Growth and structure of CdTe/Cd 1− xMn xTe multiple quantum wells showing excitonic 2S states

Abstract

Multiple quantum well structures of CdTe and the dilute magnetic semiconductor Cd 1−x Mn x Te(x⪅0.08) have been grown by molecular beam epitaxy on InSb substrates. High resolution double crystal X-ray diffraction analysis using rocking curve simulations based on the dynamical theory of diffraction shows that these layers are of excellent structural quality and uniformity. The diffraction data indicate the presence of a highly mismatched layer a few monolayers thick at the interface between the InSb substrate and the CdTe buffer layer, which is consistent with previous Raman spectroscopy studies identifying the phase as In 2Te 3. Photoluminescence and photoluminescence excitation spectroscopy measurements indicate that well width fluctuations occur on a monolayer scale. Observation of the 2S state of both light and heavy hole excitons allows the binding energy of both excitons to be deduced—17.1 meV and 19.7 meV respectively—considerably enhanced from their three-dimensional values.