Pulsed and potentiostatic electrodeposition of CuInSe2 on gold-coated alumina substrates

Abstract

CuInSe2 thin films were deposited on gold-coated alumina electrodes using constant and pulsed potential signals. In situ electrochemical measurements were recorded with an atomic force microscope 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 best stoichiometry is attained for films deposited at pulsed potentials of −0.7 V. These films are also the most compact, showing a homogeneous morphology. 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 by either technique reveal the presence of secondary phases such as Cu x Se and Se, especially at the most positive deposition potentials. After a thermal treatment at 500 °C in Se vapor, the crystallinity of the material is significantly enhanced and no secondary phases are present.