Synthesis and Optical Properties of Cadmium Selenide Thin Films and Nanowires

Kalhori, Hossein | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39191 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Iraji Zad, Azam; Dolati, Abolghasem
  7. Abstract:
  8. The interesting properties of metallic and semiconductor nanowires provide many applications in electronic and optoelectronic devices. In this project, we have synthesized Cu and CdSe nanowires using electrodeposition method. To adjust deposition bath conditions and characterize the structure of deposit first we prepared CdSe thin film on ITO substrates. The used solution was contained 0.1 M CdSO4+ 0.1 mM SeO2 in the acidic situation with pH=2.5. The best reduction potential was determined about -0.5 V. The XPS and XRD analyses showed that the ratio of cadmium to selenium in the films was 1:1 and the film’s structure is amorphous. Optical band gap of the cadmium selenide films was obtained about 1.74 eV. In the next step Cu nanowires were synthesized by electrochemical deposition method in PCT templates with 80nm pore size. Chronoampermetric diagrams showed four steps; capacitive current, growth in the holes, reaching to the surface of PCT and the growth on the surface. Then CdSe nanowires were synthesized in the PCT templates and their chronoampermetric diagrams were compared with Cu deposition. From SEM and EDAX images, the mean diameter and the aspect ratio of nanowires were 100 nm and 25, respectively and Cd/Se ratio was about 1:1. The XPS results indicated existence of oxygen on the surface of wires. The band gap of CdSe nanowires was obtained about 1.98 eV and photoconductive property of the wires in the template showed sensitivity about 10% and response time about 15s. For Cu nanowires transmittance spectrum showed there was a critical wavelength so that for the shorter wavelength of that the transmittance become zero rapidly. This wavelength has a red shift by increasing the angle of light beam
  9. Keywords:
  10. Nanowire ; Electrochemistry ; Cadmium Selenides ; Polycarbonate ; Photoconductivity

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