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Clean ZnO (0001) Zn- and (000(/1)) O-polar surfaces and metal interfaces have been systematically studied by depth-resolved cathodoluminescence spectroscopy, photoluminescence, current-voltage and capacitance-voltage measurements, and deep level transient spectroscopy. Zn-face shows higher near band edge emission and lower near surface defect emission. Even with remote plasma decreases of the 2.5 eV near surface defect emission, (0001)-Zn face emission quality still exceeds that of (000(/1))-O face. The two polar surfaces and corresponding metal interfaces also present very different luminescence evolution under low-energy electron beam irradiation. Ultrahigh vacuum-deposited Au and Pd diodes on as-received and O2/He plasma-cleaned surfaces display not only a significant metal sensitivity but also a strong polarity dependence that correlates with defect emissions, traps, and interface chemistry. Pd diode is always more leaky than Au diode due to the diffusion of H, while Zn-face is better to form Schottky barrier for Au compared with O-face. A comprehensive model accounts for the metal-and polarity-dependent transport properties.


Copyright © 2009, American Vacuum Society. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Association of Physics Teachers. The following article appeared in the Journal of Vacuum Science & Technology B and may be found at



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