Magneto-optoelectronic response in 2D atomic-layered materials

摘要：非技术性描述：美国拥有世界上最高的国内生产总值，因为它在技术突破方面一直处于领先地位。个人电脑、万维网、手机、高清晰度电视、即将问世的自动驾驶汽车和人工智能等相对较新的进步，都植根于政府资助的研发。电子和光子学领域的半导体能力的快速发展使这些领域的迅速增长成为可能。为了进入新的增长领域，现在需要开发具有新能力的灵活、更快、更薄、更节能的半导体材料。这一目标导致了所谓的范德华结合材料，这种材料可以一层一层地剥离到单个二维(2D)原子层的厚度。这种材料具有高速、更高的能效、灵活性和迄今所使用的材料所没有的新颖的电光特性。因此，本研究旨在对其材料性能进行研究，以期达到应用的目的。这项研究将在佐治亚州立大学(GSU)的物理与天文学系进行，该校是美国最多元化的大学之一。这项建议的本科科学、技术、工程和数学(STEM)教育部分旨在将STEM领域中历史上代表性不足的群体和女性的普通大学生的能力转化为STEM领域的职业道路，通过2D材料领域的微型科学项目为他们提供早期支持、建立信心和研究经验的机会。在佐治亚州亚特兰大市中心的一家南部城市内城学术机构提供的这种教育/培训，将有助于将代表不足的社会部分添加到全国电子、光电子、国防和无线通信行业的科学技术技能基础中。技术说明：大块van der Waals结合晶体的单原子层，以及由van der Waals外延建立的堆叠，包括具有不同电子、光学、自旋和超导特性的多个单原子层，提供了获得现有块体材料特性所不具备的新物理特性的可能性，这些特性可用于解决低功耗和柔性电子、传感和光子学中的突出技术问题。因此，本研究将实验研究二维原子层材料在稳态光激发下的磁光响应，包括单层和双层石墨烯、原子薄的六方氮化硼(h-BN)、单层和双层二硫化钼(MoS_2)以及其他过渡金属二卤化物。一个由研究生和博士后组成的研究团队将在参与微型科学项目的本科生的帮助下，通过范德华外延生长2D原子层状晶体；通过电子束光刻、等离子体刻蚀和金属化制造器件；并在磁场存在的情况下研究电接触和非接触器件在微波、毫米波和太赫兹光激励下的性能。在这里，一些令人感兴趣的具体问题包括石墨烯的毫米波磁响应，h-BN包裹的石墨烯和MoS_2中的电场对光响应的影响，以及石墨烯中穿过中性点的自旋性质的研究。这类研究有望深入了解2D材料的电子结构、它们的光响应、自旋g因子、自旋寿命以及感应带隙对外加电场和磁场的依赖--这些属性将确定此类系统是否适合各种理想的应用。潜在的转变结果可能包括在石墨烯中观察到新的辐射诱导磁阻振荡，在h-BN封装的石墨烯中实现和测量长自旋寿命，以及在小禁带限制下测量电场偏置的h-BN封装的石墨烯或MoS_2或其他过渡金属二卤化物中的带隙。

Abstract:Non-technical Description:The United States has the highest Gross Domestic Product in the world because it has been the leader in technological breakthroughs. Relatively recent advances such as the personal computer, the World Wide Web, the cell phone, high definition television, the forth-coming autonomous car and artificial intelligence, all have roots in government funded research and development. The meteoric growth in these areas has been made possible by the rapid advances in semiconductor capability for both electronics and photonics. To access new areas for growth, there is now a need to develop flexible, faster, thinner, and more power efficient semiconductor materials with new capability. This aim has led to the so-called van der Waals bonded materials, which are materials that can be peeled, layer by layer, down to the thickness of a single 2-dimensional (2D) atomic layer. Such materials promise high speed, greater power efficiency, flexibility, and novel electro-optic properties not found in materials utilized thus far. Thus, this research aims to study their material properties with a view towards applications. The research is to be carried out in the Physics & Astronomy Department of Georgia State University [GSU], one of the most diverse universities in the nation. The undergraduate Science, Technology, Engineering and Mathematics (STEM) educational component of this proposal aims to translate the abilities of general university students from historically underrepresented groups and women in STEM fields, into the pursuit of a career path in a STEM field, by providing them early exposure to a supportive, confidence building, research experience through mini-science projects in the 2D materials area. Such education/training provided in a southern urban inner-city academic institution in downtown Atlanta, Georgia, will help to add underrepresented sections of society to the nation's science and technology skill base for the electronics, photonics, defense, and wireless communications industries. Technical Description:Single atomic layers of bulk van der Waals bonded crystals, and stacks built up by van der Waals epitaxy including a number of single atomic layers with differing electronic, optical, spin, and superconducting properties, offer the possibility of obtaining new physical properties not available in existing bulk materials' properties that can be utilized to address outstanding technological problems in low power and flexible electronics, sensing, and photonics. Thus, this research will experimentally examine the magneto-optoelectronic response under steady state photo-excitation of 2D atomic-layered materials including mono-layer and bilayer graphene, atomically thin hexagonal boron nitride (h-BN), mono- and bilayer-molybdenum disulfide (MoS2), and other transition metal-dichalcogenides. A research team consisting of graduate students and a postdoc, with help from undergraduates participating in mini science projects, will build up 2D atomic-layered crystals by van der Waals epitaxy; fabricate devices by electron beam lithography, plasma etch, and metallization; and examine the properties of electrically contacted and non-contacted devices in the presence of a magnetic field under microwave, mm-wave, and terahertz photo-excitation. Here, some specific problems of interest include the mm-wave magneto-response of graphene, the electric field effect on photoresponse in h-BN encapsulated graphene and MoS2, and the study of the spin properties in graphene across the neutrality point. Such studies are expected to provide insight into the electronic structure of 2D materials, their photo response, spin-g-factors, spin lifetimes, and the dependence of induced bandgaps on applied electric and magnetic fields - attributes that would identify the suitability of such systems for various desirable applications. Potentially transformative results could include the observation of novel radiation-induced magnetoresistance oscillations in graphene, the realization and measurement of long spin lifetimes in h-BN encapsulated graphene, and the measurement of bandgaps in electric field biased bilayer h-BN encapsulated graphene or MoS2 or other transition metal dichalcogenides in the small bandgap limit.