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To study the quality of thin metal/ZnO Schottky contacts (SCs), temperature-dependent current-voltage (I-V), capacitance-voltage, deep level transient spectroscopy, and photoluminescence measurements were performed using bulk, vapor-phase ZnO, treated by remote oxygen plasma (ROP). Au/ZnO and Pd/ZnO contacts on both O and Zn faces are compared as a function of the ROP processing sequence and duration. We find that (i) as the duration of ROP treatment increases from 2 to 4 h, Au/ZnO contacts on the Zn face, deposited before ROP treatment, become rectifying, while those on the O face remain Ohmic; (ii) with long-term ROP treatments prior to metallization, both Au/ZnO and Pd/ZnO show high-quality SCs; however, their I-V characteristics can be significantly degraded by electric field and high temperatures; (iii) ROP treatment can cause more H removal on the Zn face than on the O face, resulting in a decrease in the near-surface carrier concentration for the Zn face only; (iv) in addition to the dominant bulk-trap E3, surface traps, E6/E7 and E8, and Es, can be observed in Au/ZnO and Pd/ZnO SCs, respectively, on the Zn face, with shorter ROP treatment; and (v) with long-term ROP treatment, E3 (or L2) significantly increases and shifts in Au/ZnO SCs on the Zn face.


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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