N-Polar GaN HEMTs Exhibiting Record Breakdown Voltage Over 2000 V and Low Dynamic On-Resistance

Nitrogen polar (N-Polar) GaN high-electron-mobility transistors (HEMT) targeting high-voltage switching applications were fabricated on epi-layers grown by metal-organic chemical vapor deposition on sapphire substrates. Devices demonstrated a combination of high breakdown voltage and low dynamic ON-resistance. Breakdown voltages of over 2000 V were observed on transistors with L-G = 1 mu m, L-GS = 1 mu m, and L-GD = 28 mu m. These devices had a drain current density of similar to 575 mA/mm at V-GS = 1 V, and the specific ON-resistance (active-area) was 4 m Omega.cm(2) (10 Omega.mm). Dynamic ON-resistance (R-ON) was characterized 5 mu s after the device was turned ON, with up to 575-V OFF-state stress. At V-DS, Q = 575 V, the dynamic R-ON was similar to 1.4 times the static R-ON (40% increase). These transistors showed an ultra-low dynamic R-ON of similar to 5% when measuredat 450-V stress. As one of the first demonstrations of N-Polar GaN HEMTs for power switching applications, the devices discussed in this letter achieve excellent V-BR and dynamic R-ON performance comparable to (and in most cases better than) the state-of-the-art Ga-Polar GaN HEMTs reported in the literature.