Ultrafast Pump-Probe Microscopy Investigations of Anisotropic ReS2 Nanoflakes and Doped Si Nanowires
Sarah Sutton
PhD Student
University of North Carolina at Chapel Hill
Abstract
This talk will highlight the pump-probe microscopy studies I have performed on ReS2 nanoflakes and Si nanowires. Due to the high spatial and temporal resolution of this spectroscopic technique, fundamental optical and electronic properties of localized structures on single nanoflakes and nanowires can be evaluated. An ultrafast pump laser pulse optically excites the sample, creating excited electrons and holes. In ReS2, excitons are also created. The excited carrier relaxation kinetics can then be studied by measuring the difference in the transmission of a probe laser pulse as its time delay increases with respect to the initial pump pulse. Imaging the samples with the pump and probe spatially overlapped at specific time delays can provide information on how physical defects (edges, thickness, bends, etc.) affect carrier lifetimes. Imaging the samples by scanning the probe across the sample plane while the pump remains spatially fixed at specific time delays illustrates excited carrier diffusion. Anisotropic effects can also be resolved by rotating the probe polarization.