离子辐照GaAs的光致发光和拉曼散射研究

利用250 keV质子和4.5 MeV氪离子(Kr17+)辐照未掺杂GaAs,注量分别为1×10~(12)-3×10~(14) cm~(-2)和3×10~(11)-3×10~(14) cm~(-2),使用光致发光谱和拉曼散射谱分析表征。发光谱的结果表明,随着剂量增大,质子辐照后的CAs峰及其声子伴线逐渐减弱,913 nm处的复合缺陷峰则先增大后减小,此峰与材料制备时的Cu掺杂无关。Kr离子辐照后本征发光峰则完全消失。拉曼散射谱的结果表明,相比于质子辐照,Kr离子辐照后LO声子峰峰位向低频方向移动,出现非对称性展宽,晶体结构发生明显改变。质子和Kr离子辐照效应的差异是由于移位损伤相差至少三个量级造成的。最后采用多级损伤累积(Multi-step damage accumulation,MSDA)模型得到了材料内缺陷的演化过程,并很好地解释了随损伤剂量增大GaAs光学性能及晶体结构的变化趋势。

Study on photoluminescence and Raman scattering in GaAs by ion irradiation

Background: GaAs is widely used as the second generation semiconductor material in the fields of aerospace and radiation detection.Purpose: Study of the irradiation effects of GaAs is of guiding significance for the evaluation of the radiation resistance of GaAs devices.Methods: Semi-insulating GaAs were irradiated by 250-keV H+ and 4.5-MeV Kr17+ ions with fluences ranging respectively from 1×1012 cm?2 to 3×1014cm?2 and 3×1011 cm?2 to 3×1014cm?2. Photoluminescence (PL) spectrum and Raman scattering spectra were used to measure GaAs samples before and after irradiation.Results: PL spectrum shows that the intensity of CAs peaks and phonon replicas decrease with increasing fluence of H+ irradiation. TheIGa-VAs peak in 913 nm was increased at lower fluence and decreased at higher fluences. But all the peaks completely disappeared with Kr17+ irradiation. The results of Raman spectra show that the longitudinal-optical (LO) phonon peak at 295-cm?1 slides towards the low-frequency side and broadens its width asymmetrically by Kr17+ irradiation, while it has no obvious change by proton irradiation.Conclusion: The difference between the effect of proton and Kr17+ irradiation is due to the difference of the displacement damage by three orders of magnitude at least. The evolution process of damage defects in GaAs is obtained by using Multi-step damage accumulation (MSDA) model, and then the trends of optical properties and crystalline structure are well explained.