Efficient infrared sunlight absorbers based on gold-covered, inverted silicon pyramid arrays

TL;DR

This paper presents a novel design of silicon-based infrared absorbers using gold-covered inverted pyramids, achieving enhanced IR absorption through surface plasmon resonances, with scalable fabrication methods demonstrated.

Contribution

Introduces a new silicon pyramid array design with gold coating for efficient IR absorption, combining simulation and experimental validation with scalable fabrication techniques.

Findings

Achieves substantial IR absorption below silicon's bandgap.

Demonstrates tunable absorption via array parameter optimization.

Provides scalable fabrication routes for integration in optoelectronics.

Abstract

The transparency of silicon in the infrared region enables the design of nano/microstructures for implementation in devices to harvest the infrared (IR) part of the solar spectrum. Herein we report a strategy that uses arrays of inverted silicon pyramids covered with a thin gold film, which exhibit substantial light absorption in the infrared spectral range (below the gap of Si). The absorption stems from the resonant excitation at infrared wavelengths of surface-plasmon polaritons at the metal/dielectric interface mainly by tuning size and separation of the inverted pyramids. The array-parameters optimization proceeded by iteration of the calculation and measurement of the infrared response using finite difference time-domain simulations and Fourier-transform IR spectroscopy, respectively. We show two fabrication routes for this kind of metal/silicon metamaterials either by photolithography or scalable nanoimprint techniques for a seamless integration in optoelectronic fabrication processes.