Magneto-optoelectronic response in 2D atomic-layered materials

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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.