RUI: Ultrafast Conductivity Measurements of Graphene Films

*非技术摘要*石墨烯是一种新型的碳材料，由单原子厚度的碳片组成。这种材料于2004年被发现，在从透明导电薄膜(用于太阳能电池)到超高速晶体管的电子应用方面有着巨大的前景。这一个人研究人员奖支持一个以本科生为主的机构的一个研究项目，该项目将调查石墨烯的导电性变化的速度有多快，这与基于石墨烯的高速电子产品的发展有关。预计石墨烯的导电性会以非常快的时间尺度变化。为了研究电导率的快速变化，石墨烯样品将被超短光脉冲激发，随后将用超短太赫兹辐射脉冲测量由此产生的电导率变化。在一系列条件下的电导率测量将使控制石墨烯电子性质的基本过程得以隔离。这项研究还将有助于培养本科生的光子学和实验凝聚态物理。在过去的15年里，研究人员的实验室培养了35名高级本科生，其中超过三分之二的人攻读了科学、数学或工程学的研究生学位。*技术摘要*石墨烯作为纳米级晶体管和高速电子设备的电子材料显示出非凡的前景。这一个人研究人员奖支持一个项目，该项目将使用时间分辨太赫兹光谱研究石墨烯和超薄石墨中的载流子动力学。现在可以很容易地从氧化石墨烯和石墨烯溶液中制备石墨烯薄片导电膜。时间分辨太赫兹和红外光谱是研究这些薄片电学性质的非常合适的工具。这些测量使用光或红外泵浦脉冲来激励样品，并使用延迟的太赫兹脉冲来探测由此产生的电导率的瞬时变化。这项研究有望确定由机械或化学剥离石墨形成的石墨烯薄片中的电子和空穴散射率、寿命和迁移率。通过这种方式，测量将有助于探索这些材料在从透明导电薄膜到晶体管的各种应用中的适用性。该研究计划还将为高级本科生提供教育和研究培训机会。在过去的15年里，调查员的实验室培养了35名高级本科生，其中超过三分之二的人攻读了科学、数学或工程学的研究生学位。

****NON-TECHNICAL ABSTRACT****Graphene is a novel carbon material consisting of one-atom thick sheets of carbon. Discovered in 2004, this material holds great promise for electronic applications ranging from transparent conducting films (used in solar cells) to ultra-high-speed transistors. This individual investigator award supports a research project at a predominately undergraduate institution that will investigate how rapidly the conductivity of graphene can be varied, which is relevant to the development of high-speed graphene-based electronics. It is expected that the conductivity of graphene can change on very fast timescales. To investigate the fast change in conductivity, the graphene sample will be excited with an ultra-short pulse of light and subsequently the resulting change in conductivity will be measured with an ultra-short pulse of terahertz radiation. Conductivity measurements under a range of conditions will enable the isolation of the fundamental processes, which control the electronic properties of graphene. This research will also serve to train undergraduate science students in Photonics and experimental Condensed Matter Physics. During the past 15 years, the investigator's laboratory has trained 35 advanced undergraduates, more than two thirds of whom have pursued graduate degrees in Science, Mathematics or Engineering.****TECHNICAL ABSTRACT****Graphene shows exceptional promise as an electronic material for nanoscale transistors and high-speed electronics. This individual investigator award supports a project that will study carrier dynamics in graphene and ultra-thin graphite using time-resolved THz spectroscopy. Conducting films of graphene flakes can now be easily produced from graphene oxide and from graphene solutions. Time resolved THz and infrared spectroscopy are well-suited tools for studying the electronic properties of these flakes. These measurements use an optical or infrared pump pulse to excite a sample and a delayed THz pulse to probe the resulting transient change in conductivity. The research is expected to determine the electron and hole scattering rates, lifetimes and mobilities in graphene flakes formed by mechanical or chemical exfoliation of graphite. In this way the measurements will help probe the suitability of these materials for a variety of applications from transparent conducting films to transistors. The research program will also provide education and research training opportunities for advanced undergraduate students. During the past 15 years, the investigator's laboratory has trained 35 advanced undergraduates, more than two thirds of whom have pursued graduate degrees in Science, Mathematics or Engineering.