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Singh R.S.,Government D T College Utai | Bhushan S.,Shri Shankaracharya Engineering College Bhilai | Singh A.K.,Government VYT PG College
Journal of Optoelectronics and Advanced Materials

Results of SEM and XRD studies, optical absorption spectra and photoluminescence (PL) emission studies are reported for Cd(Se-S):CdCl 2,Pr films prepared by chemical deposition method on glass substrates at 60°C in a water bath (WB). SEM studies show ball type structure with voids which is related to layered growth. XRD studies show prominent diffraction lines of CdSe and CdS along with lines of CdCl2. The chemically deposited CdSe-S films are found to consist of two PL emission peaks, one at 494 nm and the other shifting from 516 nm to 577 nm with increasing concentration of Se. The peak at 494 nm may be attributed to the exciton bound to neutral donor levels formed by excess sulphur/Cd, and the other peak may be attributed to the radiative decay of the free exciton. The peak at 494 nm may also be due to the shift of bulk emission of CdS at 511 nm (nano-crystalline effect). In Pr doped films, a new intense peak appears at 598 nm (as compared to the PL spectra of base material), which may be related to the transitions in Pr-levels. Source

Singh A.K.,Government Vytpg Autonomous College | Deo S.R.,P.A. College | Deshmukh L.,P.A. College | Pandey G.P.,P.A. College | And 2 more authors.
Research on Chemical Intermediates

In this paper we report the best conditions for growth of thin films of cadmium selenide (CdSe). The chemical bath deposition technique was used to deposit thin solid films of CdSe on to glass substrates. In this technique, cadmium acetate and sodium seleno sulfate were used as Cd2+ and Se2- ion precursors, respectively. 2-Mercaptoethanol was used as a capping agent. X-ray diffraction, atomic-force microscopy, scanning electron microscopy, and energy-dispersive X-ray analysis were used to determine the structure, morphology, and elemental constitution of these films. Photoluminescence studies revealed the effect of capping agent on the size of the CdSe nanoparticles. The optical properties were investigated by use of UV-visible absorbance spectroscopy. On annealing at 573 K, the phase of as-deposited CdSe thin films was transformed from metastable cubic (zinc blende) to hexagonal (wurtzite). The band gap energy for bulk, capped, and annealed films was estimated, and found to be 1.7, 2.3, and 2.04 eV, respectively. © 2013 Springer Science+Business Media Dordrecht. Source

Singh R.S.,Government D T College Utai | Bhushan S.,Shri Shankaracharya Engineering College Bhilai | Singh A.K.,Government VYT PG College | Deo S.R.,Government VYT PG College
Digest Journal of Nanomaterials and Biostructures

Chemical bath deposition (CBD) was used to prepare a CdSe semiconductor films on glass substrates. Scanning electron microscopic studies shows ball type structures with approximate grain size ranging between 4 nm and 8 nm with voids on uniform background. The crystallographic structure of the film and the size of the crystallites in the film were studied by X-ray diffraction. XRD measurement shows that the film is crystallized in the wurtzite phase and presents a preferential orientation along the c-axis. Optical constants such as refractive index n and extinction coefficient k, were determined from transmittance spectrum in the ultraviolet-visible (UV-VIS) regions using envelope methods. Absorption coefficient α and the thickness of the film t were calculated from interference of transmittance spectra. Optical excitation spectra showed maximum excitation at 389 nm. The photoluminescence (PL) emission spectra under this excitation consisted of two peaks at 485 nm and 531 nm wavelengths, which are attributed to the presence of one deep trapping site and electron hole recombination via trap state or imperfection site. The blue shift observed in the PL emission spectra corresponds to the nano-crystalline effect. Source

Singh A.K.,P.A. College | Deo S.R.,P.A. College | Thool G.S.,P.A. College | Singh R.S.,Government D T College Utai | And 2 more authors.
Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry

The synthesis and characterization of nanocrystallineCdSe thin solid films are reported in this article. Chemical bath deposition, a direct low-cost technique that involves a cadmium salt solution, a complexing agent, and a chalcogen (selenium) source, was used to prepare thin films of CdSe at a temperature 70°C (343 K) in a water bath. Commercially available microscope glass slides (7.5 cm × 2.5 cm × 2 mm) were used as substrates to deposit CdSe films. The characteristics of the prepared thin films were investigated in detail by measuring their optical properties, structural morphology and chemical composition. The films were characterized through x-ray diffraction (XRD),which indicates that the film is polycrystalline in nature. Absorption spectra of thin films have been recorded using a spectrophotometer. The spherical shaped clusters and the presence of elemental constituents were characterized using scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis. The optical properties were revealed by ultraviolet (UV)-visible absorbance spectra and the bandgap energy was estimated. Copyright © Taylor & Francis Group, LLC. Source

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