Photoluminescence and Raman study of CdS-Al 2O 3 nanocomposite films prepared by sol-gel techniques

S. K. Panda, S. Chakrabarti, A. Ganguly, S. Chaudhuri

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Abstract

The optical and microstructural properties of CdS-Al 2O 3 nanocomposite (CdS-Al 2O 3 = 20:80 to 50:50) thin films synthesized by sol-gel techniques were studied. Optical transmission spectra indicated a marked blue shift of the absorption edge due to quantum confinement. Band gaps of CdS-Al 2O 3 nanocomposites were found to vary in the range 3.69-2.61 eV. The sizes of the nanocrystals, estimated from the blue shift (0.2-1.2 eV) of the absorption edges and transmission electron microscopy, were found to vary in the range 2.8-7.0 nm. X-ray diffraction studies showed reflections from (111), (200), (220), and (311) planes of CdS in the cubic phase. Microstructural characterization by high-resolution transmission electron microscope (HRTEM) indicated well crystallinity of the nanoparticles and lattice fringes supported the cubic phase of CdS. Raman spectroscopy was carried out for CdS-Al 2O 3 nanocomposites, which indicated a prominent peak at ∼299 cm -1. Significant changes in the peak position and intensity of the Raman peak were observed with varying the annealing temperature (373-573 K). Photoluminescence measurements indicated a prominent broad peak at ∼1.81 eV due to the surface defects in the CdS nanocrystallites. The present study revealed Al 2O 3 to be a good capping material for CdS nanoparticles.

Original languageEnglish
Pages (from-to)459-465
Number of pages7
JournalJournal of Nanoscience and Nanotechnology
Volume5
Issue number3
DOIs
Publication statusPublished - 1 Dec 2005

Keywords

  • CdS-Al O nanocomposite
  • Quantum confinement effect photoluminescence
  • Raman study
  • Sol-gel

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