Band alignment of atomic layer deposited SiO2 on (010) (Al0.14Ga0.86)(2)O-3

The (AlxGa1-x)(2)O-3/Ga2O3 system is attracting attention for heterostructure field effect transistors. An important device design parameter is the choice of gate dielectric on the (AlxGa1-x)(2)O-3 and its band alignment at the heterointerface. The valence band offset at the SiO2/(Al0.14Ga0.86)(2)O-3 heterointerface was measured using x-ray photoelectron spectroscopy. The SiO2 was deposited by atomic layer deposition (ALD) onto single-crystal beta-(Al0.14Ga0.86)(2)O-3 grown by molecular beam epitaxy. The bandgap of the SiO2 was determined by reflection electron energy loss spectroscopy as 8.7 eV, while high resolution XPS data of the O 1s peak and onset of elastic losses were used to establish the (Al0.14Ga0.86)(2)O-3 bandgap as 5.0 eV. The valence band offset was determined to be 1.60 +/- 0.40 eV (straddling gap, type I alignment) for ALD SiO2 on beta-(Al0.14Ga0.86)(2)O-3. The conduction band offset was 2.1 +/- 0.08 eV, providing for a strong electron transport restriction. Published by the AVS.