CIGS thin films grown by hybrid sputtering-evaporation method: Properties and PV performance

We present a comprehensive overview on a new hybrid sputtering-evaporation (HSE) system for the deposition of Cu(In,Ga) Se2 (CIGS) thin-films aimed at photovoltaic applications. Such a technique employs the sputtering process to deposit the metal precursors on suitable rotating transfer cylinders, from which they are subsequently evaporated, in Se atmosphere, on the substrate. This procedure allows to combine the features of both the sputtering and evaporation techniques, enabling a fine tuning of the stoichiometry and an easy transfer to industrial processes. The key elements of this growth method are here explained in detail. The HSE CIGS layers have been investigated through secondary ion mass spectrometry, Raman and photoluminescence spectroscopies, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy. Moreover, the solar cell performance of the grown films has been investigated, through external quantum efficiency and J-V curves under 1 Sun illumination measurements. The obtained experimental results are exhaustively shown and discussed, indicating advantages and open issues of the presented deposition technique.