Growth and optical characterization of Cd1-xBexSe and Cd1-xMgxSe crystals

Cd1-xBexSe and Cd1-xMgxSe solid solutions were grown from the melt by the high pressure Bridgman method. Optical, luminescence and photothermal proper-ties of these materials were investigated. Spectroscopic ellipsometry was applied for determination of the spectral dependence of the complex dielectric function, epsilon(E) and refractive index n(E) at room temperature in the photon energy range 0.75-6.5 eV for samples with optic axis (c-axis) perpendicular to the air-sample interface. The critical point (CP) parameters for E-0 and E-1 transitions were determined using a standard excitonic CP function to fit the numerically calculated differential spectra partial derivative(2)epsilon(2)/partial derivative E-2. The dispersion of the refractive index of the alloys was modelled using a Sellmeier-type relation. The values of fundamental and exciton band-gap energies were estimated from the ellipsometric and photoluminescence measurements. The origin of luminescence in Cd1-xBexSe and Cd1-xMgxSe was discussed.