Polarization, piezoelectric constants and elastic constants of ZnO, MgO and CdO

TL;DR

This paper uses first principles density functional calculations to determine the polarization, piezoelectric, and elastic constants of ZnO, MgO, and CdO in the wurtzite structure, revealing larger properties than GaN, AlN, and InN.

Contribution

It provides the first-principles calculations of these properties for ZnO, MgO, and CdO, highlighting their potential for polarization field effect transistors.

Findings

Polarization values: -0.05, -0.17, -0.10 C/m$^2$ for ZnO, MgO, CdO

Piezoelectric constants: e_{33} and e_{31} values for each material

Larger internal fields predicted in ZnO-based devices

Abstract

We report first principles density functional calculations of the spontaneous polarizations, piezoelectric constants and elastic constants for the II-VI wurtzite structure ZnO, MgO and CdO. Using our self interaction corrected implementation of density functional theory we obtain polarization values of we obtain polarization values of -0.05, -0.17 and -0.10 C/m$^2$, and piezoelectric constants, $e_{33}$ ($e_{31}$) of 1.34 (-0.57), 2.26 (-0.38) and 1.67 (-0.48) C/m$^2$ for structurally relaxed ZnO, MgO and CdO respectively. These properties are consistently larger in magnitude than the corresponding GaN, AlN and InN analogues. Therefore we predict that larger internal fields will be attainable in ZnO-based polarization field effect transistors than in equivalent GaN-based devices.