“High-field Electron Transport and Interaction Induced Phenomena in 2D Materials”

Dr. Kayoung Lee
Electrical Engineering, KAIST

Apr. 1 (Fri.), 04:00 PM
https://kaist.zoom.us/j/89879980781
회의 ID: 898 7998 0781
암호: 808795

Abstract:
In this talk, I will present our research that spans from fundamental electron transport mechanisms to interaction induced phenomena in low-dimensional electron systems, each of which is in dire need of
innovation to incubate new material-based devices with high performance. Using double bilayer graphene heterostructures, separated by a hexagonal boron nitride dielectric, we studied interactions
between the two bilayers, where the interlayer spacing is smaller than the intra-layer particle spacing. I will present frictional drag probed on the double bilayer systems, a phenomenon in which charge current
flowing in one (drive) layer induces a voltage drop in the opposite (drag) layer. At temperatures (T) lower than 10 K, we observe a large anomalous negative drag near the drag layer charge neutrality, which increases dramatically with reducing T, strikingly becoming comparable to the layer resistivity at the lowest T = 1.5 K. A comparison of the drag resistivity and the drag layer Peltier coefficient suggests a thermoelectric origin of the drag. The talk will then move on to our recent investigation into electron transport and drift velocity saturation at high electric field in emerging 2D InSe semiconductor with a mobility >2700 cm2/Vs at room temperature. I will report the first measured saturation velocity of 2D InSe exceeding 2 x 107 cm/s. Employing our modified optical phonon emission model to explain the drift velocity saturation at high electric field, we estimate the energy of InSe optical phonons.