Dc and rf performance of proton-irradiated AlGaN/GaN high electron mobility transistors

Abstract

AlGaN/GaN high electron mobility transistors (HEMTs) with a range of gate lengths (0.8–1.2 μm) and widths (100–200 μm) were exposed to 40 MeV protons at fluences of 5×109 or 5×1010 cm−2. The drain–source currents in the devices decreased by 15%–20% at the higher fluence, while the extrinsic transconductance decreased by ∼30% under the same conditions. Based on the increases in the reverse breakdown voltage and the channel resistance, the main degradation mechanism is believed to be creation of deep trap states in the band gap which remove electrons from the channel. The maximum frequency of oscillation, fMAX, also decreased as a result of the proton-induced damage, with a change of −20% at the shorter gate widths and −50% at the largest widths. The reverse recovery switching time was essentially unaffected by the irradiation, remaining at ∼1.6×10−8 s. Postradiation annealing at 800 °C was successful in restoring the dc and rf performance parameters to ⩾90% of their original values. The AlGaN/GaN HEMTs are much more robust than their AlGaAs/GaAs counterparts to displacement damage and appear well-suited to radiation environment applications.