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Title: Fermi-level pinning, charge transfer, and relaxation of spin-momentum locking at metal contacts to topological insulators

Topological insulators are of interest for many applications in electronics and optoelectronics, but harnessing their unique properties requires detailed understanding and control of charge injection at electrical contacts. Here we present large-scale ab initio calculations of the electronic properties of Au, Ni, Pt, Pd, and graphene contacts to Bi 2Se 3. We show that regardless of the metal, the Fermi level is located in the conduction band, leading to n-type Ohmic contact to the first quintuplet. Furthermore, we find strong charge transfer and band-bending in the first few quintuplets, with no Schottky barrier for charge injection even when the topoplogical insulator is undoped. Our calculations indicate that Au and graphene leave the spin-momentum locking mostly unaltered, but on the other hand, Ni, Pd, and Pt strongly hybridize with Bi 2Se 3 and relax spin-momentum locking. In conclusion, our results indicate that judicious choice of the contact metal is essential to reveal the unique surface features of topological insulators.
 [1] ;  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1098-0121; PRBMDO; 519438
Grant/Contract Number:
AC04-94AL85000; N0001413IP20091; AC01-94-AL85000; DEAC01-94-AL85000
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 90; Journal Issue: 8; Journal ID: ISSN 1098-0121
American Physical Society (APS)
Research Org:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Bi₂Se₃; contacts; topological insulator; Fermi-level pinning; charge transfer
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1179988