Electrodeposition and characterization of thin selenium films modified with lead ad-atoms |
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Authors: | Murilo F Cabral Valber A Pedrosa Sergio AS Machado |
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Institution: | a Instituto de Química de São Carlos, Universidade de São Paulo, Cx. P. 780, 13560-970 São Carlos, SP, Brazil b Universidade Federal do ABC (UFABC), Centro de Ciências Naturais e Humanas, Rua Santa Adélia, 166, Bairro Bangu, 09210-170 Santo André, SP, Brazil c Instituto de Química, Universidade de São Paulo, Cx. P. 26077, 05513-970 São Paulo, SP, Brazil |
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Abstract: | The deposition and characterization of Se films doped with Pb underpotentially deposited (UPD) ad-atoms was studied in this work. The employed experimental techniques were cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, UV-vis spectroscopy and atomic force microscopy. The initial deposition of Se film by chronoamperometry yielded a thin film composed of approximately 700 layers. The Pb UPD on Se was achieved by chronoamperometry in a potential value previously determined in voltammetric experiments. This deposition yielded a deposition charge of approximately 7.5% of the total one. The film resistance altered from 320 Ω cm−2 for Se to 65 Ω cm−2 for the Se/Pb one. Flat band potential values and number of acceptors and donors were also calculated for both films and the values obtained were +0.95 and −0.51 V for Se and Se/Pb, respectively. The Se coating presented 1.2 × 1017 cm−3 acceptors while the Se/Pb one presented 3.2 × 1017 cm−3 donors. The band gap values for both films were 2.4 eV and 1.9 eV, correspondingly. |
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Keywords: | Selenium Semiconductor films UPD Band gap Flat band potential Donors Acceptors Se/Pb films |
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