Preparation and Characterization of FeSe and Bi Nanostructures on Bi 2 Se 3 (0001): A Scanning Tunneling Microscopy Study

Procedures for the preparation of Bi 2 Se 3 (0001) surfaces, FeSe atomic layers, and Bi bilayers on Bi 2 Se 3 (0001) are presented. Bi 2 Se 3 (0001) surfaces are characterized by terraces separated by quintuple layer high steps of 0.95 nm height. Epitaxial FeSe islands with lateral extensions of several hundred nanometers and a few unit cell (nm) thickness are produced by Fe deposition at room temperature and subsequent annealing at 650 K. These islands are under an anisotropic in-plane strain ( a=0.377±0.002 a = 0.377 ± 0.002 nm, b=0.385±0.004 b = 0.385 ± 0.004  nm) with respect to the bulk FeSe reference state ( a FeSe,bulk =0.377 a FeSe , bulk = 0.377  nm). Bi bilayers are formed on Bi 2 Se 3 (0001) by atomic hydrogen plasma etching, which removes Se from the Bi 2 Se 3 sample surface. Scanning tunneling microscopy and scanning tunneling spectroscopy are used to characterize the Bi 2 Se 3 substrate and the nanostructures formed on its surface. A differential conductance peak near +0.2 + 0.2  V identifies a defect-free Bi bilayer on Bi 2 Se 3 (0001).