Excitons bound to isoelectronic Te traps in ZnSe quantum wells:
A theoretical study
G.T. Einevoll,
Institutt for Fysikk, Norges Teknisk Høgskole,
Universitetet i Trondheim, 7034 Trondheim, Norway
D.S. Citrin; Yia-Chung Chang,
Department of Physics and Materials Research Laboratory,
University of Illinois at Urbana-Champaign, 1110 West Green Street,
Urbana, Illinois 61801
Physical Review B 44, 8068-8083 (1991)
Abstract
A theoretical study is made of excitons and holes bound to a single
tellurium (Te) impurity in bulk ZnSe and centered in
ZnSe-Zn_{1-x}Mn_{x}Se strained quantum wells. The authors use an
effective-bond-orbital model for the holes in order to account for the
complicated valence-band structure, and the spherical effective-mass
approximation to describe the electron. The mutual Coulomb interaction is
included, and solutions for the two-body system are obtained using the
variational method in an iterative scheme. The strong lattice-relaxation
effects present in the binding of the hole to the Te impurity are absorbed
in the value for the localized hole-attractive potential at the site of
the impurity. This value is determined by fitting the experimental value
for the binding energy of the bound exciton. The oscillator strengths, the
extension of the bound-exciton wave functions, and the energies of bound
holes are then predicted. The authors observe a discrepancy between the
fitted value for the localized impurity potential for the bulk case and
the quantum-well case. An experiment to test their explanation for the
discrepancy is proposed.