Piezoelectric properties of substitutionally doped $\beta$-Ga$_2$O$_3$

TL;DR

This study reveals that substitutionally doped $eta$-Ga$_2$O$_3$ exhibits piezoelectric properties, which are absent in pristine form, and links formation energy to piezoelectric coefficients using first principles calculations.

Contribution

It is the first to demonstrate piezoelectricity in doped $eta$-Ga$_2$O$_3$ and establishes a relationship between formation energy and piezoelectric response.

Findings

Doped $eta$-Ga$_2$O$_3$ shows piezoelectric properties.

Formation energy correlates with piezoelectric coefficients.

First principles calculations confirm the phenomenon.

Abstract

Modern semiconductor materials are increasingly used in multidisciplinary systems demonstrating cross-interactions between mechanical strains and electronic potentials, which gives rise to ubiquitous applications in high sensitivity, self-powered sensor devices. One of fundamental prerequisites for such semiconductor materials to exhibit piezoelectric properties is the noncentrosymmetry of the crystal structures. $\beta$-Ga$_2$O$_3$ has been an emerging compound semiconductor material due to its ultra-wide bandgap. However the pristine $\beta$-Ga$_2$O$_3$ has an inversion center, displaying no piezoelectric effect. This work discovered that substitutionally doped $\beta$-Ga$_2$O$_3$ possesses piezoelectric property by using first principles method, while majority of previous research on its substitutional doping has been focusing on the purposes of increasing electrical conductivity and formation of the semiconductor heterojunctions. More interestingly, it is unveiled from this work that the formation energy has a clear relation with the piezoelectric coefficient.