Optical properties of CuAlSe2

We have determined the complex dielectric tensor components of the chalcopyrite semiconductor CuAlSe2 in the energy range between 1.4 and 5.2 eV, at room temperature, using spectroscopic ellipsometry. We present results obtained on two single crystals grown by the traveling-heater method using In solvent. Values of refractive indices n, extinction coefficients k and normal-incidence reflectivity R in the two independent polarizations are reported. The structures observed in the energy region studied are analyzed by fitting the second-derivative spectra d(2)epsilon(omega)/d omega(2) to analytic critical-point line shapes. The obtained energies are assigned to certain electronic interband transitions by comparison with existing band structure calculations. (C) 2000 American Institute of Physics. [S0021-8979(00)04516-3].