Hyperspectral Electroluminescence Characterization of OFF-State Device Characteristics in Proton Irradiated High Voltage AlGaN/GaN HEMTs

Abstract

Gallium nitride-based high electron mobility transistors (HEMTs) represent a critical next-generation technology for RF amplifiers. In this work, we implement electroluminescence (EL) imaging to study breakdown mechanisms under high voltage stress conditions in as-fabricated and proton irradiated devices. After irradiation, an increased breakdown voltage and reduced buffer leakage was observed and attributed to the formation of a back barrier structure due to carrier type conversion in the buffer layer from the introduction of donor trap levels near the conduction band. In addition to identifying high field regions associated with device failure, the hyperspectral filter enables spectrum extraction, identifying peaks in the 700 nm–900 nm region associated with both defects and hot electrons that are contributing to device failure, but no change in signature after irradiation implying that radiation-induced defects are non-radiative. Complementary photoluminescence spectroscopy identified a reduction in free carrier density consistent with the generation of compensating trap levels, supporting the proposed model.