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

Journal Article · Mon Jan 05 00:00:00 EST 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4905438· OSTI ID:22395639

Qi, J. ^[1]; Brahlek, M.; Bansal, N.; Oh, S. ^[2]; Azad, A.; Bowlan, J.; Taylor, A. J.; Prasankumar, R. P.

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1. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, MS K771, Los Alamos, New Mexico 87545 (United States)
2. Department of Physics and Astronomy, Rutgers—The State University of New Jersey, Piscataway, New Jersey 08854 (United States)

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.

• OSTI ID: 22395639
• Journal Information: Applied Physics Letters, Vol. 106, Issue 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

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