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Title: Ultrafast carrier dynamics in polycrystalline bismuth telluride nanofilm

In this study, the dynamics of energy carriers in polycrystalline bismuth telluride nanofilm are investigated by the ultrafast pump-probe method. The energy relaxation processes are quantitatively analyzed by using the numerical fitting models. The extracted hot carrier relaxation times of photon excitation, thermalization, and diffusion are around sub-picosecond. The initial reflectivity recovery is found to be dominantly determined by the carrier diffusion, electron-phonon coupling, and photo-generated carriers trapping processes. High-frequency and low-frequency oscillations are both observed and attributed to coherent optical phonons and coherent acoustic phonons, respectively.
Authors:
; ;  [1]
  1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)
Publication Date:
OSTI Identifier:
22299889
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 24; Other Information: (c) 2014 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; BISMUTH COMPOUNDS; CARRIER MOBILITY; CARRIERS; DIFFUSION; ELECTRON-PHONON COUPLING; EXCITATION; NANOSTRUCTURES; OSCILLATIONS; PHONONS; PHOTONS; POLYCRYSTALS; REFLECTIVITY; RELAXATION; TELLURIDES; THERMALIZATION; THIN FILMS; TRAPPING