Timothy J. Anderson, Chemical Engineering Department, University of Florida, 300 Weil Hall, PO Box 116550, Gianesville, FL 32611-6550, Chih-hung Chang, Chemical Engineering, Oregon State University, Corvallis, OR 97331, and E. Andrew Payzant, Oak Ridge National Laboratories, One Bethel Valley Road, P.O. box 2008, Oak Rige, TN 37831.
Chalcopyrite Cu(In,Ga)Se2 is one of the most promising absorber materials for high efficiency thin film solar cells with reported conversion efficiency approaching 20%. Central to lowering the cost of cells is developing routes to formation of this material at high rates and low temperature. To better understand growth of this material a systematic assessment of the phase diagram of this 4 component system has been performed. In addition, a systematic study of the reaction pathways and kinetics for the formation of CuInxGa1-xSe2 thin films was performed using in-situ high temperature X-ray diffraction. Reaction pathways under both inert and Se overpressure were examined for a variety of elemental and bilayer precursor film structures and kinetic analysis of the data allowed mechanism differentiation and rate parameter estimation. The observed pathways are compared to those suggested by diffusion limited transport with equilibrium conditions at the interfaces.