Device Characteristics of AlGaN/GaN MIS-HFET Using Al2O3-HfO2Laminated High-kDielectric

This is the first report on an AlGaN/GaN metal-insulator-semiconductor-heterostructure field-effect transistors (MIS-HFET) with an Al 2 O 3 –HfO 2 laminated high- k dielectric, deposited by plasma-enhanced atomic layer deposition (PEALD). Based on capacitance-voltage measurements, the dielectric constant of the deposited Al 2 O 3 –HfO 2 laminated layer was estimated to be 15. The fabricated MIS-HFET with a gate length of 1.2 µm exhibited a maximum drain current of 500 mA/mm and a maximum transconductance of 125 mS/mm. The gate leakage current was at least 4 orders of magnitude lower than that of the reference HFET. The pulsed current-voltage curve revealed that the Al 2 O 3 –HfO 2 laminated dielectric effectively passivated the surface of the device.