Efficient semiconductor quantum light sources

The generation of quantised light states is a driving technology for applications of quantum devices for cryptography, sensing, imaging and computing. These research areas are funded by a UK Government Investment in excess of £600M over 10 years, aimed at accelerating the translation of quantum technologies into the marketplace. Semiconductor light sources that emit photons one-by-one, so called single photon sources, have been reported in quantum dots in Gallium Arsenide, defects in Gallium Nitride and Diamond and 2-D semiconductors, such as hexagonal Boron Nitride. The emitters operate across the visible and IR range, with different emission patterns, making direct comparisons non-trivial. The most advanced technology, InAs quantum dots, are now available from several start-up companies, each claiming high efficiency and brightness.

This project will develop novel light sources and determine their efficiency, with a view to creating a "checklist" for this measurement. Recently, standardised efficiency measurements have been introduced into research on solar cells by the prestigious Nature publishing group, enforcing a "checklist" that must be reported before claiming an efficiency in any publication. This project will identify the key measurements required to report efficiency of single photon sources, independent of material, wavelength and measurement system, which may be reproduced in separate laboratories.

The project will have access to single photon sources under study in Cardiff, such as quantum dots, 2D materials and wide bandgap semiconductors. Processing will occur in the university's Institute for Compound Semiconductor Cleanroom to create nanocavities and dielectric antennae. Optical measurements will occur in a newly installed lab at Cardiff and the UK's national standardisation institute, the National Physical Laboratory.

Through our students, following consideration of the consequences of their research and appropriate action informed by their Responsible Innovation training, impact will fall into one of 3 strands:

SOCIETAL:

As a Key Enabling Technology, Compound Semiconductors (CS) bring benefit to society in general through developing the connected society, e.g. the 5G network, the smart phones that use it, satellite communications systems and data server infrastructure;

they contribute to reducing our carbon footprint through e.g. photovoltaics, new energy efficient lighting, and, power electronics for the next generation of electric vehicles.

CS sensor technology is at the heart of early medical diagnosis and CS based light sources are essential for both cosmetic treatments, such as hair removal, and life-saving treatments such as Photodynamic Therapy.

CS based magnetic sensors are being developed for security screening and next generation secure communication.

In total these technologies support our connected world, our health, our security and the environment.

ECONOMIC: The global market for CS is large, currently worth around $33.7Bn, with a compound annual growth rate of 17.3%.

The vision of the CS cluster was first defined in 2015, to build on existing academic and industrial assets, capability and manufacturing excellence to create Europe's 5th Semiconductor Cluster and the first in the world dedicated to Compound Semiconductor Technologies. To date the cluster has secured commitments of >£500M private and public investment with a suite of innovation assets and critical manufacturing infrastructure and a purpose to drive UK growth in the CS sector.

It is absolutely critical to recognise that the formation of clusters need ongoing nurturing, cross fertilisation of people and ideas and most importantly the supply of skilled staff to support rapid growth in order to reach critical mass for sustainability. The predicted PhD level jobs increase in just the current local cluster companies would more than use all of the minimum underwritten CDT output over the next 5 years, and we need to do much more. Our CDT is essential to support the development of key elements of the rapidly emerging Compound Semiconductor Cluster and drive new linkages within the wider UK industrial supply chain. Thus addressing the issue of bringing manufacturing supply chains back to the UK - a key element of the Government's Industrial Strategy.

The EPSRC CS roadmap document , June 2012, identified a concern that the UK CS Research Community is missing an exploitation link that can provide a route to impact and economic leverage EPSRC's >£20M pa CS research investment. Many technological solutions work well in the research laboratory or as one-off demonstrators but fail to translate to industrial production or commercial success. The CDT will directly address this issue by changing the mind-set of the next generation of researchers so that they start from solutions that allow rapid translation to production.

OUTREACH:

It is critical that the public and our politicians understand the excellence and importance of CS manufacturing in the UK. Our CDT cohort will undergo training in elevator pitches and media interactions to influence decision makers and will develop videos explaining how Compound Semiconductors are made and what they can do. They will inform a diverse set of people using a range of innovative formats such as performance and theatre production skills.

A crucial part of the people pipeline, which will support our future manufacturing excellence, is the motivation of our young people. Our CDT cohort will develop a Schools programme and an Undergraduate programme.

This will ensure we attract the very best and widest range of applicants and, most importantly, inform and excite the next generation about the opportunities that CS technology and Manufacturing offers them.