Semiconducting Cu2Se thin films obtained by electrochemical deposition for possible applications in thermoelectric systems

In this work, Cu2Se thin films were obtained using a two-stage processing approach. First, the electrodeposition technique was used to obtain Cu3Se2 thin films, and then the samples were heat-treated in a tubular furnace at 250 degrees C in gaseous Ar atmosphere during 30 min to promote a phase transformation from tetragonal Cu3Se2 phase into cubic Cu2Se phase. Results on morphology, chemical composition and crystalline structure of electrodeposited and heat-treated thin films are presented and discussed. Optical characterization results have shown that semiconducting Cu2Se thin films have a band gap of 2.26 eV. Hall Effect measurements have shown that Cu2Se thin films are p-type, and that they have an average value for bulk charge-carrier concentration of 1.67 x 10(22) cm(-3), sheet charge-carrier concentration of 8.32 x 10(18) cm(-2), electrical conductivity of 3.07 x 10(3) Omega(-1) cm(-1), electrical resistivity of 3.26 x 10(-4) Omega.cm, Hall mobility of 5.64 cm(2)V(-1) s(-1), and Hall coefficient of 2.16 x 10(-3) cm(3)C(-1).