Thermal isolation through nanostructuring

This chapter discusses the cooling of a platform, which requires the electronic coolers to extract heat by coupling to phonons within the platform material. Major results obtained within the nanofunction NoE on the development of nanomodulated magnetic materials and the investigation of their main properties are also presented. The cooling power of the devices becomes paramount, as opposed to the base temperature that could be reached, and must exceed heat leaks into the platform from the surroundings. This indirect cooling is desirable for systems where electrical isolation from the refrigeration elements is required, such as in quantum information applications or superconducting transition edge sensors (TESs). Thick porous Si layers on the Si wafer constitute alternative structures that could replace the rather fragile silicon nitride membranes for use as thermal isolation platforms. The structure and morphology of porous Si determines its electrical and thermal conductivity