Light Emission from Electron-Injector Structures

Surface-plasmon-polariton-mediated luminescence is observed when electrons are injected into thin Al films from the conduction band of Si${\mathrm{O}}_2$. These electron-injector structures are strikingly similar to light-emitting tunnel junctions, although tunneling can be ruled out as the driving mechanism. The emission arises from the energy relaxation of the steady-state hot-electron distribution which exists in the metal under continuous current injection. The same mechanism must explain much of the luminescence from tunnel junctions.