Topological insulators are a new class of materials with highly interesting optoelectronic properties such as strong light absorption, polarization-dependent surface photocurrent, and topological phase transitions. In the present study, anomalous characteristics of the topological surface state (TSS) are discovered in a single-crystalline Bi2Te3 nanowire (NW) through mediated optical transitions by utilizing an optical pump-THz probe. As a result, ultra-fast carrier recombination occurs owing to the presence of TSS, and a phonon frequency shift occurs due to enhanced electron–phonon interaction. In particular, the large optical absorption of the second TSS is closely related to high optical conductivity. The photoresponse for visible light in Bi2Te3 NW with TSS represents a remarkable improvement. The result indicates that the presence of (first and second) TSS and quantum well 2D electron gas effectively contributes to the significant improvement in photocurrent sensitivity by enhancement of the photocurrent generation. In summary, TSS-assisted optical transitions affect the efficiency of the optoelectronic device.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (Grant No. 2018R1A2A1A05023214) and by Samsung Research Funding Center of Samsung Electronics under Project No. SRFC-MA1502-01. This work was supported by the Gwangju Institute of Science and Technology (GIST) Research Institute (GRI) grant funded by the GIST in 2019. The authors would like to thank Young Boo Lee and Hee-Suk Chung at the Korea Basic Science Institute for technical assistance with TEM.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics