Solution-processed novel core–shell n–p heterojunction and its ultrafast UV photodetection properties

Abstract

We demonstrate the feasibility of fabricating a solution-processed novel core–shell coaxial n–p nanorod (NR) heterojunction consisting of an n-type ZnO NR core and a p-type CuS shell through an ion-exchange route. The field emission scanning electron and high resolution transmission electron microscopy experiments show evidence of the formation of core–shell NR arrays manifesting a clear change in the side walls of the NRs, which become rougher due to CuS shell formation over ZnO NRs. The core–shell heterojunction shows diode behavior with an ideality factor of 5.8. The diode shows a very fast response time (<0.3 s) towards 365 nm ultraviolet (UV) light, which is an important criterion for the photodetection property. Furthermore, the main advantages of this solution-based method are its simplicity and low cost. This achievement demonstrates that such solution-processed novel core–shell n–p heterojunctions are promising candidates for applications in electro-optic devices.