Molecular beam epitaxial growth and structural properties of hetero-crystalline and heterovalent PbTe/CdTe/InSb structures

摘要

Rock-salt lead chalcogenides such as PbTe are of much current interest for the physics study of quantum materials as a topological insulator and practical applications for infrared photodetectors. Heterocrystalline (rock-salt on zincblende) and heterovalent PbTe/CdTe/InSb heterostructures are grown on (001) InSb substrates using a single-chamber molecular beam epitaxy system. Elemental Pb and Te sources are used to independently vary the flux conditions at the heterocrystalline interface in nearly lattice-matched PbTe/InSb and PbTe/CdTe heterostructures. A streaky (1x1) surface reconstruction is observed during the growth of thicker PbTe layers on both InSb and CdTe, signifying smooth layer-by-layer growth. The thickness required for smooth PbTe growth on nearly lattice-matched zincblende materials can be minimized with the proper choice of growth conditions, particularly at the heterocrystalline interface. Characterization with x-ray diffraction indicates good crystalline quality, and observations by transmission electron microscopy reveal sharp interfaces between the PbTe and CdTe films.