Influence of the deposition temperature on the properties of copper and indium diselenete films deposited by spray-pyrolysis
ABSTRACT The Cu0.6In0.4Se2 films were deposited on a glass substrate by the spray-pyrolysis technique, for use as a photovoltaic cell absorber layer. The following deposition parameters were adopted: substrate temperature between 250 and 400ºC, precursor solution flow of 1 mL/min and deposition time of 30 min. The structural, electrical, morphological and optical properties of the prepared films were analyzed as a function of substrate temperature variation. X-ray diffraction analysis showed that the most intense peaks are oriented (204/220) and that the films have CuSe, CuSe2 and CuInSe2 phases. . For the electric conduction process, a single activation energy with an average value of 0.73 eV was observed. Sheet resistance ranged from 0.277 to 0.576 MΩ/□. The values of electrical resistivity presented small variations having an average value of 1.44 KΩm. The analysis of the morphology of the films made by confocal microscopy revealed that in general the samples presented no cracks, and the surfaces of films with higher deposition temperature were more uniform. The optical characterization was performed in the wavelength range of 350 to 1100 nm and the films had an absorption coefficient in the order of 103 cm-1 at the wavelength of 550 nm and optical gap with an average value of 1.5 eV.