Growth and optical characterization of Cd_1‐<i>x</i>Be_<i>x</i>Se and Cd_1‐<i>x</i>Mg_<i>x</i>Se crystals

Abstract

Abstract Cd 1‐ x Be x Se and Cd 1‐ x Mg x Se solid solutions were grown from the melt by the high pressure Bridgman method. Optical, luminescence and photothermal properties of these materials were investigated. Spectroscopic ellipsometry was applied for determination of the spectral dependence of the complex dielectric function $ \tilde \varepsilon $ ( 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 ∂ 2 ε 2 /∂ 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 Cd 1‐ x Be x Se and Cd 1‐ x Mg x Se was discussed. (© 2005 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)