Optical properties of CuAlX2 (X = Se, Te) thin films obtained by annealingof copper, aluminum and chalcogen layers sequentially deposited

Thin layers of copper, aluminum and chalcogen sequentially deposited by eva poration are annealed to synthesize CuAlX2 (X = Se, Tc) films. The films cr ystallized in the chalcopyrite structure. For CuAlSe2, three characteristic energy gaps of 2.66(6), 2.78(2), and 2.91(5) eV were obtained from an anal ysis of the optical transmission spectra in the wavelength range 350-800 nm . The energies of the spin-orbit and the crystal field were found to be, re spectively, 162 meV and -143 meV. Reflectivity measurements in the far infr ared yield four mode frequencies for CuAlSe2 and CuAlTe2. (C) 2000 Elsevier Science S.A. All rights reserved.