EAGER: The Fundamentals of Exotic Exciton Complexes in 2D Janus Semiconductors

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Named after the two-faced Roman god, Janus crystals are a new class of ultrathin two-dimensional materials. Here, the name ''Janus'' originates from the ancient Roman God of beginnings and transitions with two faces one looking to the future while the other facing to the past. Similar to Janus himself, Janus materials have two different faces with two different atomic arrangement at the nanoscale. The theory tells us that these materials have rather extraordinary optical, electrical, and magnetic properties and show promise towards new technologies in quantum engineering, quantum optics, and spintronics. But our understanding of these materials are only limited to theory without any experimental insights due to limitations in sample preparation and measurement techniques. This project aims understanding the optical properties of Janus crystals using impressive synthesis and characterization techniques. Next, it takes steps to integrate them with other quantum platforms for next generation optical quantum applications. While doing so, the educational efforts create completely new lab tours to material deposition / growth labs at Arizona State University for prospective K-12 students.The project aims to investigate optical properties of post-transition metal chalcogenide 2D Janus layers and integrate them with microcavities to stabilize complex exciton complexes for new type of quantum applications. The initial experiments focus on the synthesis of epitaxial and excitonic grade 2D Janus crystals and establishing their optical properties through the state-of-the-art microscopy and spectroscopy characterization techniques. The goal is to establish the fundamental excitonic behavior of these materials such as excitonic series, exciton binding energies, dipolar-dipolar excitons, and lifetimes when the mirror symmetry is broken and large colossal polarization is present in the layer. Once established, additional studies focus on formation and understanding of Bose condensates or rich exciton complexes when these 2D Janus layers are integrated with DBR microcavities. If successful, the project provides the very first experimental insights into these new class of quantum material. This study also paves the way for development of numerous applications of quantum detectors, sensors, and valleytronics. The principal investigator continues to be committed to outreach, education and collaborative efforts within the university as well as with Phoenix middle and high schools, Sun Devil Days and Open House events and technical laboratory training and tours.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.