Optical properties and temperature dependence of critical transitions in ZnSe

The dielectric function ε of ZnSe has been deduced from ellipsometric measurements between 20 K and 380 K. ε is analysed around each critical point with the standard critical point model. The variations of the different parameters characterising each transition with temperature are presented and analysed. The temperature coefficients of the energies of the critical transitions are given. ε is essentially governed by the Coulomb interaction near the fundamental gap. Thanks to the high binding energy of the exciton and the low spectral width of the ellipsometer, the fundamental state of the exciton is found completely separated from the first excited states and the continuum at low temperature. In return the strong transition E1 near the L points of the Brillouin zone can be described equally well with a 2D or an excitonic transition

Solid State Recrystallization of II-VI Semiconductors : Application to Cadmium Telluride, Cadmium Selenide and Zinc Selenide

Solid state recrystallization (SSR) has been very rarely used for semiconductors. It has nevertheless been proposed, and industrially used, for the single crystal growth of cadmium mercury telluride according to a quench-anneal process. The reasons of the interest of this process, in specific cases of II-VI semiconductors crystal growth, will be analyzed (particular phase diagrams, phase transitions in the solid state close to the melting point, high temperature contaminations..etc.. make the use of traditional melt growth techniques unfavourable) and illustrated refering to CdHgTe literature. Original results related to the binary compounds CdTe, CdSe and ZnSe will be presented