A colloidal semiconductor nanocrystal quantum dot (QD), representing a solid state "artificial atom", is an attractive test bed for light-material interaction, as well as for light emitter applications with color tunability, high stability and quantum efficiency. The objective of this thesis was to study the CdSe-based colloidal QD and implement this material in light emitting sources in three vastly different regimes of QD spatial arrangements and photonic excitation, representing a single photon emitter, a luminescent panel, and stimulated emission of radiation, respectively. The recombination of an electron hole pair in a colloidal QD creates a single photon of the band-edge energy. Implementation of CdSe-based colloidal QDs in practical single photon sources is described in the first part of the thesis. A silica shell was grown around an individual colloidal QD, increasing the nanoparticle's diameter up to 220nm. An Electrostatic Force Self-Assembly method was developed to precisely control the position of a single colloidal nanoparticle on a 2-dimensional substrate. Single photon emission characteristics from each patterned nanoparticles were confirmed and suggested prospects for room temperature on-command single photon sources. In the second part, colloidal QDs were embedded within nanoporous GaN epitaxial thin films to create a nanocomposite medium. This potentially new photonic material platform combines the well known high performance of GaN wide bandgap semiconductor family for solid state lighting (SSL) with the high efficiency wavelength-engineered luminescent colloidal CdSe-based QDs. The early results suggest the possibility for wavelength engineered light emitting nanocomposites across the visible spectrum for SSL applications.Finally, in the high excitation regime of close-packed QD thin films, stimulated emission was achieved at a record low threshold for CdSe/ZnCdS "band structure engineered" core/shell QDs. The formation of optical gain is considered in a model of photoinduced charging effects enhanced by the designed energetically low and spatially thin potential barrier of the ZnCdS shell. Subsequently, the new type of excitonic gain material was implemented in the first optically pumped QD Vertical Cavity Surface Emitting Laser, exhibiting well defined spatial and spectral outputs, with a low pump threshold.
Dang, Cuong Huy,
"CdSe-based Colloidal Semiconductor Nanocrystal Quantum Dots: From Single Photon Emitters to Lasers"
(2010).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0TD9VK1
