Influences of different interdigital spacing on the performance of UV photodetectors based on ZnO nanofibers

ZnO nanofibers (NFs) were fabricated by using an electrospinning method and characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis absorption spectrum. Au electrodes with different interdigital spacings were deposited on the ZnO NFs to form devices. The photoresponse of the devices was studied and compared. Under the irradiation of 260 nm UV light with an 8.8 μW cm−2 irradiation-intensity, the photocurrent is 9.6 μA for device S1. At 5 V bias, device S1 gets the highest responsivity of 287 A/W, which has an UV/vis rejection ratio about three orders of magnitude. The physical mechanism of the devices was also discussed. The experimental results suggest that the responsivity of ZnO NFs UV photodetectors is obviously increasing with the reduction of the interdigital spacing.