The scientist watching light at a millionth of a millionth of a second

This Cambridge Life

The scientist watching light at a millionth of a millionth of a second

Professor Rachel Oliver in the lab

Professor Rachel Oliver

Professor Rachel Oliver

When she’s not making atomic-scale changes to create super-efficient light bulbs and cut carbon emissions, Professor Rachel Oliver has her sights set on helping to level-up equality and diversity in science. We speak to her on International Day of Women and Girls in Science (11 February).

As a child I was always very curious about why the world was the way it was. Sometimes my mum had answers and sometimes she’d tell me just to shush and get on with things – I was probably asking questions at the least convenient moment. 

I remember being particularly interested in why metal was colder on a chilly day than brick or stone. The answer often given is that metal feels colder as it has a higher thermal conductivity than other materials, and therefore it carries the heat away from your hand. But this isn’t really an answer, it’s just a description in scientific language of the same question. 

This led me to want to know how heat moves through different objects, and at that point things really do get a lot more interesting. I suppose I started off with basic questions and found the initial answers given to me rather unsatisfactory and so I began to dig and dig. 

Professor Rachel Oliver in the lab

This mindset of delving down to understand how things work has never left me. As an undergraduate at Oxford, I’d always thought I’d specialise in electrical engineering, designing circuits. But I realised that I wanted to go deeper and deeper in my understanding of materials and energy, right down to the atomic level.   

Today I’m Professor of Materials Science and Director of the Cambridge Centre for Gallium Nitride. We specialise in understanding gallium nitride, which is a human-made semiconductor. We apply this material to a number of different projects to make energy, and working with power, more efficient. 

The best-known application of gallium nitride is light emitting diodes (LEDs). LED technology is astoundingly commercially successful. Compared with the lightbulb of my childhood – the incandescent Edison style bulb – LED light bulbs cut the energy spent on lighting by a factor of five or six. 

We’re not trying to reinvent LEDs but what we are trying to do is to make them as efficient and affordable as possible. This matters, because with millions of lightbulbs across the world, even the slightest increase in efficiency can have a monumental impact. 

Professor Rachel Oliver in the lab

Lighting accounts for around 20% of the world’s energy supply, therefore even a 1% improvement in efficiency equates to tonnes and tonnes of CO2. In fact, we recently did a calculation based on one of the innovations we’d been working on and found that, if this modification could be applied across the board, you could shut down a medium-sized coal-fired power station overnight. 

The adaptions to gallium nitride involve controlling its structure at an atomic level. We use highly specialised technology like electron microscopes to look at the material’s structures. We can make tiny adaptions to these structures that in turn changes their properties and can lead to greater energy efficiency.

I recently won funding for a new £2 million microscope that will allow us to ask questions we’ve never been able to ask before. This electron microscope measures the light-emitting properties of materials in real-time, to the scale of a picosecond, that is, a millionth of a millionth of a second.

I very much care about making LED technology as efficient as possible because it’s low hanging fruit in terms of tackling the climate crisis. If you say to someone: “you can’t have a car” well, that’s a big thing to give up. But if you say to someone “use this bulb, it will last longer, save you money and you can screw it into the same light-fitting as your current lightbulb,” that’s a much easier change to make. 

Professor Rachel Oliver in the lab

As Director I don’t get to work in the lab as much as I would like, but it’s lovely to be able to work with students and postdocs to help to shape them as scientists, build them up and give them opportunities. I’m aware that as a woman, in a senior position, in my particular field, I’m very much in the minority. By default I am both a role-model and someone who should, and needs to, champion the equality of women in science. 

There are people who say: “you can’t be what you can’t see.” That’s not really true. You can be what the hell you like, but it’s hard to become something when there’s nobody you can look up to or identify with; nobody you can imagine yourself becoming or see yourself in their shoes.

When I was studying engineering as an undergraduate, women made up about a sixth of the cohort. I feel very sad that, 20 years on, the numbers haven’t changed. Zero progress has been made, and that’s quite telling, I think. 

I began thinking about what was holding women back and one of the things that struck me was the funding environment. In my field, expensive equipment like electron microscopes are vital to carrying out research, therefore securing grant funding is essential. 

Professor Rachel Oliver in the lab

Initial studies have demonstrated that there is inequality in research funding. While women may receive a similar number of grants as men, they do not receive as much funding in terms of monetary value. Even greater inequalities effect people from ethnic minorities and those with disabilities.

I’m campaigning for greater transparency in research funding. We need to consider all protected characteristics such as race, disability, and sexual orientation, in addition to characteristics that are harder to address such as socioeconomic background.  

Here at the University of Cambridge we are working to develop new processes based on an awareness of addressing these inequalities. I’m also working with UKRI (UK Research and Innovation), the UK’s leading grant giving organisation to ensure equality in funding. 

In 2019, TIGERS (The Inclusion Group for Equity in Research in STEMM) was born. We are a group of professionals and students advocating for inclusion in STEMM (Science, Technology, Engineering, Maths and Medicine). We’re passionate about seeing equality in funding and every aspect of science, and just as our name suggests we’ll keep on making noise about these issues until we see equality for all in STEMM.

This profile is part of This Cambridge Life – stories from the people that make Cambridge University unique.

Words: Charis Goodyear. Photography: Nick Saffell.