NIS chip refrigeration

Research output: Contribution to journalArticleScientificpeer-review


  • J.P. Pekola

  • J. M. Kyynäräinen
  • M. M. Leivo
  • A. J. Manninen

Research units

  • University of Jyväskylä


A normal-metal/insulator/superconductor (NIS) tunnel junction can be applied to cool electrons by biasing the junction suitably with external voltage. Two NIS junctions in series can form an efficient microrefrigerator because of the symmetry with bias voltage. Our SINIS microrefrigerator has been capable of reaching electronic temperatures of about 100 mK starting from 300 mK. To achieve appreciable refrigeration of the underlying lattice, the microrefrigerator must be thermally decoupled from the bulk substrate. We have demonstrated experimentally the reduction of lattice temperature by 23 mK at 180 mK by extending the normal electrode on a thin dielectric membrane with four suspended bridges. Methods to improve the efficiency of refrigeration, e.g., by using a superconductor with a large energy gap and/or by increasing the number of tunnel junctions, are discussed.


Original languageEnglish
Pages (from-to)653-657
Number of pages5
Issue number8
Publication statusPublished - Aug 1999
MoE publication typeA1 Journal article-refereed

    Research areas

  • Microcooler, Superconductivity

ID: 4434553