Selective electron-induced decomposition of CVD SiO2 overlayers on oxides

Abstract

The electron-induced decomposition (EID) of SiO2 overlayers on various high surface area oxide substrates was studied using Auger electron analysis (AES). Bulk SiO2 was stable upon electron bombardment, but bulk Al2O3 decomposed readily to elemental Al when the primary electron beam energy was 2 keV and the beam current was 6–16 μA. On the other hand, SiO2 overlayers having an average thickness of about 10 Å on Al2O3 decomposed selectively under the same conditions. In contrast to Al2O3 substrates, SiO2 overlayers on TiO2, ZrO2, and MgO were quite stable to the same electron bombardment. Therefore it is concluded that Al2O3 accelerates the EID of SiO2 overlayers and the SiO2 overlayer suppresses EID of Al2O3 substrates.