Preparation and properties of AlGaN/GaN MOS-HFETs with atomic layer deposited Al2O3 as gate oxide

Atomic layer deposition (ALD) technique at 300°C was used to prepare an Al₂O₃ dielectric layer, to form MOS-HFETs. The static (output and transfer) and dynamic (Capacitance-Voltage) characteristics were used for evaluation of investigated devices. From the static characteristic, an increase of the saturation drain current (up to 35%) and extrinsic transconductance (up to 10%) of the MOS-HFETs were observed. Higher nS on the MOS-structure, evaluated from the C-V measurement, can be responsible for these effects. The gate leakage current was also reduced about four orders of magnitude in comparison to the HFET.