Study on the formation of PbSe nanoclusters at the interfaces of PbSe/ZnSe multiple quantum well structure

Nanocrystalline PbSe/ZnSe multiple quantum well (MQW) structure was prepared by the sequential thermal evaporation technique. The samples were annealed at 250 °C to study the interfacial effects on the structural and optical properties. High resolution X-ray diffraction studies revealed the crystal structure and orientation of MQW structure. Cross sectional TEM images show well-ordered periodicity on as deposited structure. TEM images of annealed PbSe/ZnSe MQW show break-up of the PbSe layers which results in 3D nanoclusters formation at the interfaces. The blueshift together with the energy level splitting in the absorption spectra for annealed sample has been related with PbSe nanoclusters at the interfaces. Strain induced size effects are studied through the shift in longitudinal optical phonon modes from Raman scattering and discussed in this paper.