UV-activated room-temperature gas sensing mechanism of polycrystalline ZnO

The effects of UV illumination on the electronic properties and gas sensing performance of ZnO are reported. It is found that UV light improves the sensitivity and the sensor response and recovery rate. By investigating the photoresponse behavior of ZnO, we observe that the electrons generated by UV light promote the adsorption of oxygen and form the photoinduced oxygen ions [O(2)(-)(hv)]. These ions [O(2)(-)(hv)] are responsible for the room-temperature gas sensing phenomena and promise enhanced sensor performance through further optimization. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3243458]