A New Look at the Electronic Structure of Transparent Conductive Oxides—A Case Study of the Interface between Zinc Magnesium Oxide and Cadmium Telluride

By combining X‐ray and ultraviolet photoelectron spectroscopy, X‐ray excited Auger electron spectroscopy, and inverse photoemission spectroscopy, a detailed characterization of the chemical and electronic structure at the CdTe/(Zn,Mg)O interface is presented. In doing so, a novel approach to characterize the electronic structure of transparent conductive oxides, namely, to distinguish between optically and transport‐relevant states is presented. Consequently, “optical” and “electronic” band offsets at the CdTe/(Zn,Mg)O interface are derived and it is demonstrated that the “electronic” band offset is suitable for electron transport across the interface (a flat conduction band alignment of 0.02 ± 0.20 eV), while the “optical band offset” is not (a significant 0.48 ± 0.20 eV spike). The new approach can easily be applied to many other transparent conductive oxides and is thus of relevance for a large variety of optoelectronic applications involving transparent electrical contacts.