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Ultrafast Photo‐Response by Surface State‐Mediated Optical Transitions in Topological Insulator Bi 2 Te 3 Nanowire
Author(s) -
Park Dambi,
Jeong Kwangsik,
Maeng InHee,
Kim Dajung,
Kwon Hoedon,
Hong SeokBo,
Kim JaeHoon,
Kee ChulSik,
Kang Chul,
Cho MannHo
Publication year - 2019
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201900621
Subject(s) - photocurrent , topological insulator , materials science , nanowire , optoelectronics , polarization (electrochemistry) , photoconductivity , surface states , ultrashort pulse , condensed matter physics , optics , surface (topology) , physics , laser , chemistry , geometry , mathematics
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 Bi 2 Te 3 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 Bi 2 Te 3 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.