By examining the material at an atomic level, the team was able to establish the reason why the thin sheet of carbon cannot control the electron current.
Ever since its discovery about 10 years ago, graphene has not stopped to amaze scientists, who keep finding more and more of its properties. It is considered a super conductor, with efficiency higher than even silicon. As the European Commission reported last month, the material is expected to have much better prospects than steel and plastic for electronic gadgets. Its applications have been explored by telecom companies and solar panel manufacturers, as graphene could be used to make super thin and flexible batteries or see-through solar panels.
Having said that, one of the biggest limitations associated with the use of the element in high efficiency electronic devices and solar cells, is the fact that a single sheet of the material does not have a range of energy that can prevent electrons from existing.
Scientists have tried to overcome this problem by adding extra layers of graphene, however if used in any electronic equipment, the double layers act as if they are just a single sheet.
This is why the team at Berkeley, led by Keun Su Kim, decided to look at the bilayered material using a beam of X-ray photons, which enabled them to examine the material’s electromagnetic spectrum. They were surprised to find the presence of electrons, which act as photons, also known as Dirac fermions. Exactly these prevent the material from allowing complete switch off of the conduction.
Searching for the reasons to why these Dirac fermions appear between the two layers, the scientists had to examine the individual atoms. Unfortunately they found that a misalignment, also referred to as twists, between as few as 10 atoms within a square micron between the two layers could cause these to occur.
The authors, however, are very positive about the discovery. They believe that by finding the reasons behind the problem, they would be able to develop techniques and methods to overcome it much faster and more effectively.