Twisted ZB–CdTe/RS–PbTe (111) heterojunction as a metastable interface structure

Abstract

The heterostructures of (zinc-blende)–CdTe/(rock-salt)–PbTe are typically found to have their common cubic axes aligned to each other, as in the case of PbTe quantum dots embedded in a CdTe matrix. In this work, we perform both theoretical and experimental studies on the CdTe/PbTe heterostructure in a different geometry: a planar CdTe/PbTe (111) heterostructure. We simulate the epitaxial growth of CdTe (PbTe) on the (111) PbTe (CdTe) substrate, using a density-functional theory. A twisted CdTe/PbTe (111) interface structure has been predicted in the layer-by-layer epitaxial growth on the (111) substrate, in contrast to the non-twisted CdTe/PbTe (111) interface reported in the literature. This predicted structure has been confirmed experimentally in the heterostructure grown by molecular beam epitaxy, using a high-resolution transmission electron microscope. The twisted interface has a lower binding energy than the non-twisted one, indicating that the twisted structure is a metastable phase formed in the non-equilibrium growth process. Additionally, the interface reconstructions of the CdTe/PbTe (111) heterostructure observed by reflection high-energy electron diffraction are explained using the twisted interface model.