Properties of Cu(In,Ga)Se2 thin films prepared by chemical spray pyrolysis

Thin polycrystalline films of Cu(In,Ga)Se-2 alloy with the single-phase chalcopyrite structure were successfully grown by the chemical spray pyrolysis (CSP) method on a glass substrate at 360 and 400 degrees C. Alloy composition in the film was well controlled by that in the spray solution. The films were characterized by X-ray diffraction, optical absorption, Raman spectroscopy, van der Pauw measurement and scanning electron microscopy. It was found that lattice constants, the optical band-gap energy and the A(1) mode phonon frequency changed continuously with the alloy composition a. A grain size of about 1 mu m was obtained for Cu-rich films.