Fig. 5
UV sensing characteristics of ZnO NW FETs. a I–V characteristics under UV illumination at different back-gate voltages. Vg ranged from − 60 V to 60 V in 20 V steps. b Electrical properties of Ids vs Vg under UV illumination. c Ilignt/Idark as a change of gate voltage. Maximum Ilignt/Idark was obtained around Vg ~ − 55 V. Inset, Ids-Vg characteristics under UV illumination and under darkness. d Linear relationship between photo/dark current ratio (Ilignt/Idark) and initial on-off current ratio (Ion/Ioff) of the ZnO NW FET. The inset shows the initial Ion/Ioff ratio for various Vds. The maximum Ion/Ioff ratio was at Vds = 7 V. e Photoresponse of ZnO NW network FET photodetector with and without UV illumination in the air. The inset shows exponential decay characteristics after the UV light off. f Time-resolved photoresponse of the ZnO NW network channel devices recorded by switching on and off the UV light