Nature of energy bands of MgxZn1-xTe mixed crystals near the absorption edge

Photoluminescence (PL) and excitonic absorption spectra of undoped MgxZn1-x Te (0 less than or equal to X less than or equal to 0.48) mixed crystals we re investigated in the near-band-edge region. The PL spectra at 5 K is domi nated by the principal bound exciton (PBE) lines, for bound exciton-neutral acceptor complex, which are coupled with one or two LO-phonon replicas. A linear dependence on the composition is observed for both the lattice const ant and the excitonic band gap of zincblende MgxZn1-xTe. The excitonic band gap as a function of the lattice constant shows a linear dependence in the given composition range. The temperature dependence of the excitonic band gap in zincblende MgxZn1-xTe was fitted very well with the Varshni equation , and their temperature coefficients above about 200 K is found to be - (5. 7-6.1) x 10(-4) eV/K. (C) 1999 Elsevier Science Ltd. All rights reserved.