Impact ionisation in AlGaN-GaN heterostructure field effect transistors on sapphire substrates

Abstract

The authors report on the impact ionisation in AlGaN-GaN heterostructure field effect transistors (HFETs) grown on sapphire substrates. The measured characteristic electric field of the impact ionisation is ~ 2.8–3.15 MV/cm at room temperature. This result is in good agreement with the theoretical predictions for the breakdown field in GaN and with recent results for AlGaN-GaN HFETs on 6H-SiC substrates.