Clarification of Answer by
websearcher-ga
on
22 Jan 2003 17:50 PST
Hello travelnut:
I did some further searching and was able to come up with the
following descriptions/applications of various types of
nanotechnology. I have presented quotes from various excellent
websites. I suggest that you read the complete pages/sites if you
require further introduction.
websearcher-ga
Different Areas in Nanotechnology
*********************************
Quantum Mechanical Devices:
"QUANTUM mechanical (QM) mechanisms have played a significant role
primarily in compound semiconductor devices, such as resonant
tunneling diode functioning as a switch and quantum well lasers for
optoelectronic applications. However, due to the ever shrinking
feature size of CMOS devices (toward tens nanometers in gate length),
the QM effects manifest themselves even in the conventional silicon
devices such as CMOS. In addition, small structures bring forth
effects such as single electron tunneling, which might lead to new
types of devices."
From: Circuit/Device Modeling at the Quantum Level,
http://www-tcad.stanford.edu/tcad/pubs/device/ed00_yu.pdf
"Quantum effects are unavoidable in devices with dimensions smaller
than 100 nanometers. But we reserve the name 'quantum device' for
those devices that actually rely on quantum effects for their
operation."
From: Quantam Electron Devices,
http://www.aip.org/web2/aiphome/pt/vol-55/iss-5/pdf/vol43no2p74-77part1.pdf
"Today's advanced nanoscale fabrication technology can produce
extremely small heterostructures. As a result of their small
dimensions, these semiconductor devices exhibit enormous quantal, in
particular, tunneling effects. A few practical devices, such as the
resonant tunneling diode and the quantum interface transistor have
been manufactured. However, the temperature range within which these
quantum electron devices can be operated is extremely narrow, because
phonon scattering rapidly destroys quantum coherence at relatively low
temperatures."
From: Chi H. Mak THEORETICAL CHEMISTRY, http://www-rcf.usc.edu/~cmak/
Reduced Dimensionality Effects:
"Optically-generated electron spins in semiconductors show remarkable
resilience against environmental decoherence, making it possible to
envision a new class of magnetoelectronics based on the coherent
superposition of quantum spin states."
From: Ferromagnetic Imprinting of Nuclear Spins in Semiconductors,
http://www.eps.org/aps/meet/MAR02/baps/abs/S30.html
"Karsten's primary research interest is in the area of experimental
condensed matter physics and material science and, in particular, in
reduced dimensionality where he is studying self-organization of
nanoscale structures at surfaces and interfaces. Specific techniques
utilized in his research have included photoelectron spectroscopy
utilizing synchrotron radiation sources, high resolution inelastic
electron scattering, low energy electron diffraction and, more
recently, scanning tunneling microscopy."
From: Karsten Pohl, http://www.physics.unh.edu/people/profiles/pohl.html
Resonant Tunneling:
"The resonant tunnelling diode (or RTD) consists of an emitter and
collector region, and a double tunnel barrier structure which contains
a quantum well (as shown in the energy band diagrams of figure 2.1).
This quantum well is so narrow (5-10 nm) that it can only contain a
single, so called resonant, energy level. The principle of this device
is that electrons wishing to travel from the emitter to the collector
can only do so if they are lined up with this resonant energy level."
From: The Resonant Tunnelling Transistor,
http://ipga.phys.ucl.ac.uk/research/arrays/rtt-paper.html
"The RTD, as developed by the Texas Instruments (TI) team, consists of
a set of three ultra-thin layers. Those layers, a 'well' of silicon
sandwiched between two barrier layers of silicon dioxide with
electrical contacts on the top and bottom, permit operation in several
electrical states (as many as 19 different current steps). By
contrast, the ordinary transistor has one operating step - from on to
off or vice versa. The electrical flexibility of an RTD enables it to
represent several logic states, thereby doing the work of several
conventional traditional transistors. This leads to more complex logic
units with fewer electronic parts. Such electronic systems are
smaller, need less power, and are easier to harden in the harsh
environments of space and modern warfare. Equally important, the
fabrication of this new hybrid electronic technology is compatible
with the traditional silicon circuitry."
From: Resonant Tunneling Diode Research,
http://www.afrlhorizons.com/Briefs/0006/OSR0001.html
"Multiple resonant tunneling devices offer significant advantages for
realizing ultra-dense, ultra-high performance multivalued logic
arithmetic integrated circuits."
From: US5789940: Reduced complexity multiple resonant tunneling
circuits for positive digit multivalued logic operations ,
http://www.delphion.com/details?pn10=US05789940
Molecular Electronics:
"The field of molecular electronics seeks to use individual molecules
to perform functions in electronic circuitry now performed by
semiconductor devices. Individual molecules are hundreds of times
smaller than the smallest features conceivably attainable by
semiconductor technology. Because it is the area taken up by each
electronic element that matters, electronic devices constructed from
molecules will be hundreds of times smaller than their
semiconductor-based counterparts. Moreover, individual molecules are
easily made exactly the same by the billions and trillions. The
dramatic reduction in size, and the sheer enormity of numbers in
manufacture, are the principle benefits offered by the field of
molecular electronics."
From: Molecular Electronics, http://www.calmec.com/molecula1.htm
"Molecules have fundamental properties such as orbital structures
rather than band structures. The orbital structures can serve a viable
method to preserve electronic functionality at the nanometer scale.
Thus molecules could pave the way for generating hundreds or even
thousands more devices per unit area than with other devices limited
by size constraints.
From: Science of Molecular Electronics,
http://www.molecularelectronics.com/science.html
MEMS (Micro-Electro-Mechanical Systems) :
"Micro-Electro-Mechanical Systems (MEMS) is the integration of
mechanical elements, sensors, actuators, and electronics on a common
silicon substrate through microfabrication technology. While the
electronics are fabricated using integrated circuit (IC) process
sequences (e.g., CMOS, Bipolar, or BICMOS processes), the
micromechanical components are fabricated using compatible
'micromachining' processes that selectively etch away parts of the
silicon wafer or add new structural layers to form the mechanical and
electromechanical devices."
From: What is MEMS Technology?,
http://www.memsnet.org/mems/what-is.html
"There are numerous possible applications for MEMS. As a breakthrough
technology, allowing unparalleled synergy between previously unrelated
fields such as biology and microelectronics, many new MEMS
applications will emerge, expanding beyond that which is currently
identified or known. Here are a few applications of current interest:"
[[Read further]]
From: MEMS Applications, http://www.memsnet.org/mems/applications.html
"MEMS are the microscopic structures integrated onto silicon that
combine mechanical, optical and fluidic elements with electronics.
Typically no bigger than a grain of sand, these MEMS devices are
complex machines that enable chips to become intelligent. These
devices act as the most direct links between digital electronics and
the physical world, allowing the integration of electronics and
mechanical systems on a single chipset."
From: What is MEMS?, http://www.allaboutmems.com/whatismems.html
BioMEMS:
"MEMS technology is currently enjoying a moment of formidable
expansion in synergy with the health sciences, giving rise to the
notion of MEMS for biomedical applications - BioMEMS."
From: BioMEMS, http://www.lerner.ccf.org/bme/biomems/
"BioMEMS is targeted to have the fastest growth rate within the MEMS
market, particularly for drug discovery and delivery, diagnostics,
biotelemetry, and genomics. However, manufacturing of BioMEMS devices
differs from IC manufacture because the market requires a diversity of
materials, physical structures, input/output methods, products, and
initially lower volumes per product. This creates an obvious need for
modular, non-silicon approaches to building inexpensive disposable
chemical and biological sensors and systems."
From: Conference: Novel Microfabrication Options for BioMEMS
Technologies & Commercialization Strategies,
http://www.knowledgefoundation.com/biomems.html
Search Strategy (on Google):
"quantum electron" devices
"reduced dimensionality"
"resonant tunneling" transistors OR circuits
"molecular electronics"
"what is MEMS"
bioMEMS applications
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