X-Ray Photoelectron Spectroscopic Study of Oxidation of InP

Abstract

InP was oxidized chemically (in boiling deionized water), thermally (dry oxygen, 260°C, 30 min) and chemically under light illumination from a xenon arc lamp. The chemical compositions and their depth distributions from the surface of these oxides as well as the InP native oxide (naturally grown) were studied by angle-resolved X-ray photoelectron spectroscopy (XPS) and XPS combined with in situ Ar + ion etching. In any oxide, indium is first oxidized to form In 2 O 3 perhaps due to depletion of phosphorus from the InP surface induced by contact annealing, etc. InPO 3 and/or InPO 4 are then successively grown on an In 2 O 3 or In 2 O 3 rich layer. In and P atoms diffuse through the already grown In 2 O 3 layer and react with oxidant at the surface to form InPO 3 and/or InPO 4 . Light illumination was found to strongly enhance oxidation of InP, and substantially increase InPO 3 and InPO 4 .