Pulsed and potentiostatic electrodeposition of CuInSe2 on gold coated alumina substrates

M. VALDES; M. MOLLAR; M. VAZQUEZ; B. MARÍ

JOURNAL OF APPLIED ELECTROCHEMISTRY

SPRINGER

Lugar: Berlin; Año: 2013 vol. 43 p. 619 - 628

0021-891X

A comparative analysis is presented between CuInSe2 (CISe) thin films electrodeposited on gold coated alumina electrodes using potentiostatic and pulsed electrodeposition. One pulse consisted of a step between two potential values E1 and E2. E1 was varied between -0.4 and -0.7 V (vs. Ag/AgCl) while E2 was fixed at 0.0 V. Potentiostatic films were obtained at potential values between -0.5 and -0.7 V. In every case the electrodeposition was carried out until an electrochemical charge of 4 C was reached. For the first time, in situ electrochemical-AFM measurements were recorded at various potential values to follow CuInSe2 electrodeposition. The electrodeposited films were characterized employing scanning electron microscopy, energy dispersive spectroscopy, grazing incidence X-ray diffraction and Raman spectroscopy. The morphology and chemical composition of pulse deposited CISe films was found to be highly sensitive to the deposition potential (E1). Potentials positive to - 0.6 V lead to the deposition of acicular crystals, rich in copper and selenium. In contrast, potentiostatic films presented minor variations in their chemical composition with the deposition potential. The morphology presented porous coral-like structures. X-ray and Raman spectroscopy analysis of as-deposited films reveals the contribution of CISe and also the presence of secondary phases such as CuxSe and Se, especially at lower deposition potentials (-0.5V E -0.4 V). After a thermal treatment at 500 ºC in Se vapor the cristallinity of the material is significantly enhanced and no secondary phases are present.