Strain enhanced electron cooling in a degenerately doped semiconductor

TL;DR

This paper demonstrates enhanced electron cooling in a strained-silicon/superconductor tunnel junction refrigerator, achieving lower electron temperatures due to reduced electron-phonon coupling, with modeling predicting further improvements under optimized conditions.

Contribution

It introduces a strained-silicon-based tunnel junction refrigerator that improves cooling performance by leveraging strain to reduce electron-phonon interactions.

Findings

Electron temperature reduced from 300 mK to 174 mK in strained silicon.

Enhanced cooling compared to unstrained silicon control.

Model predicts further temperature reductions with reduced junction leakage and tunnel resistance.

Abstract

Enhanced electron cooling is demonstrated in a strained-silicon/superconductor tunnel junction refrigerator of volume 40 um^3. The electron temperature is reduced from 300 mK to 174 mK, with the enhancement over an unstrained silicon control (300 mK to 258 mK) being attributed to the smaller electron-phonon coupling in the strained case. Modeling and the resulting predictions of silicon-based cooler performance are presented. Further reductions in the minimum temperature are expected if the junction sub-gap leakage and tunnel resistance can be reduced. However, if only tunnel resistance is reduced, Joule heating is predicted to dominate.