Controlling Electron Flows at the Nanoscale: Spectroscopic and Optoelectronic Investigations of Laser Media, Interlayer Carrier Multiplication, and Spin Currents


Nanoscale fabrication methods are generating ever smaller and more precise devices that exhibit exciting physics but also require intense care to measure accurately. To address this need, we develop a modular optical microscope capable of rapidly measuring multiple parameters and generating datasets consisting of dozens of dimensions. We use this microscope to measure three very different physical systems. In the first, we spatially map excitation-emission characteristics of the laser medium neodymium aluminum nitride. We next measure interlayer charge transport in a van der Waals layered heterostructure consisting of monolayer MoSe2 and bilayer WSe2. Our experiments show carrier multiplication as current is driven between materials and we develop a charge-transport model that explains the responsible mechanism and replicates the observed temperature dependence. Finally, in a platinum-yttrium iron garnet device, we use the interaction between the spin-Seebeck effect and the Shockley-Ramo theorem to spatially map electric field lines in arbitrary device geometries.