Which one can replace graphene, graphene or carbon nanometer?

As is known to all, the global IC industry has been under the "shining" of Moore's law along the route on silicon, but when the mainstream development of CMOS technology to 10 after nanometer technology nodes, the subsequent development of more and more from the laws of physics and the limitation of the manufacturing cost, Moore's law could face the end.

On January 20, top scientific journal Nature published practice spear and physical electronics research institute of Beijing university professor Peng, deputy director of the Mr. Zhang team of world-class breakthrough in the field of carbon nanotube electronics: preparation of nanometer gate 5 for the first time high performance carbon nanotube transistors, and prove its performance beyond the same size silicon CMOS field effect transistor, push the transistor performance to theory.

Graphene VS carbon nanotubes for silicon successor?

On January 20, top scientific journal Nature published practice spear and physical electronics research institute of Beijing university professor peng, deputy director of the Mr. Zhang team of world-class breakthrough in the field of carbon nanotube electronics: preparation of nanometer gate 5 for the first time high performance carbon nanotube transistors, and prove its performance beyond the same size silicon CMOS field effect transistor, push the transistor performance to theory.

On Feb. 27, CCTV news channel broadcast a special program "the magic of graphene", mentioned in the program, graphene is expected to replace silicon, as the main material of the next generation of chips.Using graphene manufacturing a new generation of devices, are expected to make the chip manufacturing implementation corner overtaking, reached the international advanced level.

As is known to all, the global IC industry has been under the "shining" of Moore's law along the route on silicon, but when the mainstream development of CMOS technology to 10 after nanometer technology nodes, the subsequent development of more and more from the laws of physics and the limitation of the manufacturing cost, Moore's law could face the end.In more than 20 years, the scientific community and industry has been exploring all kinds of new materials and new technology, principle of transistor expected to replace silicon CMOS technology, but so far, no organization can achieve 10 nm new devices, and no new devices can be in the best performance in more than a true silicon CMOS devices.

Carbon beyond silicon?

In 2005, the international semiconductor technology route map (ITRS) commission explicitly for the first time around 2020 silicon CMOS technology will achieve its performance limit.Moore era after the study of the integrated circuit technology has become increasingly urgent, many people think that the microelectronics industry after go to the seven nanotechnology node may have to face give up continue to use silicon as the transistor conduction channel.In one of the few substitute material, carbon nano material is recognized as the most likely replace silicon material.

2008 ITRS emerging research material and emerging research devices working in examining all possible silicon CMOS alternative technologies, specifically recommended to the semiconductor industry focuses on carbon-based electronics, appeared as the next 5 ~ 10 years business value for the next generation of electronic technology.The national science foundation committee (NSF) for more than ten years in addition to the national nanotechnology program in the United States continue to carbon nano material and related devices give key support, in 2008, has launched the "more than Moore's law science and engineering project, including carbon electronics research is listed as a top priority.Followed by the increasing of carbon-based electronics research investment, the national nano program began in 2010 to "2020 years of nanoscale electronics" is set to one of three most famous plan (signatureinitiatives).In addition to the United States, the European Union and other governments also attaches great importance to the carbon nano materials and related electronics research and development application, the layout and continue to grab the commanding heights of the core areas of information technology.

Carbon nanotube materials, there are two most likely to replace silicon, carbon nanotubes and graphene.Before the graphene won a Nobel Prize, carbon nanotubes has long been regarded as the most likely to replace silicon semiconductor material, and now, due to the fanaticism of graphene in the global scope, there seems to be instead of carbon nanotubes, so, graphene and carbon nanotubes, who can be of the highest?

Carbon nanotubes advantages and current situation of the development of integrated circuit research and development

In 1991, Japan's NEC mari says the clear male in high resolution transmission electron microscope inspection graphite equipment arc of spherical carbon molecules, accidentally discovered a tubular coaxial nanotubes composed of carbon molecules, which is now known as carbon nanotubes CNT, also known as bucky tube.

Carbon nanotubes material has excellent electrical properties.Carbon nanotubes at room temperature of n-type and p-type carriers (electrons and holes) mobility is symmetrical, all can reach 10000 cm2 / (V?S) above, far beyond the traditional semiconductor materials.In addition to the diameter of only 1 to 3 nm carbon nanotubes, are more likely to be open and shut off the grid voltage is very effective.

The advantages of carbon nanotubes relative to the silicon:

1) the carrier transport is one-dimensional.This means that reduces the carrier scattering phase space, open up the possibility of ballistic transport.Accordingly, low power consumption.

2) the chemical bonds of all carbon atoms are linked, as a result, there is no need for chemical passivation process to eliminate similar to exist in the surface of a silicon suspension is key.This means that the carbon nanotube electronic doesn't have to use silica insulation, high dielectric constant and crystal insulators can be used directly.

3) strong covalent bond structure can make the carbon nanotube has high mechanical stability and thermal stability, and the em has good resistance, can withstand the current density up to 10 a/cm.

4) they are the key dimensions, namely, diameter is controlled by chemical reaction, instead of the traditional manufacturing process.

5) in principle, both active components (transistors) and interconnection link line, can be respectively by the semiconductor and metal attribute of carbon nanotubes.

Graphene VS carbon nanotubes for silicon successor?

Stanford university research team used as shown in (a) the preparation of carbon nanotube array out as shown in (b) of the world's first carbon nanotubes computer;(c) the main function of unit scanning electron microscopic images

The research progress of carbon nanotubes semiconductor devices:

Graphene VS carbon nanotubes for silicon successor?

In recent years, based on carbon nanotubes of carbon-based electronics research has achieved rapid development, and gradually from basic research to practical application.Thanks to the excellent properties of the material itself and the world of policy and financial support, research and development personnel in device physics, device preparation of carbon nanotubes, integration method and so on have made considerable achievements, at the height of the other nanomaterials has never reached.

Research indicates that compared with traditional silicon-based carbon-based electronics devices have 5 ~ 10 times the speed and power consumption advantages, can be achieved under 5 nm node of the semiconductor technology, meet the new demand for the development of semiconductor chips after 2020.Developers have implemented the basic logic unit with a variety of functions, in principle, you can use these logical unit was prepared with high complexity of carbon based integrated circuit.

Nature magazine published in 2013 by Stanford university researchers adopt 178 carbon nanotube transistors made from computer prototype.The MIT technology review reported that the United States in 2014, IBM company said it would before the use of carbon nanotubes in 2020 for the five times faster than existing chip semiconductor chips.The IBM published in relevant media results show that the semiconductor chip based on carbon nanotubes in terms of performance and energy consumption are better than traditional silicon chips have improved significantly: silicon semiconductor technology from 7 nm to 5 nm node, the corresponding chip performance increase of about 20%, and 7 nanotechnology node of carbon-based semiconductor technology 300% higher than that of the performance of silicon-based 7 nm, 15 generations of silicon-based technology improvement.These developments make semiconductor industry saw the dawn of the era, carbon-based electronics is expected to continue to improve performance of Moore's law until 2050.

However, carbon nanotubes have limitations, artificial carbon nanotubes is a combination of metal and semiconductor properties.These two properties of carbon nanotubes mutually "adhesion" into a rope or beam, makes use of carbon nanotubes, because only the electrical properties of nanotubes have transistor performance.The existing preparation method to produce the carbon nanotubes are a mixture of all kinds of chiral and different pipe diameter, chirality and pipe diameter is different, as a direct result of conductivity qualitatively different, which makes carbon nanotubes, there are many difficulties in most practical applications.

Professor peng lian spear in an interview that the current IBM on carbon nanotubes research direction is mixed preparation methods, and practice the spear and Mr. Zhang peng group USES is undoped preparation, this is the world's first, their team after 10 years of research, developed the undoped preparation method, developed at the 10 top gate CMOS nano carbon nanotubes fet, the p-type and n-type device under the lower working voltage (0.4 V), performance than the current best and work under the higher working voltage (0.7 V) silicon CMOS transistors.Now, they overcome the limit size of process, successfully developed the 5 nm gate length carbon nanotube transistors, its performance is close to the limit is determined by the principles of quantum mechanics theory.

The status and progress of graphene fet

Graphene is a two-dimensional structure of carbon material, because it has zero band gap characteristics, even if the carrier at room temperature in the mean free path of graphene and coherence length can also be used for micron level, so it is a kind of excellent conductive materials.Graphene field-effect device is one of the most important challenge is how to increase the band gap, and not reduce its mobility is very high.

Graphene transistors compared with the traditional silicon semiconductor transistor, has the following features:

(1) under the control of the electric field, the types of carrier in graphene to continuous variation between the electrons and holes, bipolar electric conductivity.GFET, therefore, cannot like conventional semiconductor transistor was effectively closed, not suitable for logic in the town of devices.But some new kind of structure could be based on the graphite associating high switching current of the device;

(2) the carrier mobility of graphene is very high, but also W by the electric field control, in the field of high frequency, especially in the field of radio frequency (RF) has great potential for application.

(3) for the two-dimensional material graphene itself, reduce the circuit size and integrated circuit.Preparation of graphene CVD can be transferred to any substrate, is advantageous to the preparation of graphene and other material heterojunction, study new physical phenomena and new electronic devices.

Graphene is better than that of carbon nanotubes is, in the manufacturing process of carbon nanotubes, generates the metal and semiconductor material mixture of carbon nanotubes, making complex circuit, carbon nanotubes must be carefully screening and positioning, has not developed a very good method, which is much easier for graphene.This unique performance make graphene as an alternative material has been applied in many new areas.

High electron/hole mobility and symmetry of band structure enables the graphene is very suitable for production of high frequency transistor, although graphene conductive ability is admirable, but it lacks the energy gap, namely graphene without the forbidden band "in" electronic state can't energy range, as the switch devices limits its applications, and graphene nano belt (GNR) can open the energy gap of graphene, as a result, class of semiconductor GNR has attracted great attention, inspire scientists widespread interest in the development of the whole graphene circuit.

AndreGeim group reported that Manchester university, besides it had developed 10 nm level outside the actual operation of graphene transistors, and they have not yet announced the latest research results, has been developed the width of a molecular smaller graphene transistors, the graphene transistor is actually composed of a single atom transistor.

In 2008, IBM's Watson research center in the world the first made low noise graphene transistors.Ordinary nano device with the decrease of the size, called the 1 / f noise will be more and more obvious, worsen device SNR, this phenomenon is the rule of "hogg (Hooge 'sLaw)".Graphene and carbon nanotubes

Tube and silicone material can produce the phenomenon, therefore, how to reduce the 1 / f noise become one of the key problems to realize nanometer element.IBM by overlapping 2 layers of graphene, successfully trial-produced the transistor.Because 2 generates strong electronic combination between layers of graphene, which control the 1 / f noise.IBM's Ming - YuLin the findings prove that 2 layer of graphene is expected to be applied to various fields.

In May 2008, Georgia institute of technology's hill with the Lincoln laboratory at the Massachusetts institute of technology cooperation on a single chip to generate hundreds of graphene transistor array.

Silicon micro computer processors at room temperature can only perform a certain number of operations per second, but electron through the graphene almost no resistance, the heat generated is also very less.In addition, graphene is in itself a good heat conductor, can quickly send out quantity of heat.Due to excellent performance, made by the graphene electronics work much faster.

Graphene devices made of the computer's running speed can reach terahertz, namely 1 x 106 KHZ 1000 times, if we can further development, its significance is self-evident.

In addition to the computer to run faster, also can used for graphene devices need high speed work communication technology and imaging technology.Concerned expert thinks, graphene may be first applied to the high frequency field, such as THZ wave imaging, one of the purposes is used to detect the hidden weapon.Speed is not the only advantage of graphene, silicon cannot be divided into less than 10 nm small pieces, otherwise it will lose its electronic properties.Compared with silicon, graphene divided into 1 nm small films, the basic physical properties do not change, but its electronic properties are likely to play.

Conclusion: silicon struggle remains to be seen

1) the development of silicon electronic material is close to the top, carbon nanotubes and graphene have a smaller size than silicon devices and more excellent electrical properties, is likely to replace silicon materials in the future.

2) carbon nanotubes excellent properties and find that the earlier, the methods of its manufacture and build more deeply, and made some achievements, enough to prove that carbon nanotubes have build the practical conditions of microelectronic device, but there exist some problems in the traditional method of building components, and the separation of different carbon nanotubes is one of the biggest challenges, carbon nanotube integrated circuit still need some time to explore.

3) Graphene and carbon nanotubes as excellent properties, and build device didn't have to go through complex separation process, practical stronger, than carbon nanotubes have also made certain breakthroughs in preparation, but its found late, on nano-electronic devices remains to be explored.In the future, they might become together constitute the dominant material of the integrated circuit.

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