High-Z Lanthanum-Cerium Hexaborate Thin Films for Low-Temperature Applications

Abstract

ABSTRACTWe have deposited and investigated thin films of lanthanum hexaborate with 1% of the lanthanum replaced by cerium. In bulk single-crystalline form, this material has, due to the Kondo-mechanism, the highest known Seebeck coefficient at sub-K temperatures. Thus it is a good candidate for several thermoelectric applications at very low temperatures. We are studying the kinetic properties of thin films such as the conductivity and Seebeck coefficient as a function of temperature and the dependence of these properties on film thickness, substrate material and deposition conditions. The consequent theoretical performance limits on the device applications of these films are considered with a focus on detectors and refrigerators.