High-breakdown voltage and low onresistance AlGaN/GaN on Si MOS-HEMTS employing an extended tan gate on HfO2 gate insulator

Proposed is a new extended gate towards a source in AlGaN/GaN metal-oxide-semiconductor-high-electron-mobility transistors (MOS-HEMTs) in order to increase breakdown voltage and reduce on-resistance. The TaN gate was isolated from the source by a 15 nm-thick RF-sputtered HfO₂ gate insulator. A high breakdown voltage of 1410 V was measured as a result of the successfully blocked gate leakage current and surface passivation by the HfO₂ gate insulator. The extended gate towards the source was an effective method to improve the on-resistance and drain current density by eliminating the gate-source space. The proposed device with the extended gate exhibited low specific on-resistance of 2.28 mΩΩcm² while that of the MOS-HEMT with the conventional structure was 2.91 mΩΩcm². Also, maximum drain current density at the V_GS of 2 V was increased from 332 to 420 mA/mm by the proposed extended TaN gate.