Photo-Induced Bandgap Renormalization Governs the Ultrafast Response of Single-Layer MoS2
Eva A. A. Pogna, Margherita Marsili, Domenico De Fazio, Stefano Dal Conte, Cristian Manzoni, Davide Sangalli, Duhee Yoon, Antonio Lombardo, Andrea C. Ferrari, A… 展开作者
Eva A. A. Pogna, Margherita Marsili, Domenico De Fazio, Stefano Dal Conte, Cristian Manzoni, Davide Sangalli, Duhee Yoon, Antonio Lombardo, Andrea C. Ferrari, Andrea Marini, Giulio Cerullo, Deborah Prezzi
备注：
This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano after peer review and technical editing by the publisher. To access the final edited and published work see: http://pubs.acs.org/articlesonrequest/AOR-fcCuTYn5m6wiDTIg98Kx
Transition metal dichalcogenides (TMDs) are emerging as promising two-dimensional (2d) semiconductors for optoelectronic and flexible devices. However, a microscopic explanation of their photophysics -- of pivotal importance for the understanding and optimization of device operation -- is still lacking. Here we use femtosecond transient absorption spectroscopy, with pump pulse tunability and broadband probing, to monitor the relaxation dynamics of single-layer MoS2 over the entire visible range, upon photoexcitation of different excitonic transitions. We find that, irrespective of excitation photon energy, the transient absorption spectrum shows the simultaneous bleaching of all excitonic transitions and corresponding red-shifted photoinduced absorption bands. First-principle modeling of the ultrafast optical response reveals that a transient bandgap renormalization, caused by the presence of photo-excited carriers, is primarily responsible for the observed features. Our results demonstrate the strong impact of many-body effects in the transient optical response of TMDs even in the low-excitation-density regime.
A new type-II lepidocrocite-type TiO2/GaSe heterostructure: Electronic and optical properties, bandgap engineering, interaction with ultrafast laser pulses
Fast Interlayer Energy Transfer from the Lower Bandgap MoS2 to the Higher Bandgap WS2
University of Warsaw（华沙大学）；Université Paris-Saclay（巴黎萨克雷大学）；ONERA（法国航空航天研究院）；CNRS（法国国家科学研究中心）；School of Basic Sciences, Indian Institute of Technology Bhubaneswar（布巴内斯瓦尔印度理工学院基础科学学院）；De Vinci Higher Education（德芬奇高等教育机构）；De Vinci Research Center（德芬奇研究中心）；Research Center for Materials Nanoarchitectonics, National Institute for Materials Science（国立材料研究所材料纳米结构研究中心）；Research Center for Electronic and Optical Materials, National Institute for Materials Science（国立材料研究所电子与光学材料研究中心）
Ultrafast Demagnetization Governed by Spin Fluctuations in CaRuO$_{3}$/SrTiO$_{3}$ Superlattice
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所凝聚态物理国家实验室）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Songshan Lake Materials Laboratory（松山湖材料实验室）
Ultrafast X-ray induced damage and nonthermal melting in cadmium sulfide
Institute of Physics, Czech Academy of Sciences（捷克科学院物理研究所）；Institute of Plasma Physics, Czech Academy of Sciences（捷克科学院等离子体物理研究所）；Higher Institute of Technologies and Applied Sciences, University of Havana（哈瓦那大学高等技术与应用科学学院）
Ultrafast Spin Injection in Graphene via Dynamical Carrier Filtering at Transition Metal Dichalcogenide Interfaces
Kansai Institute for Photon Science, National Institutes for Quantum Science and Technology (QST)（光子科学关西研究所，量子科学技术研究开发机构）；Department of Nuclear Engineering and Management, Graduate School of Engineering, The University of Tokyo（东京大学大学院工学系研究科核工程与管理学专业）
Carrier transport and electrical bandgaps in epitaxial CrN layers
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V.（柏林保罗·德鲁德固态电子学研究所，莱布尼茨柏林研究联盟协会）；Leibniz-Institut für Kristallzüchtung（莱布尼茨晶体生长研究所）
Ultrafast Energy Absorption in Silicon Controlled by Two-Color Double Pulses
The University of Tokyo（东京大学）；National Institutes for Quantum Science and Technology（量子科学技术研究机构）；National Institute of Advanced Industrial Science and Technology（产业技术综合研究所）
Intra- and Inter-Conduction Band Optical Absorption Processes in $β$-Ga$_2$O$_3$
$β$ -Ga $_2$ O $_3$是一种超宽带隙半导体，因此预期对于亚带隙波长的光在紫外线中是光学透明的。与该预期相反，在此发现，n掺杂的$β$ $_2$ O $_3$中的自由电子经由导带内和导带间光学跃迁吸收从IR到UV波长范围的光。导带内吸收通过间接光学声子介导过程发生，在可见光到近红外波长范围内具有$1/ω^{3}$依赖性。这种频率依赖性明显不同于自由载流子吸收的Drude模型预测的$1/ω^{2}$依赖性。最低导带和较高导带之间的导带间吸收经由直接光学过程在$λ\sim 349$ nm（3.55 eV）处发生。稳态和超快光谱测量明确地识别这两个吸收过程，并使导带间能量的定量测量，以及吸收的频率依赖性。而导带内吸收不依赖于光的偏振，导带间吸收被发现是强烈的偏振依赖。实验观察，在最近的理论预测的$β$ -镓$_2$ O $_3$，提供了重要的限制的子带隙的光电子学在深紫外可见光波长范围内的透明度，也是在这个新兴的半导体的高电场传输效应的重要性。
First-order kinetics bottleneck during photoinduced ultrafast insulator-metal transition in 3D orbitally-driven Peierls insulator CuIr$_{2}$S$_{4}$
尖晶石结构的CuIr $_{2}$ S $_{4}$化合物显示出相当不寻常的轨道驱动的三维Peierls类绝缘体-金属转变。由于亚稳态辐照诱导无序弱导电态的存在，低温超导破缺绝缘态特别有趣。本文利用全光超快多脉冲时间分辨光谱技术研究了强飞秒光脉冲辐照效应。我们发现，低T对称破缺态的结构相干性强烈抑制在亚皮秒的时间尺度上的阈值激发通量以上，导致在结构上不均匀的瞬态持续几十皮秒，然后恢复到低T无序弱导电状态。电子顺序示出了在显著较低的注量阈值下的瞬态间隙填充。这些数据表明，光诱导过渡到高T金属相的动力学是由一阶过渡成核动力学，防止完整的超快结构转变，即使当吸收的能量显着超过平衡焓差的高T金属相。与此相反，动态解耦的电子顺序是短暂的亚皮秒时间尺度上，而独立地抑制由于光诱导莫特过渡。
