Tunable electronic and optical properties of CdO/ZrS2 heterostructure based on first principles

Abstract

In this research, the first-principles calculations based on the density functional theory (DFT) is used to work on and to tune the geometric configuration, optical characteristic, and electronic performance of the CdO/ZrS₂ heterostructure. The results reveal that the CdO/ZrS₂ heterostructure is a Type-II van der Waals heterojunction (vdWH). It is detected that the Type-II CdO/ZrS₂ heterojunction of a layer distance of 3.04 Å has the most stable structure with a direct bandgap of 0.3311 eV. The bandgap value of the heterojunction is smaller than the bandgaps of the two monolayers, which benefits the separation of photogenerated carriers. The transformation of a semiconductor into a metal can emerge by way of both the utilization of an external applied electric field and the imposition of strain. Under the utilization of the external electric fields and biaxial strain, the heterojunction reserves a Type-II band arrangement. By applying biaxial strain of 6 %, the increase of Eg reaches its maximum value of 0.9549 eV, and the heterojunction shows a transition from direct-gap to indirect-gap. The use of an external applied electric field and the imposition of strain can improve the light absorption coefficient of the heterojunction, making the absorption spectra of the heterostructure to exhibit a blue or red shift, which adjusts the optical properties of the heterojunction. There are expectations that this research can furnish theoretical reference value for pertinent experiments and assistance for the heterostructure in the new generation of optoelectronic materials.