Quantum Dot Architecture Nanodynamics

Site controlled semiconductor quantum dots (QDs) are the subject of world-wide interest because of their potential use in quantum information technologies and nanoscale optoelectronics. The goal is to create advanced QD architectures by controlling the precise position of single dots or molecules during epitaxial growth. However, a significant limitation in the realisation of site controlled III-V quantum structures is our inability to observe how they form in real-time and hence understand how to precisely tailor their characteristics. This project will utilise a unique electron microscope in Cardiff to obtain the first real-time movies of how QDs actually form in advanced architectures. This will provide unprecedented feedback to the National Centre for III-V Technologies and allow us to fabricate QDs with the best site control and optical properties ever achieved. These optimal structures will be tested optically with a view to commercial exploitation with Hitachi Europe Ltd for the large scale integration of single-photon (SP) sources into quantum photonic circuits and networks.

The UK is investing £270M in a National Network of Quantum Technology Hubs. It is widely recognised that the miniaturisation of photonic quantum circuits is essential for technological applications. In particular, the integration of on-demand single photon (SP) sources on a chip is considered indispensable for scalable architectures in quantum information processing. However, the key obstacle preventing such large scale integration into quantum photonic circuits and networks is precise site control and narrow optical line-width of individual QDs.

To overcome this major difficulty we will utilise the Cardiff III-V LEEM to see how QDs form in real-time and rapidly establish optimal growth conditions. This unprecedented feedback to the National Centre for III-V Technologies will allow us to fabricate QDs with the best site control and optical properties ever achieved. These optimal structures will be tested optically with a view to commercial exploitation with Hitachi who have the resources and expertise to rapidly exploit the technology generated by this project.

The creation of on-demand SP sources on a chip will be a major breakthrough in the implementation and commercialisation of quantum technology and transform virtually all areas of society. This ranges from the encryption that underpins most internet/electronic data security to pattern recognition algorithms yielding almost real-time national surveillance. The ability to manipulate extremely large data sets has important implications for fundamental studies in physics, astronomy and the life-sciences while using quantum computation to simulate complex systems has relevance to pharmaceutical design, metrology and energy production. Our proposed programme therefore underpins and addresses EPSRC's four priority challenge themes of 'manufacturing the future', 'energy', 'digital economy' and 'healthcare technologies'.

Cardiff University has recently signed an agreement with leading UK semiconductor wafer company IQE to establish an Institute for Compound Semiconductors (ICS) at Cardiff with a £17.3m UK Government award to underpin the foundation. This is a key step in creating the World's first Compound Semiconductor Cluster, spanning III-V technology from basic research to full scale production. This proposal will establish the III-V LEEM in the UK and facilitate interaction with IQE via ICS to address key technological problems including IQE's specific interest in SP sources and the integration of III-V technology with silicon. This significant benefit to UK industry will maximise impact beyond the immediate scope of the proposal.

This project will provide excellent training opportunities for PDRA and PhD students involving exposure to state-of-the art equipment, unavailable elsewhere, and modelling of experimental movies. Travel to Sheffield and Hitachi Cambridge Laboratory will provide experience in MBE growth, lithography and micro photoluminescence and there will be opportunities for exposure to commercial entities such as Hitachi Europe Ltd and IQE who will also provide advanced courses in semiconductor manufacture.

Movies encapsulating dramatic events, such as QD formation, will have wide ranging appeal and form an ideal basis to communicate nanoscience to the general public. This will be achieved in collaboration with spin-out company 'science made simple' who will provide communication training to the research team.

The III-V LEEM system at Cardiff is directly applicable to many areas of III-V research and several visits to UK III-V groups are planned to communicate these capabilities. The project will bring in leading international fabrication expertise (Bracker, USNRL) to the UK and develop new capabilities in SCQD growth. This knowledge base will be used by the National Centre for III-V Technologies to fabricate SCQD structures for the UK community which will have a significant national impact on the implementation of quantum technology.