Ultrathin Broadband Metasurface Superabsorbers from a van der Waals Semimetal

摘要

Metamaterials and metasurfaces operating in the visible and near-infrared(NIR) offer a promising route towards next-generation photodetectors anddevices for solar energy harvesting. While numerous metamaterials andmetasurfaces using metals and semiconductors have been demonstrated,semimetals-based metasurfaces in the vis-NIR range are notably missing.This work experimentally demonstrates a broadband metasurface superabsorberbased on large area, semimetallic, van der Waals platinum diselenide(PtSe_2) thin films in agreement with electromagnetic simulations. The resultsshow that PtSe_2 is an ultrathin and scalable semimetal that concurrentlypossesses high index and high extinction across the vis-NIR range. Consequently,the thin-film PtSe_2 on a reflector separated by a dielectric spacer canabsorb >85% for the unpatterned case and ≈97% for the optimized 2D metasurfacein the 400–900 nm range making it one of the strongest and thinnestbroadband perfect absorbers to date. The results present a scalable approachto photodetection and solar energy harvesting, demonstrating the practicalutility of high index, high extinction semimetals for nanoscale optics.