Electronic states of NO2-exposed H-terminated diamond/Al2O3 heterointerface studied by synchrotron radiation photoemission and X-ray absorption spectroscopy

The energy band-lineup and the electronic structure of NO2-exposed H-terminated diamond/Al2O3 heterointerface have been investigated by synchrotron radiation photoemission and x-ray absorption near-edge structure (XANES) measurements. It is found that the energy band-lineup is stagger-type, so-called type-II, with its valence band discontinuity of as high as 3.9 eV and its conduction band discontinuity of 2.7 eV. The valence band maximum of the H-terminated diamond surface is positioned at Fermi level as a result of high-density hole accumulation on the diamond side. The XANES measurement has shown that the oxygen-derived interface state locates at about 1–3 eV above the Fermi level.