J. Cooper et al., NORMAL-STATE TUNNEL JUNCTION AS A TUNABLE QUASI-MONOCHROMATIC PHONON SOURCE, Physical review. B, Condensed matter, 50(12), 1994, pp. 8352-8357
The frequency distribution of the acoustic phonons emitted from a bias
ed metal-insulator-metal normal-state tunnel junction has been studied
. Electrons tunneling across the insulating layer form an excited popu
lation with a range of energies up to similar to eV(B) above the Fermi
level and then relax, producing a phonon spectrum with a frequency cu
toff at the same characteristic value. Normal-state tunnel junctions m
ade from aluminum have been produced and phonon spectra determined by
using the stress-tuned splitting of boron accepters in silicon as a sp
ectrometer. It has been shown that, in the range similar to 1-4 meV (s
imilar to 250-1000 GHa), the second differential of the signal with re
spect to junction bias (partial derivative(2)P/partial derivative V-B(
2)) is quasimonochromatic, having a spectrum of an approximately Gauss
ian form with the peak: occurring at an energy of eV(B) and a half wid
th of similar to 6kT(e).