Control of the Preferred Orientation of Polycrystalline Mo and Cu(InGa)Se-2 Thin Films by Inserting Graphene Layers

Abstract

To demonstrate the effect of graphene (Gr) layer on subsequently deposited Mo and Cu(InGa)Se-2 (CIGS) crystal orientation, graphene sheets grown on Cu foil by chemical vapor deposition were transferred to low-alkali glass substrates by a simple wet-based graphene transfer process. Mo was sputter-deposited on glass and glass/Gr substrates, and CIGS was formed by selenization of the co-sputtered CuGaIn precursors. The Mo thin films on the graphene coated glass substrates (glass/Gr) had a more preferred (110) orientation than the bare glass substrate, showing a lower sheet resistance. Subsequently, glass/Gr/Mo/CIGS revealed the (220) preferred CIGS orientation, which is potentially beneficial to the CIGS cell efficiency but difficult to obtain by selenization of the metal precursors.