Cd:O共掺杂AlN的电子结构和p型特性研究

为研究Cd：O共掺杂纤锌矿AlN的p型特性，进而揭示导致纤锌矿AlN空穴浓度增加的机理，对Cd：O共掺杂AlN进行了基于密度泛函理论的第一性原理研究.通过计算Cd_n-O（n=1，2，3，4）复合体掺杂AlN的结合能，发现Cd：O在AlN中可以稳定存在，共掺杂提高了Cd在AlN中的固溶度.分析Cd和Cd₂-O掺杂AlN体系的激活能，发现Cd₂-O的激活能比Cd减小0.21 eV，表明Cd₂-O的空穴浓度比单掺Cd大约提高关键词：Cd：O共掺杂纤锌矿AlN电子结构p型掺杂特性

Study of the electronic structure and the properties of p-type doping in Cd:O codoped AlN

In order to investigate the properties of the p-type doping and reveal the mechanism of the hole concentration increasing after Cd：O codoping of wurtizite AlN，we have carried out first-principles calculations based on density-functional theory (DFT) for wurtizite AlN system. By calculating the binding energy of the Cd_n-O（n=1，2，3，4）complex codoped AlN we found that Cd：O can be stabilized and the solubility of Cd can be increased in the system. We analysed the activation energies of the Cd and Cd₂-O doped AlN and found that the activation energy of Cd₂-O was decreased by 0.21 eV from that of Cd，which showed that the hole concentration of Cd₂-O doped system was raised 10³ times as that of Cd. We compared the band structures and densities of states，and found that the electrons of Cd atom on the 4d orbit moving to 2p orbit of N atom results in that the impurity levels which appeared near the Fermi level always occupy the highest valence band. Increasing the number of Cd atoms，the holes can occupy more states. In order to reduce the combining probability of Cd and O，hence，to enhance the Cd-N covalent characteristics and improve the hole concentration，it is important to control properly the concentrations of Cd and O.