Computational Simulation Of Proton Irradiation Effect In AlGaN/GaN High Mobility Transistors

AlGaN/GaN high mobility transistors（HEMTs）have excellent performance such as high frequency,high power and great irradiation resistance,which show a broad application prospect in aerospace field.However,in the space radiation environment,high-energy charged particles,such as protons,can cause displacement damage to AlGaN/GaN HEMTs,which severely limits the performance of the devices.Recently,experimental works on the proton irradiation effect of AlGaN/GaN HEMTs have made impressive progress,but the defect types introduced by proton irradiation are still controversial,and the theoretical mechanism of device performance degradation lacks in-depth study and quantitative analysis.Therefore,we conducted computational simulations for the proton irradiation effect of AlGaN/GaN HEMTs to analyze the degradation of electrical performance,which included constructing the physical model of AlGaN/GaN HEMTs and simulating the process of proton irradiation.The main contents and results are as follows:1.The physical model of two-dimensional electron gas（2DEG）in AlGaN/GaN HEMTs was established.2DEG is the key factor of AlGaN/GaN HEMTs.We created the physical model of AlGaN/GaN HEMTs by TCAD and found that 2DEG originates from the donor-like surface state of AlGaN.The 2DEG concentration decreases as the energy level of surface state moves away from the conduction band,while it increases as AlGaN thickness or Al mole fraction increases.2.The model for the proton irradiation effect of AlGaN/GaN HEMTs was established.Defect types generated in the GaN channel of AlGaN/GaN HEMTs were obtained by simulating the process of proton irradiation with SRIM and molecular dynamics,which also determined the function of defect concentration and proton dose.It was found that vacancies and interstitials are the main types of defects generated by proton irradiation,and the concentration of antisites is lower.3.The theoretical mechanism of device degradation was clarified and radiation hardening method was proposed.Based on TCAD simulations,it was found that the acceptor-like defects created in the GaN channel are the most important factors for device degradation,and V_Ga（Gavacancy）and N_i（N interstitial）play a dominant role in device degradation.V_Ga and N_i as acceptor-like defects have high concentration,which can reduce the 2DEG concentration by capturing electrons and lower the 2DEG mobility through Coulomb scattering,thus degrading the electrical performance of AlGaN/GaN HEMTs.Accordingly,radiation hardening method of AlGaN/GaN HEMTs was proposed.By adding gate dielectric materials such as Si₃N₄ and Al₂O₃,the displacement damage in the GaN channel can be reduced and the concentration of acceptor-like defects can be decreased.Therefore,depositing high-quality gate dielectrics is an effective way to enhance the resistance of AlGaN/GaN HEMTs to proton irradiation.Our study established the physical model of AlGaN/GaN HEMTs and investigated proton irradiation effect of the devices based on computational simulations.With analyzing the electrical degradation mechanism of the devices,the radiation hardening method was proposed.The study provided a powerful analytical method and theoretical support for the investigation of proton irradiation effect in AlGaN/GaN HEMTs.