Restoring pristine Bi2Se3 surfaces with an effective Se decapping process

Jixia Dai, Wenbo Wang, Matthew Brahlek, Nikesh Koirala, Maryam Salehi, Seongshik Oh, Weida Wu

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


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 the 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.

Original languageEnglish (US)
Pages (from-to)1222-1228
Number of pages7
JournalNano Research
Issue number4
StatePublished - Apr 1 2015

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Electrical and Electronic Engineering


  • molecular beam epitaxy
  • scanning tunneling microscopy
  • topological insulator

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