The Impact of Non-Uniform Distribution of Radiation-Induced Defects on the Electrical Performance of AlGaN/GaN HEMTs

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This study investigates AlGaN/GaN HEMTs irradiated with chlorine ions of varying energies, which introduces depth-dependent non-uniform defects beneath the gate electrode. By combining experimental and simulation methods, we systematically analyze three distinct degradation phenomena: non-uniform degradation in transfer characteristics, threshold voltage (Vth) shift saturation, and Peak transconductance (GM) collapse. Through Current deep-level transient spectroscopy (I-DLTS), electrical performance measurement, and TCAD device simulation, along with band theory analysis, it is found that high fluence chlorine irradiation generates FeGa-VNdefects (EC-0.5 eV) in the GaN layer, inducing Fermi-level pinning at these trap states. The increased defect concentration causes interfacial band bending and reduces 2DEG density. Donor defect E1 near the AlGaN/GaN interface are identified as the primary contributor toVthshift saturation behavior. Additionally, VN-VN(+1/+2) defects (EC-0.77 eV) in the AlGaN barrier layer become activated when gate voltage exceeds a critical value, significantly enhancing electron capture from the conduction band. This spatially non-uniform trapping process leads to gate-voltage-dependent degradation of drain current (Ids) and ultimately results in the phenomenon of PeakGMcollapse.