CdSe monolayers, embedded in BeTe: analysis of interface vibrations by Raman spectroscopy

We present a Raman spectroscopy analysis of CdSe monolayers (MLs), embedded in BeTe. In detail, we compare the two types of interfacial bonds, which are possible for this material combination: BeSe-interfaces versus CdTe ones. For the case of BeSe-interfaces, a broad signature of Cd-related vibrations is observed, accompanied by indications of intermixing in the BeTe, revealing rather poor interface quality. In contrast, for CdTe-interfaces, distinct vibration modes from the CdSe-layers and the CdTe-interfaces occur. When describing them by a linear chain model, quantitative agreement is obtained if assuming a CdSe-layer thickness of 1 ML with locally 2 ML-contributions. Furthermore, the BeTe-phonon shows no signature of intermixing, thus underscoring the superior quality of the CdTe-interfaces.