HfS2/MoTe2 vdW heterostructure: bandstructure and strain engineering based on first-principles calculation.

Xinge Yang,Xiande Qin,Kunming Gu,Nadeem Abbas,Jiaoning Tang,Yu Li,Junxuan Luo

doi:10.1039/c9ra10087c

Abstract

In this study, a multilayered van der Waals (vdW) heterostructure, HfS2/MoTe2, was modeled and simulated using density functional theory (DFT). It was found that the multilayers (up to 7 layers) are typical indirect bandgap semiconductors with an indirect band gap varying from 0.35 eV to 0.51 eV. The maximum energy value of the valence band (VBM) and the minimum energy value of the conduction band (CBM) of the heterostructure were found to be dominated by the MoTe2 layer and the HfS2 layer, respectively, characterized as type-II band alignment, leading to potential photovoltaic applications. Optical spectra analysis also revealed that the materials have strong absorption coefficients in the visible and ultraviolet regions, which can be used in the detection of visible and ultraviolet light. Under an external strain perpendicular to the layer plane, the heterostructure exhibits a general transition from semiconductor to metal at a critical interlayer-distance of 2.54 Å. The carrier effective mass and optical properties of the heterostructures can also be modulated under external strain, indicating a good piezoelectric effect in the heterostructure.

Highlights

In the past decade, two-dimensional materials (2D materials) have attracted great interest due to their inherent ultra-thin features and robust lattice structure.[1,2,3] Among them, the family of transition metal disul de (TMD) materials, a new generation of optoelectronic functional materials with rich physical properties, known as post-graphene materials have wide application prospects.[4]
In the ab plane, the chemical bonds between metal and sulfur atoms are hybrid ion/covalent bonds, while the interlayer is superimposed by the weak van der Waals (vdW) interaction along the c axis.[48,49]
Rst principle calculation method was used to explore in detail the construction and bandstructure, effective mass and strain effect of the hybrid layered HfS2/MoTe2 vdW heterostructure

Summary

Introduction

Two-dimensional materials (2D materials) have attracted great interest due to their inherent ultra-thin features and robust lattice structure.[1,2,3] Among them, the family of transition metal disul de (TMD) materials, a new generation of optoelectronic functional materials with rich physical properties, known as post-graphene materials have wide application prospects.[4]. TMDs such as MoS2,2,8 MoSe2,10 MoTe2,11–13 WS2,14 WSe2 15 and so on have been the focus of a lot of research

Methods

Results

Conclusion