Anomalous DC Characteristics of AlGaN/GaN HEMTs Depending on Proton Irradiation Energies

We evaluated the effect of the proton irradiation energy on the DC characteristics of AlGaN/GaN high electron mobility transistors (HEMTs). Devices were exposed to various irradiation energies, i.e., 0.5 MeV, 5 MeV, and 60 MeV, respectively, with a fluence of 1 x 10(14)p cm(-2)at room temperature. The 0.5 MeV-irradiated HEMT shows the largest degradation of transfer characteristics than other HEMTs because the lower proton energy has a larger non-ionizing energy loss (NIEL). The threshold voltage of HEMTs with 0.5 and 5 MeV proton irradiation is positively shifted due to the reduction of 2-dimensional electron gas (2DEG) density by defects created during irradiation. However, the 60 MeV-irradiated HEMT showed a negative shift of threshold voltage with no degradation of drain current. Also, the gate leakage current of fabricated HEMTs decreased with an increasing irradiation energy. These anomalous DC characteristics were expected due to the creation of a proton radiation-caused interfacial oxide layer between the gate and AlGaN layer.