Graphene - The Strongest

Graphene:-

Graphene which is about one atom thick is found to be the world's strongest material according to a latest information by scientists. It is made of carbon atoms. It is stronger than diamond which is also made of carbon.It conducts electricity 100 times better than any other materials existing now.It is expected that this graphene would replace silicon in computer chips. But it would take some time to replace as every one is known and using silicon only. Scientists celebrated it as a boon by god to the science.The right side image shows a ultra strong paper made of graphene.

Structure of Graphene:-


Graphene is closely related to buckyballs and polycyclic aromatic hydrocarbons.Some researchers believe that graphene transistors could operate in the terahertz range, about 1000 times faster than conventional silicon ones. The reason is that electrons move much faster through graphene. Unfortunately the difference in conductivity between the "on" and "off" states is less for graphene. This makes it harder to work with.

Electrons can very easily travel along the carbon sheet making graphene an extremely good electrical conductor. This conductivity suggests that graphene could have a future in the semiconductor industry, with the fabrication of high speed transistors.

Shot Noise In Graphene:-

By biasing a conductor that has sizes smaller than the electron-phonon inelastic scattering length, it is possible to study the out of equilibrium current noise generated by the system: such noise is called shot noise . These current fluctuations are due to the discreteness of charge. By probing shot noise, one can collect informations about disorder, interactions, contact quality, or carrier statistics for example. We have studied shot noise in short and large graphene strips . We used two ways to extract the Fano factor, using the formula defined in and using a tunnel junction to calibrate the noise of our devices .



We use a home made set-up especially design to work at high frequency. In perfect short and wide graphene strips (W/L ≥ 3), for heavily doped graphene leads, at the Dirac point both minimum conductivity and Fano factor are expected to reach universal values of 4e2/πh and 1/3 respectively .

3G-Technology

The International Telecommunication Union (ITU) defined the third generation (3G) of mobile telephony standards – IMT-2000 – to facilitate growth, increase bandwidth, and support more diverse applications. The third generation, as the name suggests, follows two earlier generations.

• The first generation (1G) began in the early 80's with commercial deployment of Advanced Mobile Phone Service (AMPS) cellular networks.
• The second generation (2G) emerged in the 90's when mobile operators deployed two competing digital voice standards. In North America, some operators adopted IS-95, which used Code Division Multiple Access (CDMA) to multiplex up to 64 calls per channel in the 800 MHz band.

3G NETWORK:
To provide standards for the 3G technology, 3GPP or Third Generation Partnership Project was established. Network providers that plan to cater to 3G mobile phones will then have to change their systems. Network providers can update their existing 2G systems to use 3G technology by incorporating GPRS services. GPRS or General Packet Radio Service can be the first step when upgrading into 3G technology. Network operators and providers who are already using GPRS can switch directly into 3G technology by going for a UMTS system.The 3G Standard
3G stands for third-generation wireless technology and networks. 3G is based on the International Telecommunication Union (ITU) initiative for a single global wireless standard called International Mobile Telecommunications-2000 (IMT-2000). This concept of a single standard evolved into a family of five 3G wireless standards. Of those five, the most widely accepted are CDMA2000, WCDMA(UMTS) and TD-SCDMA.

According to the ITU and IMT-2000, a wireless standard must meet minimum bit-rate requirements to be considered 3G:
• 2 Mbps in fixed or in-building environments
• 384 Kbps in pedestrian or urban environments
• 144 Kbps in wide area mobile environments
• Variable data rates in large geographic area systems (satellite)



In addition to providing faster bit rates and greater capacity over previous-generation technologies, 3G
standards excel by effectively:
• Delivering mobile data
• Offering greater network capacity