High Voltage GaN Schottky Rectifiers

Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V sub (RB)) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R sub (ON), was 6m OMEGA dot cm sup 2 and 0.8 OMEGA cm sup 2, respectively, producing figure-of-merit values for (V sub (RB)) sup 2/R sub (ON) in the range 5-48 MW dot cm sup (-2). At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high biases the current was proportional to the area of this contact. These results suggest that at low reverse biases, the leakage is dominated by the surface component, while at higher biases the bulk component dominates. On-state voltages were 3.5V for the 550V diodes and >= 15 for 2kV diodes. Reverse recover times were 0.2 mu sec for devices switched from a forward current density of ~500A dot cm sup (-2) to a reverse dias of 100V.