AlGaN/GaN HFETs for Automotive Applications

Abstract

AlGaN/GaN heterojunction field effect transistors (HFET) on sapphire substrates have demonstrated ability as power devices operating with high current densities and high breakdown voltages. Additionally, AlGaN/GaN HFET devices have a very low on-state resistance. This makes these devices ideal for automotive applications such as switching relays, DC-DC converters, and power inverters. By 2006, switching devices using GaN-based FETs are anticipated to be employed in luxury automobiles and transitioned to the mass market by 2009.

In this presentation, data from AlGaN/GaN HFET's grown in an Emcore D180 MOCVD system will be presented. Typical production-scale material results (on 2” sapphire substrates) for these wafers were: μ ∼ 1000 cm²/Vs, N_s = 1.0×10¹³ cm⁻², and R_s ∼ 450 Ω/square with <3% variation across the wafer. These wafers were then processed into devices using Pt/Au gate contacts with 2 μm gate length, 200 μm gate width, and a source to drain spacing of 13 μm. A total of 1000 FETs were combined in parallel for an effective gate width of 20 cm for high current operation (10A). These devices have a lower on-state resistance (<0.01 Ω-cm²) and higher Schottky breakdown voltages (400 V) than the theoretical limit of Si MOSFET devices. These devices demonstrate suitability for insertion in automotive electrical harnesses.