Off‐state breakdown in InAlN/AlN/GaN high electron mobility transistors

Abstract

AbstractUnpassivated InAlN/AlN/GaN high electron mobility transistors off‐state breakdown is analyzed for different gate‐to‐drain distances. The breakdown voltage linearly increases with the gate to drain distance reaching 350 V for a 10 μm contact separation; the sub‐threshold leakage current is < 10–5 A/mm. Similar breakdown voltages and leakage current are obtained on GaN buffer for two Ohmic contacts if their distance is the same. It is suggested that the breakdown is governed by injection/avalanche processes in the GaN buffer layer and is basically not affected by InAlN barrier. Our conclusions are further supported by measuring all currents in the three‐terminal configuration of the transistors before and during the breakdown and by using a drain current injection technique. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)