Off-state drain current and breakdown voltage of AlGaN/GaN MIS-HEMT with multilayered gate insulator
Abstract
We report the fabrication of AlGaN/GaN high electron mobility transistors (HEMT) with high-k /SiN and high-k /SiO2/SiN gate structures. HfO2, ZrO2, TiO2 and Ta2O5 were used as high-k materials. Both high-k /SiN and high-k /SiO2/SiN metal-insulator-semiconductor (MIS) HEMTs showed good operating characteristics. However, in the case of high-k /SiN MIS-HEMT, the off-state drain current was large. On the other hand, in the case of the high-k /SiO2/SiN MIS-HEMT, the off state current was significantly reduced due to the presence of the SiO2 layer, and the breakdown voltage characteristics were improved. The breakdown voltages of HfO2/SiO2/SiN MIS-HEMT and ZrO2/SiO2/SiN at gate-drain distance Lgd = 28 μm were 1.8 kV and 1.7 kV, respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
