Band offsets of HfO2/ZnO interface: In situ x-ray photoelectron spectroscopy measurement and ab initio calculation

High quality HfO2 dielectrics have been grown on ZnO (0001) substrates. The valence- and conduction-band offsets for HfO2/ZnO (0001) heterojunctions have been determined to be 0.14 +/- 0.05 and 2.29 +/- 0.05 eV, respectively, by using in situ x-ray photoemission spectroscopy. First-principles calculations show that the valence-band offset at the HfO2/ZnO (0001) interface of the most energetically favorable interface structure is 0.40 eV, which is consistent with the experimental results. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3253420]