Strain-Tunable Electronic and Optical Properties of Monolayer Germanium Monosulfide: Ab-Initio Study

P T T Le,Chuong V Nguyen,Nguyen N Hieu,Nguyen V Hieu,I V Ershov,V V Ilyasov,Huynh V Phuc,N A Poklonski,Bui D Hoi,Ngo X Cuong,G A Geguzina,Tuan V Vu,Doan V Thuan

doi:10.1007/s11664-019-06980-7

Abstract

In the present work, we consider systematically the electronic and optical properties of two-dimensional monolayer germanium monosulfide (GeS) under uniaxial strains along armchair (AC-strain) and zigzag (ZZ-strain) directions. Our calculations show that, at the equilibrium state, the monolayer GeS is a semiconductor with an indirect band gap of 1.82 eV. While monolayer GeS is still an indirect band gap semiconductor under ZZ-strain, an indirect–direct energy gap transition can be found in the monolayer GeS when the AC-strain is applied. The optical spectra of the monolayer GeS have strong anisotropy in the investigated energy range from 0 eV to 8 eV. Based on optical properties, we believe that the monolayer GeS is a potential candidate for applications in energy conversion and optoelectronic technologies.

Highlights

germanium monosulfide (GeS) is a semicondIuncttohr ewitphraenseinndtirewcot rbka,ndwe consider systematically the electronic and optical gap of 1.82 eV
The use of functionals greatly influences the outcome of calculations for the energy band gap.2'7 Technically, the band gap of the GeS may be changed by engineering strain or external electric field[2] and the semiconductor-metal phase transition has been observed in the monolayer GeS at large biaxial uniform strain[7] or under an external electric field.[20]
We found that each unit cell of the monolayer GeS consists of two Ge atoms and two S atoms

Summary

Introduction

GeS is a semicondIuncttohr ewitphraenseinndtirewcot rbka,ndwe consider systematically the electronic and optical gap of 1.82 eV. We systematically consider the electronic and optical properties of monolayer GeS under the uniaxial strains along individually both the armchair (ACstrain) and zigzag (ZZ-strain) directions using DFT calculations.

Results

Conclusion