Thermal stability of IrO<inf>2</inf> gate based AlGaN/GaN HEMT

Abstract

We investigate a thermal stability of iridium oxide (IrO 2 ) gate based AlGaN/GaN HEMT devices by using a long-term thermal stress at 300 °C and 450 °C for 48 hours in air atmosphere. AlGaN/GaN high electron mobility transistors with the gate contact based on IrO 2 were designed for high temperature applications. IrO 2 gate interfacial layer is formed by high temperature oxidation of 15nm thick Ir gate contact layer (T = 500 − 800 °C, for 1 min in O 2 ambience) to provide a high temperature stable gate interface. IrO 2 gate based AlGaN/GaN HEMT show excellent thermal stability after long-term storage tests at 450 °C for 48 hours in the air, and even leakage current of Schottky gate contacts is continual decreasing with the storage time. AlGaN/GaN HEMTs with Schottky gate contacts based on high temperature formed IrO 2 could be predetermined for sensing applications at high temperatures.