Resonant surface plasmon-induced modification of photoluminescence from GaN/AlN quantum dots

The photoluminescence from epitaxially grown GaN/AlN quantum dots (QDs) has been engineered by capping the surface either with a nanoscale thin silver layer or silver nanoshell structures. The spontaneous emission rate in strained and large QDs is enhanced due to resonant surface-plasmon interaction at the continuous Ag nanolayer-semiconductor interface as observed by the decrease (typically 3-5 times) in the photoluminescence (PL) intensity. The photoluminescence from strained QDs can also be dramatically enhanced by patterning the AlN-capped GaN dots layers with Ag nanoparticles. The enhancement depends on the size and distribution of the Ag nanoparticles at the surface of the QDs. The Ag nanoparticles act as radiating dipole sources and the emission from the QDs is resonantly coupled into these Ag particles, resulting in a relative enhancement of the PL emission compared to the off-resonant GaN buffer layer. The changes in luminescence in the ultraviolet regime (both quenching or enhancement) due to the modification of the emission rate in the QDs are comparable to the near-infrared regime based GaAs or InP quantum wells.