Physics

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Author: search.filters.author.Jayasuriya, K.D.

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    Plantain Pith Battery Powered Lighting System
    (Institute of Physics, Sri Lanka, 2015) Kumara, K.S.J.; Wijesundera, R.P.; Jayasuriya, K.D.
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    ITO/n-Cu2O/p-CuxS Thin Film Solar Cell
    (Sri Lanka Association for the Advancement of Science, 1997) Perera, L.D.R.D.; Wijesundera, R.P.; Siripala, W.; Jayasuriya, K.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.
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    A Study of CuInS2 Thin Films for Photovoltaic Applications
    (Proceedings of the Technical Session of Institute of Physics, 1999) Wijesundera, R.P.; Nadesalingam, M.P.; Siripala, W.; Jayasuriya, K.D.; Kalingamudali, S.R.D.; Jayanetti, J.K.D.S.; de Silva, K.T.L.
    Thin films of copper indium disulphide (CuInS2) on Ti Substrate were prepared by annealing potentiastatically electrodeposited Cu-In alloy in H2S gas at 5500 C. Films were characteristised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectral response in a polysulphide electrolyte. XRD measurements revealed the formation of the polysrystaline CuInS2 thin films and the abscence of any other phases. SEM showed the formation of crystallites having the size about 0.2 ?m. Variations of spectral response, open-circuit voltage (Voc) and short circuit current (Isc) with annealing in air have been studied. As deposited CuInS2 films exhibit a direct band gap of 1.5 eV, and shows n-type behaviour when used in a Photoelectrochemical (PEC) cell. Heat treatment shows a considerable enhancement of the photoresponse.
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    Computational Study of I-V characteristics of ITO/Cu2 O/Metal junctions, Technical Session of Institute of Physics
    (Processing of the Technical Session of Institute of Physics, 1999) Wijesinghe, W.M.P.L.; Siripala, W.; Jayasuriya, K.D.; Kalingamudali, S.R.D.
    A theoretical model for current-voltage (I-V) characteristics of back-to-back diode systems was developed using the ideal diode equation. A computer model was developed using the language C++ to fit the experimental data to the theoretical equation and to determine the ideality factors and reverse saturation currents of each diode. This model was tested with commercial back-to-back diode systems. The values obtained for the above parameters from the theoretical fits were in very good agreement with the standard values. The experimental I-V characteristics data obtained for fabricated ITO/Cu2O/Metal (Au, Ag and Hg) structures were fitted to the model and values for the relevent parameters were obtained. These values indicate that the fabricated systems are back to back diodes except the ITO//Cu2O/Hg structure. Using this model, a good understanding of I-V characteristics of metal-semiconductor-metal diodes can be gained and thereby the quality of junction devices can be tested.
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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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    ITO/ u-Cu2O/ p-Cu2S thin film solar cell
    (Srilanka association for the advancement od science proceedings of 53rd Anuual Session., 1997) Perera, L.D.R.D.; Wijesundara, R.; Jayasuriya, K.D.; de Silva, K.T.L.; Jayanetti, J.K.D.S.
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    Study of Sulphidation of Electrodeposited Cu2O Thin Films for Solar Cell Applications
    (1998) Siripala, W.; Wijesundera, R.P.; Perera, L.D.R.D.; Jayasuriya, K.D.
    Cuprous oxide (Cu20 ) layers were potentiostatically electrodeposited on glass/ITO substrates and then they were partially sulphided using Na2S and H2S. Resulting layers were used to fabricate ITO/n-Cu20/p-CuxS thin film solar cells. Spectral response measurements showed that the cell structure exhibits both n- and p-type behavior. Sulphidation of Cu20 does not produce CuxS thick layers adequate for efficient heterojunction solar cell, but improved the photovoltaic activity. The best device fabricated shows V? = 240 mV and Isc= 1.6mA/cm2 under AM 1 artificial illumination.
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    Construction of a Near Ideal Nanoammeter
    (1998) Wijesundera, R.P.; Kalingamudali, S.R.D.; Jayasuriya, K.D.
    A near ideal ac/dc nanoammeter was constructed using two operational amplifiers (op-amp) and a voltmeter. Small currents were converted into a voltage by the first op-amp and this was amplified into a larger voltage by the second op-amp. The amplified voltage was measuredby the voltmeter. The constructed meter has 10 and 100 nA ranges for the dc current measurements and 100 nA range for the ac current measurements.All the ranges were calibrated using a digital picoammeter. As compared to commercially available nanoammeters with similar features this meter has higher advantages such as almost zero internal resistance and negligible operating bias current. The construction cost of the meter is very low compared to a commercial ac/dc nanoammeter.
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    An experimental determination of the effect of pressure on the Fe3+/?Fe ratio of an anhydrous silicate melt to 3.0 GPa
    (American Mineralogist, 2006) Jayasuriya, K.D.; O-Neill, H.S.C.; Berry, A.J.; McCammon, C.C.; Campbell, S.J.; Foran, G.
    The effect of pressure on the Fe3+/?Fe ratio of an anhydrous andesitic melt was determined from 0.4 to 3.0 GPa at 1400 �C with oxygen fugacity controlled internally by the Ru + RuO2 buffer. Values of Fe3+/?Fe were determined by M�ssbauer spectroscopy on quenched glasses with a precision of �0.01, one standard deviation. This precision was verified independently by XANES spectroscopy of the same samples. The XANES spectra show a systematic increase in energy and decrease in intensity of the 1s ? 3d transition with increasing pressure. The results to 2.0 GPa are in good agreement with predictions from density and compressibility measurements fitted to a Murnaghan equation of state, but the datum at 3.0 GPa has higher Fe3+/?Fe than predicted from the trend established by the lower-pressure data. This might be due to a coordination change in Fe3+ at high pressure; although there is no evidence for this in the M�ssbauer spectra, such a change could account for the change in intensity of the 1s ? 3d transition in the XANES spectra with pressure.
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    Fabrication of CUO!CU2O Heterojunction and Its Local Structural Characterization
    (2011) Siripala, W.; Wijesundera, R.P.; Perera, L.D.R.D.; Jayasuriya, K.D.
    Cuprous oxide (Cu20) thin films on Ti substrate were potentiostatically electrodeposited at -200 mV in an acetate bath. For the growth of p-type cupric oxide (CuO) thin films , CU20 thin film s were annealed at 500 oC (for 30 min in air. In order to fabricate CuO/Cu20 hetorojunction, thin film of Cu20 was potentiostatically electrodeposited on Ti/CuO electrode . Deposits were characterized by using X-ray diffraction (XRD) and scanning electron micrographs (SEM). Results revealed that well covered n-tvpe polycrystall ine Cu20 thin film can be electrodeposied on Ti/CuO electrode at -550 mV VS the SCE in an acetate bath. The CuO/Cu20 heterojunction gave the open circuit voltage (Voc)of 210 mV and short circuit current (Jsc) of 310 uA/cm2. Layer by layer structural properties of the electrodeposited Ti/CuO/Cu20 thin film heterojunction have been studied by means of the XRD and the X-ray absorption spectra (XAS) with different grazing angles of the incident Xray beam. Results reveal that Cu20 and CuO are high quality semiconducting thin films but amorphous structure is formed between CuO and Cu20 while Cu20 deposition on CuO. It can be expected that amorphous structure formed in the middle of the CuO/Cu20 heterojunction attributes better lattice matching between CuO and Cu20 interface .