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Excitons in ZnO/Zn1-xMnxO quantum wells

Tamar Tchelidze 2Ekaterina Chikoidze 1,2Yves Dumont 1

1. CNRS, Laboratoire de Physique des Solides et de Cristallogenese, 1 Place Aristide Briand, Meudon F 92195, France
2. Tbilisi State University, Material Science Department, 3, Chavchavdze, Tbilisi 30128, Georgia

Abstract

wurtzite structure ZnO has particularly large coefficient of piezoelectric and spontaneous polarization. ZnO-based quantum structures grown in 0001 direction, are expected to reveal effects caused by the presence of built-in electric field, leading a redshift of exciton emission, reduction of exciton binding energy and oscillation strength[1].We studied electron hole Coulomb interaction in ZnO/Zn0.82Mn0.18O QWs. Exciton energies and probabilities of their radiative decay are calculated for from 2-7 nm well width. Built-in electric field is included by direct diagonalization method.Built-in electric field is assumed to be 0.9MV/cm. For 2-3nm well width electron hole interaction is very high and binding energy is increased as much as 4-5 times with respect to the bulk ZnO; Electric field effect is not significant and electron hole wave functions separation is not pronounced probability of radiative decay is close to 1.Starting from 4nm well width ground state exciton energy and decay probability decrease sharply, while binding energy of excitons of excited states and their decay probability increase, because wave functions of electrons and holes of higher levels are shifted to the area of higher potential toward the centre of QW, increasing their overlap. That menace that radiation of high energetic excitons in ZnO/Zn1-xMnxO are expected to be intensive.

1. C. Morhain, T. Bretagnon,P. Lefebvre, et al, Phys. Rev B 72, 241305R (2005)

 

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2006, Symposium F, by Ekaterina Chikoidze
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 10:16
Revised:   2009-06-07 00:44