Formation and characterization of the Cu2O overlayer on Zn-terminated ZnO(0 0 0 1) |
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| Authors: | K Ozawa Y Oba |
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| Institution: | a Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
b Department of Chemistry, Rikkyo University, Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan |
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| Abstract: | Low-energy electron diffraction, X-ray photoelectron spectroscopy and synchrotron-radiation-excited angle-resolved photoelectron spectroscopy have been used to characterize Cu-oxide overlayers on the Zn-terminated ZnO(0 0 0 1) surface. Deposition of Cu on the ZnO(0 0 0 1)-Zn surface results in the formation of Cu clusters with (1 1 1) top terraces. Oxidation of these clusters by annealing at 650 K in O2 atmosphere (1.3 × 10−4 Pa) leads to an ordered Cu2O overlayer with (1 1 1) orientation. Good crystallinity of the Cu2O(1 1 1) overlayer is proved by energy dispersion of one of Cu2O valence bands. The Cu2O(1 1 1) film exhibits a strong p-type semiconducting nature with the valence band maximum (VBM) of 0.1 eV below the Fermi level. The VBM of ZnO at the Cu2O(1 1 1)/ZnO(0 0 0 1)-Zn interface is estimated to be 2.4 eV, yielding the valence-band offset of 2.3 eV. |
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| Keywords: | Photoemission spectroscopy Valence band structure ZnO(0 0 0 1) Cu2O(1 1 1) Heterojunction |
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