Exciton-surface plasmon interaction in semiconductor quantum dot-metallic nanoparticle hybrid structures

Abstract

Enhanced light-matter interactions in light-confining structures have been extensively investigated for both fundamental studies and practical applications. Plasmonic nanostructures, which can confine and manipulate light down to 1 nm scale, are becoming increasingly important. Many areas of optical physics and devices can benefit from such extreme light concentration and manipulation. For example, quantum dot (QD) emission can be strongly modified and controlled via the coupling with localized Surface plamsons (LSP). In this dissertation, we present our theoretical and experimental studies on QD emission by metal nanoparticle that can provide extreme field concentration, enhancing light-matter interactions significantly. The surface plasmon enhanced emission of QDs is studied firstly. The maximum emission enhancement of the QDs-Au NPs appears in the resonance condition in which the optical emission frequency is consistent with the SPR peak with the 12-nm separation between them. The contributions of the excitation enhancement, SP-field enhancement, and the Purcell effect were analyzed using three-level rate equations. Both of SP-field enhancement and Purcell effect at the emission frequency which modified the spontaneous emission rate with increasing pumping power. These complex processes are observed by power-dependent-emission enhancement measurement. Maximum emission rate below the saturation is obtained when the pumping power is between 0.8 and 1 mW. It is important to select the appropriate pumping power when seeking to obtain the maximum level of enhancement in semiconductor QDs and metallic NP nanocomposites. Next, the enhancement of white light emission from quantum-dot with InGaN light-emitting diodes via localized surface plasmon resonance of metallic nanoparticles is investigated and demonstrated. Since the LSP resonant wavelength depends strongly on the dimensions of MNPs, enhancement over a wide range of wavelengths in the visible spectrum is ...