Open AccessThickness-dependent carrier and phonon dynamics of topological insulator Bi_2Te_3 thin films
Author(s) -
Jie Zhao,
Zhongjie Xu,
Yunyi Zang,
Yan Gong,
Xin Zheng,
Xin Cheng,
Tian Jiang
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.014635
Subject(s) - topological insulator , phonon , condensed matter physics , relaxation (psychology) , thin film , excitation , surface states , materials science , physics , oscillation (cell signaling) , electron , optics , topology (electrical circuits) , optoelectronics , nanotechnology , surface (topology) , quantum mechanics , chemistry , psychology , social psychology , biochemistry , geometry , mathematics , combinatorics
As a new quantum state of matter, topological insulators offer a new platform for exploring new physics, giving rise to fascinating new phenomena and new devices. Lots of novel physical properties of topological insulators have been studied extensively and are attributed to the unique electron-phonon interactions at the surface. Although electron behavior in topological insulators has been studied in detail, electron-phonon interactions at the surface of topological insulators are less understood. In this work, using optical pump-optical probe technology, we performed transient absorbance measurement on Bi 2 Te 3 thin films to study the dynamics of its hot carrier relaxation process and coherent phonon behavior. The excitation and dynamics of phonon modes are observed with a response dependent on the thickness of the samples. The thickness-dependent characteristic time, amplitude and frequency of the damped oscillating signals are acquired by fitting the signal profiles. The results clearly indicate that the electron-hole recombination process gradually become dominant with the increasing thickness which is consistent with our theoretical calculation. In addition, a frequency modulation phenomenon on the high-frequency oscillation signals induced by coherent optical phonons is observed.