24-07-2012, 11:19 AM
NANODEVICES NANOELECTRONICS AND NANOSENSORS
[attachment=28617]
VISION
In the broadest sense, nanodevices are the critical enablers that will allow mankind to
exploit the ultimate technological capabilities of electronic, magnetic, mechanical, and
biological systems. While the best examples of nanodevices at present are clearly
associated with the information technology industry, the potential for such devices is
much broader. Nanodevices will ultimately have an enormous impact on our ability to
enhance energy conversion, control pollution, produce food, and improve human health
and longevity.
CURRENT SCIENTIFIC AND TECHNOLOGICAL ADVANCEMENTS
Current Scientific Advances
In the past decade, our ability to manipulate matter from the top down, combined with
advances and in some cases unexpected discoveries in the synthesis and assembly of
nanometer-scale structures, has resulted in advances in a number of areas. Particularly
striking examples include the following:
· The unexpected discovery and subsequently more controlled preparation of carbon
nanotubes and the use of proximal probe and lithographic schemes to fabricate
individual electronic devices from these materials (Iijimi 1991; Guo et al. 1995; Tans
et al. 1997; Bockrath et al. 1997; Collins et al. 1997; Martel et al. 1998)
· The ability in only the last one or two years to begin to place carefully engineered
individual molecules onto appropriate electrical contacts and measure transport
through the molecules (Bumm et al. 1996; Reed et al. 1997)
· The explosion in the availability of proximal probe techniques and their use to
manipulate matter and thereby fabricate nanostructures (Stroscio and Eigler 1991;
Lyo and Avouris 1991; Jung et al. 1996; Cuberes et al. 1996; Resch et al. 1998)
· The development of chemical synthetic methods to prepare nanocrystals, and
methods to further assemble these nanocrystals into a variety of larger organized
structures (Murray et al. 1995)
· The introduction of biomolecules and supermolecular structures into the field of
nanodevices (Mao et al. 1999)
· The isolation of biological motors, and their incorporation into nonbiological
environments (Noji et al. 1997; Spudich et al. 1994)
78 6. Applications: Nanodevices, Nanoelectronics, and Nanosensors
Current Technological Advances
A number of examples of devices in the microelectronics and telecommunications
industries rely on nanometer-scale phenomena for their operation. These devices are, in a
sense, “one-dimensional” nanotechnologies, because they are micrometer-scale objects
that have thin film layers with thicknesses in the nanometer range. These kinds of
systems are widely referred to in the physics and electronics literature as two-dimensional
systems, because they have two classical or “normal” dimensions and one quantum or
nanoscale dimension. In this scheme, nanowires are referred to as one-dimensional
objects and quantum dots as zero-dimensional. In this document, and at the risk of
introducing some confusion, we have chosen to categorize nanodevices by their main
feature nanodimensions rather than by their large-scale dimensions. Thus, twodimensional
systems such as two-dimensional electron gases and quantum wells in our
notation are one-dimensional nanotechnologies, nanowires are two-dimensional
nanotechnologies, and quantum dots are three-dimensional nanotechnologies. Examples
include high electron mobility transistors, heterojunction bipolar transistors, resonant
tunneling diodes, and quantum well optoelectronic devices such as lasers and detectors.
The most recent success story in this category is that of giant magnetoresistance (GMR)
structures. These structures can act as extremely sensitive magnetic field sensors. GMR
structures used for this purpose consist of layers of magnetic and nonmagnetic metal
films. The critical layers in this structure have thicknesses in the nanometer range. The
transport of spin-polarized electrons that occurs between the magnetic layers on the
nanometer length scale is responsible for the ability of the structure to sense magnetic
fields such as the magnetic bits stored on computer disks. GMR structures are currently
revolutionizing the hard disk drive magnetic storage industry worth $30-40 billion/year
(Prinz 1998; Disktrend 1998, Gurney and Grochowski 1998; Grochowski 1998). Our
ability to control materials in one dimension to build nanometer-scale structures with
atomic scale precision comes from a decade of basic and applied research on thin film
growth, surfaces, and interfaces.
The extension from one nanodimension to two or three is not straightforward, but the
payoffs can be enormous. Breakthroughs in attempting to produce three-dimensional
nanodevices include the following:
· Demonstration of Coulomb blockade, quantum effect, and single electron memory
and logic elements operating at room temperature (Guo et al. 1997; Leobandung et al.
1995; Matsumoto et al. 1996)
· Integration of scanning probe tips into sizeable arrays for lithographic and mechanical
information storage applications (Lutwyche et al. 1998; Minne et al. 1996)
· Fabrication of photonic band-gap structures (Sievenpiper et al. 1998)
· Integration of nanoparticles into sensitive gas sensors (Dong et al. 1997)
GOALS FOR THE NEXT 5-10 YEARS: BARRIERS AND SOLUTIONS
In order to exploit nanometer-scale phenomena in devices, we must have a better
understanding of the electronic, magnetic, and photonic interactions that occur on and are
unique to this size scale. This will be achieved through experiment, theory, and modeling
over the next decade. In addition, new methods to image and analyze devices and device
components will be developed. These might include three-dimensional electron
microscopies and improved atomic-scale spectroscopic techniques.
Over the same time period, we believe that it will become possible to integrate
semiconductor, magnetic, and photonic nanodevices as well as molecular nanodevices
into functional circuits and chips.
The techniques now being developed in biotechnology will merge with those from
nanoelectronics and nanodevices. Nanodevices will have biological components.
Biological systems will be probed, measured, and controlled efficiently with
nanoelectronic devices and nanoprobes and sensors.
There will be significant progress in nanomechanical and nanobiomechanical systems,
which will exhibit properties that are fundamentally different from their macroscopic
counterparts.
[attachment=28617]
VISION
In the broadest sense, nanodevices are the critical enablers that will allow mankind to
exploit the ultimate technological capabilities of electronic, magnetic, mechanical, and
biological systems. While the best examples of nanodevices at present are clearly
associated with the information technology industry, the potential for such devices is
much broader. Nanodevices will ultimately have an enormous impact on our ability to
enhance energy conversion, control pollution, produce food, and improve human health
and longevity.
CURRENT SCIENTIFIC AND TECHNOLOGICAL ADVANCEMENTS
Current Scientific Advances
In the past decade, our ability to manipulate matter from the top down, combined with
advances and in some cases unexpected discoveries in the synthesis and assembly of
nanometer-scale structures, has resulted in advances in a number of areas. Particularly
striking examples include the following:
· The unexpected discovery and subsequently more controlled preparation of carbon
nanotubes and the use of proximal probe and lithographic schemes to fabricate
individual electronic devices from these materials (Iijimi 1991; Guo et al. 1995; Tans
et al. 1997; Bockrath et al. 1997; Collins et al. 1997; Martel et al. 1998)
· The ability in only the last one or two years to begin to place carefully engineered
individual molecules onto appropriate electrical contacts and measure transport
through the molecules (Bumm et al. 1996; Reed et al. 1997)
· The explosion in the availability of proximal probe techniques and their use to
manipulate matter and thereby fabricate nanostructures (Stroscio and Eigler 1991;
Lyo and Avouris 1991; Jung et al. 1996; Cuberes et al. 1996; Resch et al. 1998)
· The development of chemical synthetic methods to prepare nanocrystals, and
methods to further assemble these nanocrystals into a variety of larger organized
structures (Murray et al. 1995)
· The introduction of biomolecules and supermolecular structures into the field of
nanodevices (Mao et al. 1999)
· The isolation of biological motors, and their incorporation into nonbiological
environments (Noji et al. 1997; Spudich et al. 1994)
78 6. Applications: Nanodevices, Nanoelectronics, and Nanosensors
Current Technological Advances
A number of examples of devices in the microelectronics and telecommunications
industries rely on nanometer-scale phenomena for their operation. These devices are, in a
sense, “one-dimensional” nanotechnologies, because they are micrometer-scale objects
that have thin film layers with thicknesses in the nanometer range. These kinds of
systems are widely referred to in the physics and electronics literature as two-dimensional
systems, because they have two classical or “normal” dimensions and one quantum or
nanoscale dimension. In this scheme, nanowires are referred to as one-dimensional
objects and quantum dots as zero-dimensional. In this document, and at the risk of
introducing some confusion, we have chosen to categorize nanodevices by their main
feature nanodimensions rather than by their large-scale dimensions. Thus, twodimensional
systems such as two-dimensional electron gases and quantum wells in our
notation are one-dimensional nanotechnologies, nanowires are two-dimensional
nanotechnologies, and quantum dots are three-dimensional nanotechnologies. Examples
include high electron mobility transistors, heterojunction bipolar transistors, resonant
tunneling diodes, and quantum well optoelectronic devices such as lasers and detectors.
The most recent success story in this category is that of giant magnetoresistance (GMR)
structures. These structures can act as extremely sensitive magnetic field sensors. GMR
structures used for this purpose consist of layers of magnetic and nonmagnetic metal
films. The critical layers in this structure have thicknesses in the nanometer range. The
transport of spin-polarized electrons that occurs between the magnetic layers on the
nanometer length scale is responsible for the ability of the structure to sense magnetic
fields such as the magnetic bits stored on computer disks. GMR structures are currently
revolutionizing the hard disk drive magnetic storage industry worth $30-40 billion/year
(Prinz 1998; Disktrend 1998, Gurney and Grochowski 1998; Grochowski 1998). Our
ability to control materials in one dimension to build nanometer-scale structures with
atomic scale precision comes from a decade of basic and applied research on thin film
growth, surfaces, and interfaces.
The extension from one nanodimension to two or three is not straightforward, but the
payoffs can be enormous. Breakthroughs in attempting to produce three-dimensional
nanodevices include the following:
· Demonstration of Coulomb blockade, quantum effect, and single electron memory
and logic elements operating at room temperature (Guo et al. 1997; Leobandung et al.
1995; Matsumoto et al. 1996)
· Integration of scanning probe tips into sizeable arrays for lithographic and mechanical
information storage applications (Lutwyche et al. 1998; Minne et al. 1996)
· Fabrication of photonic band-gap structures (Sievenpiper et al. 1998)
· Integration of nanoparticles into sensitive gas sensors (Dong et al. 1997)
GOALS FOR THE NEXT 5-10 YEARS: BARRIERS AND SOLUTIONS
In order to exploit nanometer-scale phenomena in devices, we must have a better
understanding of the electronic, magnetic, and photonic interactions that occur on and are
unique to this size scale. This will be achieved through experiment, theory, and modeling
over the next decade. In addition, new methods to image and analyze devices and device
components will be developed. These might include three-dimensional electron
microscopies and improved atomic-scale spectroscopic techniques.
Over the same time period, we believe that it will become possible to integrate
semiconductor, magnetic, and photonic nanodevices as well as molecular nanodevices
into functional circuits and chips.
The techniques now being developed in biotechnology will merge with those from
nanoelectronics and nanodevices. Nanodevices will have biological components.
Biological systems will be probed, measured, and controlled efficiently with
nanoelectronic devices and nanoprobes and sensors.
There will be significant progress in nanomechanical and nanobiomechanical systems,
which will exhibit properties that are fundamentally different from their macroscopic
counterparts.