skip to main content

Title: Time-resolved terahertz dynamics in thin films of the topological insulator Bi{sub 2}Se{sub 3}

We use optical pump–THz probe spectroscopy at low temperatures to study the hot carrier response in thin Bi{sub 2}Se{sub 3} films of several thicknesses, allowing us to separate the bulk from the surface transient response. We find that for thinner films the photoexcitation changes the transport scattering rate and reduces the THz conductivity, which relaxes within 10 picoseconds (ps). For thicker films, the conductivity increases upon photoexcitation and scales with increasing both the film thickness and the optical fluence, with a decay time of approximately 5 ps as well as a much higher scattering rate. These different dynamics are attributed to the surface and bulk electrons, respectively, and demonstrate that long-lived mobile surface photo-carriers can be accessed independently below certain film thicknesses for possible optoelectronic applications.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ; ;  [5] ; ; ; ; ;  [3]
  1. Center for Emergent Materials, Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)
  2. (United States)
  3. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, MS K771, Los Alamos, New Mexico 87545 (United States)
  4. (China)
  5. Department of Physics and Astronomy, Rutgers—The State University of New Jersey, Piscataway, New Jersey 08854 (United States)
Publication Date:
OSTI Identifier:
22395639
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; BISMUTH SELENIDES; CHARGE CARRIERS; ELECTRIC CONDUCTIVITY; ELECTRONS; EXCITATION; SCATTERING; SURFACES; TEMPERATURE DEPENDENCE; THICKNESS; THIN FILMS; TIME RESOLUTION; TOPOLOGY; TRANSIENTS