Picosecond Competing Dynamics of Apparent Semiconducting-Metallic Phase Transition in the Topological Insulator Bi2Se3

被引：20

作者：

Sim, Sangwan ^{[3
]}

Lee, Seungmin ^{[4
]}

Moon, Jisoo ^{[5
]}

In, Chihun ^{[1
,2
,3
]}

Lee, Jekwan ^{[2
,3
]}

Noh, Minji ^{[2
,3
]}

Kim, Jehyun ^{[2
]}

Jang, Woosun ^{[6
]}

Cha, Soonyoung ^{[7
]}

Seo, Seung Young ^{[8
]}

Oh, Seongshik ^{[5
]}

Kim, Dohun ^{[1
]}

Soon, Aloysius ^{[6
]}

Jo, Moon-Ho ^{[7
,8
]}

Choi, Hyunyong ^{[1
,2
]}

机构：

[1] Seoul Natl Univ, Dept Phys & Astron, Seoul 08826, South Korea

[2] Seoul Natl Univ, Inst Appl Phys, Seoul 08826, South Korea

[3] Hanyang Univ, Div Elect Engn, Ansan 15588, South Korea

[4] Yonsei Univ, Sch Elect & Elect & Engn, Seoul 120749, South Korea

[5] Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08854 USA

[6] Yonsei Univ, Dept Mat Sci & Engn, Seoul 03722, South Korea

[7] Inst for Basic Sci Korea, Ctr Artificial Low Dimens Elect Syst, Pohang 37673, South Korea

[8] Pohang Univ Sci & Technol POSTECH, Dept Mat Sci & Engn, Pohang 37673, South Korea

来源：

ACS PHOTONICS | 2020年 / 7卷 / 03期

基金：

美国国家科学基金会; 新加坡国家研究基金会;

关键词：

topological insulator; ultrafast spectroscopy; terahertz spectroscopy; apparent phase transition; PHONON INTERACTION; THZ GENERATION; CONVERSION;

D O I：

10.1021/acsphotonics.9b01603

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

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 bulkinsulating 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.

引用

页码：759 / 764

页数：6

共 45 条

[1] Time-resolved terahertz dynamics in thin films of the topological insulator Bi2Se3 [J].