Talking Engineering: Dr Simon Thomas

Talking Engineering 10: Dr Simon Thomas
The Revolutionary Potential of Graphene in Electronics

Conducted by Max Hersov, December 2022

A University of Cambridge spin-off founded in 2017, Paragraf is the first company in the world to mass produce Graphene-based electronic devices using standard semiconductor processes. Their patented contamination-free deposition technology, developed by CEO, Dr Simon Thomas and Technical Director, Dr Ivor Guiney, delivers game-changing opportunities for the commercialisation of Graphene by allowing them to manufacture high-purity 2D Graphene sheets at scale.

Dr Simon Thomas discussed Graphene’s potential to revolutionise electronics with Max Hersov.

MH: Why is Graphene so useful?

ST: Graphene is pretty unique as a material; it is the first two-dimensional material to be isolated in the real world. What this means is that it has length and width, but no height: it is confined to a single layer of atoms. There are other 2D materials now, which Paragraf is working with as well, but when you create a 2D material, it changes its electronic structure. In a bulk material, such as a metal, the electrons are orbiting in regions around the atoms and are stuck in the middle of the material, although they can be pushed back and forth by electricity. However, in a 2D material, such as Graphene, you may wonder where do the electrons go? Well, you end up with a set of delocalised Pi electrons floating on the top of this 2D lattice, and this is what unlocks a whole set of new properties.

This is why Graphene became so famous and they called it the ‘wonder material’. When Graphene was isolated [in 2004 by two researchers at The University of Manchester, Professor Andre Geim and Professor Kostya Novoselov], they realised that it actually unlocks many other properties as well, for example thermal conduction. Normally, thermal conduction happens in 3D space but when you only have one plane to conduct along, it is really good. Moreover, Graphene’s incredible strength-to-weight ratio comes from the fact that you only have bonds in the atomic plane - pure covalent sigma bonds which are very strong. So, the reason why Graphene was so revered is that it was the first material to have a group of properties that were all better than lots of other materials. The only problem is that manufacturing a sheet of Graphene, which is one atom thick, is quite difficult.

MH: Are the properties of Graphene unique, or what puts graphene ahead of the other more recently discovered 2D materials?

ST: Graphene’s particular set of properties is unique at present. The other 2D materials that we are talking about also have the same manufacturing difficulty as Graphene, and although they may be better at some things, they each have their own downfalls. For example, another material that would also be very useful is Silicene, which is a single layer of silicon atoms. The problem with this is that it reacts easily with Oxygen. So, although you can make Graphene because it is stable in the real world, as soon as you make Silicene it reacts with Oxygen and disappears. There are other 2D materials coming along such as Boron Nitride which are stable in the real world, but it is much harder to manufacture a uniform layer. I would say while Graphene is largely unique now, in the future there will be many more 2D materials with various strengths that we can draw upon.

MH: On your website you highlight three main applications: Automotives, Extreme Environments and Energy Storage. Why these three in particular and are there any other applications which seem promising?

ST: There are lots of applications for Graphene: for example, it is so much more conductive than Silicon that it can basically replace it in most applications, in particular computer chips. The applications that you have mentioned are just the early applications that we have targeted because the devices that we are making there have a simpler architecture than for example a computer chip. However, in the future Paragraf is aiming to create many other devices out of Graphene that are currently made of Silicon,. Due to the greater conductivity, a Graphene chip can be up to 1000 times faster than Silicon, and also uses less than 50% of the energy that Silicon uses.

One of the biggest problems currently facing the world, with relation to global warming, is energy usage, particularly in the current situation with energy prices so high. By 2025, 20% of the world's energy will be used in information processing and data storage. That is a fifth of the world's energy, spent just on computing. So, if you replace Silicon with Graphene, you save 10% at least of the world's energy expenditure. That’s the difference Graphene can make. Instead of only focusing on trying to improve energy generation and storage, we must also reduce our energy usage: this is a two way thing, and that’s why, I would say, Graphene has such an important role to play.

MH: That’s incredible: it could have a much bigger effect than I had imagined. However, I understand that although electric cars are much more environmentally friendly than petrol cars over their lifetimes, there is some controversy around the production-energy requirements and end-of-life pollution, particularly regarding batteries. Is Graphene production-energy efficient, and does the process have a high atom economy (i.e. does it produce waste chemicals?)

ST: In the past, production of quality Graphene was very difficult, but we have used techniques learned in production of other semiconductors and other devices to create a manufacturing technique that is much more sustainable than others. I am not allowed to go into detail, but the chemicals used are much less harmful than those used in the manufacture of Silicon or other materials. Moreover, the nature of Graphene (being carbon) means that there are no harmful waste chemicals in end-of-life of Graphene devices, and in that respect, Graphene is much more sustainable.

MH: What is the main hurdle that you are facing in achieving your aim of replacing Silicon with Graphene?

ST: Sadly, the main problems we face at the moment are not technological but political: risk appetite is low for investment (especially for high tech which has to be integrated into other systems) due to the combination of a global pandemic, large-scale war with global effects, and a massive increase in energy prices in the space of just over a year. Brexit has also been an issue for all businesses as trade deals are having to be renegotiated, and also at the moment there is what is called the ‘chip war’ - China and the US don’t trust each other to make chips, so they are localising their supply chains. For example, Taiwan Semiconductor Manufacturing Company (TSMC), the biggest silicon chip manufacturer, is now constructing its largest factory in Arizona (with an investment of ~$40 bln). All of this means that people are refocusing on Silicon and are not as interested in looking at new technologies.

MH: What led you to look at Graphene?

ST: As many things are, it was quite serendipitous. I had previously worked with other semiconductors, and I was speaking with a professor at Cambridge who was working with the Nobel Prize winners at Manchester to see if they could integrate Graphene as the terminals for Gallium Nitride devices. He explained that he had these large sections of Gallium Nitride, but that all the Graphene they were sending him was in tiny, coin-sized sheets, so he asked me if I could try and find a way to help him, and it led on from there.

MH: You’ve spoken about how Graphene’s electrical conductivity is so important, but you’ve also mentioned some of its other properties, such as its incredible strength-to-weight ratio. Are there any applications in which these multiple properties are taken advantage of?

ST: I’m talking slightly outside my field here, but Graphene is split, sort of, into two different worlds: one, which we are leading, uses it in electronics, and the other, uses Graphene’s physical properties. In this “mechanical” world, Graphene has already been used for 10 or so years. Many companies have been using Graphene flakes or powder inside composite matrices to make use of its wear resistance, strength and thermal conductivity. And they're doing really well. For example, the National Graphene Institute in Manchester, are putting Graphene into concrete, paints, new road surfaces to make use of those properties. I even know of companies which have been using Graphene in shoes to make them extra durable. However, that is very different from what we do.

MH: Finally, you previously mentioned that Graphene has great potential to be used in various different types of sensors. Why is that?

ST: This is for the same reason of the electronic structure. For example, Graphene can be used in magnetosensors because the surface electrons of Graphene can be very easily pushed back and forth by even very small magnetic fields. Graphene’s sensitivity is also very useful in biosensors, since, for example, viruses are electrically charged, they can also be detected due to movement in Graphene’s surface electrons.

Many thanks to Dr Simon Thomas for his time and insight. At Paragraf, they are very keen to get youth involvement, for example Work Experience or Internships, so do not be afraid to reach out.