Rapid synthesis of CuInSe2 from sputter-deposited bilayer In2Se3/Cu2Se precursors

Abstract

Binary bilayer glass/Mo/In2Se3/Cu2Se precursors have been used to rapidly form CuInSe2. Considering their possible application to large-area deposition processes, bilayer precursors were deposited by sequential radiofrequency sputtering of In2Se3 and direct current sputtering of Cu2Se onto unheated, Mo-coated glass substrates. High-temperature X-ray diffraction analysis of the glass/Mo/Cu2Se sample confirmed that the as-deposited polycrystalline Cu2−xSe phase is likely transformed to CuSe at approximately 210°C, and then to CuSe2 at 260°C. Further increase in temperature resulted in the peritectic decomposition of CuSe2 to CuSe (+liquid) at approximately 330°C, and then to Cu2−xSe (+liquid) at around 380°C with the release of Se. Pre-annealing of In2Se3/Cu2Se precursors in Se environment resulted in the formation of a liquid phase, which is in equilibrium with CuSe. Rapid, thermal annealing of pre-annealed samples between 500 and 550°C apparently enhanced grain growth and reduced the reaction time to about 3min; this can be explained by a liquid phase-assisted grain growth mechanism.