Study of bands tails in chalcogens by measuring the optical absorption coefficient

Abstract : This internship period for 6 months within the Laboratory for Photovoltaic (LPV) of the University of Luxembourg is part of obtaining the Master degree I2E2I option «Electrical Energy» and obviously deals with renewable energy sources and especially the production of electricity. The purpose of this report is to determine by spectrophotometry and photoluminescence, the absorption coefficient of thin films of chalcopyrite type which we use in photovoltaic cells (Cu (In, Ga) Se2). The absorption coefficient allows to judge the quality of a semiconductor and is therefore a key parameter for producing the photovoltaic cell. The determination of the absorption coefficient requires several steps that are presented as follows: - Preparation of samples before each measurement that is to say the mechanical transfer films (originally on non-transparent metal substrates) on transparent substrates (glass slides). - Measurement of the thickness of thin films using a cross-section which is obtained by scanning electron microscopy (SEM). - Spectrophotometric measurement of the reflectance (R) and transmittance (T) of sample. These measurements enable to determine the absorption coefficient for high absorption values and also the refractive index. - Photoluminescence measurement at room temperature which allows to determine the optoelectronic properties of the material and can be analyzed to extract information about the parameters that directly affect the performance of solar cells such as absorption for lower energy than the width band gap.- The combination of spectrophotometric measurement and photoluminescence and their treatment using programs on the Python software which enables the extraction of the absorption coefficient on a spectral spread range.
Document type :
Master thesis
File URL :
http://docnum.univ-lorraine.fr/prive/BUS_M_2016_RACHAD_WAFAE.pdf
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https://hal.univ-lorraine.fr/hal-01767261
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Submitted on : Monday, April 16, 2018 - 9:02:21 AM
Last modification on : Monday, April 16, 2018 - 9:02:21 AM

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  • HAL Id : hal-01767261, version 1

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Wafae Rachad. Study of bands tails in chalcogens by measuring the optical absorption coefficient. Engineering Sciences [physics]. 2016. ⟨hal-01767261⟩

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