Abstract
We report on the formation of high-barrier Ti and Ni contacts to (NH 4)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)2S x-treated ZnO surface is the same as that at the Ti/(NH 4)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.
| Original language | English |
|---|---|
| Article number | 075308 |
| Journal | Journal of Physics D: Applied Physics |
| Volume | 42 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 2009 Apr 9 |
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All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Acoustics and Ultrasonics
- Surfaces, Coatings and Films
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High-barrier rectifying contacts on undoped ZnO films with (NH 4)2Sx treatment owing to Fermi-level pinning. / Lin, Yow-Jon; Chang, Shih Sheng; Chang, Hsing Cheng; Liu, Yang Chun.
In: Journal of Physics D: Applied Physics, Vol. 42, No. 7, 075308, 09.04.2009.Research output: Contribution to journal › Article
TY - JOUR
T1 - High-barrier rectifying contacts on undoped ZnO films with (NH 4)2Sx treatment owing to Fermi-level pinning
AU - Lin, Yow-Jon
AU - Chang, Shih Sheng
AU - Chang, Hsing Cheng
AU - Liu, Yang Chun
PY - 2009/4/9
Y1 - 2009/4/9
N2 - We report on the formation of high-barrier Ti and Ni contacts to (NH 4)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)2S x-treated ZnO surface is the same as that at the Ti/(NH 4)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.
AB - We report on the formation of high-barrier Ti and Ni contacts to (NH 4)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)2S x-treated ZnO surface is the same as that at the Ti/(NH 4)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.
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U2 - 10.1088/0022-3727/42/7/075308
DO - 10.1088/0022-3727/42/7/075308
M3 - Article
AN - SCOPUS:63749123493
VL - 42
JO - Journal Physics D: Applied Physics
JF - Journal Physics D: Applied Physics
SN - 0022-3727
IS - 7
M1 - 075308
ER -