Lattice-mismatched heteroepitaxy of IV-VI thin films on PbTe(001): An ab initio study

The chalcogenides of tin and lead (SnS, SnSe, SnTe, PbS, PbSe, and PbTe) have applications ranging from solar cells to thermoelectrics. Taking rocksalt structured PbTe(001) as the substrate, we explore the coherent (001)-oriented heteroepitaxy of the other five IV-VI semiconductors through first-principles electronic structure calculations. We investigate the effects of lattice strain and its relationship to the interface energy, as well as the electron redistribution, as a function of the epilayer thickness [from 1 to 5 monolayers (ML)] below the dislocation critical point. Analysis of the chemical bonding explains trends including work function shifts and surface rumpling. Among the five combinations studied SnTe/PbTe(001) has the smallest lattice mismatch, resulting in the most stable coherent interface and unique charge transfer behavior. Here, we perform orbital-resolved band structure calculations (with spin-orbit coupling effects) for the SnTe/PbTe(001) system, highlighting its potential use in topological spintronic thin-film devices.