Recent Progress in Ohmic/Schottky-Contacted ZnO Nanowire Sensors

Figure 14

The ohmic-contacted biosensor was fabricated using a single-crystal ZnO NW that shows little response to the biomolecules. (a) Pt-Ga was deposited by FIB on both ends of the NW to form ohmic-contact (inset), as proven by its corresponding I-V curve. (b) When either positively charged molecules or negatively charged molecules are introduced, the electrical signal of the device shows little change. (c) SEM image of a Schottky-contacted biosensor is shown in the upper-left inset. The I-V curve shows a typical Schottky characteristic. (d) A fast response and distinct current variations can be seen when the sensor is exposed to a series of concentrations of negatively charged molecules (pI 7.4 < pH 8.4). (e) When the molecules are positively charged (pI 7.4 > pH 5.6), the conductance of the device increases. (f) The negatively charged molecules result in a decrease in conductance [79]. Copyright 2009, John Wiley and Sons.

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