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.
@article{arxiv.1111.0465,
title = {Strain enhanced electron cooling in a degenerately doped semiconductor},
author = {M. J. Prest and J. T. Muhonen and M. Prunnila and D. Gunnarsson and V. A. Shah and J. S. Richardson-Bullock and A. Dobbie and M. Myronov and R. J. H. Morris and T. E. Whall and E. H. C. Parker and D. R. Leadley},
journal= {arXiv preprint arXiv:1111.0465},
year = {2012}
}