Resonant Thermoelectric Nanophotonics

TL;DR

This paper introduces resonant thermoelectric nanostructures that enable wavelength-specific photodetection through localized heating, achieving high responsivity and fast response times without relying on semiconductor bandgap absorption.

Contribution

It presents a novel design of nanophotonic thermoelectric structures that combine resonant absorption with thermoelectric effects for tunable, bandgap-independent photodetection.

Findings

Achieved up to 119 V/W responsivity.

Response times of nearly 3 kHz.

Demonstrated broadband, wavelength-specific detection.

Abstract

Photodetectors are typically based on photocurrent generation from electron-hole pairs in semiconductor structures and on bolometry for wavelengths that are below bandgap absorption. In both cases, resonant plasmonic and nanophotonic structures have been successfully used to enhance performance. In this work, we demonstrate subwavelength thermoelectric nanostructures designed for resonant spectrally selective absorption, which creates large enough localized temperature gradients to generate easily measureable thermoelectric voltages. We show that such structures are tunable and are capable of highly wavelength specific detection, with an input power responsivity of up to 119 V/W (referenced to incident illumination), and response times of nearly 3 kHz, by combining resonant absorption and thermoelectric junctions within a single structure, yielding a bandgap-independent photodetection mechanism. We report results for both resonant nanophotonic bismuth telluride-antimony telluride structures and chromel-alumel structures as examples of a broad class of nanophotonic thermoelectric structures useful for fast, low-cost and robust optoelectronic applications such as non-bandgap-limited hyperspectral and broad-band photodetectors.