Morphology driven ultraviolet photosensitivity in ZnO-CdS composite.

Semiconductors in the form of composite yields immense possibilities for the study of charge transfer processes at the interface. We have designed CdS nanoparticles (NPs) capped ZnO nanostructures using two morphologies of the latter namely nanorods arrays (NRAs) and nanocrystalline film to form a composite NRAs and composite films respectively. The photocurrent values in both the composites have been increased but to a different extent when these are illuminated with the ultraviolet (UV) light. More interestingly, the resultant UV photosensitivity in the composite NRAs is decreased while that in the composite films is increased as compared to the values of the respective uncapped samples. A different charge transfer process at the interface is occurred due to the difference in the morphologies resulting in a contrast change in the UV sensitivity. The photoluminescence results also show that the change in the emission property is morphology-dependent. Therefore, our results imply that the choice of the morphology while making a nanocomposite is crucial to tune its UV sensitivity as well as optical properties.