First-principles insight into the interfacial properties of epitaxial Bi2O2X (X = S, Se, Te) on SrTiO3 substrates

In this work, we construct the Bi2O2X/SrTiO3 heterostructures and explore the geometric, electronic, optical, and transport characteristics based on density functional theory (DFT) in integration with non-equilibrium Green's function (NEGF) calculations. The influence of chalcogen elements on the Bi2O2X/SrTiO3 interface is discussed. Eighteen different interface configurations with different terminations are designed and the most stable configurations are determined. The interfaces between SrO-terminated SrTiO3 and O-terminated Bi2O2X show the highest cohesive energy and strongest charge interaction regardless of the chalcogen elements, which is the best interfacial stability. Among these interfaces, the Bi2O2S/SrTiO3 interface were found to possess the largest cohesive energy and best stability due to the fewer and lower surface states around the Fermi level. By contrast, the Bi2O2Te/SrTiO3 interface shows the largest dielectric function among these three interfacial systems leading to better optical property. In addition, the electronic transport properties reveal that Bi2O2Te/SrTiO3 has the largest transmission coefficient indicates enhanced electron transport and electric current at the interface.