Nanoscale Germanium Electronics

Lead Research Organisation: University College London
Department Name: London Centre for Nanotechnology

Abstract

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.

Planned Impact

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.

Publications

10 25 50
 
Description The discoveries of the research concern the properties of the interface between various metals and the (001) surface of germanium (Ge), Ge(001). Such interfaces will play a crucial role in active Ge photonic devices like photodetectors, modulators and even lasers which will form components of electronic-photonic integrated circuits, ideal due to their perfect matching with standard telecommunication wavelengths.

The 1st major achievement of the research is the determination of a recipe to form the barium (Ba)-Ge(001) interface with two different characteristics.
1. The first is a separated Ba/Ge interface, which is desirable if the Ba-Ge interface is to promote physical or electrical isolation between the Ge surface and any subsequently deposited over layer. Such an interface has the potential to suppress surface recombination effects on n-doped Ge(001) surfaces.
2. The second, a mixed Ba-Ge interface, is desirable to promote the enhancement of electrical conductivity across the interface.

The 2nd major achievement of the research is to discover the nanoscale processes that occur during the formation of nickel germanide or cobalt germanide. Understanding these processes is essential if low resistance contacts are to be made in next generation electronic devices based on, or containing, Ge.
Exploitation Route The findings could help companies that make nanoscale electronic devices using germanium design their fabrication processes better, so to improve the electrical properties of the devices. Subsequently the devices should be faster, more reliable and more efficient.

To complete the understanding of the Ni-germanide formation on the nanoscale, in particular with respect to the potential formation of inhomogeneous Schottky barriers, complementary studies could be performed. For example, photoelectron emission/low energy electron microscopy (PEEM/LEEM) studies, making use of modern synchrotron radiation facilities, could provide spatially resolved chemical information down to the nanoscale regime, complementing the nanoscale structural information from the grant.
Sectors Digital/Communication/Information Technologies (including Software),Electronics

 
Description 2016-05-31: Author of a 17-page submission on behalf of the Thin Films and Surfaces Group of the Institute of Physics, as a direct contribution to the EPSRC's assessment of the surface science field in their Balancing Capabilities exercise.
Geographic Reach National 
Policy Influence Type Participation in a national consultation
 
Description Member of the Steering Committee of the Quantum Engineering for Silicon Technology [QuEST] Consortium (European lobbying group)
Geographic Reach Europe 
Policy Influence Type Membership of a guideline committee
URL https://ec.europa.eu/futurium/en/system/files/ged/fetflagshipsconsultation2016-questconsortium-rev3_...
 
Description Co-funding for a studentship with 50% funding from IHP and 50% from the CDT in Advanced Characterisation of Materials
Amount € 50,000 (EUR)
Organisation IHP Microelectronics GmbH 
Sector Private
Country Germany
Start 09/2016 
End 09/2020
 
Description Germanium nanoscale electronics 
Organisation IHP Microelectronics GmbH
Country Germany 
Sector Private 
PI Contribution An EPSRC funded PDRA worked on this project for one year, including spending time at IHP Microelectronics and Poznan University. The PRDA performed scanning tunnelling microscopy and Auger electron microscopy measurements and worked on data analysis and paper writing. I worked on data analysis and paper writing (5 published, 1 in preparation). I also spend a total of three weeks working at IHP.
Collaborator Contribution Scanning tunnelling microscopy, transmission electron microscopy and x-ray photoemission spectroscopy measurements were performed at IHP, by IHP Poznan academic staff. Density functional theory calculations were performed at University of Newcastle, Australia.
Impact Follow-on Grants: EPSRC Programme Grant (EP/M009564/1) Atomically Deterministic Doping and Readout For Semiconductor Solotronics (ADDRFSS), 01/02/2015-31/01/2020, £6,382,161 EPSRC Centre for Doctoral Training in the Advanced Characterisation of Materials (EP/L015277/1), 01/05/2014-31/10/2022, £4,226,129 (£2.1M to UCL). Co-Investigator with SJ Skinner. Publications: Higher Order Reconstructions of the Ge(001) Surface Induced by a Ba Layer W. Koczorowski, T. Grzela, A. Puchalska, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Applied Surface Science 435 438 (2018). STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface W. Koczorowski, A. Puchalska, T. Grzela, L. Jurczyszyn, S.R. Schofield, R. Czajka, N.J. Curson and M. W. Radny Physical Review B, 93 195304 (2016). Growth and evolution of nickel germanide nanostructures on Ge(001) T. Grzela, G. Capellini, W. Koczorowski, M.A. Schubert, R. Czajka, N.J. Curson, I. Heidmann, Th. Schmidt, J. Falta and T. Schroeder Nanotechnology, 26 385701 (2015). Initial growth of Ba on Ge(001): An STM and DFT study W. Koczorowski, A. Puchalska, T. Grzela, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Physical Review B, 91 235319 (2015). Ba termination of Ge(001) studied with STM W. Koczorowski, T. Grzela, M.W. Radny, S.R. Schofield, G. Capellini, R. Czajka, T. Schroeder and N.J. Curson Nanotechnology 26 155701 (2015). Interface and nanostructure evolution of cobalt germanides on Ge(001) T. Grzela, W. Koczorowski, G. Capellini, R. Czajka, M.W. Radny, N.J. Curson, S. R. Schofield, M.A. Schubert, and T. Schroeder Journal of Applied Physics 15 074307 (2014). Muliti-disciplinary Integration of next generation CMOS technology and optoelectronics. Spans the disciplines of Physics, Chemistry and Engineering. Led to new collaboration between UCL and IHP investigating SnGe surface properties for direct bandgap optoelectronic applications. IHP provide 50% of a studentship, UCL the other 50%.
Start Year 2012
 
Description Germanium nanoscale electronics 
Organisation Poznan University of Technology
Country Poland 
Sector Academic/University 
PI Contribution An EPSRC funded PDRA worked on this project for one year, including spending time at IHP Microelectronics and Poznan University. The PRDA performed scanning tunnelling microscopy and Auger electron microscopy measurements and worked on data analysis and paper writing. I worked on data analysis and paper writing (5 published, 1 in preparation). I also spend a total of three weeks working at IHP.
Collaborator Contribution Scanning tunnelling microscopy, transmission electron microscopy and x-ray photoemission spectroscopy measurements were performed at IHP, by IHP Poznan academic staff. Density functional theory calculations were performed at University of Newcastle, Australia.
Impact Follow-on Grants: EPSRC Programme Grant (EP/M009564/1) Atomically Deterministic Doping and Readout For Semiconductor Solotronics (ADDRFSS), 01/02/2015-31/01/2020, £6,382,161 EPSRC Centre for Doctoral Training in the Advanced Characterisation of Materials (EP/L015277/1), 01/05/2014-31/10/2022, £4,226,129 (£2.1M to UCL). Co-Investigator with SJ Skinner. Publications: Higher Order Reconstructions of the Ge(001) Surface Induced by a Ba Layer W. Koczorowski, T. Grzela, A. Puchalska, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Applied Surface Science 435 438 (2018). STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface W. Koczorowski, A. Puchalska, T. Grzela, L. Jurczyszyn, S.R. Schofield, R. Czajka, N.J. Curson and M. W. Radny Physical Review B, 93 195304 (2016). Growth and evolution of nickel germanide nanostructures on Ge(001) T. Grzela, G. Capellini, W. Koczorowski, M.A. Schubert, R. Czajka, N.J. Curson, I. Heidmann, Th. Schmidt, J. Falta and T. Schroeder Nanotechnology, 26 385701 (2015). Initial growth of Ba on Ge(001): An STM and DFT study W. Koczorowski, A. Puchalska, T. Grzela, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Physical Review B, 91 235319 (2015). Ba termination of Ge(001) studied with STM W. Koczorowski, T. Grzela, M.W. Radny, S.R. Schofield, G. Capellini, R. Czajka, T. Schroeder and N.J. Curson Nanotechnology 26 155701 (2015). Interface and nanostructure evolution of cobalt germanides on Ge(001) T. Grzela, W. Koczorowski, G. Capellini, R. Czajka, M.W. Radny, N.J. Curson, S. R. Schofield, M.A. Schubert, and T. Schroeder Journal of Applied Physics 15 074307 (2014). Muliti-disciplinary Integration of next generation CMOS technology and optoelectronics. Spans the disciplines of Physics, Chemistry and Engineering. Led to new collaboration between UCL and IHP investigating SnGe surface properties for direct bandgap optoelectronic applications. IHP provide 50% of a studentship, UCL the other 50%.
Start Year 2012
 
Description Germanium nanoscale electronics 
Organisation University of Newcastle
Department School of Mathematical and Physical Sciences
Country Australia 
Sector Academic/University 
PI Contribution An EPSRC funded PDRA worked on this project for one year, including spending time at IHP Microelectronics and Poznan University. The PRDA performed scanning tunnelling microscopy and Auger electron microscopy measurements and worked on data analysis and paper writing. I worked on data analysis and paper writing (5 published, 1 in preparation). I also spend a total of three weeks working at IHP.
Collaborator Contribution Scanning tunnelling microscopy, transmission electron microscopy and x-ray photoemission spectroscopy measurements were performed at IHP, by IHP Poznan academic staff. Density functional theory calculations were performed at University of Newcastle, Australia.
Impact Follow-on Grants: EPSRC Programme Grant (EP/M009564/1) Atomically Deterministic Doping and Readout For Semiconductor Solotronics (ADDRFSS), 01/02/2015-31/01/2020, £6,382,161 EPSRC Centre for Doctoral Training in the Advanced Characterisation of Materials (EP/L015277/1), 01/05/2014-31/10/2022, £4,226,129 (£2.1M to UCL). Co-Investigator with SJ Skinner. Publications: Higher Order Reconstructions of the Ge(001) Surface Induced by a Ba Layer W. Koczorowski, T. Grzela, A. Puchalska, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Applied Surface Science 435 438 (2018). STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface W. Koczorowski, A. Puchalska, T. Grzela, L. Jurczyszyn, S.R. Schofield, R. Czajka, N.J. Curson and M. W. Radny Physical Review B, 93 195304 (2016). Growth and evolution of nickel germanide nanostructures on Ge(001) T. Grzela, G. Capellini, W. Koczorowski, M.A. Schubert, R. Czajka, N.J. Curson, I. Heidmann, Th. Schmidt, J. Falta and T. Schroeder Nanotechnology, 26 385701 (2015). Initial growth of Ba on Ge(001): An STM and DFT study W. Koczorowski, A. Puchalska, T. Grzela, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Physical Review B, 91 235319 (2015). Ba termination of Ge(001) studied with STM W. Koczorowski, T. Grzela, M.W. Radny, S.R. Schofield, G. Capellini, R. Czajka, T. Schroeder and N.J. Curson Nanotechnology 26 155701 (2015). Interface and nanostructure evolution of cobalt germanides on Ge(001) T. Grzela, W. Koczorowski, G. Capellini, R. Czajka, M.W. Radny, N.J. Curson, S. R. Schofield, M.A. Schubert, and T. Schroeder Journal of Applied Physics 15 074307 (2014). Muliti-disciplinary Integration of next generation CMOS technology and optoelectronics. Spans the disciplines of Physics, Chemistry and Engineering. Led to new collaboration between UCL and IHP investigating SnGe surface properties for direct bandgap optoelectronic applications. IHP provide 50% of a studentship, UCL the other 50%.
Start Year 2012
 
Description Germanium nanoscale electronics 
Organisation University of Wroclaw
Department Institute of Experimental Physics
Country Poland 
Sector Academic/University 
PI Contribution An EPSRC funded PDRA worked on this project for one year, including spending time at IHP Microelectronics and Poznan University. The PRDA performed scanning tunnelling microscopy and Auger electron microscopy measurements and worked on data analysis and paper writing. I worked on data analysis and paper writing (5 published, 1 in preparation). I also spend a total of three weeks working at IHP.
Collaborator Contribution Scanning tunnelling microscopy, transmission electron microscopy and x-ray photoemission spectroscopy measurements were performed at IHP, by IHP Poznan academic staff. Density functional theory calculations were performed at University of Newcastle, Australia.
Impact Follow-on Grants: EPSRC Programme Grant (EP/M009564/1) Atomically Deterministic Doping and Readout For Semiconductor Solotronics (ADDRFSS), 01/02/2015-31/01/2020, £6,382,161 EPSRC Centre for Doctoral Training in the Advanced Characterisation of Materials (EP/L015277/1), 01/05/2014-31/10/2022, £4,226,129 (£2.1M to UCL). Co-Investigator with SJ Skinner. Publications: Higher Order Reconstructions of the Ge(001) Surface Induced by a Ba Layer W. Koczorowski, T. Grzela, A. Puchalska, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Applied Surface Science 435 438 (2018). STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface W. Koczorowski, A. Puchalska, T. Grzela, L. Jurczyszyn, S.R. Schofield, R. Czajka, N.J. Curson and M. W. Radny Physical Review B, 93 195304 (2016). Growth and evolution of nickel germanide nanostructures on Ge(001) T. Grzela, G. Capellini, W. Koczorowski, M.A. Schubert, R. Czajka, N.J. Curson, I. Heidmann, Th. Schmidt, J. Falta and T. Schroeder Nanotechnology, 26 385701 (2015). Initial growth of Ba on Ge(001): An STM and DFT study W. Koczorowski, A. Puchalska, T. Grzela, M.W. Radny, L. Jurczyszyn, S.R. Schofield, R. Czajka and N.J. Curson Physical Review B, 91 235319 (2015). Ba termination of Ge(001) studied with STM W. Koczorowski, T. Grzela, M.W. Radny, S.R. Schofield, G. Capellini, R. Czajka, T. Schroeder and N.J. Curson Nanotechnology 26 155701 (2015). Interface and nanostructure evolution of cobalt germanides on Ge(001) T. Grzela, W. Koczorowski, G. Capellini, R. Czajka, M.W. Radny, N.J. Curson, S. R. Schofield, M.A. Schubert, and T. Schroeder Journal of Applied Physics 15 074307 (2014). Muliti-disciplinary Integration of next generation CMOS technology and optoelectronics. Spans the disciplines of Physics, Chemistry and Engineering. Led to new collaboration between UCL and IHP investigating SnGe surface properties for direct bandgap optoelectronic applications. IHP provide 50% of a studentship, UCL the other 50%.
Start Year 2012