Enhancement Of Algan/Gan High Electron Mobility Transistor Off-State Drain Breakdown Voltage Via Backside Proton Irradiation

Proton irradiations from the backside of the AlGaN/GaN high electron mobility transistors (HEMTs) were employed to enhance its off-state drain breakdown voltage. Via holes were fabricated directly under the active area of the HEMTs by etching through the Si substrate for the backside irradiations. The steep drop at the end of proton energy loss profile allows radiation-induced defects to be placed at precise locations within the AlGaN/GaN HEMT structure. Neither degradation of drain current nor enhancement of off-state drain voltage breakdown voltage was observed for the HEMTs irradiated with the proton energy of 225 or 275 keV, for which the defects were put in the GaN buffer. HEMTs with defects placed in the two dimensional electron gas (2DEG) channel region and the AlGaN barrier, using 330 or 340 keV irradiations, not only showed degradations on drain current and extrinsic transconductance but also demonstrated improvements of the off-state drain breakdown voltage.