Characterization of CuGaSe2 thin films grown by MOCVD

CuGaSe2 thin films have been grown by metalorganic chemical vapor deposition (MOCVD), from three organometallic precursors. Samples of about 1-2 mu m thick are codeposited onto Pyrex and Mo-coated soda lime glass, A large range of compositions was investigated and characterized, Stoichiometric CuGaSe2 thin films are single-phased and their optical bandgap is about 1.68 eV, The features of the films are presented in relation with their composition. XRD spectra always exhibit a preferential orientation along the (112) plane. Secondary phases have been observed: Cu Se for Cu-rich films, CuGa3Se5 for Ga-rich films. Observation of the morphology reveals larger polyhedral grains for Cu-rich films becoming platelet-shaped and tilted for Ga-rich compounds. The optical properties are also sensitive to the compositional changes and related to the eventual presence of binary phases. The gap increases with the Ga-content, The CuGa3Se5 phase exhibit a gap of about 1.85 eV, All the samples have a p-type conductivity.