Fig. 1. (a) Schematic atom structure of ZnO; (b) schematic structure of as-grown ZnO MW by CVD; (c) the chemical molecular structure of PANI; (d) measured configuration of PANI/ZnO MW heterojunction UV photodetector.

Fig. 2. (a) XRD pattern and (b) normalized absorption spectrum of one single ZnO MW; (c) normalized absorption and (d) Raman spectra of PANI samples with aniline doses of 25 μL, 30 μL, 35 μL and 40 μL.

Fig. 3. (a) Optical image of one as-prepared ZnO MW on Si substrate, (b) SEM image of the as-prepared single ZnO MW; (c) SEM image of the PANI/ZnO MW core-shell heterostructure; (d) SEM image of the PANI from the core-shell heterostructure.

Fig. 4. (a-d) I-V curves of device #1, #2, #3, and #4 under dark and 350 nm light illumination; (e) rectification ratio (I+3V/I-3V) (black line) and rejection ratio (I350 nm/Idark) (red line) of the PANI/ZnO heterojunctions at -3 V as a function of aniline dose; (f) I-T curves of the four devices under a 350 nm light illumination on/off switch at -3 V.

Fig. 5. (a) Responsivities of device #2 and #3 under -3 V bias voltage; (b) 6-cycle transient time-resolved response of device #2 under 355 nm pulse laser illumination at -10 V bias voltage; (c) one single period time-resolved response of device #2 derived from (b); (d) schematic energy band diagram of the PANI/ZnO heterojunction.

Fig. 6. (a) Responsivities of device #3 under 0 V bias voltage; (b) I-T curve of device #3 under a 350 nm light on/off switch at 0 V, (c) 6-cycle transient time-resolved response of device #3 under 355 nm pulse laser illumination at 0 V bias voltage; (d) one single period time-resolved response of device #3 derived from (c); theoretical simulation of optical field distribution: (e) one single ZnO MW, (f) PANI/ZnO core-shell microwire, the incident light is vertical to one facet of the hexagonal structure.