Ultra-wideband solar capture devices based on GaAs and Ti metasurface

In this paper, a multilayer composite structure based on GaAs, Si and Ti materials and composed of three-dimensional nested geometric elements. The wide-band resonant absorption of the structure is realized by multiple mechanisms. The surface plasmon resonance (SPR), excited at the interface between the Ti layer and the semiconductor, localized and dissipated light energy on the metal surface. The Fabry -Perot cavity resonance formed by multi-layer superposition enhanced and extended the light propagation path through standing waves of different wavelengths. The dielectric interference and multimode coupling caused by the refractive index difference between GaAs and Si layers further enhanced the absorption effect. In terms of thermal radiation, the emissivity of the structure reached 96.0% at 1200 K, and the radiation efficiency reached more than 90% in the range of 800 K to 1400 K. The enhancement of high-density optical states (LDOSs) caused by the metal-semiconductor interface effectively promoted the release of thermal radiation energy. Different from the conventional circular or square symmetrical structure, this paper innovatively uses trapezoid and tetrafoil configurations as light capture units and employs three-dimensional nested geometric designs for absorption simulation. The finite-difference time-domain (FDTD) method is used to calculate the numerical value. The average absorption rate of the absorber is 94.74% in the range of 280 nm to 3000 nm, and the bandwidth is 2684 nm. The design maintains high absorption efficiency when the incident angle increases, showing polarization-independent characteristics.