High-electron-mobility transistors with metal-organic chemical vapor deposition-regrown contacts for high voltage applications

Source and drain contacts regrown by metal-organic chemical vapor deposition (MOCVD) were successfully used in nitrogen-polar GaN metal-insulator-semiconductor (MIS) high-electron-mobility transistors (HEMTs) targeting high voltage switching applications. Previous work on N-polar GaN devices utilized either alloyed ohmic contacts, or ohmic contacts regrown by molecular beam epitaxy (MBE). Using MBE regrowth, ultra-low contact resistances (RC) were demonstrated. In this study, MOCVD was used for the contact regrowth, eliminating the need for an MBE growth step. A metal-to-2DEG (two-dimensional electron gas) contact resistance (RC) of 0.16 Ω mm was demonstrated, comparable to the ultra-low contact resistances that were previously reported for contacts regrown by MBE. N-Polar MISHEMTs fabricated using this technology achieved breakdown voltages over 2000 V, with a specific on-resistance (RON) of 3.5 mΩ cm2( 8.8 Ω mm), and a dynamic RON increase of 12% at 400 V. The drain current density was 620 mA mm−1 at VGS = 1 V for device dimensions of LG = 1 μm, LGS = 1 μm, LGD = 28 μm, and WG = 50 μm. The successful contact regrowth by MOCVD eases the adoption of N-polar transistors.