Energy-Dependent Degradation Characteristics of AlGaN/GaN MISHEMTs with 1, 1.5, and 2 MeV Proton Irradiation

Abstract

We investigated the degradation characteristics of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MISHEMTs) and Schottky HEMTs induced by proton irradiation at energy levels of 1, 1.5, and 2 MeV, with a total fluence of 5 × 10 14 cm −2 . Irradiated devices exhibited degradation characteristics of positive threshold voltage (Vth) shift and drain current (ID) reduction, which increased as the proton energies decreased. Hall pattern measurement revealed that the Hall mobility (μ), sheet carrier concentration (nsh), and sheet resistance (Rsh) of the electron channel were also degraded after proton irradiation (showing the same energy dependence). This effect can be attributed to the energy-dependent energy loss of protons penetrating the semiconductor material. Protons with lower irradiation energy can degrade the device characteristics more severely because of the larger amount of nonionizing energy loss (NIEL) in the active region, in which a two-dimensional electron gas (2-DEG) is formed as compared to higher irradiation energies where the energy loss is primarily in the bulk substrate. The capacitance-voltage (C-V) measurements indicated significant degradation of the insulator interface for 1-MeV irradiation.