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The University of Southampton
University of Southampton Malaysia

Zinc Oxide Nanowire Field Effect Transistor for Proteins Sensing Seminar

17:00 - 18:00
14 April 2015

Event details

ZnO nanowire field effect transistors (NWFETs) have shown a great potential in gas and chemical sensing, high power devices, short wavelength photodetector and light emitting applications.

This is due to ZnO excellent semiconducting properties of high bulk mobility, large bandgap energy of 3.4 eV and optical transparency window from visible to the mid-infra-red spectrum. There are two approaches to realize ZnO nanowire; bottom-up and top-down. Bottom-up fabricated ZnO nanowire transistors exhibit a high field-effect mobility > 1000 cm2/V.s and large output drain current but the device’s electrical performance is difficult to reproduce due to variation in size and material quality. Therefore, a top-down fabrication approach is an attractive option since nanowire properties and size can be controlled by process parameters. I will present a top-down fabrication approach to produce nanowire using a combined photolithography, atomic layer deposition and anisotropic plasma etching technology. The ZnO nanowires were fabricated on 150 mm diameter SiO2-Si wafer with a dimension of 40 nm x 38 nm. The nanowires are made into field-effect transistors with a channel length from 1.3 µm to 18.6 µm to study channel scaling, hysteresis and surface sensitivity to the presence of proteins charges. Electrical measurements of the ZnO NWFETs give field-effect mobility of 3 cm2/V.s and improvement to 30 cm2/V.s after passivation with Al¬2O3 due to reduction of surface traps. The drain current on-off ratio (Ion/Ioff) of 2x106 has been achieved with characteristic pinch-off. An array of 100 ZnO NWFETs was fabricated and used to sense the proteins lysozyme (LYZ) and bovine serum albumin (BSA) diluted in phosphate buffered solution (PBS). Preliminary results of subthreshold voltage shift due to the net charge of the proteins and show encouraging NWFET channel sensitivity.

Speaker information

Dr Harold Chong,joined the Nano Research group as lecturer in the School of Electronics and Computer Science at the University of Southampton in October 2007. His current research interests include the investigation of photonic nanowire devices and photonic crystal structures as the building blocks for nanophotonic integrated circuits. He is also interested in nanofabrication technology and using top-down and bottom-up fabrication approach to realise nanoscale devices.

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