Fabrication and optical characterization of a hyperbolic metamaterial for Super-Planckian thermal emitters

Thumbnail Image

URL

Journal Title

Journal ISSN

Volume Title

Sähkötekniikan korkeakoulu | Master's thesis

Authors

Date

2023-08-24

Department

Major/Subject

Photonics and Nanotechnology

Mcode

ELEC3052

Degree programme

Master’s Programme in Electronics and Nanotechnology (TS2013)

Language

en

Pages

37+7

Series

Abstract

In recent years, there has been growing interest in developing nano-structured metamaterials for infrared applications. Hyperbolic meta-materials (HMMs) are materials that exhibit the hyperbolic shape of the Fresnel dispersion contours. It allows for unprecedented control over the propagation of coherent and non-coherent infrared light (such as thermal radiation). This thesis investigates the optical characteristics of a nano-structured HMM dedicated to a so-called super-Planckian thermal emitter -- a key component of a prospective thermophotovoltaics (TPV) generator. A short review of modern thermophotovoltaics and an outline of the role of HMMs in their prospective development is given with a brief review of the theory to show the frequency-selective thermal emission of the suggested nanostructure. It also describes the fabrication process of the HMM using a sputtering system. The resulting HMM samples were characterized using the scanning electron microscope and variable-angle spectroscopic ellipsometry. Unfortunately, the SEM characterization has shown that the fabrication of the target nano-structures had failed. Both fabricated samples turned out to be thicker by one order of magnitude than the required HMM. The possible reason for the failure is discussed in the thesis. Thus, the experimental part of this work turned out to be unsuccessful. However, in the theoretical part, some new results were presented on the infrared properties of the HMM which complements the literature data. For example, it is shown that the effective continuity of the sample disappears for large incidence angles. In accordance with the Kirchhoff law, it means that the emission under large angles is an emission of a continuous medium but an emission of an effectively discrete structure.

Description

Supervisor

Konstantin, Simovski

Thesis advisor

Ovchinnikov, Victor

Keywords

hyperbolic metamaterial, thermophotovoltaics, frequency-selective thermal emission, super-Planckian thermal emission

Other note

Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-202308275096

Collections

[dipl] Sähkötekniikan korkeakoulu / ELEC