Ultralow-Leakage AlGaN/GaN High Electron Mobility Transistors on Si With Non-Alloyed Regrown Ohmic Contacts

Without employing gate dielectrics, AlGaN/GaN high-electron mobility transistors (HEMTs) on Si with non-alloyed regrown ohmic contacts exhibit record-low leakage currents $sim 10^{-12}$ A/mm, high ON/OFF current ratios $> 10^{11}$ . Compared with HEMTs with conventional alloyed ohmic contacts, HEMTs with non-alloyed contacts show a reduction of $10^{6}$ in leakage current, a steeper subthreshold slope, and >50% improvement in breakdown voltage. These observations indicate that avoiding high-temperature alloyed ohmic processes can lead to improved device performance.