Engineering Electronic Structure of 2D Semiconductors with Non-Equilibrium Processing

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Technical Description: The research objective of this project is to tune the electronic structure of two-dimensional (2D) semiconductors by extremely off-equilibrium materials processing. For this purpose, 2D semiconductor alloys are formed by mixing the otherwise immiscible 2D semiconductors with kinetically controlled means to stabilize non-equilibrium phases, in which the electronic and structural properties are engineered on command. The resultant 2D semiconductor alloys are expected to offer a new platform for implementation of a wide variety of potential technologies that are not possible with existing materials. The specific aims of the research are to: i) alloy layered semiconductors in the 2D limit at arbitrary compositions. This is achieved using the pulsed laser alloying method, and the products are evaluated by structural and physical characterization tools; and ii) engineer electronic structure of 2D alloys by designing proper compositions and heterostructures. Their bandgap, band offsets, effective mass, and carrier dopability are designed and evaluated, and compared to density-functional theory and Green's function calculations for a comprehensive understanding. Non-technical Description: Layered semiconductors at the quantum limit are emerging as an important class of materials for innovative information and energy conversion technologies. Unlike the large number of existing bulk semiconductors, the full potential of these 2D semiconductors is limited by the small number of members currently available: mostly being transition metal chalcogenides. This project seeks to remove this limit by creating a library of 2D semiconductor alloys where the electronic structure is designed and continuously tuned to fit specific needs. Integrated with the research efforts, the project also includes a set of educational activities that stimulates and prepares pre-college students for careers in materials science and engineering. Within this project the PI: i) creates a series of hands-on exhibits and experiments for middle-high school students in partnership with the Techbridge Girls project; and ii) teams up with a campus education group to develop a summer class series in "Nanoscale Materials Science and Engineering" for underrepresented high-school students.