Unexpected Selectivity of UV Light Activated Metal-Oxide-Semiconductor Gas Sensors by Two Different Redox Processes

Figure 4

Current responses of the ZnO film sensor to acetone vapor under UV irradiation: (a) current response before annealing. (b) Current response after annealing under 350°C for two hours. (c) Current response of the annealed sample after 24 hours of UV light treatment. The solid arrows mark the injection of RA and dashed arrows the injection of nitrogen, serving as a nonreactive gas.

(a)

(b)

(c)