本文以在蓝绿光激光器及光电子器件中具有重要价值的ZnSe和GaAs材料为研究背景，以ZnSe的掺杂与补偿机制研究为重点，对照GaAs中的掺杂问题，运用离散变分-局域密度泛函(DV-LDF)方法及团簇模型，系统研究了ZnSe和GaAs中的单杂质，及ZnSe中的本征缺陷和杂质缺陷复合体。 研究了I族和V族单杂质在ZnSe中的掺杂行为。结果表明N是其中掺杂结构最稳定且唯一没有导致晶格的Jahn-Teller形变的掺杂元素，从理论上解释了N是ZnSe中相对最好的p型掺杂剂的原因。计算得到了各元素掺杂后的带隙(均约为2.9eV)，及受主能级的数值。并且根据单杂质的有关结果，对N，As掺杂后ZnSe中可能出现的杂质缺陷复合体进行了研究。 研究了III族和VII族单杂质在ZnSe中的掺杂行为。从理论上得到Cl应是ZnSe良好的n型掺杂剂的结论。研究表明Al, Ga掺杂后晶格有着显著的Jahn-Teller形变，因而不可能成为ZnSe良好的n型掺杂剂。 对GaAs的掺杂进行的对照研究表明，Si掺入GaAs中时应替位Ga并形成浅的施主态，Si和Be分别是GaAs良好的n型和p型掺杂剂。 研究了ZnSe中的Vse, Znint本征缺陷态。 结果表明它们在ZnSe中形成较深的施主态, 同时计算结果显示它们在ZnSe中难于形成，据此可以认为独立的Vse及Znint缺陷不能成为ZnSe受主补偿的主要因素。 首次从第一原理性质的方法出发研究了ZnSe中Vzn空位的三种电荷态的性质,从理论上提出了描述了三种缺陷体系间跃迁的电荷态变化及结构变化的物理图景, 得出了1.05, 1.44, 1.7和2.6eV几种可能的跃迁峰, 并很好地解释了实验结果。 研究了ZnSe中可能存在的杂质缺陷复合体。结果表明，在N掺杂的ZnSe中，Nse-Zn-Vse相对于Nse-Znint起到更大的受主补偿作用，而在As掺杂的ZnSe中，Asse-Znint相对于Asse-Zn-Vse的受主补偿作用更大。由此得到, 对于不同元素的同种类型的复合体其补偿作用的大小可能不同的结论，从而澄清了文献中在上述问题上有关理论与实验间的矛盾。 通过对多N复合体的研究，首次提出了ZnSe中“氮分子施主态”的概念, 从理论上首次指出, 在高N掺杂的ZnSe中Nse-Zn-Nse，Nse-Nzn及其它高N复合体将是受主补偿的主要因素的结论。 本文的研究表明, 在ZnSe的受主掺杂中, 避免和抑制Vse 等本征缺陷尤其是Nse-Nzn等多N复合体的形成是需要特别注意的问题。
ZnSe and GaAs are very important semiconductors for their use ofblue-green lasersand optoelectronic devices. Cluster model with DV-LDF method is used to the studyof doping and cotnpensation mechanism of ZnSe and GaAs. Properties of ZnSe doped with group I and V elements are studied. It is found thatthere is almost no Jahn-Teller distortion and it is the most stable for Nse, while thereare Jahn-Teller distortions for all the other dopants in ZnSe. The band gaps and dopantlevels are calculated, which are close to the experimental values. The reasons why N isthe most efficient p-type dopant in ZnSe are explained. Based on the results ofNse andASse, the possible compensating complexes in ZnSe are discussed. Properties of ZnSe doped with group 111 and V11 elernents are studied. It indicatesthat there is no Jahn-Teller distortion for Clse and there are Jahn-Teller Distortion forthe other dopants. It is concluded that Cl is the best dopants in n-type ZnSe. It is shown that SiGa form more favour than SiAs when GaAs is doped with Si. Beand Si are good dopants for p-type and n-type GaAs respectively. Vsg and Znint in ZnSe is studied. It is found that it is difficult for their formation inZnSe, and so Vsg and Znint will not play an important role in acceptor compensation ofZnSe independently.are theoretically studied using the first principlemethod for the first time. The transition peaks of 1.05,1.44,1.7 and 2.6eV arecalculated out, which agree with experiments well, and the changes of charge statesand structures during the transitions are studied. The dopant-defect complexes in ZnSe are studied. It is found that Nsg-Zn-Vsg ismore an effective compensator than Nsg-Zni,, while ASSe-Znint is more effective thanAsse-Zn-Vse for the acceptor compensation in ZnSe. The reasons of the conflictbetween experiment and theory are given. N clusters in ZnSe are studied. A new concept of donor state of Nz molecular isproposed. It is concluded that N clusters such as Nse-Nzn could play the main role ofacceptor self compensation in high N-doped ZnSe. ~ased on our studies, we propose that it is important to avoid Vsg and NscNzn in Ndoping ofZnSe.
