Effects of oxygen contamination on monolayer GeSe: a computational study

Abstract

Natural oxidation is a common degradation mechanism of both mechanical and electronic properties for most of the new two-dimensional materials. From another perspective, controlled oxidation is an option for tuning material properties, thereby expanding possibilities for real-world applications. Understanding the electronic structure modifications induced by oxidation is highly desirable for new materials like monolayer GeSe, which is a new candidate for near-infrared photodetectors. By means of first-principles calculations, we study the influence of oxygen defects on the structure and electronic properties of the single-layer GeSe. Our calculations show that oxidation is an exothermic process, and it is nucleated in the germanium sites. Oxidation can cause severe local deformations on the monolayer GeSe structure and introduces a deep state in the band gap or a shallow state near the conduction band edge. Furthermore, oxidation increases the band gap by up to 23%, and may induce direct to indirect band-gap transitions. These results suggest that natural or intentionally induced monolayer GeSe oxidation can be a source of new optoelectronic properties, adding another important building block to the two-dimensional layered materials.