Temperature dependence of the dielectric function and the interband critical points of CdSe

The real and imaginary parts of the ordinary and extraordinary dielectric functions of CdSe have been investigated with a scanning rotating analyzer ellipsometer. Strong edge excitons and structure in the 4--5-eV region are observed. With the use of the second derivative versus frequency of these dielectric functions, a critical-point analysis of the observed structures and their temperature dependences has been performed. The obtained results are analyzed in terms of real and imaginary self-energies due to the electron-phonon interaction.