Influence of oxygen vacancies on the spontaneous polarisation and piezoelectricity of ZnO: a first-principles study

By using the Berry phase method, influence of oxygen vacancy (Vo) on the polarisation property of ZnO has been investigated. Calculated results indicate that the spontaneous polarisation, the piezoelectric constants e31 and e33 are very sensitive to the concentration and distribution of Vo. The absolute values of them decrease nonlinearly as Vo concentration increases. At the same concentration, non-uniform distribution of Vo is favoured in energy, and can enhance the impact on spontaneous polarisation and e31. 1.56% Vo-Vo complex can even reverse the orientation of the spontaneous polarisation, while the case for e33 is opposite, the influence is weakened. These findings suggest that the polarisation property of ZnO might be adjusted by controlling the point defects.