Visible Light Photodetectors Based on Hydrothermally Synthesized Cd-Se-Te Nanostructures

Metal chalcogenides are currently in the limelight for various optoelectronic sectors. Cd-Se-Te nanomaterials are hydrothermally synthesized by varying Se and Te while keeping the Cd content constant. A structural study provides information on the formation of hexagonal CdSe and cubic CdTe phases. The material crystallinity increased with an increase in the Te content. Raman spectroscopy showed the presence of various Cd-Te and Cd-Se modes present in the material. The morphology of the material changes from a cylindrical to a spherical shape. The optical study illustrates the reduction in the bandgap and red shift in the absorption edge. The refractive index of the material behaves exactly opposite of the optical bandgap. The X-ray photoelectron spectra provided the +2-oxidation state of Cd and the −2 oxidation state of both Se and Te. A photoluminescence (PL) study provides the defect states present in the material and shows a red shift in the PL peak, which is the same as the absorption edge. A current–voltage study of the material shows the increased pattern in the photocurrent with an increment in the Te concentration. The photoresponse study was done by the illumination of white light, which results in good responsivity and detectivity. All of these results show the material is suitable for visible light photodetector applications.