Meet Matthew, the NGI’s award-winning post-doc
Matthew Hamer is a post-doctoral research associate in The University of Manchester’s Department of Physics and Astronomy, based in the National Graphene Institute. In November 2020, he received the Elsevier/Scopus Early Career Research UK award for his work with graphene and other 2D materials. We sat down to discuss his research in more detail and find out what it meant to him to be honoured in this way.
Tell me about your work and what sets it apart from other areas of 2D materials research…
I make stacks of 2D materials called heterostructures, where different layers have different properties, so you can tailor the properties of the device you’re making. These devices can be simple things such as field-effect transistors or LEDs, or more complicated structures such as quantum dots.
One thing that sets my work apart is that we work with materials that are sensitive to the air and that degrade in ambient conditions. So they lose the properties that we’re interested in looking at – for example, superconductivity or magnetism. Many of the materials that show the most interesting properties happen to be the ones that are most sensitive.
The traditional way of working with these materials is inside a glovebox, where you have an inert atmosphere – usually argon or nitrogen – and this means you can work with the materials in this environment and they don’t break down. That’s what a lot of my early PhD was on.
More recently, we’ve managed to develop some technology which uses ultra-high vacuums and this piece of equipment allows us to suck all the air out of the system. We can then exfoliate these materials and have pristine interfaces. This leads to a significant improvement in the interface quality and therefore the device quality compared to glovebox encapsulated samples that we’ve worked with in the past.
How do you stop these materials degrading once they’re out of their protective environment?
Good question! Essentially we make a sandwich of the air-sensitive materials so it’s encapsulated on all sides by a more stable material. This encapsulation layer is impermeable to the things in the air that might degrade the central layer and then you can do all the processing that you would normally associate with these devices.
Usually, we use hexagonal boron nitride (h-BN), which is a very wide-band-gap insulator. So if, say, we’re concerned with conductive properties, because h-BN is an insulator, it doesn’t matter. If you were looking at optical properties, h-BN is going to change the dielectric environment a little – it may absorb a bit of the light coming in – so you may get a reduced intensity. But generally, by engineering the encapsulation layers, you can negate any adverse effects. Generally it’s better than no encapsulation at all.
What sort of products and applications might lend themselves to adoption of these devices?
That’s a more difficult question because the type of work we do doesn’t lend itself so easily to that kind of categorisation. Because of the nature of these air-sensitive materials, using gloveboxes and ultra-high vacuum systems is a necessity which leads to very low throughput. You can only make a couple of devices and it’s difficult.
One thing we can do is to see physical properties that we might not otherwise be able to observe – for example, unconventional superconductivity or electron-electron interactions. With these very pristine interfaces, the layers have fewer impurities and defects so the crystal structure can be of higher quality, and we can see effects that might otherwise be ‘blurred out’, so to speak, because of background interference.
If I had to name an application, quantum computing would probably stand out, because in theory we could make qubits with the UHV system and reduce one of the problems with them – that of decoherence. Even if we could make just a couple of qubits, that might be enough to revolutionise quantum computing.
Watch Matthew talk about his work in this winner film from the Scopus awards.
The main thing we’re doing is to significantly improve sample quality, which enables us to test different physical phenomena, which in turn gives us a better understanding of the unusual materials we’re working with. It allows us to test our theories through physical experimentation and modify and tweak our theories to better match reality. And this improved understanding will help us in the future to develop further applications, even if we don’t know exactly what they are yet.
A good way of understanding this is to look at when the first silicon-based devices like field-effect transistors were invented. If you’d asked then what the purpose of them was, no-one would have been able to give you a clear answer, but now they completely underpin all of modern technology.
Tell me about the process behind this award…
What Scopus have done is to look at all of the researchers in the UK who have published over the last five years or so and the impact that their work is having. Then, based on different fields – mine is in physical science – they take the top three or four people in terms of the number of citations, quality of publications etc, and then get a panel of experts together to look at the research itself and then make the award based on that.
What does it mean to you to win?
It was a bit out of the blue, to be honest. But it’s a really good validation of the research that I’m doing. It’s nice to feel appreciated. And it’s not just me – it’s good for everyone that I’m working with, all of the collaborations. It makes everything a little bit more worthwhile. It’s good to know that people are reading my research and finding it useful.
So what’s next for you in the short and medium term?
In the next six months or so, I plan to apply for fellowships. The idea would be to get a prestigious five-year fellowship – there’s one called the Leverhulme Fellowship that I’m going to apply for and there are different European research councils which also offer fellowships, so that what I’m aiming for. Eventually, my aim would be to set up my own research group based on what I’ve learnt so far.
And having an award like this on your CV can’t do any harm…
Sure – as you build these things up it acts as a badge of competence, if you like. So a fellowship panel will look at it and assume you probably know what you’re doing. It can’t hurt your chances!