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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