Connecting semiconductor defect chemistry with electrochemistry: Impact of the electrolyte on the formation and concentration of point defects in ZnO

We study the effect an aqueous electrolyte can have on the concentration and electronic character of native point defects in a semiconducting electrode by utilising a recently derived grand canonical approach. Constructing defect phase diagrams which show the majority defect species as function of applied bias and chemical potential we identify which native point defects of ZnO become important when this semiconductor comes into contact with an aqueous electrolyte at varying pH and bias. Our results show that in thermodynamic equilibrium Zn rather than O vacancies are stable under electrochemical conditions.