Friday, November 27, 2009
Intel Express Chipsets
It’s quite natural that new technologies are emerging from time to time. The technology leader should not be backward in this process. Intel has been showing its leadership by developing new and new technologies like processors. This time Intel shows its power by the development of a new chipset series. Chipsets are not always cared by everyone. All focus on the Processors. But a processor without a good chipset to support its capabilities is not of full use. Here Intel makes a breakthrough by the development of new 9XX series chipsets. This seminar talks on the new chipsets of Intel, the 9XX series. The seminar discuss the breakthrough capabilities of the new Chipsets, The PCI Express Bus, The Graphics Media Accelerator 900, The Matrix storage technology, Intel High Definition Audio etc with a focus on the PCI Express Bus. It is because of the fact that there is no merit gained by using a very fast processor and fast memories or graphic cards with a slow interconnect between them. There PCI Express Bus comes into play. PCI Express will serve as a general purpose I/O interconnect for a wide variety of future computing and communications platforms. Key PCI attributes, such as its usage model and software interfaces are maintained whereas its bandwidth-limiting, parallel bus implementation is replaced by a long-life, fully-serial interface. A split-transaction protocol is implemented with attributed packets that are prioritized and optimally delivered to their target. The GMA 900 is the successor of Intel Extreme Graphics 2. RAID 0/1 technologies included in matrix storage method improves the storage.
Tri-Gate Transistor
Transistors are the microscopic, silicon-based switches that process the ones and zeros of the digital worlds and are the fundamental building block of all semiconductor chips. With traditional planar transistors, electronic signals travel as if on a flat, one-way road. This approach has served the semiconductor industry well since the 1960s. But, as transistors shrink to less than 30 nanometers (billionths of a meter), the increase in current leakage means that transistors require increasingly more power to function correctly, which generates unacceptable levels of heat.
Intel's tri-gate transistor employs a novel 3-D structure, like a raised, flat plateau with vertical sides, which allows electronic signals to be sent along the top of the transistor and along both vertical sidewalls as well. This effectively triples the area available for electrical signals to travel, like turning a one-lane road into a three-lane highway, but without taking up more space. Besides operating more efficiently at nanometer-sized geometries, the tri-gate transistor runs faster, delivering 20 percent more drive current than a planar design of comparable gate size.
The tri-gate structure is a promising approach for extending the TeraHertz transistor architecture Intel announced in December 2001. The tri-gate is built on an ultra-thin layer of fully depleted silicon for reduced current leakage. This allows the transistor to turn on and off faster, while dramatically reducing power consumption. It also incorporates a raised source and drain structure for low resistance, which allows the transistor to be driven with less power. The design is also compatible with the future introduction of a high K gate dielectric for even lower leakage.
Intel researchers have developed "tri-gate" transistor design. This is one of the major breakthroughs in the VLSI technology. The transistor is aimed at bringing down the transistor size in accordance with the Moore’s Law. The various problems transistors with very small size face have to be overcome. A reduction in power dissipation is another aim. This is to develop low power micro processors and flash memories.
Tri-gate transistors show excellent DIBL, high sub threshold slope, high drive and much better short channel performance compared to CMOS bulk transistor. The drive current is almost increased by 30%. The thickness requirement of the Si layer is also relaxed by about 2-3 times that of a CMOS bulk transistor.
Tri- gate transistors are expected to replace the nanometer transistors in the Intel microprocessors by 2010. 60 nm tri-gate transistors are already fabricated and 40 nm tri-gate transistors are under fabrication. Tri-gate transistor is going to play an important role in decreasing the power requirements of the future processors. It will also help to increase the battery life of the mobile devices.
Intel's tri-gate transistor employs a novel 3-D structure, like a raised, flat plateau with vertical sides, which allows electronic signals to be sent along the top of the transistor and along both vertical sidewalls as well. This effectively triples the area available for electrical signals to travel, like turning a one-lane road into a three-lane highway, but without taking up more space. Besides operating more efficiently at nanometer-sized geometries, the tri-gate transistor runs faster, delivering 20 percent more drive current than a planar design of comparable gate size.
The tri-gate structure is a promising approach for extending the TeraHertz transistor architecture Intel announced in December 2001. The tri-gate is built on an ultra-thin layer of fully depleted silicon for reduced current leakage. This allows the transistor to turn on and off faster, while dramatically reducing power consumption. It also incorporates a raised source and drain structure for low resistance, which allows the transistor to be driven with less power. The design is also compatible with the future introduction of a high K gate dielectric for even lower leakage.
Intel researchers have developed "tri-gate" transistor design. This is one of the major breakthroughs in the VLSI technology. The transistor is aimed at bringing down the transistor size in accordance with the Moore’s Law. The various problems transistors with very small size face have to be overcome. A reduction in power dissipation is another aim. This is to develop low power micro processors and flash memories.
Tri-gate transistors show excellent DIBL, high sub threshold slope, high drive and much better short channel performance compared to CMOS bulk transistor. The drive current is almost increased by 30%. The thickness requirement of the Si layer is also relaxed by about 2-3 times that of a CMOS bulk transistor.
Tri- gate transistors are expected to replace the nanometer transistors in the Intel microprocessors by 2010. 60 nm tri-gate transistors are already fabricated and 40 nm tri-gate transistors are under fabrication. Tri-gate transistor is going to play an important role in decreasing the power requirements of the future processors. It will also help to increase the battery life of the mobile devices.
Thursday, November 26, 2009
CRUSOE PROCESSOR
Mobile computing has been the buzzword for quite a long time. Mobile computing devices like laptops, notebook PCs etc are becoming common nowadays. The heart of every PC whether a desktop or mobile PC is the microprocessor. Several microprocessors are available in the market for desktop PCs from companies like Intel, AMD, Cyrix etc. The mobile computing market has never had a microprocessor specifically designed for it. The microprocessors used in mobile PCs are optimized versions of the desktop PC microprocessor.
Mobile computing makes very different demands on processors than desktop computing. Those desktop PC processors consume lots of power, and they get very hot. When you're on the go, a power-hungry processor means you have to pay a price: run out of power before you've finished, or run through the airport with pounds of extra batteries. A hot processor also needs fans to cool it, making the resulting mobile computer bigger, clunkier and noisier. The market will still reject a newly designed microprocessor with low power consumption if the performance is poor. So any attempt in this regard must have a proper 'performance-power' balance to ensure commercial success. A newly designed microprocessor must be fully x86 compatible that is they should run x86 applications just like conventional x86 microprocessors since most of the presently available software has been designed to work on x86 platform.
Crusoe is the new microprocessor, which has been designed specially for the mobile computing market .It has been, designed after considering the above-mentioned constraints. A small Silicon Valley startup company called Transmeta Corp developed this microprocessor.
The concept of Crusoe is well understood from the simple sketch of the processor architecture, called 'amoeba’. In this concept, the x86 architecture is an ill-defined amoeba containing features like segmentation, ASCII arithmetic, variable-length instructions etc. Thus Crusoe was conceptualized as a hybrid microprocessor, i.e. it has a software part and a hardware part with the software layer surrounding the hardware unit. The role of software is to act as an emulator to translate x86 binaries into native code at run time. Crusoe is a 128-bit microprocessor fabricated using the CMOS process. The chip's design is based on a technique called VLIW to ensure design simplicity and high performance. The other two technologies using are Code Morphing Software and LongRun Power Management. The crusoe hardware can be changed radically without affecting legacy x86 software: For the initial Transmeta products, models TM3120 and TM5400, the hardware designers opted for minimal space and power.
Mobile computing makes very different demands on processors than desktop computing. Those desktop PC processors consume lots of power, and they get very hot. When you're on the go, a power-hungry processor means you have to pay a price: run out of power before you've finished, or run through the airport with pounds of extra batteries. A hot processor also needs fans to cool it, making the resulting mobile computer bigger, clunkier and noisier. The market will still reject a newly designed microprocessor with low power consumption if the performance is poor. So any attempt in this regard must have a proper 'performance-power' balance to ensure commercial success. A newly designed microprocessor must be fully x86 compatible that is they should run x86 applications just like conventional x86 microprocessors since most of the presently available software has been designed to work on x86 platform.
Crusoe is the new microprocessor, which has been designed specially for the mobile computing market .It has been, designed after considering the above-mentioned constraints. A small Silicon Valley startup company called Transmeta Corp developed this microprocessor.
The concept of Crusoe is well understood from the simple sketch of the processor architecture, called 'amoeba’. In this concept, the x86 architecture is an ill-defined amoeba containing features like segmentation, ASCII arithmetic, variable-length instructions etc. Thus Crusoe was conceptualized as a hybrid microprocessor, i.e. it has a software part and a hardware part with the software layer surrounding the hardware unit. The role of software is to act as an emulator to translate x86 binaries into native code at run time. Crusoe is a 128-bit microprocessor fabricated using the CMOS process. The chip's design is based on a technique called VLIW to ensure design simplicity and high performance. The other two technologies using are Code Morphing Software and LongRun Power Management. The crusoe hardware can be changed radically without affecting legacy x86 software: For the initial Transmeta products, models TM3120 and TM5400, the hardware designers opted for minimal space and power.
Saturday, November 21, 2009
Surface-conduction electron-emitter display
A surface-conduction electron-emitter display (SED) is a flat panel color television technology currently being developed by a number of companies. SED's use nanoscopic-scale electron emitters to energize colored phosphors and produce an image. In a general sense, an SED consists of a matrix of tiny cathode ray tubes, each "tube" forming a single sub-pixel on the screen, grouped in threes to form red-green-blue (RGB) pixels.
SEDs combine the advantages of CRTs, namely their high contrast levels, wide viewing angles and very fast response times, with the packaging advantages of LCD and other flat panel technologies. They also use much less power than an LCD system of the same size. To date, however, manufacturing and financial problems have prevented any SED system from entering commercial production.
SEDs are closely related to another developing display technology, the field emission display, or FED. The two differ primarily in the details of the electron emitters.
Description
A conventional cathode ray tube (CRT) is powered by an electron gun, essentially an open-ended vacuum tube. At one end of the gun electrons are produced by "boiling" them off a metal filament, which requires relatively high currents and consumes a large proportion of the CRT's power budget. The electrons are then accelerated and focused into a fast moving beam, flowing forward towards the screen. Electromagnets surrounding the gun end of the tube are used to steer the beam as it travels forward, allowing the beam to be scanned across the screen to produce a 2D display. When the fast moving electrons strike phosphor on the back of the screen, light is produced. Color images are produced by painting the screen with spots or stripes of three colored phosphors, one each for red, green and blue (RGB). When viewed from a distance, the spots, known as "sub-pixels", blend together in the eye to produce a single colored spot known as a pixel.
The SED replaces the single gun of a conventional CRT with a grid of nanoscopic emitters, one for each sub-pixel of the display. The surface conduction electron emitter apparatus consists of a thin slit across which electrons jump when powered with high-voltage gradients. Due to the nanoscopic size of the slits, the required field can be on the order of tens of volts. A few of the electrons, on the order of 3%, impact with slit material on the far side and are scattered out of the emitter surface. A second field, applied externally, accelerates these scattered electrons towards the screen. This field is on the order of kilovolts, but is a constant field and requires no switching, so the electronics that produce it are quite simple
SEDs combine the advantages of CRTs, namely their high contrast levels, wide viewing angles and very fast response times, with the packaging advantages of LCD and other flat panel technologies. They also use much less power than an LCD system of the same size. To date, however, manufacturing and financial problems have prevented any SED system from entering commercial production.
SEDs are closely related to another developing display technology, the field emission display, or FED. The two differ primarily in the details of the electron emitters.
Description
A conventional cathode ray tube (CRT) is powered by an electron gun, essentially an open-ended vacuum tube. At one end of the gun electrons are produced by "boiling" them off a metal filament, which requires relatively high currents and consumes a large proportion of the CRT's power budget. The electrons are then accelerated and focused into a fast moving beam, flowing forward towards the screen. Electromagnets surrounding the gun end of the tube are used to steer the beam as it travels forward, allowing the beam to be scanned across the screen to produce a 2D display. When the fast moving electrons strike phosphor on the back of the screen, light is produced. Color images are produced by painting the screen with spots or stripes of three colored phosphors, one each for red, green and blue (RGB). When viewed from a distance, the spots, known as "sub-pixels", blend together in the eye to produce a single colored spot known as a pixel.
The SED replaces the single gun of a conventional CRT with a grid of nanoscopic emitters, one for each sub-pixel of the display. The surface conduction electron emitter apparatus consists of a thin slit across which electrons jump when powered with high-voltage gradients. Due to the nanoscopic size of the slits, the required field can be on the order of tens of volts. A few of the electrons, on the order of 3%, impact with slit material on the far side and are scattered out of the emitter surface. A second field, applied externally, accelerates these scattered electrons towards the screen. This field is on the order of kilovolts, but is a constant field and requires no switching, so the electronics that produce it are quite simple
WIMAX
In recent years, Broadband technology has rapidly become an established, global commodity required by a high percentage of the population. The demand has risen rapidly, with a worldwide installed base of 57 million lines in 2002 rising to an estimated 80 million lines by the end of 2003. This healthy growth curve is expected to continue steadily over the next few years and reach the 200 million mark by 2006. DSL operators, who initially focused their deployments in densely-populated urban and metropolitan areas, are now challenged to provide broadband services in suburban and rural areas where new markets are quickly taking root. Governments are prioritizing broadband as a key political objective for all citizens to overcome the “broadband gap” also known as “digital divide”.
Wireless DSL (WDSL) offers an effective, complementary solution to wireline DSL, allowing DSL operators to provide broadband service to additional areas and populations that would otherwise find themselves outside the broadband loop. Government regulatory bodies are realizing the inherent worth in wireless technologies as a means for solving digital-divide challenges in the last mile and have accordingly initiated a deregulation process in recent years for both licensed and unlicensed bands to support this application. Recent technological advancements and the formation of a global standard and interoperability forum - WiMAX, set the stage for WDSL to take a significant role in the broadband market. Revenues from services delivered via Broadband Wireless Access have already reached $323 million and are expected to jump to $1.75 billion.
There are several ways to get a fast Internet connection to the middle of nowhere. Until not too long ago, the only answer would have been "cable" — that is, laying lines. Cable TV companies, who would be the ones to do this, had been weighing the costs and benefits. However this would have taken years for the investment to pay off. So while cable companies might be leading the market for broadband access to most people (of the 41% of Americans who have high-speed Internet access, almost two-thirds get it from their cable company), they don't do as well to rural areas. And governments that try to require cable companies to lay the wires find themselves battling to force the companies to take new customers.
Would DSL be a means of achieving this requisite of broadband and bridging the digital divide?
The lines are already there, but the equipment wasn't always the latest and greatest, even then. Sending voice was not a matter of big concern, but upgrading the system to handle DSL would mean upgrading the central offices that would have to handle the data coming from all those farms.
The most rattling affair is that there are plenty of places in cities that can't handle DSL, let alone the country side. Despite this, we’ll still read about new projects to lay cable out to smaller communities, either by phone companies, cable companies, or someone else. Is this a waste of money? Probably because cables are on their way out. Another way to get broadband to rural communities is the way many folks get their TV: satellite, which offers download speeds of about 500 Kbps —faster than a modem, but at best half as fast as DSL — through a satellite dish. But you really, really have to want it. The system costs $600 to start, then $60 a month by the services provided by DIRECWAY in the US.
There are other wireless ways to get broadband access.
MCI ("Microwave Communications Inc.") was originally formed to compete with AT & T by using microwave towers to transmit voice signals across the US. Unlike a radio (or a Wi-Fi connection), those towers send the signal in a straight line —unidirectional instead of omni directional. That's sometimes called fixed wireless or point-to-point wireless. One popular standard for this is called LMDS: local multipoint distribution system. Two buildings up to several miles apart would have microwave antennas pointing at each other. One (in, say, the urban area) would be connected to the Internet in the usual way, via some kind of wire; the other (in the rural area you want to connect) would send and receive data over the microwave link, and then be connected to homes and farms via cables. Those cables would be much shorter and less expensive, with the bulk of the transmission being done through the ether.
WiMAX:
WiMax delivers broadband to a large area via towers, just like cell phones. This enables your laptop to have high-speed access in any of the hot spots. Instead of yet another cable coming to your home, there would be yet another antenna on the cell-phone tower. This is definitely a point towards broadband service in rural areas. First get the signal to the area, either with a single cable (instead of one to each user) or via a point-to-point wireless system. Then put up a tower or two, and the whole area is online. This saves the trouble of digging lots of trenches, or of putting up wires that are prone to storm damage.
However there is one promising technology that still uses cables to deliver a broadband signal to, well, wherever. It doesn't require laying any new wires (like cable Internet), and it doesn't require overhauling a lot of existing systems (like DSL).It's BPL: (broadband over power lines). As the name suggests, it piggybacks a high speed data signal on those ubiquitous power lines. Those aren't the low-voltage ones that come to your house, but the medium-voltages ones that travel from neighborhood to neighborhood. The signal, like those power lines, can travel a long way thanks to "regenerators" that not only pass the data along, but clean the signal so it doesn't degrade over distance. That means the signal can travel as long as the lines do. Those regenerators can also include Wi-Fi antennas, so if you space them properly they can be placed near homes and farms and whatnot. You can also connect a cable to one to take the signal to the door if you don't feel like going the W-Fi way.
However there have been certain hiccups in the case of BPL. Unlike some early (and ongoing) attempts to do Internet through power lines, BPL doesn't go into individual homes. That's because in order to do so, the signal would have to make its way through a transformer and through a circuit-breaker box, both of which play havoc with it. The result is that the data get through, but much more slowly than leaving the power line before the transformer.
Combine BPL with Wi-Fi, WiMAX, or even (short) cables, and we have an inexpensive way to get the power of the Internet down on the farm using the power of power.
WiMAX is revolutionizing the broadband wireless world, enabling the formation of a global mass-market wireless industry. Putting the WiMAX revolution in the bigger context of the broadband industry, this paper portrays the recent acceleration stage of the Broadband Wireless Access market, determined by the need for broadband connectivity and by the following drivers:
Wireless DSL (WDSL) offers an effective, complementary solution to wireline DSL, allowing DSL operators to provide broadband service to additional areas and populations that would otherwise find themselves outside the broadband loop. Government regulatory bodies are realizing the inherent worth in wireless technologies as a means for solving digital-divide challenges in the last mile and have accordingly initiated a deregulation process in recent years for both licensed and unlicensed bands to support this application. Recent technological advancements and the formation of a global standard and interoperability forum - WiMAX, set the stage for WDSL to take a significant role in the broadband market. Revenues from services delivered via Broadband Wireless Access have already reached $323 million and are expected to jump to $1.75 billion.
There are several ways to get a fast Internet connection to the middle of nowhere. Until not too long ago, the only answer would have been "cable" — that is, laying lines. Cable TV companies, who would be the ones to do this, had been weighing the costs and benefits. However this would have taken years for the investment to pay off. So while cable companies might be leading the market for broadband access to most people (of the 41% of Americans who have high-speed Internet access, almost two-thirds get it from their cable company), they don't do as well to rural areas. And governments that try to require cable companies to lay the wires find themselves battling to force the companies to take new customers.
Would DSL be a means of achieving this requisite of broadband and bridging the digital divide?
The lines are already there, but the equipment wasn't always the latest and greatest, even then. Sending voice was not a matter of big concern, but upgrading the system to handle DSL would mean upgrading the central offices that would have to handle the data coming from all those farms.
The most rattling affair is that there are plenty of places in cities that can't handle DSL, let alone the country side. Despite this, we’ll still read about new projects to lay cable out to smaller communities, either by phone companies, cable companies, or someone else. Is this a waste of money? Probably because cables are on their way out. Another way to get broadband to rural communities is the way many folks get their TV: satellite, which offers download speeds of about 500 Kbps —faster than a modem, but at best half as fast as DSL — through a satellite dish. But you really, really have to want it. The system costs $600 to start, then $60 a month by the services provided by DIRECWAY in the US.
There are other wireless ways to get broadband access.
MCI ("Microwave Communications Inc.") was originally formed to compete with AT & T by using microwave towers to transmit voice signals across the US. Unlike a radio (or a Wi-Fi connection), those towers send the signal in a straight line —unidirectional instead of omni directional. That's sometimes called fixed wireless or point-to-point wireless. One popular standard for this is called LMDS: local multipoint distribution system. Two buildings up to several miles apart would have microwave antennas pointing at each other. One (in, say, the urban area) would be connected to the Internet in the usual way, via some kind of wire; the other (in the rural area you want to connect) would send and receive data over the microwave link, and then be connected to homes and farms via cables. Those cables would be much shorter and less expensive, with the bulk of the transmission being done through the ether.
WiMAX:
WiMax delivers broadband to a large area via towers, just like cell phones. This enables your laptop to have high-speed access in any of the hot spots. Instead of yet another cable coming to your home, there would be yet another antenna on the cell-phone tower. This is definitely a point towards broadband service in rural areas. First get the signal to the area, either with a single cable (instead of one to each user) or via a point-to-point wireless system. Then put up a tower or two, and the whole area is online. This saves the trouble of digging lots of trenches, or of putting up wires that are prone to storm damage.
However there is one promising technology that still uses cables to deliver a broadband signal to, well, wherever. It doesn't require laying any new wires (like cable Internet), and it doesn't require overhauling a lot of existing systems (like DSL).It's BPL: (broadband over power lines). As the name suggests, it piggybacks a high speed data signal on those ubiquitous power lines. Those aren't the low-voltage ones that come to your house, but the medium-voltages ones that travel from neighborhood to neighborhood. The signal, like those power lines, can travel a long way thanks to "regenerators" that not only pass the data along, but clean the signal so it doesn't degrade over distance. That means the signal can travel as long as the lines do. Those regenerators can also include Wi-Fi antennas, so if you space them properly they can be placed near homes and farms and whatnot. You can also connect a cable to one to take the signal to the door if you don't feel like going the W-Fi way.
However there have been certain hiccups in the case of BPL. Unlike some early (and ongoing) attempts to do Internet through power lines, BPL doesn't go into individual homes. That's because in order to do so, the signal would have to make its way through a transformer and through a circuit-breaker box, both of which play havoc with it. The result is that the data get through, but much more slowly than leaving the power line before the transformer.
Combine BPL with Wi-Fi, WiMAX, or even (short) cables, and we have an inexpensive way to get the power of the Internet down on the farm using the power of power.
WiMAX is revolutionizing the broadband wireless world, enabling the formation of a global mass-market wireless industry. Putting the WiMAX revolution in the bigger context of the broadband industry, this paper portrays the recent acceleration stage of the Broadband Wireless Access market, determined by the need for broadband connectivity and by the following drivers:
Friday, November 20, 2009
FINFET
Since the fabrication of MOSFET, the minimum channel length has been shrinking continuously. The motivation behind this decrease has been an increasing interest in high speed devices and in very large scale integrated circuits. The sustained scaling of conventional bulk device requires innovations to circumvent the barriers of fundamental physics constraining the conventional MOSFET device structure. The limits most often cited are control of the density and location of do pants providing high I on /I off ratio and finite sub threshold slope and quantum-mechanical tunneling of carriers through thin gate from drain to source and from drain to body. The channel depletion width must scale with the channel length to contain the off-state leakage I off. This leads to high doping concentration, which degrade the carrier mobility and causes junction edge leakage due to tunneling. Furthermore, the do pant profile control, in terms of depth and steepness, becomes much more difficult. The gate oxide thickness tox must also scale with the channel length to maintain gate control, proper threshold voltage VT and performance. The thinning of the gate dielectric results in gate tunneling leakage, degrading the circuit performance, power and noise margin.
Alternative device structures based on silicon-on-insulator (SOI) technology have emerged as an effective means of extending MOS scaling beyond bulk limits for mainstream high-performance or low-power applications .Partially depleted (PD) SOI was the first SOI technology introduced for high-performance microprocessor applications. The ultra-thin-body fully depleted (FD) SOI and the non-planar FinFET device structures promise to be the potential “future” technology/device choices.
In these device structures, the short-channel effect is controlled by geometry, and the off-state leakage is limited by the thin Si film. For effective suppression of the off-state leakage, the thickness of the Si film must be less than one quarter of the channel length.
The desired VT is achieved by manipulating the gate work function, such as the use of midgap material or poly-SiGe. Concurrently, material enhancements, such as the use of a) high-k gate material and b) strained Si channel for mobility and current drive improvement, have been actively pursued.
As scaling approaches multiple physical limits and as new device structures and materials are introduced, unique and new circuit design issues continue to be presented. In this article, we review the design challenges of these emerging technologies with particular emphasis on the implications and impacts of individual device scaling elements and unique device structures on the circuit design. We focus on the planar device structures, from continuous scaling of PD SOI to FD SOI, and new materials such as strained-Si channel and high-k gate dielectric.
Alternative device structures based on silicon-on-insulator (SOI) technology have emerged as an effective means of extending MOS scaling beyond bulk limits for mainstream high-performance or low-power applications .Partially depleted (PD) SOI was the first SOI technology introduced for high-performance microprocessor applications. The ultra-thin-body fully depleted (FD) SOI and the non-planar FinFET device structures promise to be the potential “future” technology/device choices.
In these device structures, the short-channel effect is controlled by geometry, and the off-state leakage is limited by the thin Si film. For effective suppression of the off-state leakage, the thickness of the Si film must be less than one quarter of the channel length.
The desired VT is achieved by manipulating the gate work function, such as the use of midgap material or poly-SiGe. Concurrently, material enhancements, such as the use of a) high-k gate material and b) strained Si channel for mobility and current drive improvement, have been actively pursued.
As scaling approaches multiple physical limits and as new device structures and materials are introduced, unique and new circuit design issues continue to be presented. In this article, we review the design challenges of these emerging technologies with particular emphasis on the implications and impacts of individual device scaling elements and unique device structures on the circuit design. We focus on the planar device structures, from continuous scaling of PD SOI to FD SOI, and new materials such as strained-Si channel and high-k gate dielectric.
The spin-valve transistor
The spin-valve transistor is a magnetoelectronic device that can be used as a magnetic field sensor. It has a ferromagnet-semiconductor hybrid structure. Using a vacuum metal bonding technique, the spin-valve transistor structure Si/Pt/NiFe/Au/Co/Au/Si is obtained. It employs hot electron transport across the spin valve (NiFe/Au/Co). The hot electrons are injected into the spin valve across the Si/Pt Schottky diode. After traversing across the spin valve these hot electrons are collected across the Au-Si Schottky diode with energy and momentum selection. The output current is found to be extremely sensitive to the spin-dependent scattering of hot electrons in the spin valve. This gives a magnetocurrent above 200% in a few oersted of magnetic field at room temperature. The different physical effects which govern the output current of the device are examined by studying different types of spin-valve transistors that have Si/Au, Si/Pt and Si/Co collector Schottky diodes and Si(100) and Si(111) orientations. It has been observed that along with the Schottky diodes the vacuum metal bonding also plays an important role in determining the output current. In addition, it is realized that collector diodes with extremely low leakage currents, are essential in order to observe huge magnetotransport properties at room temperature
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