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Nanotechnology and Nanoscience The Royal Society

Nanotechnology: views of Scientists and Engineers

Electronics and optoelectronics

a) What would you add to/change about the working group’s definition of nanotechnology?

Nanoscience is the study of matter at atomic and molecular scales (typically 0.1nm to 100nm), where properties differ significantly from those at larger scale.

  • Generally the group was happy with this definition.
  • The group noted that even though this definition of nanoscience is broad, it is not intended to replace existing disciplines (e.g. chemistry).
  • It was agreed that a length scale needs to be included and that the scale given was appropriate, as it is below 100nm that properties change becoming dependent upon size and shape.

Nanotechnology is the application of this knowledge to make useful materials, structures and devices.

  • It was agreed that ”…by controlling shape and size at the nanometer scale” be added to the end of the definition, so that the control/manipulation element to nanotechnology was captured.

It was agreed that debate over definitions of nanoscience and nanotechnology could be very time-consuming, and that the working group’s definition was broadly accepted and workable.

b) What is the current state of knowledge in the field of your breakout group, and where is research going?
b) What is the current state of research

i) Electronics

  • Current research mainly involves silicon-based semiconductors. The International Technology Roadmap for Semiconductors (ITRS) (http://public.itrs.net/) sets out the progress of semiconductor technology and is well-defined until 2016.
  • Chip dimensions have been shrinking for 4 decades (100nm transistor in production in 1988, 15nm transistor today). Nanotechnology has featured for many years in characterization and fabrication, as well as devices.
  • Semiconductors is a highly focused area where the science and technology are closely coupled. Around 10% of all world trade and 1% of all R&D is in IT and electronics.
  • Data storage technology (e.g. magnetic hard disk, optical (CD and DVD) and flash memory) is strongly linked to Si roadmap and already uses nanotechnology, though its roadmap does not extend as far as that of the ITRS.
  • Modeling: Issues in describing short gate-length transistors are basically understood. Work is continuing to simulate highly confined devices either by modifying a Monte Carlo treatment or by incorporating a full quantum mechanical approach. How modeling develops once the end of roadmap is reached is less clear.

ii) Optoelectronics

  • Currently, elements for circuits are of the order of several microns in size, and circuits of the order of cms.
  • There are examples of nanotechnology in optoelectronics - eg quantum well lasers and liquid crystal displays have nanometre precision in 2-D - but in general no commercial device needs 1nm precision to work.
  • There is now an optoelectonics roadmap, which builds substantially on the silicon roadmap but is 10-20 years behind it in terms of dimensional tolerances.
  • Almost all tools in optoelectronics come from electronics. As metrology becomes more demanding the nanotechnology tools in electronics will be the first choice for optics.
  • Unlike semiconductors, there is no single fabrication technology in optoelectronics.
  • Optical components are beginning to be integrated into silicon e.g. vertical lasers.
b) Where is research going?
  • It was agreed that the distinction should be made between research that is on the silicon roadmap, and that that is beyond or alternative to it. (For example Semitech have developed an alternative roadmap for alternative materials).

On roadmap

  • New, improved architectures.
  • High-K dielectrics, new light sources, new interconnects

Beyond roadmap

  • New materials. Although also part of the roadmap, research into development and characterization of fundamentally new nanostructured materials with tailored physical properties will be important. Allied to this will be new processes for incorporating these materials. The importance of being aware of but not driven by industry needs was highlighted.
  • Nanotube transistors
  • Plastic electronics. Here key enabling processes are needed. Devices such as plastic transistors have many potential applications (e.g. environmental monitoring, customs, as alternative to bar codes) if prices can be kept down.
  • Molecular electronics. Here the difference between plastic and molecular electronics was highlighted – plastic electronics is based on condensed phase properties of polymers, whereas molecular is based on properties of individual or a small number of molecules. The group were not convinced that single-molecule electronics existed yet.

The need for realism about new device structures, especially as a replacement for silicon, was noted. Bio or plastic electronics may offer a key niche market but there is such investment in silicon that it will continue to be the dominant technology for the foreseeable future. The III-V’s industry was also noted as an important one.

c) What applications of this technology currently exist, and what can be envisaged in the short and long term?

i) Near-term (< 10 years)
–Quantum dots for broadband amplifiers
–Integrating sensors on silicon, and with communications
–Nanostructured materials for roadmap
–Solid-state lighting
–Single photons on demand for quantum cryptography
–All-plastic circuits (smartcards etc)
–Advanced characterization
–Biocompatibility
–Solid-state memory

ii) Long-term (> 10 years)
–Smart dust
–Nanoscale molecular logic
–Process convergence
–Point-of-care health screening
–Quantum computing

d) What are the potential hold-ups in turning research into products? What is needed (time, money etc) to enable this process to happen?

The need for research to link into technology drivers at an early stage was highlighted.

The following potential hold-ups were identified

  • Processability – there are intrinsic difficulties in manufacturing such small devices.
  • Scale-up – need to integrate nano-phenomena to the macro world in order for people to view or use it.
  • Cost of demonstrator stage (accessing a FAB facility).
  • Public perception and engagement – if the public perceive these technologies negatively or do not engage with them this will adversely affect their development.
  • Regulatory issues (for healthcare applications)
  • Skills base (especially in the UK). The need for government promotion of interdisciplinary research was discussed. Funding agencies play a critical role in encouraging collaboration and should coordinate to produce common calls in a common language. However, the idea of developing ‘nanotechnology’ degrees was considered premature; what is needed are good multidisciplinary teams, not interdisciplinary people. Training at a Masters level was considered ideal - the example was given of the joint Cambridge-MIT Institute which is developing an interdisciplinary Masters programme which will be awarded jointly by engineering, mathematics, medicine and biology departments. In order to facilitate cooperation, good networking and technical help is needed.
    H. Fuchs, of Physikalisches Institut, Munster, and H. Craighead at Cornell University in USA were also highlighted as two examples of people who have established a strong interdisciplinary environment although there are many other examples.
  • Nationally and internationally networked facilities.
e) What are the science 'fictions' in this field?

The group took a broad view of science ‘fictions’ and included not only those ideas that are physically impossible but those that are very unlikely due to economic, social or technological constraints.

  • Practical single-molecule electronics
  • Practical single-atom data storage
  • Virtual life systems – the digitization of all matter
  • 3D totally self-assembled functional architectures
  • Controlling physical properties beyond isolated nanostructures. It has been suggested that nanotechnology could potentially convert one element or compound into another at will. It was agreed that neither the technological nor the economic arguments supported this assertion. There is an enormous difference between controlling the physical properties of a single nanostructure in isolation and manufacturing a material whose properties are those of the individual nanostructures.
f) Consider the same questions with respect to a related or interfacing technology

The group chose bionanotechnology because they considered the interface between biology and electronics to promise the biggest breakthroughs. Nanotechnology is providing the tools for the structure-function relationship of molecules to be probed and understood. Potential applications of such knowledge included sensing (single-cell, single-molecule), monitoring, treatment, targeted drug delivery. In order to maximize potential of this area there needs to be promotion of interdisciplinary activities (e.g. Masters programmes), cohesion between funding agencies, and a networking of resources.

However, such developments also have important ethical and regulatory implications, and must proceed carefully.

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