REFRIGERATION OF A DIELECTRIC MEMBRANE BY SUPERCONDUCTOR INSULATOR/NORMAL-METAL/INSULATOR/SUPERCONDUCTOR TUNNELING/

We have applied tunneling of electrons between a normal metal and a su perconductor to refrigerate thin dielectric membrane attached to the n ormal electrode of a or/insulator/normal-metal/insulator/superconducto r (SINIS) structure. Starting from T approximate to 200 mK, a decrease in temperature of several mK was observed, measured by a separate the rmometer on the membrane. It should be straightforward to improve the refrigerator performance to the level of the recently demonstrated SIN IS electron cooling method, such that the drop in the lattice temperat ure would be more than an order of magnitude larger. (C) 1997 American Institute of Physics.