The Electronic and Optical Properties of InSe-GeTe Heterobilayer via Applying Biaxial Strain.

Guofeng Yang,Rui Sun,Feng Xie,Qian Fan,Xianfeng Ni,Yueke Wang,Yu Ding,Yan Gu,Xing Gu,Bin Hua,Xiumei Zhang

doi:10.3390/nano9121705

Abstract

A comprehensive insight into the electronic and optical properties of small-lattice-mismatched InSe-GeTe heterobilayer (HBL) is performed based on the density functional theory (DFT) with van der Waals corrections from first-principles perspective. The optimization of most stable geometric stacking mode for the InSe-GeTe HBL is demonstrated. In addition, it is found that the InSe-GeTe HBL forms a type-II heterostructure of staggered-gap band alignment, resulting in an indirect band gap of 0.78 eV, which could be employed as a separator for electron-hole pairs. Moreover, the influence of biaxial strain on the electronic and optical properties of the InSe-GeTe HBL are systematically explored by calculating the band structures, density of states (PDOS), electron density differences, and optical absorption spectra of InSe-GeTe HBL under compressive and tensile biaxial strains. The results indicate that the electronic structures and optical performance of InSe-GeTe HBL could be modulated by changing the biaxial strain conveniently. Our findings provide new opportunities for the novel InSe-GeTe HBL to be applied in the electronic and optoelectronic fields.

Highlights

The promising and sustainable strategies of how to improve the utilization of solar energy has become a hot research topic, including solar cells, photo-degradation of contaminants, and so on [1]
The geometric structure optimizations and calculations were carried out by first-principles based on density functional theory (DFT) with the Linear combination of atomic orbitals (LCAO) model in QuantumATK O-2018.06 code [15,16,17]
GeTe Van der Waals (vdW) HBL under biaxial strains based on first-principles calculations

Summary

Introduction

The promising and sustainable strategies of how to improve the utilization of solar energy has become a hot research topic, including solar cells, photo-degradation of contaminants, and so on [1]. Appropriate band structure and advantageous charge separation are extremely important for efficient use of solar energy. The vast majority of electron-hole pairs generated by photo excitation usually readily recombine in single semiconductor materials, owing to the occupation of the same area in space. There was still no effective strategy to work out an appropriate single material system to satisfy these requirements. Until 2013, the advent of two-dimensional (2D) Van der Waals (vdW) heterostructures, formed by stacking different 2D atomic semiconductor materials on top of each other, opened up new strategies for researchers to modulate 2D material properties to achieve superior optoelectronic device performance [3]. Based on previous reports, type-II staggered-gap structure could achieve effective spatial separation of photo-generated hole-electron pairs, breaking the limitations of an individual material.

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