arXiv subjects

Aymeric Ramiere

Publications and source records attributed to Aymeric Ramiere.

4 recordsLinked to original sources

arXiv2023

Through-chip microchannels for three-dimensional integrated circuits cooling

Cooling high-power electronics in multilayer integrated circuits (ICs) is challenging for existing cooling methods. In this work, we designed through-chip microchannels (TCMCs) that cross the entire chip perpendicularly to the layers, with water circulating inside to provide direct cooling to each layer. TCMCs are organized in a square array where the pitch and radius of the microchannels are explored. Our computational fluid dynamics (CFD) simulations show that a pitch 10 μm and a radius 1 μm optimize the cooling performance to support a power higher than 10^4 W/cm2 while the maximum temperature rise remains below 60 K with a water inlet temperature of 300 K. We show that the cooling properties do not change with the number of layers for a given chip thickness which provides flexibility to the functional design of the chip. Though manufacturing may be challenging, TCMCs offer a new way for chip cooling that could provide a leap forward in the performance of multilayer 3D ICs and high-power electronics.

physics.flu-dyn↗

arXiv2022

A model for hot spots and Q-slope in granular Niobium thin film superconducting RF cavities

We propose a model to explain power dissipation leading to the formation of hot spots in the inner walls of niobium thin film superconducting RF cavities. The physical mechanism that we explore is due to the constriction of surface electrical current flow at grain interface boundaries. This constriction creates an additional electrical contact resistance which induces localized punctual heat dissipation. The temperature at these spots is derived; and the electrical contact resistance is shown to depend on the magnetic field, on the gain contact size over which dissipation occurs, and on other key parameters, including the effective London penetration depth and the frequency. The surface resistance and the quality factors are determined using our model and are shown to be in excellent agreement with experimental data.

cond-mat.supr-con↗

arXiv2016

Heat guiding and focusing using ballistic phonon transport in phononic nanostructures

Unlike classical heat diffusion at the macroscale, nanoscale heat transport can occur without energy dissipation because phonons can travel in straight lines for hundreds of nanometres. Despite recent experimental evidence of such ballistic phonon transport, control over its directionality, and thus its practical use, remains a challenge, as the directions of individual phonons are chaotic. Here, we show a way to control the directionality of ballistic phonon transport using silicon thin-films with arrays of holes. First, we demonstrate the formation of directional heat fluxes in the passages between the holes. Next, we use these nanostructures as a directional source of ballistic phonons and couple the emitted phonons into nanowires. Finally, we introduce a nanoscale thermal lens in which the phonons converge at a focal point, thus focusing heat into a spot of a few hundred nanometres. These results provide a basis for ray-like heat manipulations that enable nanoscale heat guiding, dissipation, localization, confinement and rectification.

cond-mat.mes-hall↗

arXiv2016

Heat conduction tuning using the wave nature of phonons

The world communicates to our senses of vision, hearing and touch in the language of waves, as the light, sound, and even heat essentially consist of microscopic vibrations of different media. The wave nature of light and sound has been extensively investigated over the past century and is now widely used in modern technology. But the wave nature of heat has been the subject of mostly theoretical studies, as its experimental demonstration, let alone practical use, remains challenging due to the extremely short wavelengths of these waves. Here we show a possibility to use the wave nature of heat for thermal conductivity tuning via spatial short-range order in phononic crystal nanostructures. Our experimental and theoretical results suggest that interference of thermal phonons occurs in strictly periodic nanostructures and slows the propagation of heat. This finding broadens the methodology of heat transfer engineering by expanding its territory to the wave nature of heat.

cond-mat.mes-hall↗