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NCUEIR > College of Science > Graduate Institute of Photonics Technologies > Periodical Articles > Item 987654321/17427

Please use this identifier to cite or link to this item: http://ir.ncue.edu.tw/ir/handle/987654321/17427

Title:	High-barrier Rectifying Contacts on Undoped ZnO Films with (NH4)2Sx Treatment Owing to Fermi-level Pinning
Authors:	Lin, Yow-Jon;Chang, Shih-Sheng;Chang, Hsing-Cheng;Liu, Yang-Chun
Contributors:	光電科技研究所
Keywords:	Condensed matter: electrical, magnetic and optical;Surfaces, interfaces and thin films
Date:	2009-03
Issue Date:	2013-10-02T08:37:07Z
Publisher:	IOP Publishing Ltd
Abstract:	We report on the formation of high-barrier Ti and Ni contacts to (NH4)2Sx-treated ZnO films grown by pulsed-laser deposition. The x-ray photoelectron spectroscopy (XPS) results show that the position of the Zn 3d core-level peak at the (NH4)2Sx-treated ZnO surface is the same as that at the Ti/(NH4)2Sx-treated ZnO or Ni/(NH4)2Sx-treated ZnO interfaces, suggesting the occurrence of Fermi-level (EF) pinning and the formation of a barrier height of ~2.7 eV. From the photoluminescence and XPS measurements, it is suggested that a high Zn-vacancy density might cause the ZnO EF to be pinned close to the Zn-vacancy defect level at approximately 0.7 eV above the valence band maximum. In addition, the discrepancy in barrier-height values obtained from XPS and current–voltage measurements suggests the formation of S–Zn surface dipoles with S atoms on the surfaces.
Relation:	Journal of Physics D: Applied Physic, 42(7): 075308
Appears in Collections:	[Graduate Institute of Photonics Technologies] Periodical Articles

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