Mechanism analysis of double-layer nanoscale thermal cloak by silicon film

J Zhang and HC Zhang and WB Sun and Q Wang, COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 634, 128022 (2022).

DOI: 10.1016/j.colsurfa.2021.128022

Cloaking technology has always been a topic of interest, and the advent of transformation optics and metamaterials have made a major step forward in this area of research. Subsequently, metamaterials extend to the field of thermotics, making thermal cloaks a reality. In recent years, researchers have designed several nanoscale thermal cloaks based on graphene, silicon and explained their cloaking mechanisms by phonon localization theory. However, the influence of the interface between the functional and background regions is not well clear. In the present study, we construct a double-layer nanoscale thermal cloak by perforating and the "melt and quench" technique, and create two interfaces in the functional and background regions to investigate the heat transport mechanism. To study the working performance, we calculate the response temperature and ratio of thermal cloaking. As the amorphous region and the number of holes increase, the cloaking performance is enhanced and the perturbation to the background region decreases. To explore the working mechanism, we calculate the spectral decomposition of the heat current at the interface. We find that the crystal-amorphous interface impedes the heat flux more than the crystal-perforation interface. Using the phonon localization theory, we calculate the phonon density of states and mode participation rate. The reason for cloaking is the reduced thermal conductivity in the functional area due to phonon localization. Our study deepens the understanding of nanoscale heat flux regulation. Besides, it can promote the development of spectral decomposition of the heat current and phonon localization theory.

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