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

• AlGaN/GaN MOS-HEMT with TaN gate and Ti/Al/TaN ohmic contact is proposed.
• High sputtering power of TaN damages gate insulator and cause high leakage current.
• Annealing temperature for Ti/Al/TaN is optimized for low specific on-resistance.
• High on/off current ratio of 6 × 109 and low Ron,sp of 3.58 m Ω cm2 are achieved.
• High breakdown voltage of 1.4 kV is achieved at a gate–drain distance of 10 μm.

We report on a low specific on-resistance (Ron,sp) of 3.58 mΩ-cm2 and a high breakdown voltage of 1.4 kV 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 50 W, 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 10 μm. These results indicate that the TaN process is a promising technique for power-switching GaN devices with CMOS compatibility.

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