Characterization of CuInSe2 and InxSey thin films by coevaporation method

Abstract

CuInSe2 and InxSey thin films mere prepared and characterized for photovoltaic applications. The CuInSe2 films were prepared by the sequential coevaporation of In-Se, Cu-Se, and In-Se from elemental sources. It was possible to obtain a CuInSe2 film on which a thin layer of the CuIn3Se5 phase formed, as shown by AES and XRD analysis. Also, InxSey buffer layers were deposited on the CuIn3Se5/CuInSe2 films in the same coevaporator without breaking the vacuum. The InxSey buffer layer had its lowest resistivity, 3x10(4) Omega.cm at 350 degrees C, when the gamma-In2Se3 phase was obtained. A solar cell fabricated with an Al/ITO/ZnO/In2Se3/CuIn3Se5/CuInSe2/Mo structure yielded an efficiency of 8.12%, which considered to be a high value for a Cu-In-Se system. It is necessary to add Ga to the CuInSe2 films to increase the low open-circuit voltage.