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 CuxSe and Se, especially at the most positive deposition potentials. After a thermal treatment at 500 ºC in Se vapor the crystallinity of the material is significantly enhanced and no secondary phases are present.