A full treatment of the electromagnetic modes supported by Al-${\mathrm{Al}}_2$${\mathrm{O}}_3$-Au metal-oxide-metal tunnel junction is presented. The detailed analysis includes the dispersion relation of these modes and their comparison to similar surface polaritons supported by a single metal-dielectric interface. The variation of effective index, propagation constant, and propagation lengths of these transverse magnetic modes with respect to wavelength in the region from 200 to 1000 nm, as well as their magnetic field profiles are given and the significance of these results are put into perspective with respect to the light-emitting properties of these devices.

• Received 27 March 1986

DOI:https://doi.org/10.1103/PhysRevB.34.3980