Phonon Imaging by Electron Beam Scanning

Abstract

Following the pioneering experiments of von Gutfeld and Nethercot [1] more than 25 years ago, the propagation of heat pulses in solids at low temperatures has been intensively studied. In these experiments a region near the crystal surface is locally heated and the transport of this thermal energy across the crystal is measured with high time resolution. This energy transport is usually associated with phonons which propagate through the crystal ballistically and/or diffusively. Of course, the magnitude of the diffusive component depends upon the purity of the sample. Typical phonon frequencies are in the gigahertz to terahertz range. Following their passage through the crystal, the phonons are registered with a sensitive phonon detector.