THERMAL-BOUNDARY RESISTANCE FOR THIN-FILM HIGH-T-C SUPERCONDUCTORS ATVARYING INTERFACIAL TEMPERATURE DROPS

High-temperature thin-film superconducting devices are becoming common place for applications such as Josephson junctions, superconducting qu antum interference devices, interconnects and radiation bolometers. Th e thermal stability of these devices is critical and for effective hea r transfer it is required to know the thermal boundary resistance at t he interface of the high-Tc thin films and their substrates. Many meas urements of thermal contact resistance for bulk samples and metallic t hin films have been reported, but only a few measurements have been ma de for high-T-c films. In the present study, the thermal boundary resi stance between Er-Ba-Cu-O films on MgO and SrTiO3 substrates is measur ed as a function of both temperature and the applied heat flux, and fo r the first time at temperatures as low as 19 K. The boundary resistan ce shows a decrease with increasing heat flux. Possible explanations f or this trend are given by three proposed hypotheses. (C) 1997 Elsevie r Science Ltd.