Nanoscale Germanium Electronics

This proposal is a feasibility study to determine the practicality of fabricating nanoscale electronic devices in germanium, of dimensions ranging from tens of nanometres to the atomic scale. The multi-billion pound semiconductor industry is based on integrated circuits (ICs) fabricated on silicon wafers and has been for the last forty years, with components being made smaller by a factor of two every eighteen months (Moore's Law). However, in recent years, the small size of circuit components has introduced a number of troublesome device performance issues due to quantum effects, such as tunnelling, and the incorporation of germanium into device components is seen as a potential solution. One positive aspect of the above mentioned quantum effects, seen in devices approaching nanoscale dimensions, is that new device paradigms which explicitly exploit quantum mechanics are being explored for future generations of ICs and for quantum information processing (QIP) applications. For example there are interesting proposals to make quantum computers from impurities in germanium or from dopants in strained Si-Ge heterostructures. Thus it has become crucial to understand the electrical transport through nanoscale germanium devices and the quantum properties of single and interacting dopants in germanium. In order to provide a clear pathway towards the fabrication of germanium nanoscale dopant devices, techniques will be developed to (i) place dopant atoms at controlled positions in a germanium crystal, with atomic precision, in order to learn about their fundamental properties and (ii) fabricate and electrically characterise buried 1-atom thick dopant layers (delta-doped layers) in germanium. The techniques will utilise a scanning tunnelling microscope (STM), which can image and manipulate matter atom-by-atom, to pattern a single atom thick resist layer made from hydrogen atoms, with a precursor gas supplying the dopants. The same STM will then be used to characterise the fabricated structures.

This project will impact on commerce, other academics, students and the general public. Commercial Industrial involvement will primarily be with technology company Zyvex Labs, USA, although other companies will be sought. The PI has strong links with Zyvex with whom he shares information on basic science issues related to fabricating devices in semiconductors using novel scanning tunnelling lithography techniques and about development and commercialisation opportunities. There is a non-disclosure agreement between LCN and Zyvex and an exploitation agreement is currently being discussed. Face-to-face meetings between the PI and Zyvex CEO, John Randall, will occur once per year for the two years of the grant (one in the US, the other in the UK) and there will be four Skype conference calls per year, also involving the PDRA and PhD student. While the proposal is not expected to produce near-term commercial benefits, there are significant medium and term long term commercialisation opportunities for the research outputs and these will primarily be exploited through the filing of patents. Further links with industry will be sought through the exploitation of the PIs position as an expert scientist for the BNC, where he has carried out consultancy work for companies such as solar cell manufacturer Oerlikon. Academic It is expected that the outcomes of the proposed research on buried dopants and devices in germanium will create similar academic interest to the PI's previous work in silicon, which received 280 citations for the three key papers and was reviewed in New Scientist and Science Now, Editors Choice in Science Magazine and Research News in Materials Today Magazine. Researchers in the following fields will be interested in the work; novel devices and next generation ICs; quantum information processing and quantum computing; novel fabrication techniques; surface science (particularly gas-surface interfaces); semiconductor physics. Students The LCN is a high profile centre with impressive laboratories that can act as an inspiration to school students considering science as a career. The PI will invite groups of school and sixth-form students to visit the LCN and speak to them about working in science in the UK. It is also valuable to promote UK science to the academic community abroad and this year the PI made presentations to 23 French students and embassy staff and 30 students of the Physical Study Association, University of Amsterdam. The PI has also organised a UK-China summer school in Beijing, Trends in cross-disciplinary nano, bio and IT research, to be held 5th-11th September 2010 where 12 students and 6 lecturers from the UK will engage with equal numbers of Chinese students and academics. Here, each lecturer presents their work in a broad academic and commercial context. Public Sector This proposal comprises of a number of themes that will capture the imagination of the general public; namely manipulation and visualisation of matter on the atomic scale, next generation electronics and quantum computing. The ability to image individual atoms and molecules provides the work with a valuable 'Wow!' factor. The PI will write articles for the popular scientific press, such as Physics World, which he already has experience of doing (Physics World Vol. 17 p.22 (2004).). The work will be publicised through laboratory tours to visiting politicians, industry and media. The recently redesigned LCN website and the video sharing website YouTube will be used for posting newsworthy research outcomes. The PI will continue to publicise his field of science through the Thin Films and Surfaces Group of the Institute of Physics of which he is a committee member. The PhD student will be encouraged to engage with the general public through schemes such as the New Outlooks in Science and Engineering (NOISE) campaign to raise science awareness.