Band offsets in HfO2/InGaZnO4 heterojunctions

The valence band discontinuity (Delta E-V) of sputter deposited HfO2/InZnGaO4 (IGZO) heterostructures was obtained from x-ray photoelectron spectroscopy measurements. The HfO2 exhibited a bandgap of 6.07 eV from absorption measurements. A value of Delta E-V = 0.486 +/- 0.025 eV was obtained by using the Ga 2p(3/2), Zn 2p(3/2), and In 3d(5/2) energy levels as references. This implies a conduction band offset Delta E-C of 2.39 eV in HfO2/InGaZnO4 heterostructures and a nested interface band alignment. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3673905]