Comparative study of AlGaN/GaN metal–oxide–semiconductor heterostructure field-effect transistors with Al 2O 3 and HfO 2 gate oxide

Abstract

AlGaN/GaN metal–oxide–semiconductor heterostructure field-effect transistors (MOSHFETs) with Al 2O 3 gate oxide which was deposited by atomic layer deposition (ALD) were fabricated and their performance was then compared with that of AlGaN/GaN MOSHFETs with HfO 2 gate oxide. The capacitance ( C)–voltage ( V) curve of the Al 2O 3/GaN MOS diodes showed a lower hysteresis and lower interface state density than the C– V curve of the HfO 2/GaN diodes, indicating better quality of the Al 2O 3/GaN interface. The saturation of drain current in the I D– V GS relation of the Al 2O 3 AlGaN/GaN MOSHFETs was not as pronounced as that of the HfO 2 AlGaN/GaN MOSHFETs. The gate leakage current of the Al 2O 3 MOSHFET was five to eight orders of magnitude smaller than that of the HfO 2 MOSHFETs.