Photoluminescence spectroscopy and effective concentration determination of CdxZn1?xSe

A detailed photoluminescence spectrometric analysis near the band edge and broadband characterizations of CdxZn1−xSe, for two nominal concentrations, x = 0.25 and 0.50, was performed at various temperatures from 25 K to room temperature. A photoluminescence approach was used to determine the effective concentrations x = 0.22 and 0.43. The parameters that describe the temperature dependence of energy have been evaluated based on the Varshni and Bose–Einstein models. Two broad bands are observed, a higher energy band I centered at 1.991 and 1.773 eV and a lower energy band II centered at 1.844 and 1.705 eV for the two samples, respectively. The emission bands are attributed to donor–acceptor pair transitions. The energy scheme shows two donors and two acceptor levels, the binding energies of the donors for Cd0.22Zn0.78Se are 29 and 208 meV, the binding energies of the acceptors are 472 and 511 eV. The binding energies of the donors for Cd0.43Zn0.57Se are 27 and 137 meV, the binding energies of the acceptors are 393 and 423 meV. A significant blue shift in energy with increasing temperature was observed for the lower energy band. The ionization temperatures for the deep donors are 279 and 287 K for Cd0.22Zn0.78Se and Cd0.43Zn0.57Se, respectively.