近地轨道质子和α粒子入射InP产生的位移损伤模拟

Simulation of displacement damage of InP induced by protons andα-particles in low Earth orbit

磷化铟(InP)材料具有禁带宽度大、电子迁移率高、耐高温、抗辐照等优点,是制备航天器电子器件的优良材料.近地轨道内的质子和α粒子对近地卫星威胁巨大,其在InP电子器件中产生的位移损失效应是导致InP电子器件电学性能下降的主要因素.本文使用蒙特卡罗软件Geant4研究近地轨道的质子与α粒子分别经过150μm二氧化硅和2.54 mm铝层屏蔽后,在500/1000/5000μm InP材料中产生的非电离能量损失(non-ionizing energy loss,NIEL)、平均非电离损伤能随深度分布以及年总非电离损伤能.研究发现:低能质子射程短且较易发生非电离反应,入射粒子能谱中低能粒子占比越大,材料厚度越小,NIEL值越大;计算质子和α粒子年总非电离损伤能,质子的年总非电离损伤能占比达98%,表明质子是近地轨道内产生位移损伤的主要因素;α粒子年总非电离损伤能占比小,但其在InP中的NIEL约为质子的2-10倍,应关注α粒子在InP中产生的单粒子位移损伤效应.本文计算为InP材料在空间辐射环境的应用提供了参考依据.

Indium phosphide(InP)material hasmany advantages,such as large band gap,high electron mobility,high photoelectric conversion efficiency,high temperature resistance,and radiation resistance,which is superior to silicon(Si)and gallium arsenide(GaAs).Meanwhile InP is widely used in optical communication,high-frequency millimeter waves,optoelectronic integrated circuits,satellite communication,space solar cells,and other fields.Radiation particles incident on InP device can generate displacement atoms inside the device through elastic processes.And these displacement atoms continue cascade collisions to generate lattice defects which are vacancies,interstitials,and clusters.These defects capture electrons-holes by defective energy levels in the energy band,and then resulting in a decrease in the life of minority carriers which is the reason of degradation of InP devices.The process of degradation of InP device,induced by lattice defects from ion-irradiation,is called displacement damage effect(DDE).The non-ionizing loss energy(NIEL)scaling is a useful method to predict the degradation of device caused by DDE of radiation particles.Many studies have shown that the NIEL is linearly related to the damage coefficient of InP device.Previous studies of radiation damage effect of InP device mainly focused on single-energy protons,electrons,and neutrons.Of the particles in low earth orbit(LEO),the vast majority of particles are protons,with a few beingαparticles and electrons,while the electron’s NIEL is too small and its DDE is negligible.The InP’s NIEL induced by proton andαenergy in LEO has not been studied in detail.Therefore,this paper uses Monte Carlo software Geant4 to study the NIEL,damage energy distribution with depth,and annual total non-ionization loss energy generated by protons andαparticles in LEO in 500/1000/5000μm InP materials.The shielding of 150-μm-thick SiO2 layer and 2.54-mm-thick Al layer from protons andαparticles are used as InP solar cell and InP devices in spacecraft,respectively.It is found that the energy spectrum determines the non-ionizing damage energy Tdam distribution,and then influences the NIEL value:the NIEL value increases with Tdam increasing and thickness of InP material decreasing.AndαNIEL is larger than proton’s,the single particle DDE of InP device,induced byαparticles,should be concerned.The annual non-ionizing damage energy of proton accounts for 98%,which means that proton is the main factor degrading InP devices in LEO.