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Journal of Nanomaterials
Volume 2013, Article ID 560542, 9 pages
Research Article

Surface Modification on the Sputtering-Deposited ZnO Layer for ZnO-Based Schottky Diode

1Institute of Electro-Optical and Material Science, National Formosa University, Yunlin 63201, Taiwan
2ITRI South, Industrial Technology Research Institute, Tainan 73445, Taiwan
3Metal Industries Research & Development Centre, Kaohsiung 81160, Taiwan

Received 14 September 2013; Accepted 5 November 2013

Academic Editor: Liang-Wen Ji

Copyright © 2013 Ren-Hao Chang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We prepare a zinc oxide- (ZnO-) based Schottky diode constructed from the transparent cosputtered indium tin oxide- (ITO-) ZnO ohmic contact electrode and Ni/Au Schottky metal. After optimizing the ohmic contact property and removing the ion-bombardment damages using dilute HCl etching solution, the dilute hydrogen peroxide (H2O2) and ammonium sulfide (NH4)2Sx solutions, respectively, are employed to modify the undoped ZnO layer surface. Both of the Schottky barrier heights with the ZnO layer surface treated by these two solutions, evaluated from the current-voltage (I-V) and capacitance-voltage (C-V) measurements, are remarkably enhanced as compared to the untreated ZnO-based Schottky diode. Through the X-ray photoelectron spectroscopy (XPS) and room-temperature photoluminescence (RTPL) investigations, the compensation effect as evidence of the increases in the O–H and OZn acceptor defects appearing on the ZnO layer surface after treating by the dilute H2O2 solution is responsible for the improvement of the ZnO-based Schottky diode. By contrast, the enhancement on the Schottky barrier height for the ZnO layer surface treated by using dilute (NH4)2Sx solution is attributed to both the passivation and compensation effects originating from the formation of the Zn–S chemical bond and acceptors.