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

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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 (R C) 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 (R C) 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 (R ON) of 3.5 mΩ cm2( 8.8 Ω mm), and a dynamic R ON increase of 12% at 400 V. The drain current density was 620 mA mm−1 at V GS = 1 V for device dimensions of L G = 1 μm, L GS = 1 μm, L GD = 28 μm, and W G = 50 μm. The successful contact regrowth by MOCVD eases the adoption of N-polar transistors.