Temperature-dependent ultrafast carrier and phonon dynamics of topological insulator Bi1.5Sb0.5Te1.8Se1.2

• Main Authors: Cheng, Liang, La-o-vorakiat, Chan, Tang, Chi Sin, Nair, Saritha K., Xia, Bin, Wang, Lan, Zhu, Jian-Xin, Chia, Elbert E. M.
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2014
• Subjects: DRNTU::Science::Physics
• Online Access: https://hdl.handle.net/10356/103713; http://hdl.handle.net/10220/20019
• Institution: Nanyang Technological University

Using ultrafast optical pump-probe technique, we studied the temperature-dependent carrier and phonon dynamics of the topological insulator Bi1.5Sb0.5Te1.8Se1.2 single-crystal from 10 K to 300 K. Two relaxation processes of carriers and coherent optical/acoustic phonons have been observed. By using the two-temperature model, we are able to attribute the fast (∼ps) relaxation component to carrier-phonon coupling involving carriers in the conduction band. We also studied the temperature dependence of the dephasing time and frequency of optical phonon, and the optical penetration depth of Bi1.5Sb0.5Te1.8Se1.2.