The interface between Pt and Bi2Se3: Instability and formation of a new ordered phase

In this work the interface between a Pt film and a Bi₂Se₃ (0001) surface is investigated using electron microscopy and microanalysis, in order to characterize the structure of the interface and verify if it is chemically stable or an interaction occurs. At room temperature, the Pt film is composed of small clusters (∼10 nm) and the interface is stable. However, already upon mild annealing (200 °C) the interface displays instability and forms an interfacial phase. The interfacial phase, not previously reported in literature, is a long-range ordered ternary Pt:Bi:Se phase aligned with the Bi₂Se₃ crystal, most probably an intermetallic compound. The presence of a new phase at Pt/Bi₂Se₃ interface, together with the possible effects on the topological surface states, has to be considered in all the applied studies where this interface is present, as well as in the models for theoretical studies.