This thesis presents my research at the interface of material science, engineering and physics. The collaborative atmosphere at the University of California, Santa Barbara has given me the opportunity to both work on the design and fabrication of complex semiconductor devices and to investigate these systems in the context of cavity quantum electrodynamics (QED). The materials that I have grown and the devices that I have made have also served the research activities of some of my fellow researchers. This implies that the content of this thesis has several facets and that complementary theoretical and experimental results directly associated with the materials and devices that I have produced are covered in other theses and research articles. Here, I focus on those topics in which I have significantly contributed to the scientific studies of the produced semiconductor devices.
Self-assembled InAs quantum dots (QDs) embedded in GaAs photonic crystal cavities and oxide apertured micropillar cavities are promising systems for cavity QED experiments and quantum information studies. The first experimental topic of this thesis is the demonstration of strong coupling between a single QD and a photonic crystal cavity mode by obtaining the QD position information with an optical method before cavity fabrication.
For the second experiment, a GaAs photonic crystal membrane structure has been grown which has two QD layers within the membrane. By applying a voltage across only one of the QD layers the QD emission frequency of one QD layer can be tuned independently of the other. Photonic crystal cavities have been fabricated using this type of structure, and a quality factor of greater than 5,000 has been achieved. The next phase of this research will be to use this structure to couple two QDs to a single cavity mode.
The third topic concerns a proposed method to detect a single electron spin state in a QD by exploiting QD-cavity interaction effects in micropillar cavities. This requires highly efficient coupling, still within the weak-coupling limit of cavity QED, of photons in an oxide-apertured microcavity to embedded charge controlled QDs.
The fourth topic is a demonstration of site-controlled QD island growth at pre-patterned positions using electron beam lithography and a molecular beam epitaxy regrowth technique. This technique is expected to become important for scalable designs for quantum information systems.
The final topic of this thesis is the investigation and applications of quantum posts which are novel semiconductor nanostructures with confined electronic states. Quantum posts show intraband transitions in the THz frequency range. Furthermore it is shown that they can be used as the active medium for low threshold electrically pumped lasing in vertical cavity surface emitting lasers in the near infrared regime. At low temperatures, quantum post devices show remarkably lower lasing current thresholds than equivalent QD devices.
The appendices report on some of the research for which I have produced materials and samples, but for which I have marginally been involved in subsequent measurements. The appendices include descriptions of GaP photonic crystals for integration of diamond nanocrystals and the development of fiber-coupled micropillar devices.
|Advisor:||Bouwmeester, Dirk, Petroff, Pierre M.|
|Commitee:||Ludwig, Andreas, Martinis, John|
|School:||University of California, Santa Barbara|
|School Location:||United States -- California|
|Source:||DAI-B 71/02, Dissertation Abstracts International|
|Subjects:||Condensed matter physics, Materials science|
|Keywords:||Cavity QED, Micropillar, Photonic crystals, Quantum dots, Quantum posts, Strong coupling|
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