1.8 kV AlGaN/GaN HEMTs with High-k/Oxide/SiN MIS structure

We report the fabrication of AlGaN/GaN high electron mobility transistors (HEMTs) having metal-insulator-semiconductor (MIS) gate structure with the high-k/SiN and high-k/oxide/SiN insulator structures. The SiO2 and Al2O3 were used as the oxide, and the HfO2, ZrO2 and TiO2 were used as the high-k materials. Both high-k/SiN and high-k/oxide/SiN MIS-gate HEMTs showed good DC operating characteristics. However, there was significant difference in the breakdown voltage characteristics. In the case of the high-k/oxide/SiN MIS-HEMT, the off-state drain current was significantly reduced due to the presence of the SiO2 or Al2O3 layer, and the breakdown voltage characteristics were improved. The breakdown voltage of HfO2/SiO2/SiN and ZrO2/SiO2/SiN MIS-HEMT for the gate-drain distance L-gd = 28 mu m were 1.8 kV and 1.7 kV, respectively.