Perfect meta-absorber by using pod-like nanostructures with ultra-broadband, omnidirectional, and polarization-independent characteristics

Yu-Sheng Lin,Wenjun Chen

doi:10.1038/s41598-018-25728-7

Abstract

The on-chip perfect meta-absorber (PMA) is an important optical and thermal energy component in photovoltaics, thermal emitters, and energy harvesting applications. However, most reported PMAs rely on the complicated lithography techniques, which imposed a serious cost barrier on the development of practical applications, especially in the visible to near-infrared (NIR) wavelength range and at very large scales. Importantly, it is hard to realize PMA in the UV wavelength range by using current lithography techniques. In this article, we develop an ultra-broadband PMA by using natural lithography (NL) technique. The morphology of proposed PMA is randomly distributed pod-like nanostructures composed of a nanocomposite (Au/SiO2) covered a gold layer. It can be formed easily on Si substrate to function as an ultra-broadband, omnidirectional, and polarization-independent PMA by controlling the conditions of sputtering deposition and thermal annealing treatment. We experimentally realized an on-chip ultra-broadband PMA with almost 100% absorption spanned from UV-visible to NIR wavelength ranges. This cost-effective and high-efficiency approach would release the manufacturing barrier for previously reported PMAs and therefore open an avenue to the development of effectively energy harvesting, energy recycling, and heat liberation applications.

Highlights

Researches in plasmonic fields are rapidly maturing
We adopted an inverted configuration by using sputtered Au layer and thermal annealing treatment processes to form the pod-like nanostructures on Si substrate directly
A SiO2 layer in 20 nm thickness was deposited on sample surface by using plasma enhanced chemical vapor deposition (PECVD) (Fig. 1(b-3))

Summary

Introduction

Researches in plasmonic fields are rapidly maturing. One emerging field of them is taking advantage of unique electromagnetic properties to achieve perfect meta-absorber (PMA) due to the huge interest in the development of materials for harvesting solar energy. There is no light either transmitted or reflected and the material surface appears black color to human eyes[1] This emerged with the recent development of PMA is capable of angle-insensitive and polarization-insensitive[2,3,4], which are important optical and thermal energy components for practical applications. Despite the efficient absorption of light, the fabrication of these nanostructures requires the fine control of geometrical dimensions at the nanoscale achieved by using electron beam lithography (EBL), focused ion beam (FIB), and nanointerference lithography (IL)[33,34,35]. These techniques hinder their upscaling and practical use. The fabrication technique of our PMA is relatively simple, cost-effective, and compatible with current industrial methods for mass production, which makes our design an outstanding candidate for high efficiency absorber materials

Methods

Results

Conclusion