Short-range effect at the semi-coherent metal/its native oxide interface

Abstract

Fundamentally understanding the variations of atomistic and electronic properties at the interface of metal/its native oxide systems plays a critical role in many important technological processes and applications, such as oxidization, corrosion, chemical catalysis, fuel reactions, and thin-film process. Here, we have adopted the representatively semi-coherent Cu2O(111)/Cu(100) interface and demonstrated, by first-principles calculations on energetic and electronic structures of a total 9 candidate interfacial models, that the preferred geometries (i.e., that having the largest adhesion energy) are those possess the shortest interfacial distance between O terminated Cu2O and substrate Cu. Using several analytic methods, we have thoroughly characterized the variation of electronic states from the interface to Cu2O constituent, and determined that the large degree of charge accumulation at the interface is at the expense of depletion of charge in both substrate Cu and neighboring Cu (Cu2O) to the interfacial O atoms. Strikingly, in Cu2O the conducting states appear only in monolayer proximal to Cu2O/Cu interface, as well, the second layer remains in semi-conducting state as its bulk, indicating a short-range effect in electronic properties induced by Cu substrate. The theoretical calculations provide insight into the complex electronic properties of the functional Cu2O/Cu interface, which was quite difficult to observe by experimental methods alone. The unique properties are of practical importance for further understanding and improvement of such a promising class of metal/native oxide interface at the atomic scale.