Study on the doping stability and electronic structure of wurtzite Zn1−xCdxO alloys by first-principle calculations

An ab initio calculation based on density functional theory is applied to study the doping stability and electronic structure of wurtzite Zn1−xCdxO alloys. It is found that the different alloy configurations of Zn1−xCdxO with a given Cd content are possible thermodynamically, but having different band gaps. With increasing Cd content, the formation enthalpy of Zn1−xCdxO alloy increases sharply. The Cd-content dependence of the band-gap values can be fitted with a second-order polynomial. The reduction of band gap can be attributed to the contributions of the hybridization of Zn-4s and Cd-5s, the enhancement of p–d repulsion, and the tensile strain due to Cd-doping.