Enhancement of excitonic emission in semiconductor heterostructures due to resonant coupling to multipole plasmon modes in a gold particle.

We apply an exact electrodynamic theory to analyze experimental data on the emission enhancement in epitaxial semiconductor structures, induced by resonant interaction of emitting excitons with plasmons localized in a gold nanoparticle. Near-field scanning optical microscopy was employed to investigate the effect of the gold particle positioned near the surface of a rough InGaN film or a CdSe/ZnSe quantum dot heterostructure fabricated by molecular-beam epitaxy. It is shown that the frequently used quasistatic approximation is unable to explain the experimental data due to the inability to take into consideration the contribution of higher-order multipole plasmon resonances. In particular, it follows from the performed calculations that the observed effect of the emission enhancement owes mainly to the resonant interaction with the quadrupole and octupole plasmon modes in the spherical gold particle. The design of optimized metal-semiconductor structures is proposed. [ABSTRACT FROM AUTHOR]