Creating Silicon Based Platforms for New Technologies

Si-based structures are likely to be central to a new era of technologies with a major impact on society, spanning computing and health monitoring, to combating climate change. For this, serious and well established Group IV semiconductor (Si, Ge) epitaxy capabilities will be in great demand.

The Warwick Nano-Silicon group focuses on epitaxial growth of Group IV heterostructures; their structural and electrical properties; the physics of these materials and functional devices fabricated from them. The Group has a unique growth capability, with both flexible research and industrially compatible systems, that enables it to respond to exciting new developments in silicon-based technologies: nano-electronics, silicon photonics, solar power, quantum computing, spintronics and electronic refrigeration ("cooltronics"). A major strategy of the Group has been to use expertise established in the field of nanoelectronics for novel and diverse applications.

This Platform Grant would be used to establish a flexible infra-structure to realise the huge potential of the epitaxy facilities at Warwick. A set of feasibility studies would be spawned on specific ideas that are either too speculative, under developed or individually too incremental to gain Responsive Mode support. These would enable expertise to be developed in a wide range of novel epitaxy techniques that anticipate demands and, by pushing the boundaries of epitaxy, generate new disruptive technologies. Each activity would be supported by staff effort from Research Assistants seconded from, or between, existing funded projects or by providing short RA appointments to recently completed PhD students who are in their most productive period just after thesis submission. Full programmes subsequently generated will contribute to the longer term future of the Nano-Silicon Group, enhancing its already significant international reputation, and could themselves generate considerable impact.

Researchers in the Group would receive a significant career boost from training in epitaxy and characterization. There would be opportunities for exchanges to other European institutes, which are extremely beneficial for collaboration and career development. Researchers would also develop new skills by attending international workshops. By being given responsibility for delivering a feasibility study, each researcher would have opportunities for leadership development.

Some activities will directly support the Group's current projects. For instance, development of low temperature epitaxy using new CVD precursors, for which processes currently only exist for specific cases and many are commercially confidential. This will enable novel multi-layered structures with advanced and unique electronic and optical properties, and will improve the abruptness of interfaces and doping control required in existing structures such as superlattices, THz diodes and quantum cascade lasers. Another example is incorporating tin with the other Group IV elements to provide a larger lattice constant and hence a route to integrating a wide range of III-V devices on silicon.

The flexibility to respond rapidly to new ideas will be a great benefit, especially in a field where device performance doubles every 18 months. Similarly, opportunities often arise in existing projects to investigate alternative directions. Within a Platform these could be followed alongside the original work, adding value to the existing programme yet avoiding mission creep or spreading existing resources too thinly.

Overall the flexible resources available within a Platform Grant will be of great assistance in pursuing our long term strategic goals of developing silicon based epitaxy for a diverse range of applications.

This proposal aligns with the EPSRC Grand Challenges in Silicon Technology, as well as those in Microelectronic Design through downstream applications and fits in the broad remit of developing technology for the Digital Economy, Energy and Healthcare Technologies.

There are many companies operating in the field of III-Vs for whom a flexible interface to Si would be invaluable. Specifically, development of tin based epitaxy would directly benefit the UK precursor manufacturer SAFC Hitech. It will also provide a new impetus to four element solar cell development and a benefit to companies, such as IQE Silicon Compounds Ltd who are actively pursuing this market opportunity for more efficient elements, and to Circadian Solar who are developing complete concentrator PV systems; both have expressed interest in collaborating with us or licensing the technology once acquired.
Strained Ge lasers could become the source of light that is eagerly awaited within Si photonics for fast, low power intra and inter chip communication. Exploitation through IPR protection and licensing is again the preferred route and several UK companies are already interested, including SELEX Galileo and M Squared Lasers. Similarly, in the renewable energy sector, Puurgen and Doosan Babcock have expressed interest in the high performance SiGe thermoelectric generators that we intend to develop with Glasgow.
As well as providing a detector for the IR astronomy groups in Cardiff and Chalmers to use in their space instruments, success in the cold electron bolometer sub-project could lead to commercialisation of a more generally applicable IR imaging sensor for low light conditions. Possible paths to exploitation would be through the Cardiff University spin-out company QMC Instruments Ltd. and/or the Leicester University spin-out Bioastral that has interests in biomedical imaging.
Longer term, demonstration of a strained Ge MOSFET with GeO2 as a gate dielectric would transform the future plans of semiconductor giants like Intel and ST Microelectronics and could ultimately lead to a new generation of microprocessors.

The high profile of a Platform Grant will be used to raise understanding in society of the exciting science and technology that underpins the all pervasive silicon technology. The Group web site will explain our own activities and have sections written for the general public and school children. All members of the team will have opportunities to be engaged in outreach with visiting schools in the Midland region, at Open Days and through the Coventry Physics Club lectures. The Physics department employs an Ogden Teaching Fellow (Ally Caldecote) specifically to interact with schools and she will provide assistance and openings for these outreach activities.

Impact in the people pipeline will come through increasing both the technical and transferrable skills of the researchers and technicians in the Group. This will be achieved through the activities set out in the Case for Support and especially the variety of experience gained from working on and leading a range of activities and from exchange visits to other prestigious laboratories. Presentations at meetings with collaborators, conferences, the above outreach opportunities and teaching graduate students through the Midland Physics Alliance will all help to develop communication skills. RAs will be involved with Warwick Ventures in all the commercial exploitation mentioned above which will sharpen their business skills. The enhanced international standing of the Nano-Silicon Group that will come from success in this programme will also benefit these researchers and graduate students as they seek employment. The development of our researchers clearly benefits the Group, but it also serves to increase the supply of highly employable workers in the UK.