C-doped semi-insulating GaN HFETs on sapphire substrates with a high breakdown voltage and low specific on-resistance

Abstract

High breakdown voltage (BV) AlGaN∕GaN heterojunction field effect transistors (HFETs) with a low specific on-resistance (ARDS(on)) were successfully fabricated using intentionally C-doped semi-insulating GaN buffers with a high resistivity on sapphire substrates. With the improvement of not only the resistivity of a C-doped GaN buffer but also the layout design near the gate feeding region, the fabricated devices exhibited a high BV of ∼1600V and low ARDS(on) of 3.9mΩcm2. This result even reaches the 4H-SiC theoretical limit and the best ever reported for the high-power GaN-based HFETs realized on sapphire substrates to the best of our knowledge.