Study of Terahertz Emission Spectroscopy in Topological Insulator Sb2Te3 thin film

• Main Authors: Chen, Yi- Cheng, 陳奕成
• Other Authors: Luo, Chih-Wei
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/00698767289598710294

碩士 === 國立交通大學 === 電子物理系所 === 104 === In this thesis, we show the helicity-dependent terahertz emissions from topological insulator (TI) Sb2Te3 thin films by ultrafast optical excitation. We observed the polarity-reversal of the emitted THz radiation as the helicity of optical pulses reverses. The observed phenomenon is consistent with the characteristics of the helicity-dependent photocurrent on TIs. Employing a decomposition-recombination procedure in time domain, the individual contributions of circular photogalvanic effect, linear photogalvanic effect and photon drag effect are revealed completely. Additionally, based on the Tr-ARPES results and considering transient-current radiation as well as far-field diffraction, our results are the same as that from Tr-ARPES results. Finally, our results not only demonstrate that helicity-dependent THz emission originated from topological insulator surface states can be manipulated by ultrafast optical pulses but also pave a way towards applications of THz emission spectroscopy on spintronics.