| Title |
1.5 kV GaN Schottky Barrier Diode for Next-Generation Power Switches |
| DOI |
https://doi.org/10.5370/KIEE.2012.61.11.1646 |
| Keywords |
GaN ; AlGaN ; Schottky barrier diode ; Power device ; O_2 annealing |
| Abstract |
The O_2 annealing technique has considerably suppressed the leakage current of GaN power devices, but this forms NiO at Ni-based Schottky contact with increasing on-resistance. The purpose of the present study was to fabricate 1.5 kV GaN Schottky barrier diodes by improving O_2-annealing process and GaN buffer. The proposed O_2 annealing performed after alloying ohmic contacts in order to avoid NiO construction. The ohmic contact resistance (R_C) was degraded from 0.43 to 3.42{Ω}-mm after O_2 annealing at 800°C. We can decrease RC by lowering temperature of O_2 annealing. The isolation resistance of test structure which indicated the surface and buffer leakage current was significantly increased from 2.43×10^7 to 1.32×10^{13}{Ω} due to O_2 annealing. The improvement of isolation resistance can be caused by formation of group-III oxides on the surface. The leakage current of GaN Schottky barrier diode was also suppressed from 2.38×10^{-5} to 1.68×10^{-7} A/mm at -100 V by O_2 annealing. The GaN Schottky barrier diodes achieved the high breakdown voltage of 700, 1400, and 1530 V at the anode-cathode distance of 5, 10, and 20μm, respectively. The optimized O_2 annealing and 4μm-thick C-doped GaN buffer obtained the high breakdown voltage at short drift length. The proposed O_2 annealing is suitable for next-generation GaN power switches due to the simple process and the low the leakage current. |