The exceptional properties of the purely two-dimensional (2D) sheet of carbon atoms, graphene, has spurred the discovery of a whole host of 2D material systems with exceptional electronic, mechanical, optical and thermal properties. These new 2D materials promise a new generation of technologies such as flexible displays, ultrafast computing, high-efficiency low-cost solar cells, and quantum information processing. Specifically in the context of optoelectronics, the unusually large strength of light-matter interaction of 2D materials has made them highly attractive for practical device applications. However, single-layer graphene has no direct bandgap, which limits its use in a range of optoelectronic applications. The recent discovery of 2D atomic crystals based on transition metal dichalcogenides, many of which have large bandgaps in the visible and infrared spectrum, now opens entirely new areas of investigation in optical and optoelectronic devices. In this program, building blocks for next generation classical and quantum information processing will be developed based on precise control of electronic excited states, hybrid half-light half-matter quasiparticles (exciton-polaritons), and collective excitations in 2D transition metal dichalcogenides. The motivation is to develop next generation photonic and electronic systems and sub-systems that exploit the unique advantages of 2D semiconductors such as large interaction strength with light, mechanical flexibility, and low fabrication cost. Specifically, (i) low energy consuming, ultrafast logic gates will be developed using neutral and charged excitations (ii) Quantum nonlinear devices where even a single photon can alter the state of the system will be investigated using polaritons and (iii)Exotic phases of matter that rely on ideas from mathematical topology will be explored using collective excitations will be developed In addition to the technological impact on society, the program will include extensive Educational and Outreach. CCNY, the lead institution, is a minority-serving institution and through close collaboration with MIT expects both graduate and undergraduate students from diverse ethnic and social backgrounds to become part of the proposed cutting-edge research. The program will also provide educational opportunities for local underrepresented minority high school students/teachers and will engage them in summer projects. Outreach efforts for bringing the science to the general public is another targeted effort under the program.
This program will develop excitonic and polaritonic (exciton-photon quasiparticles) devices that operate in the visible and near infrared spectral range based on 2D atomic layers of transition metal dichalcogenides (MoS2, WS2, WSe2 etc). The 2D materials have an inherently strong interaction with light and other attractive properties such as valley polarization and strong spin-orbit coupling. These unique properties open up avenues for the development of heretofore inaccessible device features with tremendous potential applications in classical and quantum information processing. Devices that rely on control of exciton and polariton transport and localization as well as approaches to emergent topological phases in 2D materials will be the focus of this program. Specifically, the following devices/ device concepts using 2D transition metal dichalcogenides and their heterostructures will be developed: (i) transistors and logic gates that utilize neutral and charged excitons, (ii) quantum nonlinear optical devices and light emitters based on exciton polaritons, and (iii) exploratory optoelectronic device concepts based on topological phases that can be realized in 2D semiconductors. The device development will be closely guided by growth and synthesis efforts as well as theoretical efforts to better understand exciton and polariton transport and for realizing novel topological phases and strain engineering for electronic band structure manipulation. Development of excitonic and polaritonic devices based on 2D semiconductors that have the potential to operate at room temperature presents a unique opportunity to develop practical devices using previously unexplored fundamental physical concepts.
