Optimization of the ohmic contact processing in InAlN/GaN high electron mobility transistors for lower temperature of annealing

In this article, we optimized the ohmic contact processing in InAlN/GaN high electron mobility transistors for the lower temperature of annealing by recessing of metallization to approach the 2DEG at the InAlN/GaN interface. The ohmic contacts which were recessed down to 5 nm depth and annealed at 700 degrees C 2 min. exhibited the contact resistance of 0,39 Omega mm while the channel sheet resistance was 210 Omega/square. These values are comparative to values of contacts processed at more conventional annealing conditions (800 degrees C, 2 min). Moreover we applied the recessed ohmic contact technology to fabricate Schottky barrier (SB) HEMTs and MOSHEMTs with Al2O3 dielectric film. For MOSHEMTs, we measured the maximal reduction of the gate leakage current by about 6 orders of magnitude if compared with SB HEMTs. The maximal drain current of MOSHEMTs was about 750 mA/mm at V-GS = 0 V and the maximal extrinsic transconductance (g(me)) reached 101 mS/mm. (c) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim