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Zinc Oxide Nanowire Field Effect Transistor Used as a pH Sensor

N. M. J. Ditshego
Electrical, Computer, and Telecommunications Engineering Department, CET, Botswana International University of Science and Technology, Private bag 16, Palapye, Botswana

Abstract—An ion sensitive field effect transistor can outperform conventional ion-selective electrodes. Thus, a zinc oxide (ZnO) nanowire field effect transistor (NWFET) pH sensor was fabricated and measured. The sensor contained a channel with 1.7×1018 cm-3 donor concentration and 100 ZnO nanowires in parallel, each with the following dimensions: 10 μm×120 nm×20 nm. The active channel is passivated with an 18 nm Al2O3 layer. The device was measured under a controlled environment with and without pH solutions. The pH range was 3–9 with a sensitivity of 2.48 mV to 10.3 mV. The voltage sensitivity translates to a percentage value of 15%. The measurements obtained before and after the pH solution treatment demonstrate the possibility of re-use of the device by rinsing and brushing the sensing layer.
 
Index Terms—Device sensitivity; ion sensitive field effect transistor; nanowire; pH sensor; zinc oxide (ZnO)

Cite: N. M. J. Ditshego, "Zinc Oxide Nanowire Field Effect Transistor Used as a pH Sensor," International Journal of Electrical and Electronic Engineering & Telecommunications