PHASE EVOLUTION IN LOW-PRESSURE SE VAPOR SELENIZATION OF EVAPORATED CU IN BILAYER PRECURSORS/

Evolution of elemental binaries and single-phase copper indium diselen ide, CuInSe2 (CIS) during Se vapor selenization of evaporated Cu/In bi layer metal precursors at pressures of 0.3-10 mbar and temperatures in the range of 260-400 degrees C has been investigated. At low pressure s, the relative kinetics of selenization of Cu and In are changed resu lting in the formation of single-phase CIS even at very low temperatur es (260 degrees C). Optical, Auger, and x-ray photoelectron spectrosco py investigations are employed to characterize the chalcopyrite absorb er layer. At higher pressures (approximate to 7-10 mbar), simultaneous formation of the equilibrium binaries, CuSe and In2Se3 at low tempera tures leads to the formation of CIS through a diffusion:limited reacti on of the binaries at higher temperatures. The availability of Se reac ting species varies significantly in the pressure regime. At low react or pressures and Se availability, the reaction CuSe+In(1)+Se-->CIS, pr oceeds to completion even at low temperatures. The detailed study of t he phase evolution is made by x-ray diffraction and scanning electron microscopy investigations and correlated with the Se availability in t he reactor. (C) 1996 American Institute of Physics.