Chinese Optics Letters, 2019, 17 (2): 020005, Published Online: Feb. 14, 2019
Electron–phonon coupling in topological insulator Bi2Se3 thin films with different substrates
Abstract
Broadband transient reflectivity traces were measured for Bi 2 Se 3 thin films with various substrates via a 400 nm pump–white-light-probe setup. We have verified the existence of a second Dirac surface state in Bi 2 Se 3 and qualitatively located it by properly analyzing the traces acquired at different probe wavelengths. Referring to the band structure of Bi 2 Se 3 , the relaxation mechanisms for photo-excited electrons with different energies are also revealed and studied. Our results show a second rise of the transient reflection signal at the time scale of several picoseconds. The types of substrate can also significantly affect the dynamics of the rising signal. This phenomenon is attributed to the effect of lattice heating and coherent phonon processes. The mechanism study in this work will benefit the fabrication of high-performance photonic devices based on topological insulators.
Tian Jiang, Runlin Miao, Jie Zhao, Zhongjie Xu, Tong Zhou, Ke Wei, Jie You, Xin Zheng, Zhenyu Wang, Xiang'ai Cheng. Electron–phonon coupling in topological insulator Bi2Se3 thin films with different substrates[J]. Chinese Optics Letters, 2019, 17(2): 020005.