AlGaN/GaN MOS-HEMTs-on-Si employing sputtered TaN-based electrodes and HfO2 gate insulator

Abstract

We report on a low specific on-resistance (Ron,sp) of 3.58mΩ-cm2 and a high breakdown voltage of 1.4kV in a CMOS-compatible AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistor (MOS-HEMT). The MOS-HEMT is on a Si substrate and uses TaN electrodes and a HfO2-gate insulator. The sputtered TaN – a substitute for Au that has low resistivity, high work function, and thermal stability – was applied at room temperature to the gate, source, and drain. In order to obtain a low Ron,sp and high breakdown voltage, sputtering power and post-annealing temperature were optimized by measuring the characteristics of TaN. Using optimized conditions, a sputtering power of 50W, and an annealing temperature of 880°C, we successfully achieved a high on/off current ratio of 6×109 for the proposed AlGaN/GaN MOS-HEMT at a gate–drain distance of 10μm. These results indicate that the TaN process is a promising technique for power-switching GaN devices with CMOS compatibility.