Scientists from the University of California, Berkeley have created metallic cables of graphene, a pure carbon-based material which for some time has shown promise in various fields: from the fabrication of more powerful batteries to the coming generation of computers. Why are transistors of carbon going to unseat those of silicon?
A Familiar Material
Carbon is nothing new in the field of electronics. The first transistors of this material were from 1997, the year the University of Delft and the technology giant IBM joined forces to fabricate them.
Transistors are the basic components of computers. However, it was 16 years until engineers of the Stanford University would succeed in producing an actual computer from transistors made of carbon. It was a pretty primitive machine that only did calculations and classifications, but which served to demonstrate that it was possible to integrate carbon in electronic devices that went further than simple circuits.
This proves important because carbon, which is a crucial element of the proteins that comprise humans, conducts electricity more efficiently, with less energy spent (an example of this can be seen in the human brain).
In a world more conscious of the importance of conserving energy, this characteristic of carbon is very valuable. This value is not solely because of ecological concerns related to energy usage, but also because carbon adds durability to the devices, which, in the end, is also a relevant factor for the environment, being that it would reduce e-waste.
The reduced energy consumption of the transistors made of carbon is due to the fact that they are thinner, and they do not heat up as much as transistors made of silicon, with which in order to increase the capacity of the computer, one would need to increase the concentration of these in a single space, which generates more heat (and this, in excess, leads to rapid deterioration and malfunction). It is because of this that, in order to avoid these inherent difficulties of silicon transistors (which are at their limits of the speeds they can reach without generating additional problems brought on by the heat), researchers are turning to alternative materials. And carbon is clearly leading the race.
The UC Berkeley breakthrough will allow for the production of carbon-based computers to be much easier, because the architecture of their integrated circuits will be.
The metallic carbon (graphene) wires, developed by a team of chemists and physicists of the university, interconnect the semiconducting elements within the transistors with the intrinsic electroconductive capabilities of the carbon. In this way, they construct a metallic conductor that is ultrathin and ultraefficient, not in the form of nanotubes of carbon, but of nanoribbons of graphene, which are more precise and reproducible on a grand scale.
The wires of the study, that was published in Science, are formed of a version of these semiconducting nanoribbons, assembled chemically in short segments that unite electrons across tens of nanometers in length, but of only one in width, achieving a conductivity similar to that of bidirectional graphene.
Pure carbon also allows for the acceleration of wireless communications with graphene nanoantenna, developed by Georgia Tech in 2013. The behavior of electrons in graphene produces a range of lower frequency, resulting in lower energy consumption than conventional antennas. In trials, it was observed that at a few centimeters of distance, they reached speeds up to 100 TB per second. In the future, graphene nanoantenna could exponentially improve the wireless connections of mobile devices and laptops, if the costs of production of the antenna are able to be lowered.
On another front, in 2014 IBM created the first graphene computer chip exclusively for mobile telephony. This chip also enabled a much faster transmission of data with lower energy consumption. However, it did not enter into the market, also because of high costs. Although carbon allows for higher performance, in practice silicon is much more profitable, because of this the day has not yet arrived in which it is not commonly utilized.
Later on graphene was utilized by the Gwangju Institute of Science and Technology (South Korea) in producing supercapacitors in batteries for electric vehicles (EVs), which resulted in a faster charge time compared to that of lithium batteries that are commonly employed today.
Lastly, graphene can contribute to the improvement of quantum computers. In 2017, at the Federal Polytechnic School of Lausanne (Switzerland), a team of researchers formed non-linear capacitors by inserting boron nitride between two sheets of graphene. The capacitors served to produce stable qubits (the unit of measure for quantum storage), harnessing the ultra conductivity of carbon-based circuits, which (as was previously mentioned) does not increase temperature. Having reduced electromagnetic sensitivity of the carbon, qubits are not affected as easily by their environment in that regard. Pure carbon stabilizes the qubits and helps better process quantum information.