Optical properties of CuAlSe2

We have determined the complex dielectric tensor components of the chalcopy rite semiconductor CuAlSe2 in the energy range between 1.4 and 5.2 eV, at r oom temperature, using spectroscopic ellipsometry. We present results obtai ned on two single crystals grown by the traveling-heater method using In so lvent. 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 fitt ing 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].