This blog examines research about a new promising material known as graphene, a name which indicates the original mechanical sawing process at atomic level of a graphite block, and has recently changed the way we think regarding modern electronics technology. This new material holds promise of becoming a reference in terms of performance for just about all ICs which may be realized by combining graphene with other materials to obtain unprecedented efficiencies. Graphene, indeed, has an exceptional low thickness, due to the precision of the mechanical process fabrication that is so effective in reaching a mono-atomic layer thickness for the graphene substrate. Due to this exceptional thickness, but not only due to this characteristic, the graphene material has really good properties as a conductor of electricity and heat:
“One of the most useful properties of graphene is that it is a zero-overlap semimetal (with both holes and electrons as charge carriers) with very high electrical conductivity. Carbon atoms have a total of 6 electrons; 2 in the inner shell and 4 in the outer shell. The 4 outer shell electrons in an individual carbon atom are available for chemical bonding, but in graphene, each atom is connected to 3 other carbon atoms on the two dimensional plane, leaving 1 electron freely available in the third dimension for electronic conduction. These highly-mobile electrons are called pi (π) electrons and are located above and below the graphene sheet. These pi orbitals overlap and help to enhance the carbon to carbon bonds in graphene. Fundamentally, the electronic properties of graphene are dictated by the bonding and anti-bonding (the valance and conduction bands) of these pi orbitals.
Combined research over the last 50 years has proved that at the Dirac point in graphene, electrons and holes have zero effective mass. This occurs because the energy – movement relation (the spectrum for excitations) is linear for low energies near the 6 individual corners of the Brillouin zone. These electrons and holes are known as Dirac fermions, or Graphinos, and the 6 corners of the Brillouin zone are known as the Dirac points. Due to the zero density of states at the Dirac points, electronic conductivity is actually quite low. However, the Fermi level can be changed by doping (with electrons or holes) to create a material that is potentially better at conducting electricity than, for example, copper at room temperature.” (Source: Graphenea)
Furthermore graphene is showing a new amazing property, as it is revealed by the recent research project at MIT (Massachusetts Institute of Technology) by researchers (see Figure 1):
“A team of international researchers from the US (MIT), Israel, Croatia, and Singapore, have discovered that under certain circumstances, a flow of electric current running through a sheet of graphene can exceed the speed of slowed-down light and produce a kind of optical “boom”: an intense, focused beam of light.” (Source: EETimes Europe)
“Graphene plasmons have been found to be an exciting plasmonic platform, thanks to their high field confinement and low phase velocity, motivating contemporary research to revisit established concepts in light–matter interaction.” (Source: nature.com)
Graphene represents a valid option for silicon photonics because it might minimize the loss of efficiency due to the interfacing between optical guides and the silicon metal stripes for the light-on-chip solution (see Figure 2):
The graphene material offers many opportunities to become a reference substrate to be utilized in applications that require high efficiency in the transportation of light, a new interesting solution that is quickly becoming adopted in the electronics industry. Do you think graphene is a good solution?