Investigations of HfO2 AlGaNGaN metal-oxide-semiconductor high electron mobility transistors

Abstract

We report the studies of AlGaNGaN metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) using reactive-sputtered HfO2 as the gate dielectric and the surface passivation layer. X-ray photoemission method reveals a conduction-band offset of 1.71 eV for the HfO2 GaN heterostructure. The dielectric constant of HfO2 is estimated to be 21 by capacitance-voltage measurements. MOS-HEMTs with a 1.5-μm -long gate exhibit a maximum drain current of 830 mAmm and a peak transconductance of 115 mSmm, while the gate leakage current is at least five orders of magnitude lower than that of the reference HEMTs. Good surface passivation effects of HfO 2 have also been confirmed by pulsed gate measurements, with MOS-HEMTs showing a significant drain current recovery from current collapse observed in HEMTs. © 2006 American Institute of Physics.