Surface Plasmon Enhanced Emission From Defects in Gallium Doped ZnO

In this work, the optical properties of defects coupled with surface plasmons (SPs) in gallium-doped ZnO (ZnO:Ga) grown by molecular beam epitaxy (MBE) have been explored. The photoluminescence intensity is enhanced by up to 4.9 times as a result of SPs coupling by decorating the sample with silver nanospheres (Ag NSs), with a fast plasmonic decay lifetime of 0.1ns compared with the defect-assisted carrier recombination lifetime of 3.77ns in the as-grown sample. The enhanced emission intensity depends on the plasmonic modes determined by the diameter of Ag NSs, verified by power-dependent photoluminescence measurements. Confocal mapping reveals that the plasmonic hot-spots, that is, enhanced emission around the Ag NSs, exhibit a highly optical stability with reduced photoluminescence blinking. This work demonstrates that a defect coupled with SPs in ZnO is a promising high-efficiency emitter for applications in nanophotonics.