Electrons can travel over 100 times faster in graphene than in silicon

March 25th, 2008 - 5:20 pm ICT by admin  

Washington, March 25 (ANI): Physicists at the University of Maryland, US, have shown that electrons can travel over 100 times faster in graphene than in silicon.

This has proven that in graphene, the intrinsic limit to the mobility, which is a measure of how well a material conducts electricity, is higher than any other known material at room temperature.

Graphene, a single-atom-thick sheet of graphite, is a new material that combines aspects of semiconductors and metals.

The findings are the first measurement of the effect of thermal vibrations on the conduction of electrons in graphene, and show that thermal vibrations have an extraordinarily small effect on the electrons in graphene.

In graphene, the vibrating atoms at room temperature produce a resistivity of about 1.0 microOhm-cm, which is about 35 percent less than the resistivity of copper, the lowest resistivity material known at room temperature.

According to physics professor Michael S. Fuhrer of the University of Marylands Center for Nanophysics and Advanced Materials, “Other extrinsic sources in today’s fairly dirty graphene samples add some extra resistivity to graphene, so the overall resistivity isn’t quite as low as copper’s at room temperature yet.

However, graphene has far fewer electrons than copper, so in graphene, the electrical current is carried by only a few electrons moving much faster than the electrons in copper,” he explained.

In semiconductors, a different measure, mobility, is used to quantify how fast electrons move.

The limit to mobility of electrons in graphene is set by thermal vibration of the atoms and is about 200,000 cm2/Vs at room temperature, compared to about 1,400 cm2/Vs in silicon.

Mobility determines the speed at which an electronic device can turn on and off.

The very high mobility makes graphene promising for applications in which transistors much switch extremely fast, such as in processing extremely high frequency signals.

The low resitivity and extremely thin nature of graphene also promises applications in thin, mechanically tough, electrically conducting, transparent films. Such films are sorely needed in a variety of electronics applications from touch screens to photovoltaic cells.

Graphene is also a very promising material for chemical and bio-chemical sensing applications. (ANI)

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