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    The effect of electric and magnetic fields on the operation of a photovoltaic cell
    (Elsevier Science Bv, 2002) Erel, S.
    In this work, we have investigated the effects of electric and magnetic fields on the operation of a CdS/CuInSe2 photovoltaic cell. Various electric field intensities changing from 0 to 35000 V-dc/m, were applied to the sample while it was irradiated by a He-Ne laser with a wavelength lambda = 670 nm. As a result, the typical values for the open circuit voltage of the photovoltaic cell significantly changed with various intensities of the electric field E-dc. We also applied magnetic fields varying from 0.003 to 0.079 T using a solenoid with an inductance of 10.55 mH and the response of the sample was observed. In the third step of the experiment, instead of the laser beam, various intensities of white light of 50, 100,150 and also 250 lux were utilised. 250 lux was measured to be equivalent to the radiation power of lie-Ne laser beam on the surface of the photovoltaic cell, The effect of electric fields from 0 up to 3 x 10(5) V-dc was applied and some significant experimental results were obtained. As a result of the illumination of the photovoltaic cell by the stimulated and spontaneous light emission sources under the effect of various intensities of electric field E-dc, different electrical behaviours were observed. (C) 2002 Elsevier Science B.V. All rights reserved.
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    The energy distribution of the interface state density of Pb/p-Si Schottky contacts exposed to clean room air
    (Elsevier Science Bv, 2003) Çetinkara, H.A.; Turut, A.; Zengin, DM.; Erel, S.
    Pb/p-Si Schottky barrier diodes (SBDs) with and without thin native oxide layer have been fabricated. The previously polished p-Si wafer has been cleaned by using a traditional RCA clean with the final dip in diluted HF for 30 s. The ohmic contact on the back surface of the wafer was made by evaporation of Aluminium metal and then the wafer was cut into pieces of 5 mm x 5 mm. Other than the sample PbD1, before Schottky contact formation, these pieces with ohmic contact were exposed to clean room air for 1, 5, 10, 15, 30, 45 and 60 days at room temperature to obtain the samples with the native oxide layer on the clean Si surface. The value of the barrier height (BH), Phi(b) first increases with the increasing exposure time to air and then tends to that of the initial sample PbD1. Furthermore, the energy distribution curves of the interface states localized at the native oxide layer-semiconductor interface were determined from the forward bias current-voltage (I-V) characteristics by taking into account the bias dependence of the barrier height. It was seen that the density value of the interface states for the samples with the native oxide layer at all energy positions is lower than that for the initial sample. This is attributed to the passivation of the cleaned Si surface due to the formed native oxide layer. (C) 2002 Published by Elsevier Science B.V.