Ultra-high voltage electron microscopy investigation of irradiation induced displacement defects on AlGaN/GaN HEMTs

Irradiation effects produced by high energy heavy ions and electrons on AlGaN/GaN high electron mobility transistor (HEMT) were investigated using ultra-high voltage electron microscopy (HVEM), optical measurements, and device characteristics analysis. The dislocation loop created on a thick (1.5 μm) sample irradiated by 18 MeV Ni ions was observed by HVEM. The distribution of the defects matched the calculated distribution obtained using the stopping and range of ions in matter (SRIM) code. In-situ dislocation loop generation was observed in the sample during a high energy (2 MeV) electron irradiation by using HVEM. Device characteristics were found to remain stable, no increase in leakage current or electric field intensity being noticed up to a high radiant fluence of Ni and electron irradiation. These results demonstrate a high radiation tolerance of the device for space applications