Abstract
We have proposed and theoretically analyzed nonmetallic broadband visible-light absorbers based on alternating SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /InAs thin films on SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> substrate. Compared with the conventional absorbers, the proposed SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /InAs structure can achieve excellent absorption within a smaller volume. The average absorption can exceed 97% in the wavelength range of 300-850 nm. With a two-dimensional InAs grating atop, the device can achieve the average absorption of >92% with insensitivity to light polarization and incident angles. Due to the advantages of broadband and near-unity absorption, polarization and incident angle insensitivity, controllable and mature fabrication processes, the proposed visible-light absorbers will find wide applications in solar energy harvesting, thermal emission, and water splitting.
Highlights
Light absorption is of central importance in solar cells, photodetectors, controlled-emissivity surfaces, and sensors [1]–[3]
We have proposed and theoretically analyzed nonmetallic broadband visiblelight absorbers based on alternating SiO2/InAs thin films on SiO2 substrate
Narrowband absorbers have wide applications in optical sensing [4]–[6], modulation [7], [8], and thermal emission tailoring [9], while broadband light absorbers are highly desired in areas of solar energy harvesting and thermal emission
Summary
Light absorption is of central importance in solar cells, photodetectors, controlled-emissivity surfaces, and sensors [1]–[3]. Other methods include slow-light waveguides constructed from an array of tapered hyperbolic metamaterials [19]–[21], ultrathin absorbers based on dispersion engineering [22]–[24], and film-coupled structures integrated with nanoparticles of different sizes [25], [26] These types of structures usually require complicated fabrication processes. III–V semiconductors have been widely used for solar cells because of their strong visible-light absorption, high temperature stability, compatibility with large-scale integration, and mature fabrication processes [29], [30]. They can be substituted for noble metals to achieve perfect optical absorption in the visible spectral range
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