Photoluminescence and electromodulation spectroscopy characterization of a Zn0.81Be0.04Mg0.15Se mixed crystal.

We present an optical characterization of a Bridgman-grown zinc-blende-type Zn_0.81Be_0.04Mg_0.15Se mixed crystal in the near-band-edge interband transitions using temperature-dependent photoluminescence (PL), contactless electroreflectance (CER), and photoreflectance (PR) in the temperature range of 15–400 K. Typical PL spectrum at low temperature consists of an exciton line, an edge emission due to recombination of shallow donor-acceptor pairs, and a broad band related to recombination through deep level defects. Interband transitions, originating from the band edge and spin-orbital splitting critical points of the sample, have been observed in the CER/PR spectra. The peak positions of the excitonic emission lines in the PL spectra correspond quite well to the energies of the fundamental transitions determined from electromodulation data. The parameters that describe the temperature dependence of the fundamental and spin split-off band gaps, and the broadening function of the band edge exciton are evaluated and discussed. [ABSTRACT FROM AUTHOR]