Excitons in ZnO/Zn_1–xMn_xO quantum wells

Abstract

In order to estimate the perspectives of using ZnO/Zn 1-x Mn x O quantum wells for reliable high temperature ferromagnetism (specially for increasing Curie temperature in this structure) we investigate excitons in ZnO/Zn 1-x Mn x O quantum wells. The existence of weak built-in electric field is investigated. Electric field and Coulomb interaction is accounted by means of direct diagonalization. Calculations showed weak dependence of exciton binding energy on well width. Electric field only slightly increases the distance between electron and hole. It rotates ground state excitons and aligns them along the field. Calculations also showed increase of ground state exciton lifetime with increasing well width.

Multi‐band theory of magnetoexcitons in ZnO/ZnMnO quantum wells

“…One obvious obstacle on route towards room temperature ferromagnetism in ZnMnO comes from the fact that doping with Mn 2+ ions does not generate valence band holes so other techniques such as co-doping must be applied in order to obtain a p-type material. Recently it has been also proposed that the built-in and external electric field in ZnO quantum wells with ZnMnO barriers may be used to control the coupling of photo-generated valence band holes with manganese ions in the barriers and thereby changing the Curie temperature [4]. Given the fact that in addition the precise structure of the ZnO valence band is still under debate the detailed theoretical model of the absorption spectra in the vicinity of the fundamental gap is therefore of fundamental importance in studying such systems, especially in the presence of the magnetic field.…”