Excitonic Metamaterials from Low-Dimensional Semiconductors

The isolation of stable atomically thin two-dimensional (2D) materials on arbitrary substrates has led to a revolution in solid state physics and semiconductor device research over the past decade. A variety of other 2D materials (including semiconductors) with varying properties have been isolated raising the prospects for devices assembled by van der Waals forces. Particularly, these van der Waals bonded semiconductors exhibit strong excitonic resonances and large optical dielectric constants as compared to bulk 3D semiconductors. First, I will focus on the subject of strong light-matter coupling in excitonic 2D semiconductors, namely chalcogenides of Mo and W. Visible spectrum band-gaps with strong excitonic absorption makes transition metal dichalcogenides (TMDCs) of molybdenum and tungsten as attractive candidates for investigating strong light-matter interaction formation of hybrid states. We will present our recent work on the fundamental physics of light trapping in TMDCs and their superlattices where-in strong modulation of optical constants can result in metamaterial behavior emerging from excitons. Next, we will show the extension of these results to halide perovskites and metal-organic chalcogenates. If time permits, I will also present our recent work on exciton tunability in random network and aligned carbon nanotubes as well as control of light in magnetic semiconductors. Our results highlight the vast opportunities available to tailor light-matter interactions and building practical devices with 2D and 1D semiconductors. I will conclude with a broad vision and prospects for 2D and 1D materials in the future of semiconductor opto-electronics and photonics.