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  • IBM Develops A New Graphene-Based IC With Performances On Par With Current Silicon Technology

    IBM has developed what is reported to be one of the fastest graphene-based integrated circuits (IC) to date, with an overall performance that is up to 10,000 times better compared to similar devices developed previously

    IBM built the graphene-based IC as a radio frequency receiver that can perform signal amplification, filtering, and mixing. The circuit was able to process text messages without any distortion in a series of tests performed by the IBM research team.

    One of the first examples of the use of graphene in electronic applications took place in 2010 when Big Blue researchers engineered a graphene device with a band gap large enough to be used in infrared (NYSE:IR) detectors and emitters. This development was followed up a year later when IBM developed a graphene transistor that can operate with frequencies up to 100 GHz

    After another six months, IBM developed the first graphene-based IC circuit, which was the predecessor of the model discussed in this article. The precursor circuit served as a basic radio component called as broadband radio-frequency mixer, which processes signals by finding the difference between two high-frequency wavelengths.

    Supratik Guha, director of physical sciences at IBM research, in a recent press conference said that "this is the first time that someone has shown graphene devices and circuits to perform modern wireless communication functions which so far have only been seen in silicon ICs."

    The new graphene-based ICs were also able to overcome problems such as the degradation of transistor performance with time. The solution used to solve the issue was a new manufacturing method where graphene is added in a later stage of the process in order to prevent being damaged. However, the manufacturing method developed by the IBM team still requires an expensive process to produce the high-quality graphene needed. New methods of producing high-quality graphene at lower costs are under development.

    In spite of all the doubts about the potential of graphene to yield benefits in electronic applications due to the lack of an inherent band gap, IBM has invested heavily in research and the latest results show that new applications in smartphones and gadgets may soon become a reality

    Shu-Jen Han of IBM Research described the impact of this research in an IBM blog, saying that the development of the graphene-based radio frequency receivers has the potential to enhance the communication speed of wireless devices and pave the way toward new applications in consumer electronics with performances beyond what is possible to achieve with current silicon technology.

    Han stated that the integration of graphene radio frequency (NYSE:RF) devices into current low-cost silicon technology platforms could also spur a new wave of pervasive wireless communication, which in turn would allow the development of smart sensors, RFID tags, and similar devices to send data signals at significant distances.

    The so-called "Internet-of-things", a concept coined by Kevin Ashton back in the late 90s, would rely heavily on smart sensors and RFIDs to create an environment where objects and people would interact in an intelligent way using an internet-like backbone.

    About the Author

    This article was written by Matteo Martini, author and CEO of Martini Tech, a company that provides nanoimprint, PSS patterning, MOCVD deposition, sputtering, MEMS foundry, GaN wafer, GaN LED Technology and other microfabrication-related services. Please have a look at our blog.

    May 29 4:06 PM | Link | Comment!
  • Gallium Carbide Or Silicon Nitride: Which Is Best Material For Power Electronics Devices

    As an alternative to silicon for power electronics evices, the main two options are without doubt silicon carbide and gallium nitride, the reason being the higher breakdown voltage that both of them have comparing to silicon.

    Generally speaking, each one of two materials has its advantages and disadvantages: gallium nitride has a higher breakdown voltage when compared to silicon carbide, however, silicon carbide has a higher thermal conductivity and this property bodes well with applications that require high thermal dissipation

    The power electronics industry is divided in two camps, each one of them supporting the use of one or the other candidate material as replacement of silicon.

    California, US-based Efficient Power Conversion is betting high on gallium nitride.

    Believed to be the first company to actually having marketed MOSFETs based on gallium nitride, Efficient Power Conversion is now planning to move most of its offer about power electronics devices to GaN.

    According to EPC`s co-founder Alex Lidow, gallium nitride is expected to reach price parity with silicon in a couple of years at latest and after that it is likely that silicon will mostly disappear from the power market.

    Transphorm, another US-based company betting on gallium nitride, has recently reached an agreement with Fujitsu Inc. and Fujitsu Semiconductor to work together on gallium nitride- based devices by integrating their respective power device businesses.

    International Rectifier, another company based in the US dealing with power electronic devices and formerly headed by the EFP co-founder Alex Lidow, has also adopted gallium nitride as their material of reference.

    International Rectifier` s system and applications director Marco Palma explained this choice as follows: "We went directly to the best choice which is without any doubt gallium nitride. We are already serving some our major customers with GaN-based devices.

    According to Mr. Palma, International Rectifier has been able to both raise the breakdown voltage of its inverters and make them more compact at the same time by moving away from silicon as material of reference.

    Other companies all around the world are also betting high on gallium nitride.

    But in the industry there is not a full consensus on gallium nitride as the best alternative to silicon for power electronics devices.

    Anvil Semiconductors, a company based in the United Kingdom, is now working almost exclusively with silicon carbide. Silicon carbide, as discussed above, has the main advantage of having a higher thermal conductivity than gallium nitride and therefore SiC-based devices are more resistant to heat shocks and can be placed in positions where the heat would otherwise damage a device based on gallium nitride or silicon.

    According to most researchers, in the medium to long-term future, it is likely that the two materials will coexist in the power electronics ecosystem and each one will be mostly used for particular applications: silicon carbide is likely to become most used in applications such as smart grids and high-speed trains while gallium nitride may become more popular with engine controlling systems in the automotive business (especially electric vehicles)

    In other words, silicon carbide may become the solution of choice for devices requiring an amperage of less than 10KA to 50KA while gallium nitride may be used for applications that require higher amperages.

    About the Author-

    This article is written by Matteo Martini, a nanotechnology expert based in Tokyo, Japan, specialized in: nanoimprint technology, patterned sapphire substrates for LED applications, sputtering, MEMS, GaN power devices and other related topics.

    Apr 25 12:12 PM | Link | Comment!
  • Why Future Looks Bright For Carbon Nanotubes

    Carbon nanotubes, often abbreviated as CNTs, are very small allotropes of carbon, with dimensions in the range of few nanometers or lower, which have properties that make them very much suitable for a number of applications

    It has an enormously high tensile strength and they have a very high electrical conductivity along with other advantages such as the ability to withstand high temperatures and other extreme conditions.

    As for physical strength, it has been shown that potentially they can reach a modulus up to 1TPa, which would put them much beyond the limits of steel or other high-toughness materials available today

    However, such theoretical properties have not been fully achieved yet, with current production methods such as CVD or spinning being able to produce them with substantially lower strength properties. Currently carbon nanotube-based yarns have been demonstrated with strengths of 10 GPa but having defects in the structure bringing down such value to 1GPa in real world applications

    While the production of carbon nanotubes has so far proven expensive, they are making a slow but steady advance in many fields such as medicine, military, automotive field, in the construction and electronics business among others.

    So far, they have been also successfully adopted in small quantities in carbon fibers for the production of tennis rackets, baseball bats, automobile parts and for other mission-critical tools where strength and light weight are needed.

    The issue of high cost has been so far the stumbling block preventing widespread adoption of carbon nanotubes for a range of applications, but efforts made by some major players such as Arkema S.A., CNano Technology Ltd., Hyperion Catalysis International Inc., are driving prices down and this may further increase their adoption for new applications, such as adoption in the IC market or in the MEMS market.

    For example, new potential applications in the IC market are most interesting as IC based on CNTs, also known as carbon nanotube field-effect transistors, have been demonstrated to operate at room temperature and being able to switch using only one electron. Since the year 2000, several IC components have been developed, such as: nanotube-based transistors, nanotube-based memory components, nanotube-based memory switches; density of such components, however, is not even remotely comparable to today silicon-based ICs.

    Another future big market for CNTs may be the solar market, as they have shown the interesting property of being able to absorb infra-red light and therefore being able to increase the efficiency of classic silicon-based solar cells.

    Finally, they may have yet another potential application in hydrogen storage, as they have the property to allow molecules of condensed gases being stored inside a single walled CNT.

    Geographically wise speaking, the major growth in year 2012 in their utilization has been in the Asia-Pacific and United States markets, due to an increase of number of applications in the electronics and other semiconductor markets.

    As of today, main players in the CNTs market are Nanocyl S.A. of Belgium, Showa Denko K.K. of Japan in addition to the companies already mentioned above: Arkema of France, CNano Technology Ltd. and Hyperion Catalysis International Inc. of the US.

    About the Author-

    This article was written by Matteo Martini, author and CEO of Martini Tech, a company that provides Nano imprinting, PSS patterning, MOCVD deposition, sputtering, MEMS foundry, GaN wafer, GaN LED Technology and other microfabrication-related services. Please have a look at our blog.

    Mar 26 12:43 PM | Link | Comment!
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