Search for Electronic Cooling from Carbon-Based Field Emitters

摘要

In a 1999 paper, Likharev and Korotkov proposed a model of resonance Fowler-Nordheim (rFN) tunneling that can result in electronic cooling [1]. The emitter consists of a thin (nm) dielectric layer on top of a conductive material. The corresponding I-V curve of such an emitter is a superposition of two I-V curves. At low fields, rF-N dominates and at high fields F-N dominates. At resonance, a leveling off or even a maximum in the I-V curve develops. For appropriate material parameters, cooling of the emitter can result. For a diverse number of carbon-based emitters, we have observed such shapes in the I-V curves. These include carbon black, nanocrystalline graphite, carbon nanotubes and others. To observe possible cooling, an experiment was designed consisting of gluing a small silicon chip (1cm×1cm) onto a thermistor. The chip contains a 1 mm diameter emitter film near its center that is a composite of nanocrystalline graphite and carbon nanotubes (Figures 1 and 2). A second thermistor is placed close by and serves as a temperature reference. With this system, it is possible to observe changes in temperature as small as 0.01 K.