Thermalization arrangement at cryogenic temperatures
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Solution Overview
Problem
Cryogenic devices face inefficiencies in thermalization due to phonon reflections at the interface between dielectric substrates and metal heat sinks, leading to ineffective cooling and increased thermal noise.
Innovation Solution
A thermalization arrangement with a dielectric substrate and a conductive layer between the substrate and heat sink, where phonons are absorbed by electrons, minimizing thermal boundary resistance and allowing efficient energy transfer to the heat sink, utilizing high-purity single crystalline silicon and degenerately doped silicon for optimal lattice matching and phonon propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a dielectric substrate is attached directly to a metal heat sink layer, then the structure is simple, but phonon reflections occur at the interface causing poor thermalization
Solution Approach 1:
A conductive layer is introduced as an intermediary between the dielectric substrate and metal heat sink. This conductive layer has acoustic impedance intermediate between the dielectric substrate and metal, reducing phonon reflection at the interfaces. The conductive layer enables more effective phonon transmission and thermal energy transfer to the heat sink, resolving the thermalization effectiveness issue while maintaining structural simplicity.
2Reliability
If a connection layer is used between substrate and heat sink, then thermal boundary resistance increases, but phonon reflections are reduced
Solution Approach 1:
The conductive layer is designed with specific material parameters - electrical conductivity and thermal conductivity are optimized to balance phonon transmission and electron-mediated heat transfer. By adjusting the conductivity parameters of the conductive layer, the system achieves effective phonon transmission while minimizing thermal boundary resistance through enhanced electron-phonon coupling.
3Loss of energy
If phonons are allowed to reflect multiple times in the substrate, then thermal energy is trapped, but cooling efficiency decreases
Solution Approach 1:
The patent replaces the traditional phonon-dominated heat transfer mechanism with an electron-mediated thermalization mechanism. The conductive layer enables electrons to absorb thermal energy from phonons through electron-phonon coupling, and transport this energy to the heat sink. This substitution of the heat transfer mechanism eliminates multiple phonon reflections and significantly improves cooling efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This arrangement enhances cooling efficiency by reducing phonon reflections and parasitic capacitance, enabling effective thermal energy transfer and improved sensitivity of cryogenic devices, particularly at very low temperatures.
Implementation Method 1
Inside the conductive layer phonons are absorbed by electrons
Implementation Method 2
Another joint between the conductive layer 5 and the heat sink layer 4 is electrically conductive which thermalizes the electrons of layer 5 efficiently to the heat sink layer 4
Implementation Method 3
The interface between the cooling layer and the substrate, or between a connection layer 3 (like adhesive in the example of FIG. 1) and the substrate typically forms a reflection surface for the phonons in the substrate, because there is a mismatch, called as acoustic mismatch, between said materials
Data Source
AI summary
An inventive embodiment comprises a thermalization arrangement at cryogenic temperatures. The arrangement comprises a dielectric substrate (2) layer on which substrate a device/s or component/s (1) are positionable. A heat sink component (4) is attached on another side of the substrate. The arrangement further comprises a conductive layer (5) between the substrate layer (2) and the heat sink component (4). A joint between the substrate layer (2) and the conductive layer (5) has minimal thermal boundary resistance. Another joint between the conductive layer (5) and the cooling heat sink layer (4) is electrically conductive.