Methods for Reducing Response Times in Superconducting Devices Governed by Quasiparticle Relaxation and Recombination
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Treating the surface of the top film of a superconductive device, so as to remove phonons, increases speed of response. Treatments include evaporation of the top film in oxygen background, adsorption of impurities or condensed gas on the top film surface, and thallium chloride or indium overlay on top film. These treatments reduce response times in superconducting devices governed by quasiparticle relaxation and recombination, by removing pair- breaking phonons and thus reducing the effective quasiparticle lifetimes. Quasiparticle (QP) excess concentrations, created in superconducting films by tunnel injection or by phonon or photon absorption, decay with a characteristic time teff, which is determined by the coupled system of quasiparticles, phonons and Cooper pairs.