Detailed Visualization of Phase Evolution during Rapid Formation of Cu(InGa)Se-2 Photovoltaic Absorber from Mo/CuGa/In/Se Precursors

Abstract

Amongst several processes which have been developed for the production of reliable chalcopyrite Cu(InGa)Se-2 photovoltaic absorbers, the 2-step metallization-selenization process is widely accepted as being suitable for industrial-scale application. Here we visualize the detailed thermal behavior and reaction pathways of constituent elements during commercially attractive rapid thermal processing of glass/Mo/CuGa/In/Se precursors on the basis of the results of systematic characterization of samples obtained from a series of quenching experiments with set-temperatures between 25 and 550 degrees C. It was confirmed that the Se layer crystallized and then melted between 250 and 350 degrees C, completely disappearing at 500 degrees C. The formation of CuInSe2 and Cu(InGa)Se-2 was initiated at around 450 degrees C and 550 degrees C, respectively. It is suggested that pre-heat treatment to control crystallization of Se layer should be designed at 250-350 degrees C and Cu(InGa)Se-2 formation from CuGa/In/Se precursors can be completed within a timeframe of 6 min.