Two-dimensional photonic crystal composite structure enhancing broad spectrum light absorption

Abstract

The invention discloses a two-dimensional photonic crystal composite structure enhancing broad spectrum light absorption. The composite structure is formed by compositing an absorption layer and a reflective layer. The absorption layer is in a photonic crystal structure, wherein the structure is formed by arranging a two-dimensional periodic inverted pyramid-shaped groove in the upper end face of a non-metallic material Si, and the inverted pyramid-shaped groove is filled with a polymeric film or a colloidal quantum dot film. According to the reflective layer, random pyramid grooves are arrnaged in x and y directions in the bottom end face of the non-metallic material Si, and the surface of the bottom end face is coated by a metal material Au. According to the composite structure, the absorption of p-polarized and s-polarized incident lights from ultraviolet to infrared band, and even efficient, broadband and wide-angle electromagnetic waves of a wider band is enhanced, and is beyond the Yablonovitch limit in infrared band; an electric field in the inverted pyramid-shaped groove on the surface of the absorption layer and an electric field in a cavity formed by the inverted pyramid on the surface of the absorption layer and the reflective layer are significantly enhanced; and the composite structure in particular has a great application prospect in solar cells, photodetectors, military stealth and other aspects.

Description

technical field [0001] The invention relates to a compound structure composed of an absorbing layer and a reflective layer, in particular to a compound structure containing a two-dimensional photonic crystal structure and a random metal pyramid groove reflective structure to improve wide-spectrum light absorption efficiency. Background technique [0002] Efficient broadband light absorbers have attracted great attention for applications in solar cells, photodetection, and other fields. In 1982, Yablonovitch proposed the light absorption limit in homogeneous semiconductor thin films. However, the Yablonovitch limit is only applicable to geometrical optics. For subwavelength structures, the absorption efficiency can far exceed the Yablonovitch limit by rationally designing the structure. [0003] At present, scientists have proposed many optical coupling structures containing noble metal materials to achieve the enhancement of broadband light absorption. These coupling struct...

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Problems solved by technology

However, the composite structure of this invention only has a triangular groove photonic crystal structure with one-dimensional direction on the upper end surface, and a random triangular groove structure with one-dimensional direction on the lower end surface, so this structure only realizes high-efficiency light in TM polarization (p polarization) wide band Absorption, failed to realize the efficient light absorption of TM polarization and TE polarization (s polarization) at the same time, in order to further improve the high efficiency light absorption of p polarization and s polarization incident light in the broadband band, the inventors studied again and conducted multiple experiments at the same time Research further obtained a structure that simultaneously realizes high-efficiency light absorption in both p-polarization and s-polarization broadband

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