Scalable van der waals superlattices for absorbers and emitters

Abstract

Two-dimensional (2D) crystals have renewed opportunities in artificial lattice design and assembly without the constraints of epitaxy. However, the lack of thickness control in exfoliated van der Waals (vdW) layers prevents realization of repeat units with high fidelity. Uniform, wafer-scale samples permits engineering of both electronic and optical dispersions in stacks of disparate 2D layers with multiple repeating units. Systems, methods, and devices present optical dispersion engineering in a superlattice structure including alternating layers of 2D excitonic chalcogenides and dielectric insulators. Examples demonstrate >90% narrowband absorption in <4 nm active layer excitonic absorber medium at room temperature, concurrently with enhanced photoluminescence in cmsamples. These superlattices show evidence of strong light-matter coupling and exciton-polariton formation with geometry-tunable coupling constants. The results demonstrate proof of concept structures with engineered optical properties and pave the way for a broad class of scalable, designer optical metamaterials from atomically-thin layers.