Presentation Details
| Scalable Nanogap Fabrication and Non-Destructive Metrology for Near-Field Thermophotovoltaic Devices Yuting Li, Yeonghoon Jin, Debarati Sen, Titilope Dada, Eric Tervo. University of Wisconsin–Madison, Madison, WI, USA |
Abstract
Near-field thermophotovoltaic (TPV) and thermophotonic (TPX) devices offer a promising route for converting low-grade heat into electricity by enabling radiative heat transfer across nanoscale gaps that can exceed the far-field (blackbody) limit. A major challenge in translating these concepts into practical devices is the fabrication and reliable characterization of uniform nanogaps over large areas while minimizing parasitic thermal conduction. In this work, we report the fabrication and characterization of large-area nanogap structures designed to enable near-field radiative heat transfer for TPV and TPX applications. The nanogaps are formed between a processed silicon wafer and a pristine silicon wafer using long, narrow silicon support posts to reduce thermal conduction, with a dielectric spacer defining the gap thickness. Using standard microfabrication processes, we fabricated large area (0.6 cm × 0.6 cm) nanogap devices. An additional challenge is measuring the gap size after assembly without disturbing the structure. To address this, we employ Fourier-transform infrared (FTIR) reflectance spectroscopy, where Fabry–Pérot interference within the nanogap is analyzed using a transfer-matrix model to extract the gap size. With this method, we measure minimum gap sizes for our samples of approximately 350 nm with good uniformity across the device. To establish device feasibility for near-field TPX operation, bandgap-matched photovoltaic cells and light-emitting diodes capable of operation at the target temperatures are characterized separately on silicon substrates. Together, these results establish a scalable platform for nanogap fabrication and characterization, providing a critical enabling element for future near-field TPV and TPX energy conversion devices.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
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