Abstract
Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder. Ubiquitous charged bulk defects, however, pull the Fermi energy into the bulk bands, denying access to surface charge transport. Here we demonstrate that irradiation with swift (∼2.5 MeV energy) electron beams allows to compensate these defects, bring the Fermi level back into the bulk gap and reach the charge neutrality point (CNP). Controlling the beam fluence, we tune bulk conductivity from p- (hole-like) to n-type (electron-like), crossing the Dirac point and back, while preserving the Dirac energy dispersion. The CNP conductance has a two-dimensional character on the order of ten conductance quanta and reveals, both in Bi2Te3 and Bi2Se3, the presence of only two quantum channels corresponding to two topological surfaces. The intrinsic quantum transport of the topological states is accessible disregarding the bulk size.
Highlights
Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder
Three-dimensional (3D) topological insulators are a spectacular example of this1—narrow-band semiconductors, well known for their high performance as thermoelectrics[2], they were discovered to support unusual gapless robust two-dimensional (2D) surface states that are fully spin-polarized with Dirac-type linear electronic energy-momentum dispersion[3,4], which makes them protected against backscattering by disorder[3,4,5,6]
We demonstrate that bulk conductivity in topological insulators (TIs) can be decreased by orders of magnitude to charge neutrality point on a large scale by the controlled use of electron beams, which for energies below B3 MeV are known to produce a well-defined, stable and uniform spread of Frenkel pairs[15] within their penetration range of hundreds of micrometres
Summary
Topological insulators are potentially transformative quantum solids with metallic surface states which have Dirac band structure and are immune to disorder. We demonstrate that bulk conductivity in topological insulators (TIs) can be decreased by orders of magnitude to charge neutrality point on a large (depth) scale by the controlled use of electron beams, which for energies below B3 MeV are known to produce a well-defined, stable and uniform spread of Frenkel (vacancy-interstitial) pairs[15] within their penetration range of hundreds of micrometres.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
