First-principles study on the stability and electronic structure of monolayer GaSe with trigonal-antiprismatic structure

TL;DR

This study uses first-principles calculations to analyze the stability and electronic properties of a new trigonal-antiprismatic GaSe monolayer, revealing its stability and strain-dependent phase stability, aiding understanding of its formation.

Contribution

It introduces the stability and electronic structure of the recently discovered AP phase GaSe monolayer through first-principles calculations, comparing it with the conventional phase.

Findings

AP phase GaSe monolayer is stable.

Energy and lattice constants are similar to the P phase.

Tensile strain reverses phase stability.

Abstract

The structural stability and electronic states of GaSe monolayer with trigonal-antiprismatic (AP) structure, which is a recently discovered new polymorph, were studied by first-principles calculations. The AP phase GaSe monolayer was found stable, and the differences in energy and lattice constant were small when compared to those calculated for a GaSe monolayer with conventional trigonal-prismatic (P) structure which was found to be the ground state. Moreover, it was revealed that the relative stability of P phase and AP phase GaSe monolayers reverses under tensile strain. These calculation results provide insight into the formation mechanism of AP phase GaSe monolayers in epitaxially-grown GaSe thin films.