Electrical and luminescent properties of CuGaSe2 crystals and thin films

CuGaSe2 thin films with thicknesses of about 2 μm were prepared by flash and single source evaporation onto mica and (1 1 0)-oriented ZnSe substrates in the substrate temperature range 150–450°C. The obtained polycrystalline CuGaSe2 films had the chalcopyrite structure with the predominant growth direction 〈2 2 1〉. Hall effect, conductivity and luminescence measurements have been carried out on CuGaSe2 thin films and source materials: CuGaSe2 single crystals grown by Bridgman technique and by chemical vapour transport using I2 as transport agent. All films and crystals are p-type. Two acceptor levels with ionization energies EA1∼50–56 meV and EA2∼130–150 meV have been identified as due to Ga vacancy and presence of Se atoms on interstitial sites respectively.