The search for new functionality in two-dimensional (2D) materials has recently evolved in
the direction of making heterostructures of two-dimensional materials like graphene (G),
hexagonal Boron Nitride (h-BN) and the transition metal dichalcogenides (TMDC) . While
most efforts have focused on few-layer heterostructures, artificial van der Waals solids that
are formed by self-assembling 2D monolayers into bulk, three-dimensional structures 
offer an alternate and novel route.
In today’s talk, I will discuss our use of optical pump terahertz probe spectroscopy to
measure the ultrafast opto-electronic response of a 3D van der Waals solid made by
self-assembling h-BN and G in varying ratios. We observe that the photo conductivity tunes
from the completely insulating h-BN phase to the conductive G phase, and for certain ratios
of hBN and G, we observe dissipation-less, purely capacitive opto-electronic behavior.
During the talk, I will also introduce the new Okinawa Institute of Science and Technology
– a graduate university on the resort island of Okinawa with a unique perspective on science
and education; and I will briefly introduce the other activities of the Femtosecond