Low temperature thin film transistors with hollow cathode plasma-assisted atomic layer deposition based GaN channels

We report GaN thin film transistors (TFT) with a thermal budget below 250 degrees C. GaN thin films are grown at 200 degrees C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3 nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (I-ON/I-OFF) of 10(3) and sub-threshold swing of 3.3 V/decade. The entire TFT device fabrication process temperature is below 250 degrees C, which is the lowest process temperature reported for GaN based transistors, so far. (C) 2014 AIP Publishing LLC.