Energy-band parameters of atomic layer deposited Al2O3 and HfO2 on InxGa1-xAs

X-ray photoelectron spectroscopy (XPS) combined with reflection electron energy loss spectroscopy (REELS) were used to determine the energy-band parameters, valence-band offsets Delta E-V, conduction-band offsets Delta E-C, and energy-band gaps E-g, of the atomic layer deposited (ALD) Al2O3 and HfO2 on InxGa1-xAs (x=0, 0.15, 0.25, and 0.53). Using REELS, E-g values of the ALD-Al2O3 and -HfO2 were estimated to be 6.77 and 5.56 +/- 0.05 eV, respectively. The Delta E-V's were determined by measuring the core level to valence band maximum binding energy difference from the XPS spectra. The Delta E-C's were then extracted from Delta E-V's and the energy-band gaps of the oxides and InxGa1-xAs, and are in good agreement with those estimated from the Fowler-Nordheim tunneling. The Delta E-C's and Delta E-V's are larger than 1.5 and 2.5 eV, respectively, for all the ALD-oxide/InxGa1-xAs samples.