Study on Defects in GaAs by means of Positron Annihilation

1.LEC-GaAs的研究(1)对电子辐照的LEC-GaAs进行了正电子寿命测量和多普勒展宽湮没实验。电子诱导缺陷的恢复和聚集发表在《应用物理》A 58，59(1994)(2)上。(2)用正电子湮没技术研究了质子辐照诱导缺陷的温度依赖性。在300K以下，研究了电荷态Si掺杂引起的缺陷，并在质子辐照后产生了Ga空位和反位GaAs(提交于《应用物理A》)。用VF回旋加速器产生慢正电子束。(1)慢正电子束产生系统的建立。对系统进行了改进，以获得高质量的慢正电子束和低本底。(2)用氮化硼(BN)、碳、Si_3N_4和NaF等靶进行了β_+衰变反应。对于BN，获得了1.4×10~(-4)/秒的慢正电子强度。

1. Study of LEC-GaAs(1) Measurement of positron lifetime and Doppler-broadened annihilation have been performed on electron irradiated LEC-GaAs. Recovery and clustering of electron induced defects were published in Applied Physics A 58,59(1994)(2) Temperature dependence of proton irradiation induced defects were studied using positron annihilation technique. Below 300K the charge state Si doping induced defects were investigated and Gallium vacancies and antisite GaAs were produced after proton irradiation (submitted in Applied Phys A).2. Production of slow positron beam using A VF Cyclotron.(1) Construction of System for production of slow positron beam. System has been modified for high quality slow positron beam and low background.(2) Several targets such as boron nitride (BN), Carbon, Si_3N_4 and, NaF were used for beta_+ decay reaction. For BN slow positron intensity of 1.4 X 10^4/sec was obtained.