For the first time, UV irradiation is used to improve the carbon monoxide (CO) sensing properties of ZnO. In addition, when the pressure is decreased to 0.05 mBar, the conductivity of the NWs increases ∼ 2 and 3.5 times for NWs with 300-nm and 100-nm diameter, respectively. Moreover, due to the increased electron density in the presence of UV, the type of oxygen species on the surface of ZnO changes to more reactive negative ions. The UV response has a fast component, due to electron-hole generation, as well as a slower component, attributed to the release of oxygen. The nanowire devices illustrate 4 orders of magnitude increase in conductivity when exposed to ultra violet (UV) irradiation of 1220 μW/cm².
In this PhD thesis, vertical arrays of zinc oxide (ZnO) nanowires (NWs) are synthesized in a CVD system and then deposited on patterned electrodes using dielectrophoresis (DEP).
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