Evidence for 870-GHz Phonon Emission from Superconducting Al Tunnel Diodes through Resonant Scattering by Oxygen in Silicon

Abstract
Thin-film aluminum superconducting tunnel junctions can be used to generate phonons up to 1012 Hz. This is substantiated by the observation of the 29-cm1 absorption line of O16 impurities in silicon, so far only known from infrared spectra.