Study on interactions between Cadmium and defects in Cd-doped ZnO by first-principle calculations

摘要

An ab initio calculation based on density functional theory is applied to study the formation energy and transition energy level of defects and complexes in Cd-dopped ZnO. The calculation shows that the incorporation of Cd into ZnO leads to the increase of the O vacancies (V_o). V_o exists in the form of Cd_(Zn)-V_o complex, which can balance the strain caused by Cd_(Zn) and V+o. Due to high formation energy of the Zn interstitials (Zn,) and deep transition energy level of V_o, Zn_i and V_o cannot serve singly as the source of the n-type carriers in Cd-dopped ZnO. It is also found that the Zn_i-Cd_(Zn)-V_o complex is a shallow donor like Zn_i, but has lower formation energy. Thus, the source of n-type carriers is believed to be a complex with Zn_iCd_(Zn)-V_o structures in Cd-doped ZnO.