Atomically-thin tunable metasurfaces
Optical metasurfaces use compact arrays of optically-resonant nanostructures to collectively scatter light to perform an optical function (e.g. focussing, beam steering). While highly efficient, state-of-the-art metasurfaces are static and thus cannot actively tune the optical function. In this project, we use patterned monolayer 2D semiconductors to realize optical metasurfaces that have a thickness of a single layer of atoms. By external manipulation of the exciton resonace, we actively control the excitonic light scattering and thereby realize optical metasurfaces with tunable optical properties.
Nanoscale 2D tunable photodetector
Exciton resonances in monolayer 2D semiconductors exhibit strong and spectrally-narrow absorption peaks. In this project, we study how we can leverage this absorption peak to realize an electrically-tunable nanoscale photodetector. We fabricate single-flake devices using exfoliation, deterministic stamping, and electron-beam lithography. Using a home-built photocurrent mapping spectroscopy setup, we investigate the role of the exciton in the photocurrent spectra and manipulate it using gate voltages to tune the photodetector's optical responsivity.
