Surface plasmon coupled light-emitting diode with metal protrusions into p-GaN

An Ag protrusion array is fabricated on the p-GaN layer of an InGaN/GaN quantum-well (QW) light-emitting diode (LED) for generating surface plasmon coupling with the radiating dipoles in the QWs and hence LED emission enhancement. The tips of the Ag protrusions penetrating into the p-GaN layer are close to the QWs such that the induced near field around the tips can strongly interact with the dipoles in the QWs. With the Ag protrusions, the fabricated flip-chip LED shows a 74.6% enhancement in output intensity at 100 mA in injection current, when compared with a control sample of no Ag protrusion. The simulation results of Ag protrusion absorption agree reasonably well with the experimental data of protrusion reflectance. The simulation also shows a strong near field distribution around the tip of an Ag protrusion for coupling with the radiating dipoles in the QWs.