Interface band offset determination of ultra-thin oxides grown on TiO2 and ZnO by x-ray photoelectron spectroscopy

Abstract

The knowledge of the electronic structure of the interface is important when designing microelectronic devices with maximum efficiency, based on oxide heterostructures. The design of microelectronic devices tends to utilize thinner layers of materials in order to reduce their overall volume and to maximize their efficiency, resulting in layers up to a few nanometers. Incorporation of sub-nanometer oxides onto oxide surfaces is often used to improve the efficiency of polymer solar cells. In this work, the chemical composition and the valence band of interfaces formed by ultra-thin, less than 1 nm, atomic layer deposited Al2O3, ZrO2, HfO2, Ta2O5 and ZnO films, onto TiO2 and ZnO substrates, were studied by x-ray photoelectron spectroscopy. The electronic structure of the interface was examined, based on the conduction and valence band offsets, which were determined using the Kraut method.