Phonon Stopbands in Amorphous Superlattices
The development of thin film technology in the last years made it possible to prepare periodic multilayer structures, consisting of alternating very thin crystalline or amorphous films of about nm thicknesses. The periodic structure of such multilayers is the origin of some new properties of those “superlattices” . The acoustic properties of superlattices have been widely studied with resonant raman scattering techniques. Because of the coupling mechanism, in this method only longitudinal phonons are involved. Spectroscopy with superconducting tunnel junctions as generators and detectors of high-frequency acoustic phonons was first used to demonstrate a stopband like behaviour of a GaAs/AlxGa1-x As superlattice, prepared by using MBE techniques .
KeywordsQuartz Helium Paration
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