Research Projects

Two-dimensional (2D) materials typically have weak van der Waals (vdW) bonding between layers and strong bonding within layers. Some vdW materials, such as black phosphorus (bP), GeSe, SnSe, and ReS2, possess in-plane anisotropy (IPA), which significantly influences the symmetry of optical and electronic properties. Twisted IPA BL-HS, prepared by stacking monolayers (MLs), can control the period of lateral confinement, nature of exciton, and modify electronic correlations. The emerging moiré structure offers a new super-structure in real space and a modified Brillouin zone in momentum space. Twisted IPA BL-HS can be powerful tools for studying crossover from two to one and zero dimensions, modifying optical transitions and vibrational modes. Flat bands with large effective masses, narrow bandwidth, and 1D localization can offer a test-bed for strongly correlated systems and topological phenomena. Quasi-1D excitations can only be generated by creating stacks of IPA materials, resulting in robust nanoscale channels for optoelectronic transport. To fully understand these emerging systems, optoelectronic measurements and electron microscopy of twisted IPA BL-HS are proposed. Mechanical stacking in an inert-environment glovebox will create pristine HS in the BL or few-layer limit, while steady-state and time-resolved optical spectroscopy will probe emerging optical resonances and vibrational modes. Electron microscopy will measure reconstruction and domain formation in low twist angle BL-HS, and the impact of carrier density on geometrically constrained excitations will be measured.