Recent Presentations

Wide Bandgap Sensors

Semiconductor nanowire device structures are expected to have potential advantages in improved carrier confinement over their thin film counterparts. For GaN nanowires, there are possible applications in low power and high density field-effect transistors (FETs), solar cells, terahertz emitters and UV detectors. The high surface-to-volume ratio of nanowires means that if their surfaces are sensitive to external stimuli or can be functionalized to be sensitive to specific chemicals or biogens, then they are likely to be attractive for gas and chemical sensor arrays. ZnO is a piezoelectric, transparent wide bandgap semiconductor used in surface acoustic wave devices. The bandgap can be increased by Mg doping. ZnO has been effectively used as a gas sensor material based on the near-surface modification of charge distribution with certain surface-absorbed species. In addition, it is attractive for biosensors given that Zn and Mg are essential elements for neurotransmitter production and enzyme functioning. InN is currently receiving attention because of its recently reported considerably narrower direct bandgap (0.7 ~ 0.8 eV) and superior electron transport characteristics. This makes it a promising material for high efficiency IR emitters, detectors, and solar cells as well as high frequency electronic devices. Reports on the growth, properties, and applications of InN nanowires, however, are very limited.

These lightweight sensors with the possibility of being integrated with on-chip wireless communication and remote data transmission could be used for perimeter defense, early-warning of chemical attacks and possible detection of improvised explosive devices.

SEM images of selectively grown ZnO nanorods (courtesy Sam Kang)

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