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Journal of Nanomaterials
Volume 2013 (2013), Article ID 152079, 7 pages
Research Article

pH-Sensing Characteristics of Hydrothermal Al-Doped ZnO Nanostructures

1Department of Electronics Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan
2Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, Hsinchu 30010, Taiwan
3Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

Received 12 May 2013; Accepted 5 August 2013

Academic Editor: Tifeng Jiao

Copyright © 2013 Jyh-Liang Wang 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.


Highly sensitive and stable pH-sensing properties of an extended-gate field-effect transistor (EGFET) based on the aluminum-doped ZnO (AZO) nanostructures have been demonstrated. The AZO nanostructures with different Al concentrations were synthesized on AZO/glass substrate via a simple hydrothermal growth method at 85°C. The AZO sensing nanostructures were connected with the metal-oxide-semiconductor field-effect transistor (MOSFET). Afterwards, the current-voltage (I-V) characteristics and the sensing properties of the pH-EGFET sensors were obtained in different buffer solutions, respectively. As a result, the pH-sensing characteristics of AZO nanostructured pH-EGFET sensors with Al dosage of 3 at.% can exhibit the higher sensitivity of 57.95 mV/pH, the larger linearity of 0.9998, the smaller deviation of 0.023 in linearity, the lower drift rate of 1.27 mV/hour, and the lower threshold voltage of 1.32 V with a wider sensing range (pH 1 ~ pH 13). Hence, the outstanding stability and durability of AZO nanostructured ionic EGFET sensors are attractive for the electrochemical application of flexible and disposable biosensor.