Electrodeposition of In-Se, Cu-Se, and Cu-In-Se thin films

Indium-selenium, copper-selenium, and copper-indium-selenium thin films have been prepared by electrodeposition techniques on molybdenum substrates. Electrodeposited precursors are prepared at varying potentials, pH, and deposition times. The adhesion and uniformity of indium selenide on molybdenum substrates are improved by electrodepositing an initial copper layer (500 A) on molybdenum. The films (In-Se, Cu-Se, and Cu-In-Se) are annealed at 250 and 450°C in Ar for 15 min and are slow-cooled (3°C/min). The films are characterized by electron microprobe analysis, inductive-coupled plasma spectrometry, x-ray diffraction analysis, Auger electron spectroscopy, and scanning electron microscopy. The as-deposited precursor films are loaded in a physical evaporation chamber and additional In or Cu and Se are added to the film to adjust the final composition to CuInSe2. The device fabricated using electrodeposited Cu-In-Se precursor layers resulted in a solar cell efficiency of 9.4%.