Restoring Pristine Bi2Se3 Surface with an Effective Se Decapping Process

Abstract

High quality thin films of topological insulators (TI) such as Bi2Se3 have been successfully synthesized by molecular beam epitaxy (MBE). Although the surface of MBE films can be protected by capping with inert materials such as amorphous Se, restoring an atomically clean pristine surface after decapping has never been demonstrated, which prevents in-depth investigations of the intrinsic properties of TI thin films with ex-situ tools. Using high resolution scanning tunneling microscopy/spectroscopy (STM/STS), we demonstrate a simple and highly reproducible Se decapping method that allows recovery of the pristine surface of extremely high quality Bi2Se3 thin films grown and capped with Se in a separate MBE system then exposed to atmosphere during transfer into the STM system. The crucial step of our decapping process is the removal of the surface contaminants on top of amorphous Se before thermal desorption of Se at a mild temperature (~210 °C). This effective Se decapping process opens up the possibility of ex-situ characterizations of pristine surfaces of interesting selenide materials and beyond using cutting-edge techniques.

10 pages, 3 figures

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• Momentum-Resolved Landau-Level Spectroscopy of Dirac Surface State in Bi2Se3
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• Record Surface State Mobility and Quantum Hall Effect in Topological Insulator Thin Films via Interface Engineering
• Characterizing the Structure of Topological Insulator Thin Films
• In-situ spectroscopy of intrinsic Bi2Te3 topological insulator thin films and impact of extrinsic defects
• Solution to the hole-doping problem and tunable quantum Hall effect in Bi${}_2$Se${}_3$ thin films
• Stability of low-carrier-density topological-insulator Bi${}_2$Se${}_3$ thin films and effect of capping layers
• Coexistence of bulk and surface states probed by Shubnikov-de Haas oscillations in Bi${}_2$Se${}_3$ with high charge-carrier density
• Two-dimensional ferromagnetic extension of a topological insulator
• Structural and electronic properties of ultrathin FeSe films grown on Bi${}_2$Se${}_3$(0001) studied by STM/STS
• From classical to quantum regime of topological surface states via defect engineering
• Spectroscopy of van der Waals nanomaterials: Opportunities and Challenges