Subcategory: Materials Science
Eden Berga - University of Washington
Intense research on graphene has sparked the interests in atomically-thin semiconductors, especially transition metal dichalcogenides (TMD) such as WS2, MoS2, WSe2, and MoSe2. Having direct bandgap semiconductors in monolayer form, these materials have shown promise in ultrathin optoelectronic applications. However, probing the fundamental properties of these materials is challenging because conventional metal contacting introduces defects and Schottky barriers that masked some physical phenomena, as well as degrading device performance. In this study graphene in contact with WS2 Van der Waals heterostructures was constructed to achieve relatively defect-free interfaces for probing the excitonic physics under smoothly varying doping concentration. The use of Van der Waals structures offers two advantages: first, the underlying and encapsulating hexagonal boron nitride (HBN) provide clean and atomically flat interfaces and shield the WS2 from contamination. Second, FLG is relatively transparent so that the WS2 underneath can be optically probed. The results will allow unique properties of WS2 compared to other semiconducting TMDs to be identified and to study the behavior of WS2 arising from the Van der Waals interface. Studying these properties will help improve optoelectronic devices and understand the theories behind their performances. For future work, one can research the properties of a Van der Waals heterostructure made from multiple TMDs instead of just one.ERN abstract .docx
Funder Acknowledgement(s): This material is based in part upon work supported by the State of Washington through the University of Washington Clean Energy Institute and via funding from the Washington Research Foundation ; University of Washington Office of Research
Faculty Advisor: Lisa Peterson, email@example.com
Role: I worked on every part of the research with the help of my mentor.