Development of site-controlled III-Nitride Quantum Dots

Quantum dots are quantum confined structures. Thanks to their zero-dimensional nature, due to their confinement in all three dimension, a plethora of potential applications and enhancements of current applications are possible. For example, there is their application in the improvement of light-emitting diode design and improvement in the design of laser diodes. In particular, III-nitride site-controlled quantum dots have been demonstrated to show single photon emission at room temperature [1]. However, many existing techniques of creating quantum dots create random distributions in location and size (within a certain range), leading to limits to their performance. The creation of site-controlled quantum dots, which have predetermined locations and sizes, is a less mature field. These site-controlled quantum dots have a broad scope of interesting, potential applications, especially in the field of quantum information processing.

This project concerns the creation of site-controlled quantum dots using the technique of Displacement Talbot Lithography in combination with Metal Organic Vapour Phase Epitaxy. III-Nitride quantum dots will be grown selectively upon these sites to reveal a variety of site-controlled III-Nitride quantum dot structures in a variety of configurations in order to identify the best route. There have been a number of studies already which have achieved quantum dots upon nanopyramids and nanorods and gaining a deeper understanding of the growth mechanism and its dependence on the pre-patterning of the starting material will be the focus of this project. The characterisation of these nanostructures, thanks to a number of different tools, will be used to confirm their presence and suitability as efficient optical emitter, with the detection of a single photon source being the final aim.

[1] Holmes. M, Choi. K, Kako. S, Arita. M, Arakawa. Y (2014), Room-Temperature Triggered Single Photon Emission from a III- Nitride Site-Controlled Nanowire Quantum Dot; Nano Lett. American Chemical Society, 14, 982-98

The Institute of Physics has estimated that physics-dependent businesses directly contribute 8.5% to the UK's economic output, employ more than a million people and generated exports amounting to more than £100bn in 2009. They go on to say: "It is important for businesses to have access to a range of highly skilled (and motivated) individuals capable of thinking 'outside of the box', particularly physics-trained postgraduates due to the highly numerate, analytical and problemsolving skills that are acquired during their training." If funded, the graduates of this CDT will have such skills and motivation. We would hope that this would significantly contribute towards satisfying the UK's need for trained scientists, particularly in the field of condensed matter physics. The impact would go further than this. By working more closely with industry and other partner organisations, we would reshape the conventional PhD programme to improve the experience for all.

In addition to the training aspect of the CDT there would be an important research impact. The Universities of Bristol and Bath have many world-leading researchers across the condensed matter field. By working with the high-quality students that we hope to recruit into the programme we will produce significant cutting edge research in condensed matter. The research would bear on some of the grand challenges facing condensed matter physics such as: understanding the emergence of new phenomena far from equilibrium; the nanoscale design of functional materials such as graphene; and harnessing quantum Physics for new technologies. Ultimately, this would contribute to improvements in many technologies, for example, energy or data storage technology.