Temperature-driven Emergence of Negative Photoconductivity in Semimetal MoTe2 Film Probed with Terahertz Spectroscopy
2022-01-08
状态已发表
摘要

Layered two-dimensional (2D) materials MoTe2 have been paid special attention due to the rich optoelectronic properties with various phases. The nonequilibrium carrier dynamics as well as its temperature dependence in MoTe2 are of prime importance, as it can shed light on understanding the anomalous optical response and potential applications in far infrared (IR) photodetection. Hereby, we employ time resolved terahertz (THz) spectroscopy to study the temperature dependent nonequilibrium carrier dynamics in MoTe2 films. After photoexcitation of 1.59 eV, the 1T’-phase MoTe2 at high temperature behaves only THz positive photoconductivity (PPC) with relaxation time of less than 1 ps. In contrast, the Td-phase MoTe2 at low temperature shows an ultrafast THz PPC initially followed by emerging THz negative photoconductivity (NPC), and the THz NPC signal relaxes to the equilibrium state in hundreds of ps time scale. Small polaron formation induced by hot carrier has been proposed to be ascribed to the THz NPC in the polar semimetal MoTe2 at low temperature. The polaron formation time after photoexcitation increases slightly with temperature, which is determined to be ~0.4 ps at 5 K and 0.5 ps at 100 K. Our experimental result demonstrates for the first time the dynamical formation of small polaron in MoTe2 Weyl semimetal, this is fundamental importance on the understanding the temperature dependent electron-phonon coupling and quantum phase transition, as well as the designing the MoTe2-based far IR photodetector.

关键词Negative photoconductivity small polaron THz spectroscopy electronphonon coupling Weyl semimetal
DOIarXiv:2107.01399
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出处Arxiv
WOS记录号PPRN:12030769
WOS类目Physics, Condensed Matter
资助项目National Natural Science Foundation of China (NSFC)[92150101] ; null[61735010] ; null[61975110]
文献类型预印本
条目标识符https://kms.shanghaitech.edu.cn/handle/2MSLDSTB/348224
专题物质科学与技术学院
物质科学与技术学院_PI研究组_刘伟民组
作者单位
1.Shanghai Univ, Dept Phys, Shanghai 200444, Peoples R China
2.Shandong Normal Univ, Sch Phys & Elect, Jinan 250014, Peoples R China
3.Univ Shanghai Sci & Technol, Terahertz Technol Innovat Res Inst, Terahertz Spectrum & Imaging Technol Cooperat Innovat Ctr, Shanghai Key Lab Modern Opt Syst, 516 JunGong Rd, Shanghai 200093, Peoples R China
4.ShanghaiTech Univ, Sch Phys Sci & Technol, Shanghai 201210, Peoples R China
5.Tianjin Univ, Inst Laser & Optoelect, Coll Precis Instrument & Optoelect Engn, Tianjin 300072, Peoples R China
6.STU & SIOM Joint Lab Superintense Lasers, Applicat, Shanghai 201210, Peoples R China
推荐引用方式
GB/T 7714
Chen, Jiaming,Suo, Peng,Zhang, Wenjie,et al. Temperature-driven Emergence of Negative Photoconductivity in Semimetal MoTe2 Film Probed with Terahertz Spectroscopy. 2022.
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