Technological bottlenecks
The problem that prevented graphene from initially being available for developmental research in commercial uses was that the creation of high-quality graphene was a very expensive and complex process (of chemical vapour disposition). It involved the use of toxic chemicals to grow graphene as a monolayer by exposing platinum, nickel or titanium-carbide to ethylene or benzene at high temperatures.
Also, it was previously impossible to grow graphene layers on a large scale using crystalline epitaxy on anything other than a metallic substrate. This severely limited its use in electronics as it was difficult, at that time, to separate graphene layers from its metallic substrate without damaging the graphene.
However, later studies found that, by analysing graphene’s interfacial adhesive energy, it is possible to effectively separate graphene from the metallic board on which it is grown. Besides, it is also possible to reuse the board for future applications (theoretically, an infinite number of times), thereby reducing the toxic waste previously created by this process.
Further, quality of graphene that was separated by using this method was high enough to create molecular electronic devices successfully. While this research is very highly regarded, quality of graphene produced will still be the limiting factor in technological applications.
Graphene needs to be produced on very thin pieces of metal or other arbitrary surfaces (tens of nanometres thick) using chemical vapour deposition at low temperatures. And it has to be separated in a way that can control such impurities as ripples, doping levels and domain size, while also controlling the number and relative crystallographic orientation of graphene layers. With production techniques becoming more simplified and cost-effective, graphene will be more widely utilised in various applications in general and electronics in particular.
Graphene has a tremendous number of possible applications, and scientists and engineers are just getting started in their work to develop it. Let us hope that their sincere efforts in this direction will create good chances of developing new graphene based electronics applications that are faster, flexible, robust, cheaper and efficient.
Dr S.S. Verma is a professor at Department of Physics, Sant Longowal Institute of Engineering and Technology, Sangrur, Punjab
