Annealing-Induced Modifications in Physicochemical and Optoelectronic Properties of Ag-Doped Nanostructured CdS Thin Films

Abstract

The Ag-doped nanostructured CdS thin films are grown by simple, cost effective chemical ion exchange technique at room temperature on ITO-coated glass substrate. These as grown thin films are annealed at 100, 200, 300, and 400°C in air atmosphere for 1 hour. To study the effect of annealing on physicochemical and optoelectronic properties, these as grown and annealed thin films are characterized for structural, compositional, morphological, optical, and electrical properties. X-ray diffraction (XRD) pattern reveals polycrystalline nature of these thin films with increase in crystallite size from 6.4 to 11.2 nm, from XRD the direct identification of Ag doping in CdS thin films cannot be judged, while shift in characteristics peak position of CdS is observed. The Raman spectrum represents increase in full width at half maxima and intensity of characteristic peak, confirming the material modification upon annealing treatment. Presence of Cd, Ag, and S in energy dispersive X-ray analysis spectra (EDAX) confirms expected elemental composition in thin films. Scanning electron microscopy (SEM) images represent grain growth and agglomeration upon annealing. Red shift in optical absorbance strength and energy band gap values from 2.28 to 2.14 eV is obtained.I-Vresponse obtained from as grown and annealed thin films shows an enhancement in photosensitivity from 72% to 96% upon illumination to 100 mW/cm2light source.

New systematic study approach of green synthesis CdS thin film via Salvia dye

“…These defects function as trap centres and affect optical absorbance. Consequently, the formation of localized energy states at the band edge, the reduction in optical band intensity could be attributed to an optical defect or, more possibly, defect-induced band tailing 24 . The intensity peak corresponding to mixing all additives led to a slight blue shift for the absorption edge, possibly due to a decrease in the electron density inside the valence band.…”

“…The potential difference noted between the conduction band of the CdS and the Fermi level of Ag helped in transferring electrons between the doped material and the semiconductor matrix 23 . Taur et al analysed the impact of annealing on the physical–chemical and optoelectronic properties and reported I–V responses from the growing and annealed of thin films showed an improvement from 72 to 96% of photosensitivity after illumination to 100 mW/cm 2 light source 24 . Whereas Ferrá-González et al noticed that the bandgap in energy and roughness is considerably increasing with the concentration of silver, to the point that cadmium is depleted and stopped being substituted, silver sulphide (Ag 2 S) is starting to form at this point, the bandgap and film roughness is beginning to decline with the rise in the concentration of AgNO 3 25 .…”

Optical Changes in Rock-salt CdS System under Increasing Silver Concentrations Effects

“…This fact might cause reordering of extranuclear electrons suggesting weak interaction of Ag to CdS [32]. Because of this, no plasmonic effects or appreciable broadening is observed [39]. So a high concentration of Ag is suggested because it will bring more prominent effects as obvious from 12.5% concentration in comparison to rest in our theoretical study.…”

Structural, Optical and Electrical Properties of Thermally Deposited CdS Thin Films

“…It is clear from Figure 1 that annealing leads to increase in the peak intensity. The increase in the peak intensity as a result of annealing suggests improvement in the film crystallinity [19][20][21][22] . The Scherrer's relation was used to find out the crystallite size of the films from XRD patterns 23 .…”