SiNPLs/CoPc hybrid heterostructures based photodetector with low dark current and enhanced sensitivity

Fabrication of hybrid heterostructures, consisting of two different nanostructured materials are an efficient approach for further improving photodetecting performance over their individual counterparts. In this paper, we demonstrate the fabrication of an inorganic-organic hybrid heterostructure comprising of Si-nanopillars (SiNPLs) and cobalt phthalocyanine (CoPc). Photodetecting performance of SiNPLs/CoPc heterostructure is investigated in photoconductive mode. It exhibits a low dark current of 2.05 x 10(-8) A and enhanced sensitivity (similar to 4.5 times) in contrast to pristine SiNPLs. Suppression of dark current with enhanced sensitivity is ascribed to the transfer of electrons from SiNPLs to CoPc layer and their trapping in disorder states present in CoPc layer. The process of electron transfer is confirmed by work function measurements. These results indicate that by employing heterostructure method, the trap states originating from the non-uniform molecular packing of organic semiconductors may be used to further improve the photodetecting performance of one-dimensional nanostructured materials. Additionally, the long-term stability of the SiNPLs/CoPc heterostructure was evaluated by exposing it to ambient conditions for 20 days.