Photosensitive activity of fabricated core-shell composite nanostructured p-CuO@CuS/n-Si diode for photodetection applications.

Development of photo detectors based on different semiconducting materials with high performance has been in progress in recent past, however, there is a lot of difficulties in developing the more effective photo detectors-based devices with high responsivity, detectivity and quantum efficiency. Hence, we have synthesized pure CuS and CuO@CuS core-shell heterostructure based photo detectors with high performance by simple and cost-effective two-step chemical co-precipitation method. The phase purity of CuS and CuO@CuS composite was observed by XRD analysis and the result were verified with Raman spectroscopy studies. Sphere like morphology of pure CuS and core-shell structure formation of CuO@CuS are observed with scanning and transmission electron microscopes. The presence of expected elements has been confirmed with EDX elemental mapping. Light harvesting photodiodes were fabricated by using n-type silicon substrate through drop cost method. Photo sensitive parameters of fabricated diodes were analyzed by I-V characteristics. The p-CuO@CuS (1:1)/n-Si diode owned a maximum photosensitivity (Ps) ∼ 7.76 × 104 %, photoresponsivity (R) ∼ 798.61 mA/W, external quantum efficiency ( E Q E )∼309.66 % and specific detectivity (D*) ∼ 8.19 × 1011 Jones when compared to p-CuS/n-Si diode. The obtained results revealed that the core/shell heterostructure of CuO@CuS is the most appropriate for photo detection.

Shape controlled synthesis of hierarchical nickel sulfide by the hydrothermal method.

Hierarchical structures of nickel sulfide have been grown by the hydrothermal method. Nickel nitrate hexahydrate and thiourea were used as precursor materials to synthesize nickel sulfide. Ethylenediaminetetraacetic acid was used as a capping agent to achieve monodispersity. The different phases of nickel sulfide and its dependency on the precursor concentration were analyzed by X-ray diffractometry. Transmission electron microscopy analysis was used to confirm the phase changes and morphological behavior of the synthesized material. The morphological evolution of the hierarchical structure formation was studied systematically by scanning electron microscopy. In this study, we explore a novel method to control the synthesis of nickel sulfide hierarchical structures by varying the precursor concentration. The two mixed phases enhanced the catalytic activity in the 4-nitro phenol reduction reaction.