Coupling Behaviors of Surface Plasmon Polariton and Localized Surface Plasmon with an InGaN/GaN Quantum Well

Abstract

Surface plasmon (SP) coupling behaviors of an InGaN/GaN quantum well (QW) with surface plasmon polariton (SPP) induced on a smooth Ag-film/GaN interface and localized surface plasmon (LSP) induced on randomly distributed surface Ag nanoparticles (NPs) are compared based on temperature-dependent, excitation power-dependent, and time-resolved photoluminescence (PL) measurements. By comparing the variations of PL excitation power-dependent emission at 10 and 300 K, the contribution of SP coupling to the increase of PL intensity can be differentiated from that of PL excitation-intensity increase at the QW due to the enhanced reflection at the Ag/GaN interface. The observed stronger SP coupling effect through SPP, when compared with that through LSP, is attributed to its larger available SP state number per unit area for coupling with the QW. Although the SP coupling strength through LSP on the surface Ag NPs is weakly dependent on PL excitation power, that through SPP at the smooth Ag-film/GaN interface increases significantly with PL excitation power. Such different behavior is due to the abundant SPP states available for coupling with the QW of a higher carrier density. It can also be attributed to the spectral blueshift of QW emission through the screening of the quantum-confined Stark effect and the band filling effect for QW coupling with SPP of a higher density of state.