Science

Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/1

Browse

End date: 1999Subject: search.filters.subject.Copper

Search Results

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Growth and Characterization of Copper Indium Diselenide
    (Proceedings of the Technical Session of Institute of Physics, Sri Lanka, 1996) Chithrani, B.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.; Siripala, W.
    CuInSe2 thin films were prepared on Ti plates by electrodeposition from an aqueous solution containing CuCl2, InCl3 and SeO2. The deposition was carried out at -0.5V Vs SCE. X-ray diffraction and Scanning electron microscopy have been used to study the crystallographic and morphological properties of the samples. Effects of annealing in air have also been monitored. Apparent bulk structure changes have been observed during annealing. Annealing of films at 350 0C was found to result in the formation of CuInSe2 films having a chalcopyrite structure, indicating that the samples are of good quality.
  • No Thumbnail Available
    Item
    Observation of n-type Photoconductivty in Electrodeposited Copper Oxide Film Electrodes in a Photoelectrochemical cell
    (Solar Energy Materials, 1986) Siripala, W.; Jayakody, J.R.P.
    Copper oxide films were cathodically deposited on various metal substrates (Cu, Ti and Pt) using a basic solution of CuSO4, and it is found that they produce n-type photoconductivity in a photoelectrochemical cell. The photoresponse of these films is more pronounced than the previously known thermally grown p-Cu2O films, and the n-type behaviour could be converted to p-type by heating the samples in air. It is tentatively proposed that oxygen ion vacancies in the electrodeposited copper oxide films would result in n-Cu2O.
  • No Thumbnail Available
    Item
    Study of Annealing Effects of Cuprous Oxide Grown by Electrodepostion Technique
    (Solar Energy Materials and Solar Cells, 1996) Siripala, W.; Perera, L.D.R.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.; Dharmadasa, I.M.
    Low temperature electrochemical deposition of cuprous oxide from aqueous solutions has been investigated. X-ray diffraction, scanning electron microscopy, optical absorption, and photo-response of liquid/cuprous oxide junctions have been used to study the deposits' crystallographic, morphological, optical, and electrical properties. Effects of annealing in air have been studied using the above mentioned methods. As-deposited cuprous oxide exhibits a direct band gap of 2.0 eV, and shows an n-type behaviour when used in an liquid/solid junction. Annealing below 300�C enhances the n-type photocurrent produced by the junction. Type conversion occurs after heat treatments in air at temperatures above 300�C. No apparent bulk structure changes have been observed during annealing below this temperature, but heat treatments above this temperature produce darker films containing cupric oxide and its complexes with water.
  • No Thumbnail Available
    Item
    Band Edge Shifts of p-type Copper Indium Diselenide Electrodes in Aqueous Electrolytes
    (Applied Physics Letters, 1993) Siripala W; Vedel, J.; Lincot, D.; Cahen, D.
    Impedance measurements were used to evaluate the relative band edge positions of single crystalp?CuInSe2electrodes in various aqueous electrolytes, by measuring the extrapolated flatband potentials, V fb. We find that V fb can be shifted, depending on the extent of the potential scan and on the pH of the electrolyte used, over a range of up to 1.7 V (between pH 0?pH 14). In the pH range 0?6, V fb can be fixed at intermediate values, which, in their turn, are determined by the pH of the electrolyte.
  • No Thumbnail Available
    Item
    A Photoelectrochemical Investigation of n- and p-type semi�conducting behaviour of Copper Oxide Films
    (Semiconductor Science and Technology, 1989) Siripala W; Kumara K P
    Copper(I) oxide films were prepared on copper substrates by exposing them to solutions containing Cu2+ ions, and it was observed that the photoresponse of these films electrodes in a photoelectrochemical cell is both n- and p-type. However, it was observed that the n-type behaviour of these film electrodes could be enhanced and the p-type behaviour could be reduced by adjusting the pH of the solution in which the oxide films had been prepared. The simultaneous existence of spatially separated n- and p-type regions in the Cu2O film is suggested as the possible reason for these observations. The anodic oxidation of copper was considered to be the origin of the p-type regions while the n-type regions were considered to be the result of the cathodic deposition of Cu2O.