Thursday, 14 February 2019 at 3:15 pm
McCullough, First Floor Auditorium, Room #115
Host: Ben Feldman
Electron, phonon, and interfacial transport in 2D materials and heterostructures
This talk will present recent highlights from our research on two-dimensional (2D) materials. Results span from fundamental measurements and simulations, to applications taking advantage of unusual 2D material properties. We measured record velocity saturation in graphene, and the thermal properties of graphene nanoribbons. We have also grown monolayer 2D semiconductors by CVD over large areas, including MoS2, WSe2, MoSe2, and multilayer MoTe2 and WTe2. ZrSe2 and HfSe2 have native high-K dielectrics ZrO2 and HfO2, which are of key technological relevance. Improving electrical contacts, we demonstrated 10 nm transistors using monolayer MoS2, with the highest current reported to date (>400 µA/µm), near ballistic limits. Current density in such 2D devices is ultimately limited by self-heating and phonon scattering, in part due to the weak van der Waals bonds between 2D materials and their environment, which lead to a large thermal resistance of this interface. On the other hand, we exploited this weak interface to improve energy efficiency in phase-change memory, and we tuned it by Li intercalation, demonstrating MoS2-based thermal transistors. These studies reveal fundamental limits and some applications of 2D materials, taking advantage of their unique properties.