Ferroelectricity in Zn1-xMgxO solid solutions

Abstract

First-principles calculations based on density functional theory to identify the effects on ZnO's structural, electronic, and polar properties when doped with Mg2+ ions are presented. The results showed that the lattice parameters decreased with increasing Mg2+ concentrations up to 37%. The calculated gap value of 3.056 eV for the undoped ZnO increased to 3.692 eV with increasing Mg2+ concentration. A spontaneous polarization of ∼134 μC/cm2 was calculated for 37% Mg-doped ZnO along the [0001] direction. The high polarization values of Mg-doped ZnO are due to the local distortion and increased ionicity of the compound along the [0001] direction, accentuated by the structural changes and corresponding bond length modifications that the ZnO structure undergoes. The results reported in this study agree with those reported experimentally and shed light on the origin of the high ferroelectric polarization values measured in Zn1-xMgxO, opening up great potential for memory applications.