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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Cdn-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0.21eV,表明Cd2-O的空穴浓度比单掺Cd大约提高了103倍.对比各掺杂体系的能带及态密度,发现Cd-4d和N-2p态由轨道杂化在费米能级附近形成的杂质能级始终位于价带顶,空穴态随着Cdn-O复合体中Cd数目的增加占据了更多的能态密度.研究表明共掺体系中,适当控制Cd和O的浓度,可以减小Cd和O的复合概率,加强Cd-N的共价特性,对改善AlN的p型特性有重要意义.
In order to study the p-type properties of AlN doped with Cd: O co-doped wurtzite and reveal the mechanism of the increase of AlN hole concentration in wurtzite, the first-order density functional theory Principle calculations. By calculating the binding energy of AlN doped with Cdn-O (n = 1, 2, 3, 4) complexes, it was found that Cd: O can be stably present in AlN and co- The activation energies of Cd and Cd2-O-doped AlN system were analyzed and it was found that the activation energy of Cd2-O was reduced by 0.21eV compared with that of Cd, indicating that the hole concentration of Cd2-O was about 103 times higher than that of Cd-doped Cd. It is found that the energy levels of the Cd-4d and N-2p states formed by orbital hybrids near the Fermi level are always located at the top of the valence band, and the hole states follow the Cdn-O complex The increase of Cd number occupies more energy density.The research shows that proper co-doped Cd and O concentration can reduce the recombination probability of Cd and O and enhance the covalent property of Cd-N, It is important to improve the p-type properties of AlN.