Strain Benefits of Monolayer α‐GeTe and its Application in Low‐Power Metal–Oxide–Semiconductor Field‐Effect Transistors

Abstract

2D semiconductors, which have been the candidate channel materials for next‐generation field‐effect transistors (FETs), are now reaching the fundamental limits to what they can offer for higher driving current and switching speed. Low carrier mobility and correspondingly high effective mass hinder such materials to become the ideal electron transport systems. Herein, the electronic and transport properties of strained α‐GeTe are studied for low‐power transistor applications. It is found that monolayer α‐GeTe exhibits a sensitive strain response and undergoes an indirect‐to‐direct bandgap transition at about 2% of tensile uniaxial strain in the zigzag direction, significantly decreasing the electron effective mass and improving electron mobility. In addition, applying tensile strain in the armchair direction can effectively reduce the band‐edge energy of the conduction band minimum (CBM), suggesting that strain can reduce the energy barrier of electrons. These favorable strain responses considerably impact the device performance where both steeper subthreshold swing (SS) and higher on‐state currents can be achieved in monolayer α‐GeTe‐based metal–oxide–semiconductor FETs (MOSFETs). It is hoped that such strain benefits can provide an effective way to modulate the properties of α‐GeTe and finally enhance the device performance.