EAPSI: Experimental Study of an Atomically-Thin, Semiconducting/Metallic Material to Develop Next-Generation Nanotechnology

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The recent explosion in progress towards realizing atomically thin electronics has resulted from the search for newer fabrication methods, materials, and device operation principles that will advance beyond the physical limits of conventional silicon-based semiconductor technology. Transition metal dichalcogenides (TMDs) have been shown to undergo a structural transformation to produce a metallic state upon transfer of electrons into the pristine semiconducting material. This gives a route towards atomically sharp metal-semiconductor junctions and could enable a new class of efficient, fully 2D integrated circuit technologies. This project will study the structural change mechanism, and manipulation thereof, in atomically thin TMDs using a scanning tunneling microscope (STM). This instrument features an atomically sharp tip that can directly transfer electrons into the material as well as provide structural and electronic information with atomic-scale precision. Stability as a function of temperature will also be studied in order to inform about suitable operating temperatures for devices. The results of this research will deepen our understanding of control over these materials for nano-device fabrication. This work will be done in collaboration with Professor Michael Fuhrer, a leader in experimental physics research of two-dimensional materials, at Monash University in Melbourne, Australia. This project aims to correlate atomic structures with local electronic properties at the metallic-semiconducting interface using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). STM and STS will be done at low temperature in the vicinity of a phase boundary to provide topographical characterization of the local electronic density of states. Then, the effect of controllably injecting electrons into the pristine material or into a phase boundary, with attention being paid to phase boundary migration, phase creation, and changes in electronic state can be studied. Phase boundary migration will also be studied as a function of temperature. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.