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Cha, Soon Young
원자제어 저차원 전자계 연구단
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Picosecond Competing Dynamics of Apparent Semiconducting-Metallic Phase Transition in the Topological Insulator Bi2Se3

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Title
Picosecond Competing Dynamics of Apparent Semiconducting-Metallic Phase Transition in the Topological Insulator Bi2Se3
Author(s)
Sim, Sangwan; Lee, Seungmin; Moon, Jisoo; In, Chihun; Lee, Jekwan; Noh, Minji; Kim, Jehyun; Jang, Woosun; Soonyoung Cha; Seo, Seung Young; Oh, Seongshik; Kim, Dohun; Soon, Aloysius; Moon-Ho Jo; Choi, Hyunyong
Subject
apparent phase transition, ; terahertz spectroscopy, ; topological insulator, ; ultrafast spectroscopy
Publication Date
2020-03
Journal
ACS PHOTONICS, v.7, no.3, pp.759 - 764
Publisher
AMER CHEMICAL SOC
Abstract
© 2020 American Chemical Society. Resolving the complex interplay between surface and bulk response is a long-standing issue in the topological insulators (TIs). Some studies have reported surface-dominated metallic responses, yet others show semiconducting-like bulk photoconductance. Using ultrafast terahertz spectroscopy with the advent of Fermi-level engineered TIs, we discovered that such difference arises from the time-dependent competing process of two parameters, namely, the Dirac-carrier surface scattering rate and the bulk Drude weight. After infrared femtosecond pulse excitation, we observed a metal-like photoconductance reduction for the prototypical n-type Bi2Se3 and a semiconductor-like increased photoconductance for the p-type Bi2Se3. Surprisingly, the bulk-insulating Bi2Se3, which is presumably similar to graphene, exhibits a semiconducting-to-metallic phase apparent transition at 10 ps. The sign-reversed, yet long-lasting (≥500 ps) metallic photoconductance was observed only in the bulk-insulating Bi2Se3, indicating that such dynamic phase transition is governed by the time-dependent competing interplay between the surface scattering rate and the bulk Drude weight. Our observations illustrate new photophysical phenomena of the photoexcited-phase transition in TIs and demonstrate entirely distinct dynamics compared to graphene and conventional gapped semiconductors
URI
https://pr.ibs.re.kr/handle/8788114/8336
DOI
10.1021/acsphotonics.9b01603
ISSN
2330-4022
Appears in Collections:
Center for Artificial Low Dimensional Electronic Systems(원자제어 저차원 전자계 연구단) > 1. Journal Papers (저널논문)
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