Fabrication and Optical Characterization of Laser-Patterned III-V Quantum Dot Arrays

This thesis investigates the fabrication and optical behavior of ordered IIIV quantum dot (QD) arrays using a novel in-situ direct laser interference patterning (DLIP) technique integrated with molecular beam epitaxy (MBE). By merging the precision of MBE with the spatial control of DLIP, the research demonstrates a scalable, contamination-free approach to deterministic quantum dot array formation—a key requirement for quantum information processing applications. The study explores two QD systems: InGaAs/AlGaAs/GaAs QDs fabricated via droplet epitaxy and InAs/GaAs QDs grown through both Stranski–Krastanov and droplet epitaxy modes. An automated photoluminescence (PL) mapping system was developed to conduct spatially resolved optical characterization across millimetre-scale regions with high throughput. Key achievements of the study include the successful integration of a fourbeam DLIP system within an MBE chamber, controlled nucleation of ordered QD arrays with tunable morphology via laser energy and material coverage, and the attainment of narrow photoluminescence linewidths down to approximately 17 meV, signifying high optical quality. A quantitative correlation was established between DLIP parameters and resulting QD properties such as size, density, and emission spectra. Furthermore, the work demonstrates highly ordered and optically active QDs without the need for complex ex-situ lithographic steps. These findings advance the field of site-controlled quantum dot growth by offering a repeatable and contamination-free fabrication method. The developed approach holds significant promise for photonic quantum computing circuits, where spatial precision and emission purity are critical. Future outlooks include integrating these arrays in single-photon sources and exploring their applications in quantum plasmonic and telecom technologies. This work paves the way toward scalable quantum photonic devices through hybrid epitaxial-lithographic strategies.