The Study Of Radiation Traps In AlGaN/GaN HEMT

AlGaN/GaN high electron mobility transistors(HEMTs)devices have shown unique advantages in high frequency and power applications,and have broad application prospects in key areas such as communications,radar,electronic warfare,aerospace,and nuclear reactors.When HEMTs are used as detectors,power supplies,and signal transceiver modules in extreme environments such as aerospace,due to their special radiation environment,the reliability of the device will seriously restrict the performance of the device,even cause burn.Therefore,studying the reliability of AlGaN/GaN HEMTs devices in radiating environments is of great significance for realizing space applications.As the main component of the Van Allen belt,protons are one of the main threats to AlGaN/GaN HEMTs devices in space.This paper will conduct the following research on radiation defects induced by proton radiation.The degree of the device performance induced by proton radiation.By comparing the DC characteristics of the device before and after proton radiation,it was found that proton radiation will cause the maximum leakage current and the maximum transconductance to decrease,the threshold voltage offset and the gate leakage current to increase.The degree of device performance degradation is closely related to the proton radiation energy.And the degree of device is positively related to the proton fluence,the higher the fluence,the more severe the device degradation,and even the device will be burned.According to the calculation results of the SRIM simulation,it can be known that when the proton energy is low(ke V),the maximum range of the proton is in the channel,and when the energy is high(Me V),the maximum range is in the substrate.This explains well that low energy proton radiation can cause severe degradation of device performance.The characterization of radiation defects at the Gate Metal/AlGaN Interface.In this paper,the radiation defects at the interface are characterized by pulsed-IV.The change in the density of defect states can be determined by comparing the current collapse of the device under different static bias voltages.By comparing the test results of different pulse widths,the time constant range of the radiation defect can be calculated indirectly.The characterization of radiation defects at AlGaN/GaN heterojunction interfaces.The frequency-dependent conductance method was used to characterize the radiation defects at the heterojunction interface.The capacitance and conductance at different frequencies are obtained,and the change in G_P/?near the threshold voltage with frequency is obtained.Finally,information such as the energy level,density,and time constant of the radiation defect are obtained.We found that the defects at the heterojunction interface changed from shallow to deep levels after irradiation,and the defect density increased.Through the change of the energy level,it can be inferred that the defect was partially changed from E_C-0.24[V_N]^3-to E_C-0.44[V_Ga-V_N]^3-.The 1/f low frequency noise method is used to characterize the radiation defects of the device.Because the defects characterized by the pulsed-IV method and the conductance method are fast defects,the 1/f low-frequency noise method can make up for the shortcomings of the pulse method and the conductance method,which can detect not only fast defects but also slow defects.Through the low-frequency noise test results,we can find that the defect density of the device increases after radiation.Comparing with the frequency-dependent conductance method,we can see know that radiation also introduces slow radiation defects.Photoelectron Microscopy(PEM)characterizes radiation defects.The position of the radiation defect was determined with the help of PEM,and the sensitivity of the device to electrical stress before and after the radiation was compared with the location of the excited defect.Finally,the breakdown position of the device after the breakdown of the electrical stress is determined.