Device characteristics of AlGaN/GaN MIS-HFET using Al2O3-HfO2 laminated high-k dielectric

Abstract

This is the first report on an AlGaN/GaN metal-insulator-semiconductor-heterostructure field-effect transistors (MIS-HFET) with an Al2O3-HfO2 laminated high-k dielectric, deposited by plasma-enhanced atomic layer deposition (PEALD). Based on capacitance-voltage measurements, the dielectric constant of the deposited Al2O3-HfO2 laminated layer was estimated to be 15. The fabricated MIS-HFET with a gate length of 1.2mum exhibited a maximum drain current of 500mA/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 Al2O3-HfO2 laminated dielectric effectively passivated the surface of the device.