A Brief History of Graphene

For 70 years, scientists believed that 2-dimensional materials such as graphene cannot exist in the free state because it was believed to be thermodynamically unstable unlike its curved structures such as carbon nanotubes and fullerenes. 

The figure above shows that the 2-D material is graphene.When graphene is shaped into a ball, it becomes fullerene and when it is rolled to a tube, it becomes carbon nanotubes.It requires at least 10 layers of graphene for it to be called graphite.

The melting temperature of thin films decreases as the dimension of the materials decreases. When the 3-D structure of graphite turns into a 2-D structure graphene, the melting temperature is thought to be too low for it to be stable. However, it turned out that the hexagonal arrangements of carbons on graphene made it pretty stable. This is the reason why scientists have done researcch on carbon nanotubes (CNTs) and fullerene for a longer period of time than they have done on graphene. Graphene has been studied actively starting from 2004 but CNTs have been studied on since 1952 by L.V. Radushkevich and V.M. Lukyanovich. 

Importantly, graphene exhibited high crystal quality the material is highly conductive. The pure it can get, the more conductive the material becomes. For this reason, lots of researchers are trying to make graphene-based electronics. In addition, due to the limits set by the thermodynamics and quantum mechanimcs as to how much computing power you can have with silicon, scientists are mentioning graphene or carbon nanotubes as the new, faster material for computer chips. 

However, the problem for the applications of graphene is that graphene has 0eV band gap, which means graphene is conductive 24 hours. So, if graphene was used to make a electronic device, the device would not be able to be turned off. To fix this problem, physicists suggested solutions solutions. We can induce a band gap so that graphene-based optoelectronics can be stopped working when the switch is off. In an experiment, 0.3 eV of band gap was induced in bilayer graphene. In a single layer graphene, more work should be done to induce band gap.