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 LG= 1 μm, LGS= 1 μm, and LGD= 28 μm. These devices had a drain current density of ~575 mA/mm at VGS= 1 V, and the specific ON-resistance (active-area) was 4 mQ · cm2(10 Ω · mm). Dynamic ON-resistance (RON) was characterized 5 μs after the device was turned ON, with up to 575-V OFF-state stress. At VDS,Q= 575 V, the dynamic RONwas ~1.4 times the static RON(40% increase). These transistors showed an ultra-low dynamic RONof ~5% when measured at 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 VBRand dynamic RONperformance comparable to (and in most cases better than) the state-of-the-art Ga-Polar GaN HEMTs reported in the literature.