Dependence of Exciton Linewidth on the Composition of Zn_xMg_1-xSe Layers Grown by MBE

Abstract

This work deals with the study of the photoluminescence and reflectivity properties of ZnxMg1-xSe epilayers grown by molecular beam epitaxy on (001)GaAs and (111)ZnTe substrates. The photoluminescence spectra of Zn x Mg 1x Se layers grown on GaAs and ZnTe substrates are dkinated by blue emission bands. The energetical positions and relative intensities of the bands depend on Mg contents in the epilayers. The shift of the maxima of blue emission toward higher photon energies and a simultaneous steep increase in the linewidth with an increase in Mg concentratioii are observed. A small amount of Mg added to ZnSe leads to a sharp increase in the linewidth from 2 meV in pure ZnSe layer grown on GaAs substrate to about 180 meV in Zn0.78 Μg0.22 Se.

Optical Properties of Zn1-xMgxSe Epilayers Studied by Spectroscopy Methods

“…The band-gap energies of all samples were estimated from measurements of reflection and transmission spectra near to the fundamental absorption edge at different temperatures [4,5]. The temperature dependence of E g for Zn1-x M g…”

Raman Analysis of Zn1-xMgxSe Layers Grown on GaAs and ZnTe Substrates

“…The occurrence of both the LOZn-Se and LOMg-Se vibrational modes is typical for the two-mode behaviour of the Zn 1 -x Mgx Se crystals. Since the energy Eg of Ζn1-x Mgx Se also depends on the Mg content in the layer [5,8,9], the choice of the excitation energy is of cucial importance in order to obtain the optimum signal intensity. Moreover, for strained layers grown at different temperatures possible ad ditional frequency shifts have to be taken into account.…”

“…Mgx Se epilayers have been grown on semi-insulating (001) GaAs and (111)Zn ZnTe substrates with the Mg contents from 0 to 40% in a MBE system (home made). The growth conditions were described in detail elsewhere [4,5] Raman spectra were taken at room temperature in backscattering geometry at several exciting energies. Spectra were recorded using a double monochromator equipped with holografic grating and a S20 photomultiplier or CCD detecting system.…”