Impact of Al2O3 incorporation on device performance of HfO2 gate dielectric AlGaN/GaN MIS-HFETs

Abstract

We report the effects of Al2O3 interfacial layer incorporation on the dc performance of AlGaN/GaN metal-insulator-semiconductor field effect transistors (MISHFETs) using HfO2 as the gate dielectric and surface passivation layer. The HfO2/Al2O3 bi-layer MIS-HFETs exhibit a larger maximum drain current by ∼8.5 %, larger gate voltage swing by ∼6.3 %, and smaller gate leakage by 4∼5 times, compared to the HfO2 single layer MIS-HFETs at room temperature. Furthermore, the HfO2/Al2O3 transistors are observed to have better thermal stability than the HfO2 transistors, and the estimated lifetime (in hour) of the former is longer than that of the latter by over an order of magnitude from 25 to 150 °C. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.