Electrodeposition and characterization of thin selenium films modified with lead ad-atoms

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.