Physics

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Start date: 1981End date: 1989

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Now showing 1 - 10 of 23
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    n-type electrical conductivity in cuprous oxide thin films
    (Natural Resources, Energy and Science Authority of Sri Lanka, 1988) Siripala, W.; Kumara, K.P.
    Electrodeposited cuprous oxide thin films were investigated to determine whether their electrical conductivity is n-type or p-type. The experimental results based on the measurements of thermoelectric e.m.f, sheet resistance, dark and light current-voltage characteristics of Cu2O/CuxS and Cu2O/CuCNS heterojunctions reveal that the electrodeposited cuprous oxide films produce n-type electrical conductivity. These observations are in very good agreement with the previously reported n-type behavior of the electro-deposited Cu2O film electrodes in a photo-electrochemical cell.
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    Electrolyte Electroreflectance Study of CdIn2Se4 Liquid Junction Solar cells
    (American Physical Soc. Meeting, Los Angeles,USA, 1983) Tomkiewicz M; Siripala W
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    The Interrelation Between the Potential Distribution and the Dark Charge Transfer Across n-TiO2 - Aqueous Electrolyte Interface
    (Symposia on Photoelectrochemical Process and Measurements Techniques for Photoelectrochemical Solar Cells, 1981) Tomkiewicz M; Siripala W
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    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.
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    A Home Made Double Slab Pyranometer for Irradiance Measurements
    (Proceedings of the 44th Technical Session of the Sri Lanka Association for the Advancement of Science (SLAAS), 1988) Punyasena, M.A.; Jayasuriya, K.D.
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    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.
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    Characterization of Surface States at a Semiconductor Electrolyte Interface by Electroreflectance Spectroscopy
    (Journal De Physique, 1983) Tomkiewicz M; Siripala W
    Supra bandgap and subband gap Electrolyte Electroreflectance is being used to characterize surface states at semiconductor liquid interfaces. The surface states can manifest themselves either through direct optical transitions as in the case of n - TiO2 - aqueous electrolyte interface or through their effect on the response of the Fermi level to small changes in the electrode potential as in the case of single crystal CdIn2Se4 in polysulfide solutions.
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    The specific heat of samarium metal (80-400 K)
    (Materials Chemistry and Physics, 1986) Jayasuriya, K.D.; Stewart, A.M.; Campbell, S.J.
    We have measured the specific heat of several high purity polycrystalline specimens of samarium metal over the temperature range 80 K to 400 K. A broad peak is observed at TNh ~106K, the temperature at which antiferromagnetic ordering first sets in with ordering of the moments on hexagonal sites. This behaviour contrasts with the sharp peak observed by previous workers on samarium samples of lower purity.
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    Specific heat study of a holmium single crystal
    (Journal of Physics F: Metal Physics, 1985) Jayasuriya, K.D.; Campbell, S.J.; Stewart, A.M.
    The magnetic transition at the Neel temperature, TN, of the heavy rare-earth metal holmium has been examined by specific heat measurements. The transition at TN=(132.245+or-0.080)K is found to be continuous and the data around TN have been analysed in terms of the equation C+or-=(A+or-/ alpha +or-) mod t mod - alpha +or-(1+E+or- mod t mod x+or-)+B+or-+D+or-t where t=(T-TN)/TN. The value of the critical exponent alpha is 0.27+or-0.02 for the data in the critical regions -3.8
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    A specific heat study of natural haematite around the Morin transition and the effects of entrapped water
    (Journal of Physics and Chemistry of Solids, 1985) Jayasuriya, K.D.; Stewart, A.M.; Campbell, S.J.
    The Morintransition in samples of natural haemitite has been examined by specificheat and M�ssbauer measurements. Specificheat measurements on as-received samples reveal an anomaly at ? 273.2 K and irregular behaviour at higher temperatures. However, heat treatment of samples demonstrated that these effects were due to water trapped inside the natural specimens. No anomaly due to the Morintransition was observed in the specificheat although the expected changes in the M�ssbauer hyperfine parameters were observed for the different magnetic phases below and above the Morintransition. The results are consistent with a coexistence of the two phases and a spread of temperatures ? 40 K over which the transitions take place throughout the material of purity 99.6 wt%.