Light emission from small metal particles and thin metal films excited by tunneling electrons

Abstract

We have measured the light intensity versus photon energy of six types of electron tunnel junctions and compared the experimental results to the localized plasmon model of Rendell, Mühlschlegel, and Scalapino, and to the smooth and slightly roughened junction model of Laks and Mills. The types of junctions used to test the theories were Al-${\mathrm{Al}}_2$ ${\mathrm{O}}_3$ junctions completed with a top electrode consisting of either an evaporated metal film of Au or Ag, or evaporated Au or Ag particles that were electrically connected by an evaporated Au or Ag film. The $p-s$-polarized light emitted by junctions with Au or Ag particles is consistent with the localized plasmon model. The "$s$"-polarized light of the particle junctions and the essentially unpolarized light of the Au and Ag film junctions may be consistent with the theory of Laks and Mills for slightly roughened junctions.