Band Alignments of Atomic Layer Deposited ZrO2 and HfO2 High-k Dielectrics with (-201) β-Ga2O3

The energy band alignment between atomic layer deposited (ALD) high-k dielectrics of ZrO2 and HfO2 with n-type beta-Ga2O3 was evaluated using x-Ray photoelectron spectroscopy. The valence band offset was found to be -0.3 +/- 0.04 eV and -0.5 +/- 0.04 eV for ZrO2 and HfO2, respectively, which produced type II, staggered gap alignments for both dielectrics with conduction band offsets greater than 1 eV. Capacitance-voltage measurements were conducted on metal-oxide-semiconductor (MOS) diodes and used to extract the dielectric constants (epsilon) of both oxides. ZrO(2)films had a nearly ideal e of 24.7 (epsilon similar to 25), while HfO2 exhibited a significantly lower epsilon of 14 (epsilon similar to 25-30). These results, combined with the small hysteresis (<= 0.09 eV) in the capacitance-voltage behavior for both films, is indicative of the high quality of these ALD oxides and their interface with the beta-Ga2O3 making them potential candidates as gate dielectrics in power devices based on this relatively new ultra-wide bandgap material. (C) 2016 The Electrochemical Society. All rights reserved.