Abstract
A thermal rectifier/diode is a nonreciprocal element or system that enables preferential heat transport in one direction. In this work we demonstrate a single-material thermal diode operating at high temperatures. The diode is made of nanostructured silicon membranes exhibiting spatially and temperature-dependent thermal conductivity and, therefore, falling into the category of spatially asymmetric, nonlinear nonreciprocal systems. We used an all-optical state-of-the-art experimental technique to prove rectification along rigorous criteria of the phenomenon. Using sub-milliwatt power we achieve rectification of about 14%. In addition, we demonstrate air-triggered thermal switching and passive cooling. Our findings provide a CMOS-compatible platform for heat rectification and applications in energy harvesting, thermal insulation and cooling, as well as sensing and potentially thermal logic. • Single material thermal rectifier/diode is fabricated from thin holey silicon membranes. • The diode operates at 300–1000 K, sub-milliwatt driving power and rectification of about 14%. • The device can operate as air-triggered thermal switch or passive cooler. • The surface-to-volume ratio is the key parameter governing the rectifier performance.
Highlights
Given the numerous heat-associated challenges currently facing humanity, ranging from global warming to the future of technological miniaturization, there is pressing need for solutions to control the direction of thermal flow
The well-accepted explanation for this effect at high temperatures is the shortening of the phonon mean free path (MFP) due to phonon diffusive scattering at hole boundaries [30,34,35,36,37,38,39,40]
We have showed that using these values as input values of the position and temperature dependent thermal conductivity in a Finite Element Method (FEM) simulation of the diffusive heat transport, the model gives a good account of the rectification
Summary
Given the numerous heat-associated challenges currently facing humanity, ranging from global warming to the future of technological miniaturization, there is pressing need for solutions to control the direction of thermal flow. This issue becomes even more important for the processes performed at temperatures ranging from room temperature to hundreds of Kelvin. High temperature is a huge value market for thermal sensing, energy harvesting and cooling applications In this regard, despite the wealth of new materials, silicon and silicon on insulator (SOI) technologies remain most mature for production of miniaturized and robust devices operating in high temperature environments [3]. The demonstration of thermal rectification in miniaturized systems biased with temperature gradients exceeding hundreds of Kelvin remains an experimental challenge
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