler broadening profiles of the annihilation radiation and those of lifetime spectra. For the SiO2 films grown by a chemical vapor deposition technique, the formation probability of Ps was found to decrease. This was attributed to interactions between positrons and -OH bonds and to the trapping of positrons by point defects. In order to know annihilation characteristics of Ps in the SiO2 films in more detail, a lifetime spectrum for a vitreous silica glass was also measured.
© EDP Sciences 1993