Magneto-optoelectronic response in 2D atomic-layered materials

摘要：非技术描述：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（World Wide Web）、手机、高清电视、即将问世的自动驾驶汽车和人工智能等相对较新的技术进步，都源于政府资助的研发。电子和光子学领域半导体能力的快速发展使这些领域的快速增长成为可能。为了进入新的增长领域，现在需要开发具有新功能的柔性，更快，更薄和更节能的半导体材料。这个目标导致了所谓的范德华键合材料的产生，这种材料可以一层一层地剥离，直至达到单个二维原子层的厚度。这种材料有望实现高速度、更高的功率效率、灵活性和迄今为止所使用的材料所没有的新型电光特性。因此，本研究旨在研究其材料性能并着眼于应用。这项研究将在乔治亚州立大学（GSU）的物理和天文系进行，这是美国最多元化的大学之一。本提案的本科科学、技术、工程和数学（STEM）教育部分旨在将STEM领域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对STEM领域职业道路的追求，通过在2D材料领域的小型科学项目为他们提供早期接触支持性、建立信心的研究经验。这种教育/培训是在佐治亚州亚特兰大市中心的一所南部城市内城学术机构提供的，将有助于将社会中代表性不足的部分加入到国家的电子、光子学、国防和无线通信行业的科学和技术技能基础中。技术描述：大块范德华键合晶体的单原子层，以及由范德华外延（包括许多具有不同电子、光学、自旋和超导特性的单原子层）构建的堆叠，提供了获得现有大块材料特性中无法获得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、传感和光子学方面的突出技术问题。因此，本研究将通过实验研究稳态光激发下二维原子层状材料的磁光电响应，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（MoS2）以及其他过渡金属-二硫族化合物。一个由研究生和博士后组成的研究小组，在参与小型科学项目的本科生的帮助下，将通过范德华外延构建二维原子层状晶体；通过电子束光刻、等离子体蚀刻和金属化制造器件；并研究了在微波、毫米波和太赫兹光激发下，电接触和非接触器件在磁场存在下的性能。在这里，一些具体的感兴趣的问题包括石墨烯的毫米波磁响应，电场对h-BN封装石墨烯和MoS2的光响应的影响，以及石墨烯在中性点上的自旋特性的研究。这些研究有望深入了解二维材料的电子结构，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在各种理想应用中的适用性。潜在的变革结果可能包括观察石墨烯中新的辐射诱导磁阻振荡，h-BN封装石墨烯中长自旋寿命的实现和测量，以及在小带隙极限下测量电场偏置双层h-BN封装石墨烯或MoS2或其他过渡金属二硫族化合物的带隙。

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.