Group III-nitride semiconductor quantum dots (QDs) exhibit large exciton binding energy (> 26 meV) and band offsets, making them an ideal candidate to exploit various quantum optical effects at the high temperature including single-photon emission, strong-coupling, indistinguishable photon generation and polariton lasing. These phenomena can lead to future quantum information technology. The practical use of the III-nitride QDs as quantum light sources requires the addressability of a single QD, both in its position and emission energy. To date, most semiconductors QDs are epitaxially grown by the self-assembled processes such as the Stranski-Krastanov growth which possess very limited control over the QDs' positions and dimensions, making them difficult to be utilized at the device level.;In this thesis, we investigate novel processes for the fabrication of site- and dimension-controlled III-nitride QDs. Two lithography-based techniques have been considered including selective area epitaxy (SAE) and top-down etching. In SAE, the formation QDs is controlled by the pre-patterned mask openings. Different source supply and growth mechanisms determine QD's growth morphology. Morphology evolution in SAE is studied experimentally which qualitatively agrees with the theoretical phase-field model. The non-uniformity of the InGaN thickness was found to be the origin of the broad photoluminescence (PL). In the top-down etching approach, InGaN QDs are formed by etching a patterned InGaN single quantum well. Each QD is disk-shaped and embedded in a nanopillar. Strong and distinct PL signal of a single quantum disk was observed even at room temperature. The emission was found to exhibit characteristics from a discrete energy state that is homogeneously broadened. The single InGaN QD was extensively studied using micro-PL. A model based on 2-dimensional Poisson's equation was developed to quantitatively explain the large blue shift observed in the experiment. The saturation of the PL linewidth at high temperatures was also interpreted using a sidewall charge center model.;To demonstrate the scalability and device integration of the site-controlled Ill-nitride QDs, large-area nanolithographic processes and photonic-crystal optical cavities have been developed. Pattern shrinkage by spacer and by electrodeposition were introduced and demonstrated, with the former aiming at sub-10 nm patterning and the latter at large-scale nanofabrication.
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