Localized excitons in ZnMnO

Abstract

Lines a, b, c, d and impurity absorption edge of ZnMnO for sigma- and π-polarizations of light in temperature interval of 7-300 K were registered in this paper. Intensive lines aπ and asigma are clearly observed in interval of 7-100 K, while other lines are observed only at low temperatures. For determination of type of optical transitions, to which excitonic lines a, b, c, d are corresponding the calculation of oscillator strength of most intensive lines was made. Lines aπ and asigma have Lorentz form, parameters of this form were calculated with OriginPro 9.1 program. The energy of impurity absorption edge was determined. Lines a, b, c and d were analyzed in model of Mn2+-4O2- cluster. Optical transitions take place from antibonding (p+d5)*-states in forbidden gap to state, which is splitted from the bottom of conduction band of ZnMnO. Electron-hole pairs which are localized inside the cluster are called as local excitons. Keywords: zinc oxide, localized excitons, antibonding states.