Yenilikçi aygıt uygulamaları için lokal plazmon katkılı yarı iletken nanokristal ışıyıcılar

Quantum confinement allows for the development of novel luminescent materials such ascolloidal semiconductor quantum dots for a variety of photonic applications spanningfrom biomedical labeling to white light generation. However, such device applicationsrequire efficient photoluminescence. To this end, in this thesis we investigate thespontaneous emission characteristics of semiconductor nanocrystal emitters underdifferent conditions and their enhancement and controlled modification via plasmonicresonance coupling, placing metallic nanoparticles in their proximity, for innovativedevice applications. We first present our theoretical and experimental work on the opticalcharacterization of nanocyrstals (e.g., CdSe, CdS, and CdSe/ZnS) includingabsorption/photoluminescence, time-resolved luminescence, and excitation spectrameasurements. Here we demonstrate very strong electromodulation (up to 90%) ofphotoluminescence and absorption of such nanocrystals (nanodots and nanorods) foroptical modulator applications. Second, we present our electromagnetic modeling on theoptical response of metal nanoparticles using finite-difference-time-domain method. Forthe first time, using localized plasmons of metal nanoisland films (nano-silver) carefullyspectrally and spatially tuned for optimal coupling conditions, we report very significantcontrolled modifications of nanocrystal emission including the peak emission wavelengthshift (by 14nm), emission linewidth reduction (by 10nm with 22% FWHM reduction),photoluminescence intensity enhancement (15.1- and 21.6-fold compared to the controlgroups of the same nanocrystals with no plasmonic coupling and those with identicalnano-silver but no dielectric spacer in the case of non-radiative energy transfer,respectively), and selectable peaking of surface-state emission at desired wavelengths.Such localized plasmonic engineering of nanocrystal emitters opens new possibilities forour light-emitting and photovoltaic devices.Keywords: Quantum confinement, quantum dots, nanocrystals, nanorods, spontaneousemission, photoluminescence, electromodulation, metal nanoparticles, localizedplasmons, metal-enhanced luminescence, FDTD.