- Date:
- 2004-2005
- Theme:
- Nanomaterials and Dielectrics
The International Technology Roadmap for semiconductors has identified a new gate stack and material as one of the grand challenges for the coming years. The thickness of the incumbent SiO2 gate oxide has been scaled down to less than 2 nm, and further reduction is impossible because of the leakage currents due to direct tunneling. For this reason, the present gate oxide dielectric materials will eventually be replaced by a high-k dielectric gate oxide. The current proposal aims at identifying promising materials for CMOS gate high-k dielectrics by using combinatorial methods for synthesis and screening of materials in a collaboration between the departments of Electronics & Computer Science and Chemistry of the University of Southampton. Unlike industrial methods such as atomic layer chemical vapour deposition, our multiple e-beam deposition will allow us to vary the concentration and thickness of the gate oxide on the same wafer. Not only will this enable identification of the most promising materials, it will also show systematic correlation between chemical and structural properties on one side and electrical properties on the other side over a wide range of concentrations and elements. This makes it feasible to detect patterns in the correlation which will lead to a much better physical understanding of the factors influencing the electrical properties of the gate dielectric in CMOS transistors.
Primary investigators
- lhc02r
- km2
Associated research group
- Electronics and Computer Science
- Date:
- 2005-2014
- Theme:
- Quantum Electronics and Spintronics
- Funding:
- EU (FP6 Network of Excellence Sinano)
We have fabricated and measured single domain wall magnetoresistance devices with sub-20 nm gap widths using a novel combination of electron beam lithography and helium ion beam milling. The measurement wires and external profile of the spin valve are fabricated by electron beam lithography and lift-off. The critical bridge structure is created using helium ion beam milling, enabling the formation of a thinner gap (and so a narrower domain wall) than that which is possible with electron beam techniques alone. Four-point probe resistance measurements and scanning electron microscopy are used to characterize the milled structures and optimize the He ion dose. Successful operation of the device as a spin valve is demonstrated, with a 0.2% resistance change as the external magnetic field is cycled.
The critical dimensions used in CMOS technology and RAM memory are conventionnaly defined by photo-lithography and hence limited in size by the wavelength of the light. Methods to create smaller dimensions, such as electron beam writing, exist, but are prohibitively expensive for production purposes. Self-assembly of nanostructures is a fundamental from-bottom-to-top technique in which solid structures of nanometer dimensions are synthesized by self-organized processes from constituents like atoms, molecular beams, or macro-molecules. In the current project, magnetic nanostructures are defined by electrodeposition on Si through a mask of a self assembled template from poly(styrene) latex. The samples will be characterized by magnetic and magneto-resistance measurements and will provide unique information on giant and domain-wall magnetoresistance. Application as MRAM is envisioned.
Primary investigators
- Kees De Groot
- Prof. P.A. de Groot
- Prof. P. Bartlett
- Prof H. Fangohr
Secondary investigators
- ydw08r
- xl04r
- dcg04r
- mk03r
Associated research groups
- Nano Research Group
- Southampton Nanofabrication Centre
- Date:
- 2004-2006
- Theme:
- Machine Learning
- Funding:
- EPSRC
Classes of kernels which operate on discrete structures have been proposed relatively recently which allow the successful family of kernel-based algorithms to work directly on strings, trees, and other objects without the need to first convert them into an explicit vector representation first. It has been shown that there is a probablistic interpretation of the string kernel, which strongly relates string kernels and fisher kernels. This has lead to a kernel over a finite state automata which deals with variable-length substrings. This project intends to extend the work in this area by examining the area of kernels from generative models, with applications to text-categorisation, bioinformatics tasks and image classification. The project will also consider clustering algorithms using domain-specific kernels.
Primary investigator
- cjs
Secondary investigator
- av
Associated research group
- Information: Signals, Images, Systems Research Group
Creating archives of data on crystallography using the GNU EPrints software and creating a federated search system which harvests the metadata via OAI-PMH and provides additional services.
Primary investigators
- Liz Lyon (UKOLN)
- Les Carr
- David De Roure
Secondary investigators
- Monica Duke (UKOLN)
- Michael Day (UKOLN)
- Rachel Heery (UKOLN)
- Jeremy Frey
- Simon Coles
- Mike Hursthouse
- Christopher Gutteridge
Partners
- UKOLN
- PsiGate
Associated research group
- Intelligence, Agents, Multimedia Group
- Date:
- 2002-2005
- Themes:
- Decentralised Information Systems, E-Business Technologies, Web Science
- Funding:
- EPSRC (GR/N35816/01), QinetiQ
Recommender systems have been widely advocated as a way of coping with the problem of information overload for knowledge workers. Given this, multiple recommendation methods have been developed. However, it has been shown that no one technique is best for all users in all situations. Thus we believe that effective recommender systems should incorporate a wide variety of such techniques and that some form of overarching framework should be put in place to coordinate the various recommendations so that only the best of them (from whatever source) are presented to the user. To this end, we show that a marketplace, in which the various recommendation methods compete to offer their recommendations to the user, can be used in this role. Specifically, we aims to the principled design and the development of such a marketplace (including the auction protocol, the reward mechanism and the bidding strategies of the component recommender agents) and evaluates the market's capability to effectively coordinate multiple methods. Through analysis, we show that our market is capable of shortlisting recommendations in decreasing order of user perceived quality and correlating the individual agent's internal quality rating to the user's perceived quality.
Primary investigators
- Nick Jennings
- lavm
- Wendy Hall
Secondary investigators
- David De Roure
- yzw01r
Partner
- QinetiQ
Associated research group
- Intelligence, Agents, Multimedia Group
- Date:
- 2003-2005
- Themes:
- Agent Based Computing, Knowledge Technologies, Pervasive Computing and Networks
- Funding:
- DTI
The ANS (Autonomic Networked System) is a ubiquitous computing managementtool which is designed to mimic the ANS (Autonomic Nervous System) of living creatures. The organic ANS is the part of the nervous system controlling many organs and muscles within thebody. It is flexible, constantly in operation and that it happens in the background without our interference or knowledge of its mechanism. This metaphore is being adapted to support ubiquitous computing environments, especially in the application of the intelligent home and medical applications where constant technical supportis impossible. Such a system will provide the intelligence to optimise its operation through constant monitoring and tuning to achieve its goal.
Primary investigators
- trp
- David De Roure
Secondary investigators
- Roxana Belecheanu
- Mariusz Jacyno
Partners
- Imperial College, London
- Lancaster University
- CDC: Central Data Control Ltd
- Telewest PLC
- Orange PLC
Associated research group
- Intelligence, Agents, Multimedia Group
- Date:
- 2004-2008
- Theme:
- Materials & Technology
- Funding:
- EPSRC (GR/S86341/01)
Southampton Universities Microfabrication Facility is the national centre for silicon based microelectronics with a 600m2 cleanroom with full lithographic, deposition, etching and characterisation capability. Currently the facility does not have standardised solar cell processes. This workpackage will establish facility processes for the fabrication of crystalline and polycrystalline solar cells with efficiencies of ~20% and ~14% respectively. This will directly be of benefit to the wider UK photovoltaic research community who will then have access to these baseline capabilities via EPSRC facility requests. This work will also provide important first steps towards our longer term goals from this baseline we will be able to readily attempt new structures, devices and processes.
Primary investigators
- Darren Bagnall
- Dr T. Markvart
Secondary investigators
- pk02r
- ap
Associated research group
- Nano Research Group
- Date:
- 2001-2006
- Themes:
- Silicon Based Photonics, Materials & Technology
A visible wavelength linear photosensor featuring a pixel size of 3 mm has been designed for fabrication using commercial 0.25 mm CMOS technology. For the photo-sensing element, the design uses a special deep N-well in P-epi diode offered by the foundry for imaging devices. Pixel reset is via an adjacent p-FET, thus allowing high reset voltages for a wide pixel voltage swing. The pixel voltage is buffered using a voltage-follower op-amp and a sampling scheme is used to allow correlated double sampling (CDS) for removal of reset noise. Reset and signal levels are buffered through a 16:1 multiplexer to a switched capacitor amplifier which performs the CDS function. Incorporated in the CDS circuit is a programmable gain of 1:8 for increased signal-to-noise ratio at low signal levels. Data output is via 4 analogue output drivers for off-chip conversion. Each driver supplies a differential output voltage with a 71V swing for improved power supply noise rejection. The readout circuitry is designed for 12 bit accuracy at frame rates of up to 6.25 kHz. This gives a peak data rate at each output driver of 10M samples/s. The device will operate on a 3.3V supply and will dissipate approximately 950mW. Simulations indicate an equivalent noise charge at the pixel of 66.3 for a full well capacity of 255,000, giving a dynamic range of 71.7 dB.
Primary investigators
Secondary investigator
- qrm01r
Partner
- N.R. Waltham, Rutherford Appleton
Associated research groups
- Nano Research Group
- Electronic Systems and Devices Group
- Electronics and Electrical Engineering
- Date:
- 2004-2006
- Themes:
- Materials & Technology, Silicon Based Photonics
- Funding:
- EPSRC (GR/S68583/01)
Planar waveguides and photonic crystal structures are being intensively investigated as primary solutions for integrated photonic devices. However, there may be an alternative approach to the manufacture of highly integrated optical devices with structural elements smaller than the wavelength, which nevertheless enable strong guidance and manipulation of light - the use of metallic and metallodielectric nanostructures and propagating plasmonÂpolanton waves. This approach is now branded as "the next big thing" in nanotechnology. Here we propose, for the first time, a research programme to investigate the basic principles of active nanoscale functional elements operating with surface plasmon-polanton signals. We will employ an original and revolutionary active control concept that will use structural transformations in the waveguide material to control the signals. The proposed solution takes advantage of the most characteristic features of surface plasmon-polantons, namely their localization in nanometer thick surface layers of metal, and the fact that their propagation is strongly dependent on the metal's dielectric properties. If successful, our approach could provide an alternative means of developing active integrated photonic (logic) circuits.
Primary investigators
- Darren Bagnall
- Prof. N.I. Zheludev
Partner
- School of Physics
Associated research groups
- Nano Research Group
- Quantum Technology Centre
- Date:
- 2001-
- Themes:
- Photovoltaics and Energy, Quantum Electronics and Spintronics
As the range and scope of thermal imaging and sensing applications expand quantum well infrared photodetectors (QWIPs) are emerging as a new and important technology. The best known and most widely discussed are the n-type devices based on GaAs/AlGaAs. The combined promise of normal incidence detection, a route to integration and the potential for far-infrared ( >20 micron) detection, with Si/SiGe quantum well and quantum dot infrared photodetectors (QDIPS), provides the motivation behind this challenging projects that will develop SiGe epitaxy still further.
Primary investigator
Secondary investigators
- nsl
- pi01r
Partners
- Prof. P. Harrison, EEE, Leeds University
- Dr M. Halsall, UMIST/Manchester
Associated research groups
- Nano Research Group
- Southampton Nanofabrication Centre