ELECTRONIC-STRUCTURE OF SEMICONDUCTOR OXIDES - INPO4, IN(PO3)3, P2O5, SIO2, ALPO4, AND AL(PO3)3

The electronic structure of InP oxides, AlP oxides, and SiO2 is investigated both experimentally and theoretically. X-ray-photoemission valence-band spectra are compared with tight-binding calculations in order to analyze the different contributions to each spectrum. Oxygen-oxygen interactions must be included to explain the experimental features. A systematic analysis of the SiO2-AlPO4-InPO4 and InPO4-In(PO3)3-P2O5 family evolution is made. The nature of the atomic states participating in the valence-band spectra is identified. The role of In and Al atoms in the valence band is analyzed, and we conclude that their influence is not negligible in the cases of InPO4 and AlPO4. We can distinguish two types of oxygen atoms in some oxides: Ob bridging different PO4 tetrahedra, and Onb only linked to one P atom. We conclude that the presence or absence of Ob has observable consequences in the XPS valence-band spectra. © 1990 The American Physical Society.