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基于极化子和双极化子的物理图像,采用无拟合参数的巨正则统计方法计算了Si掺杂的AlxGa1-xAs的导带载流子浓度,计算得到的理论结果从高温到低温都与实验结果定量一致.计算证实了AlxGa1-xAs:Si中的DX中心的基态DX-是电子-晶格相互作用产生的负电双极化子.处于热平衡状态时,施主Si在AlxGa1-xAs中除了电离状态,处于不同晶格构型的单、双极化子态共存,低温时双极化子态被冻结;光照下发生持续光电导时,双极化子态变成单极化子态同时向导带释放一个电子,此过程伴随着进一步的晶格弛豫.理论与实验的对照说明单电子局域的DX0态在热平衡时并不能稳定存在,这和提出的双极化子机制是完全一致的.
Based on the physical images of polaron and bipolaron, the conduction band carriers of Si-doped AlxGa1-xAs were calculated by using the giant regular statistical method without fitting parameters. The theoretical results obtained from high temperature to low temperature Which is in agreement with the experimental results. The calculations confirm that the ground state DX- of the DX center in AlxGa1-xAs: Si is the negatively charged bipolaron produced by the electron-lattice interaction and that the donor Si is in AlxGa1-xAs except at the thermal equilibrium Ionization state, in the different lattice structure of single and bipolar sub-state coexistence, low-temperature bipolar sub-state is frozen; under sustained light-induced photoconductivity, the bipolar sub-state into a unipolar sub-state at the same time The release of an electron by the conduction band is accompanied by further lattice relaxation.The theoretical and experimental comparisons show that the DX0 state at the single electron site does not exist stably at thermal equilibrium, which is in complete agreement with the proposed bipolar mechanism of.