【摘要】 研究了高掺硅的n型GaAs在中子辐照前后和150℃—500℃等时热退火以后的光致发光光谱。观察到在中子辐照后积分发光强度降低为辐照前的1/36。在退火温度超过250℃时,积分发光强度显著增长,当退火温度达400℃以上时,在带边峰的低能侧出现能量为1.35eV、1.30eV和1.26eV的发光峰。假设250℃退火阶段对应于较大的空位团分解为较小的空位团,400℃退火阶段对应于较小的空位团分解出V_Ga,可以较好地解释实验现象。更多还原

【Abstract】 Transmutation doping is a well established technique for obtaining low doping concentration in silicon.Similarly, in GaAs,this technique can be very useful in order to introduce low doping without compensation.However, these is a lack of data concerning the damage introduced by thermal neutron irradiation and the effect of annealing on the defects appearing during the irradiation.In this work we have studied the defects appearing during the neutron irradiation and the effect of annealing by means of photoluminescence at 77K.The starting samples were (111) oriented GaAs slices doped with Si and grown by the horizontal-zone method. Some parameters of the starting sample are given in the table.The thermal neutron integrated incident flux was 1.02×1017neutrons/cm2. The samples were annealed in vacuum at temperature of 310℃, 350℃, 400℃ or 500℃ for an hour after irradiation.The experimental set-up for the photoluminescence measurements is just like the typical one. The excitation light source was a 20 mW Helium-Neon laser modulated at a frequency of 1kHz.The following three experimental results are observed: 1. The PL intensity is decreased to less than one thirty-sixth after neutron irradiation; 2. The PL intensity increases after thermal annealing. When the annealing temperature is over 250℃,the integrated intensity increases obviously. When the annealing temperature is equal to about 400℃ the PL integrated intensity recovers to its starting level;3. Three emission peaks at about 1.36 eV, 1.30 eV and 1.26 eV appear when the annealing temperature is above 400℃.Experimental result 1 shows that non-radiation centers are produced in GaAs by neutron irradiation. We believe that the non-radiation centers are vacancy clusters. If we suppose that the vacancy clusters disociate into small one begining at 250℃ and VGa are released at 400℃ or higher temperature, the experimental facts can be explained,更多还原