Fluorescence, Phosphorescence, Thermoluminescence and charge transfer in synthetic diamond

Fluorescence and Phosphorescence underpin many of the discrimination techniques use to separate natural from synthetic diamond and these physical processes are at the heart of many new photonic and quantum technologies based on colour centres in diamond. In HPHT synthetic diamond the phosphorescence observed is explained in terms of donor-acceptor pair recombination. This is undoubtedly correct, and the thermal activation of electrons to neutral boron acceptors shows that boron plays a key role. However, there are a number of things that we struggle to explain. The phosphorescence peak positions are not explained, there is no conclusive link between the emission and charge transfer involving the nitrogen donor, and the role of other defects in quenching the luminescence. Furthermore, in diamonds grown by chemical vapour deposition, and subsequently treated (e.g. high pressure high temperature annealing, irradiated and annealed, etc.) there is unexplained fluorescence and phosphorescence. This project will use photoluminescence, phosphorescence and thermoluminescence, allied with quantitative measurements of defect and impurity content and theory, to investigate the defects involved and the underlying mechanisms of luminescence in synthetic diamond.

Students: A CDT is first and foremost a training activity. The students will benefit from an interdisciplinary programme taught by leaders in their respective fields from our eight partner universities and industrial collaborators, focusing on the fundamentals of material science, from the classical to the quantum, but with an emphasis on diamond and related materials and application driven themes. Students will be recruited from a wide range of disciplines, maximising both quality and diversity to provide a richer experience. Our structure ensures that our students will experience at least three different research environments during their studentship; the PhD home university and two different partner institutes (of which one can be industry or that of our international academic partners). This greatly enhances the student experience, promotes mobility and encourages research across disciplines. When they graduate Diamond Science and Technology (DST) students, with a breadth of training no one institution could deliver alone will be ideally placed for employment in academia and industry. Our students will also be able to communicate across disciplines and make the required DST transformative breakthroughs in a wide range of societally important areas, e.g. electronics, optics, quantum computing, photonics, composite materials, energy efficiency and sensing.

Industry and Economy: Our industrial partners are focused on products, jobs and wealth creation. To achieve this they need appropriately skilled people and university R&D to sustain and grow their business in a world where competition is intense. The training programme has been devised to produce graduates who understand the interdisciplinary challenges faced and can communicate across fields, for employment in industries innovating in DST or other high performance material enabled products, businesses that exploit these materials or new businesses created. The industrial letters of support clearly demonstrate the demand for our students and the enthusiasm for the research. Market sectors such as electronics, photonics, sensors, defence and security, materials, abrasives, communications and healthcare will benefit. Through collaboration, industry will gain access to world-class academics and facilities. The training programme is also accessible to industrialists who will profit from accessing MSc modules. With the knowledge gained, companies will be able rapidly exploit DST technologies to position themselves at the cutting-edge. This CDT CDT will enable joined-up and efficient collaboration between universities, companies and users, greatly strengthening impact.

Society: Diamond is so much more than a gemstone. This CDT will actively drive DST in areas of huge societal impact such as, energy (e.g. efficient power devices, nuclear safety), the environment (e.g. decontamination, water quality monitoring), food safety (e.g. sensing contaminants) and health (e.g. ultra-high resolution functional imaging). Inside Science (11/7/13; www.bbc.co.uk/programmes/b036kxv8) very recently reported on the growing importance of DST to many aspects of modern society and highlighted the £20M Element Six Ltd investment in a new diamond research centre in the UK. We will ensure that DST is used to motivate school children via innovative approaches such as "How to grow a diamond" BBC Bang Goes the Theory, 2011, (>81,000 hits on www.youtube.com/watch?v=s8qgE4LkZa4). To bring diamond to the forefront of public attention we will showcase the work through exhibitions using thought provoking and fun demonstrations, host public understanding lectures, produce podcasts/videos about our work, and host an interactive web-based forum where people have an opportunity to contact "the scientist" in order to ask questions about DST. This is in addition to publishing the results of our research in leading scientific journals, at international conferences and through the DST CDT website.