October 9, 2014
EE Conference Room
Speaker: Dr. Yilei Li, Department of Physics, Columbia University
Atomically thin transition metal dichalcogenides is a group of novel semiconductingÂ two-dimensional crystals. Their electronic properties are distinct from the corresponding bulk materials due to reduced dimensionality and altered symmetry properties. Motivated by the important optical response of the fundamental excitations in these materials, as well as their potential to be used as building blocks for new two-dimensional photonics devices, we measured their linear and second-order nonlinear dielectric response by optical spectroscopy. The linear response demonstrates strong overall light-matter interaction, and shows clear signature of excitonic optical transitions. The second-order nonlinear response reveals layer-by-layer variation in the symmetry of the atomically thin crystals, as well as their in-plane rotational symmetry.
Yilei Li received his PhD degree in Physics at Columbia University and is continuing work at Prof. Tony Heinz's research group at Columbia's Electrical Engineering Department.
Hosted by Richard Osgood.