In0.53Ga0.47As/InP量子阱与体材料的1 MeV电子束辐照光致发光谱研究

为获得对In_0.53Ga_0.47As/InP材料在电子束辐照下的光致发光谱变化规律, 开展了1 MeV电子束辐照试验, 注量为 5×10¹²-9×10¹⁴ cm^-2. 样品选取量子阱材料和体材料, 在辐照前后, 进行了光致发光谱测试, 得到了不同结构In_0.53Ga_0.47As/InP材料在1 MeV电子束辐照下的不同变化规律; 对比分析了参数退化的物理机理. 结果显示: 试验样品的光致发光峰强度随着辐照剂量增大而显著退化. 体材料最先出现快速退化, 而五层量子阱在注量达到6×10¹⁴ cm^-2时, 就已经退化至辐照前的9%. 经分析认为原因有: 1)电子束进入样品后, 与材料晶格发生能量传递, 破坏晶格完整性, 致使产生的激子数量减少, 光致发光强度降低; 电子束辐照在材料中引入缺陷, 增加了非辐射复合中心密度, 导致载流子迁移率降低. 2)量子阱的二维限制作用使载流子运动受限, 从而能够降低载流子与非辐射复合中心的复合概率; 敏感区域截面积相同条件下, 体材料比量子阱材料辐射损伤更为严重. 3)量子阱的层数越多, 则异质结界面数越多, 相应的产生的界面缺陷数量也随之增多, 辐射损伤越严重.

Photoluminescence spectra of 1 MeV electron beam irradiated In0.53Ga0.47As/InP quantum well and bulk materials

Minimizing the impact of radiation-induced degradation on optoelectronic devices is important in several applications. Satellites and other spacecraft that fly in near-earth orbits (below 3.8 earth radius) are extremely susceptible to radiation damage caused by the high flux of electrons trapped in the earth’s magnetosphere. Optoelectronic devices are particularly vulnerable to displacement damage caused by electrons and protons. Effects of 1 MeV electron beam irradiation on the photoluminescence properties of In_0.53Ga_0.47As/InP quantum well (QW) and bulk structures, which are grown by metal-organic vapor phase epitaxy, are investigated. Samples are irradiated at room temperature using an ELV-8II accelerator with 1 MeV electron at doses ranging from 5×10¹² to 9×10¹⁴ cm^-2, and a dose rate of 1.075×10¹⁰ cm^-2·s^-1. Photoluminescence measurements are made using a 532 nm laser for excitation and a cooled Ge detector with lock-in techniques for signal detection. Photoluminescence intensity of all the structures is degraded after irradiation, and its reduction increases with increasing total dose of irradiation. Electron beam irradiation causes a larger reduction in the photoluminescence intensity and carrier lifetime of the bulk than that of quantum well. Photoluminescence intensity of five-layer quantum wells degenerates to 9% that before irradiation as the fluence reaches 6×10¹⁴ cm^-2. As the electron beams bombard into the sample, the destruction of the lattice integrity will cause the decrease in the number of excitons and intensity of photoluminescence. Electron beam irradiation introduces defects in the samples, increases the density of the nonradiative recombination centers, and results in the decrease of carrier mobility. In a quantum well structure, due to the two-dimensional confinement, the probability of carrier nonradiative recombination at radiation-induced defect centers will be reduced. The reduction of photoluminescence intensity in the bulk is severer than in the quantum well while the cross-sectional area which is sensitive to radiation is kept the same. The number of interface defects which are produced by electron irradiation will increase with the number of layers in quantum well and the heterojunction interface of quantum wells, so is the degration of photoluminescence intensity. The degration is mainly due to the increase of non-radiative centers in the samples. By comparing the different structures, the quantum well structure shows a better radiation resistance.