Optical properties and temperature dependence of critical transitions in ZnSe
Laboratoire de Physique des Solides, INSA, CS 14315, 35043 Rennes Cedex, France
2 Laboratoire de Physique des Solides, CNRS, 92195 Meudon Cedex, France
Revised: 15 June 1999
Published online: 15 February 2000
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.
PACS: 78.40.Fy – Semiconductors / 78.20.Ci – Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) / 71.20.Nr – Semiconductor compounds
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000