  Silver nanoparticles dispersed on the surface of an inverted GaN LED were
found to plasmonically enhance the near-bandedge emission. The resonant surface
plasmon coupling led to a significant enhancement in the exciton decay rate and
the ensemble of nanoparticles provided a mechanism to scatter the coupled
energy as free space radiation. The inverted LED structure employed a tunnel
junction to avoid the standard thick p+ GaN current spreading contact layer. In
contrast to a standard design, the top contact was a thin n++ AlGaN layer,
which brought the quantum well into the fringing field of the silver
nanoparticles. This proximity allowed the excitons induced within the quantum
well to couple to the surface plasmons, which in turn led to the enhanced band
edge emission from the LED.
