热处理对非掺杂半绝缘GaAs本征缺陷和电特性的影响

Effects of Annealing on Native Defects and Electrical Properties of Undoped Semi-insulating LEC GaAs During Annealing

在 95 0℃和 112 0℃温度下 ,对非掺杂 (ND)半绝缘 (SI)液封直拉 (LEC)GaAs单晶进行了不同砷气压条件的热处理 ,研究了热处理对本征缺陷和电特性的影响。在 95 0℃和低砷压条件下进行 14h热处理 ,可在样品中引入本征受主缺陷并导致体霍尔迁移率大幅度下降和体电阻率明显增加。这些受主缺陷的产生是由于高温和低砷压条件下GaAs晶体中发生砷间隙原子的外扩散。提高热处理过程中的砷气压 ,可以抑制这些受主缺陷的产生和电参数的变化。真空条件下 ,在 112 0℃热处理 2～ 8h并快速冷却后 ,可使样品中的主要施主缺陷EL2浓度下降近一个数量级 ,提高热处理过程中的砷气压 ,可以抑制EL2浓度下降 ,这种抑制作用是由于高温、高砷压条件下GaAs晶体发生了砷间隙原子的内扩散。

Annealing was carried out at 950℃ and 1120℃ under various arsenic(As) pressure for undoped(ND) semi-insulating(SI) LEC GaAs. The effects of the annealing on intrinsic defects and the electrical properties were investigated. The experimental results indicate that after annealing at 950℃ f or 14 h under low As pressure, the Hall mobility decreases and the resistivity i ncreases dramatically for the samples. These changes in electrical properties ar e due to the generation of intrinsic acceptor defects, and the generation of the intrinsic acceptor defects originates from the outdiffusion of As interstitial at high temperature. The generation of the intrinsic defects and these changes i n electrical properties can be suppressed by increasing the applied As pressure during annealing. The concentration of the main donor defect EL2 can be decrease d by about one order of magnitude by a evacuated annealing at 1120℃ for 2～8 ho urs followed by a fast cooling. The decrease in EL2 concentration can also be suppre ssed by increasing the As pressure during annealing due to the occuring of the i ndiffusion of As interstitial under high temperature and high As pressure condit ions.