Ultrahigh absorption modulation in semiconductor/silver-nanoarray hybrid metasurface

Abstract

Plasmonic metasurface with extraordinary properties are promising for numerous frontier applications. In this work, we reported the ultrahigh multiband absorption in a silver-nanoarray and semiconductor hybrid metasurface. The structural parameters, carrier mobility and the medium environment dependence were discussed in detail. Comparing with traditional SiO2 spacer, metasurface with semiconductor interlayer can be beneficial in expanding the absorption band and increasing the absorbance. The carrier mobility and thickness of the semiconductor film were proved to be key factors in adjusting and enhancing the absorption bands. The spectra split and shift can be attributed to the combination effect of the cavity resonance mode and the local SPR mode of the silver bar. According to the proper design, absorption of 95% for both visible and NIR band was achieved. This structure also showed a sensitivity of ~250 nm/RIU during the refractive index sensing. These findings provided a promising path to achieve ultrahigh efficiency and adjustable multiband absorption by applying semiconductors, and can be instructive in the design of tunable plasmonic absorber and photoelectric detector.