20-04-2012, 03:46 PM
Nanoelectronic systems
[attachment=20465]
INTRODUCTION
Nanoelectronic systems are considered crucial to the continued miniaturization of electronic devices. Nanotechnology has demonstrated more hyperbole than substance for many years—and the “nano” label has been applied to items ranging from motor oil to lipstick. A single nanotube in the nano radio device performs the function of multiple components in larger radios. The nanoapparatus may ultimately find uses in drug delivery devices, prosthetics or explosives detectors.
The breakthrough nanoradio consists of a single carbon-nanotube molecule that serves simultaneously as all the essential components of a radio -- antenna, tunable band-pass filter, amplifier and demodulator. The nanoradio is less than one micron long and only 10 nanometers wide -- or one ten-thousandth the width of a human hair -- making it the smallest radio ever created.Because of unique array geometry used, nanotubes are almost perfectly aligned and parallel to each other, which is helpful to make a large number of transistors. Since the tubes in each transistor device operate in parallel and independently,the device can produce large current outputs ,ie. They have high levels of amplification and gain in both the RF and audio frequency range.
Nanotechnology is arguably one of the most overhyped “next big things” in the recent history of applied science. According to its most
radical advocates, nanotechnology is a molecular manufacturing system that will allow us to fabricate objects of practically any arbitrary complexity by mechanically joining molecule to molecule, one after another, until the final, atomically correct product emerges before our
eyes..
CARBON NANO TUBES
Carbon nanotubes (CNTs) are allotropes of carbon ie fullerene family ,with a nanostructure that can have a length to diameter ratio upto 28,000,000:1, which Is significally longer than any other material. The CNTs, also known as tubular fullerenes. These nanotubes are concentric graphitic cylinders closed at either end due to the presence of five-membered rings. The CNTs can be multiwalled with a central tube of nanometric diameter surrounded by graphitic layers separated by ~0.34nm . Unlike the multi-walled carbon nanotubes (MWNTs), in single-walled carbon nanotubes (SWNTs) there is only the tube and no graphitic layers i.e. SWNTs consist of singular grapheme cylindrical walls These cyclindrial carbon molecules have vovel properties that makes them potentially useful in many application in nanotechnology ,electronic,optics and other fields of materials science as well as potential uses in architectural fields. They exhibit extraordinary strength and unique electrical properties and are efficien conductors of heat .. They come in a large variety of sizes and shapes: they are single- walled, double-walled and multiwalled. Some are straight, some are bent and some even looped back on themselves in toroidal configurations. Common to them all is their exceptional tensile strength, the resistance to being pulled apart along their length without atoms together in the carbon nanotube is the strongest bond in nature.
Nanotubes are also excellent conductors of electricity, far better than copper, silver or even superconductors. It’s because the electrons don’t hit anything.The tube is such a perfect structure. Nanotubes have attracted a lot of attention because of unique electrical properties that arise at the atomic scale.They can behave as a semiconductor or metallic system and they have a very high physical strength.Carbon nanotubes (CNTs) were discovered by S. Iijima, (in 1991)who was looking for new carbon structures, in the deposit formed on graphite cathode surfaces during the electric-arc evaporation (or discharge) that is commonly employed to produce fullerene soot. These nanotubes are concentric graphitic cylinders closed at either end due to the presence of five-membered rings.
HISTROY OF CARBON NANOTUBE RADIO
The following table , is a breakdown of the most important dates pertaining to the major discoveries and experiments that have been important in learning about the properties and the possible applications for the carbon nanotube including the nano radio.
1970’sDiscovery of Carbon filaments
Discovered by Morinobu Endo He grew carbon fibres about 7 nm in diameter by using a vapour-growth technique, but these filaments were not recognized as nanotubes and were not studied systematically.
1985Discovery of C60
The discovery of soccer-ball shaped molecules created by linking together 60 or more carbon atoms in 1985, led to carbon nanotubes. Due to the architectural designs of R. Buckminster Fuller, these soccer-ball shaped molecules are also called bucky balls.
1991Discovery of multi-wall carbon nanotubes
Sumio Iijima, of the NEC Corporation, a Japanese electronics company, had been studying the atomic-scale structure of carbon fibers for many years. In 1990, researchers at Heidelberg, Germany and Tucson, Arizona reported a method for making large quantities of the carbon molecules called buckminsterfullerene or C60, justifying Iijima's own experiments on carbon stretching back for over a decade. Sumio Iijima used high- resolution transmission electron microscopy to observe carbon nanotubes, that the field really started to take off. Sumio Iijima, who was studying the material deposited on the cathode during the arc-evaporation synthesis of fullerenes, discovered first tubular molecules.
1992Conductivity of carbon nanotubes
Thomas Ebbesen and P. M. Ajayan at NEC found a way to produce nanotubes in higher yields and make them available for studies by different techniques. Subsequently they found a way to purify them.
1993 Synthesis of single-wall nanotubes
The many- layered tubes had given way to single-walled versions, whose properties were much easier to predict. Because the bonds between the atoms are very strong and there are no loose edges where cracks could start, the nanotubes are both strong and stiff. An addition of a small amount of transition-metal powder (cobalt, nickel or iron) favors the growth of so-called single-walled nanotubes.
1996 Ropes of single-wall nanotubes
In 1996 the Rice group, led by Smalley, synthesized bundles of aligned single-wall carbon nanotubes for the first time. The bundles contained many nanotubes with an arrow distribution of diameters, making it possible to perform experiments relevant to one- dimensional quantum physics.
[attachment=20465]
INTRODUCTION
Nanoelectronic systems are considered crucial to the continued miniaturization of electronic devices. Nanotechnology has demonstrated more hyperbole than substance for many years—and the “nano” label has been applied to items ranging from motor oil to lipstick. A single nanotube in the nano radio device performs the function of multiple components in larger radios. The nanoapparatus may ultimately find uses in drug delivery devices, prosthetics or explosives detectors.
The breakthrough nanoradio consists of a single carbon-nanotube molecule that serves simultaneously as all the essential components of a radio -- antenna, tunable band-pass filter, amplifier and demodulator. The nanoradio is less than one micron long and only 10 nanometers wide -- or one ten-thousandth the width of a human hair -- making it the smallest radio ever created.Because of unique array geometry used, nanotubes are almost perfectly aligned and parallel to each other, which is helpful to make a large number of transistors. Since the tubes in each transistor device operate in parallel and independently,the device can produce large current outputs ,ie. They have high levels of amplification and gain in both the RF and audio frequency range.
Nanotechnology is arguably one of the most overhyped “next big things” in the recent history of applied science. According to its most
radical advocates, nanotechnology is a molecular manufacturing system that will allow us to fabricate objects of practically any arbitrary complexity by mechanically joining molecule to molecule, one after another, until the final, atomically correct product emerges before our
eyes..
CARBON NANO TUBES
Carbon nanotubes (CNTs) are allotropes of carbon ie fullerene family ,with a nanostructure that can have a length to diameter ratio upto 28,000,000:1, which Is significally longer than any other material. The CNTs, also known as tubular fullerenes. These nanotubes are concentric graphitic cylinders closed at either end due to the presence of five-membered rings. The CNTs can be multiwalled with a central tube of nanometric diameter surrounded by graphitic layers separated by ~0.34nm . Unlike the multi-walled carbon nanotubes (MWNTs), in single-walled carbon nanotubes (SWNTs) there is only the tube and no graphitic layers i.e. SWNTs consist of singular grapheme cylindrical walls These cyclindrial carbon molecules have vovel properties that makes them potentially useful in many application in nanotechnology ,electronic,optics and other fields of materials science as well as potential uses in architectural fields. They exhibit extraordinary strength and unique electrical properties and are efficien conductors of heat .. They come in a large variety of sizes and shapes: they are single- walled, double-walled and multiwalled. Some are straight, some are bent and some even looped back on themselves in toroidal configurations. Common to them all is their exceptional tensile strength, the resistance to being pulled apart along their length without atoms together in the carbon nanotube is the strongest bond in nature.
Nanotubes are also excellent conductors of electricity, far better than copper, silver or even superconductors. It’s because the electrons don’t hit anything.The tube is such a perfect structure. Nanotubes have attracted a lot of attention because of unique electrical properties that arise at the atomic scale.They can behave as a semiconductor or metallic system and they have a very high physical strength.Carbon nanotubes (CNTs) were discovered by S. Iijima, (in 1991)who was looking for new carbon structures, in the deposit formed on graphite cathode surfaces during the electric-arc evaporation (or discharge) that is commonly employed to produce fullerene soot. These nanotubes are concentric graphitic cylinders closed at either end due to the presence of five-membered rings.
HISTROY OF CARBON NANOTUBE RADIO
The following table , is a breakdown of the most important dates pertaining to the major discoveries and experiments that have been important in learning about the properties and the possible applications for the carbon nanotube including the nano radio.
1970’sDiscovery of Carbon filaments
Discovered by Morinobu Endo He grew carbon fibres about 7 nm in diameter by using a vapour-growth technique, but these filaments were not recognized as nanotubes and were not studied systematically.
1985Discovery of C60
The discovery of soccer-ball shaped molecules created by linking together 60 or more carbon atoms in 1985, led to carbon nanotubes. Due to the architectural designs of R. Buckminster Fuller, these soccer-ball shaped molecules are also called bucky balls.
1991Discovery of multi-wall carbon nanotubes
Sumio Iijima, of the NEC Corporation, a Japanese electronics company, had been studying the atomic-scale structure of carbon fibers for many years. In 1990, researchers at Heidelberg, Germany and Tucson, Arizona reported a method for making large quantities of the carbon molecules called buckminsterfullerene or C60, justifying Iijima's own experiments on carbon stretching back for over a decade. Sumio Iijima used high- resolution transmission electron microscopy to observe carbon nanotubes, that the field really started to take off. Sumio Iijima, who was studying the material deposited on the cathode during the arc-evaporation synthesis of fullerenes, discovered first tubular molecules.
1992Conductivity of carbon nanotubes
Thomas Ebbesen and P. M. Ajayan at NEC found a way to produce nanotubes in higher yields and make them available for studies by different techniques. Subsequently they found a way to purify them.
1993 Synthesis of single-wall nanotubes
The many- layered tubes had given way to single-walled versions, whose properties were much easier to predict. Because the bonds between the atoms are very strong and there are no loose edges where cracks could start, the nanotubes are both strong and stiff. An addition of a small amount of transition-metal powder (cobalt, nickel or iron) favors the growth of so-called single-walled nanotubes.
1996 Ropes of single-wall nanotubes
In 1996 the Rice group, led by Smalley, synthesized bundles of aligned single-wall carbon nanotubes for the first time. The bundles contained many nanotubes with an arrow distribution of diameters, making it possible to perform experiments relevant to one- dimensional quantum physics.