Formation Mechanism of Superconducting Fe_1+<i>x</i>Te/Bi₂Te₃ Bilayer Synthesized via Interfacial Chemical Reactions

This work focuses on the formation mechanism of a superconducting Fe_1+<i>x</i>Te/​Bi₂Te₃ bilayer fabricated through chemical reactions between a Bi₂Te₃ flux and an annealed Fe layer grown on a ZnSe­(111)­B buffer via the molecular beam epitaxy technique. The studies using energy-dispersive X-ray spectrometry and high-resolution transmission electron microscopy performed on a number of samples fabricated with different desired schemes provide evidence that several interfacial chemical reactions taking place at the Fe/ZnSe interface through the edges of voids of the annealed Fe layer contributed to the formation of the superconducting bilayer. We have also revealed that the bonding strength of the involved Fe compounds at the bottom interface of the annealed Fe layer seems to play an essential role