Preparation and characterization of CuAlSe2 thin films prepared by co-evaporation

CuAlSe₂ thin films were deposited using three-source co-evaporation technique. The spectral transmittance data in the wavelength range 350-900 nm revealed three characteristic band gaps 2.62 eV, 2.73 eV and 2.91 eV. The first one is attributed to fundamental optical absorption process. Additional band gaps are attributed to the transitions occurring from the energy levels arising out of crystal field and spin-orbit interactions. Powder X-ray diffraction pattern revealed the films to be chalcopyrite in structure. The lattice parameters determined from XRD data were found to be a=0.562 nm and c=1.099 nm. The spin orbit (Δ_SO) and crystal field (Δ_CF) parameters are found to be 0.19 and -0.12 respectively. The resistivity of the films at room temperature was found to be 300 Ωcm.