The Effect of Radiation on the Electrical Properties of Aluminum Gallium Nitride/Gallium Nitride Heterostructures
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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AlGaNGaN Heterojunction Field Effect Transistors HFETs were irradiated at low temperature and the temperature dependent changes to drain current, gate current, capacitance, and transconductance were measured. The results were compared to the charge control model of the drain current and trap-assisted tunneling model of the gate current to determine the source of the radiation-induced changes. AlGaNGaN HFETs demonstrated threshold voltage shifts and drain current changes after irradiation. After electron and neutron irradiation applied at 80 K, measurement of the drain current at this temperature showed an increase that saturated after 1013 electronscm2 or 1010 neutronscm2 due to positive charge build-up in the AlGaN layer. Measurement at room temperature after low-temperature irradiation showed a decrease in drain current due to the build up of charged defects along the AlGaN-GaN interface that decrease the mobility in the 2DEG and hence decrease the current. Gate leakage currents increased after low temperature irradiation and the increase was persistent after room temperature annealing. The increased leakage current was attributed to trap-assisted tunneling after application of the trap-assisted tunneling model. Comparison of the model to post-irradiation vs. pre-irradiation data showed that the dominant parameter change causing increased gate current was an increase in trap concentration.
- Inorganic Chemistry
- Electricity and Magnetism