Dr George Serghiou is part of a team of researchers who have created a new silicon-based material, which could make everyday computing devices faster and more efficient by processing information through light as well as electricity.

For over 70 years, electronic devices have been manufactured using a semiconducting form of silicon (Si) which has a cubic diamond structure. This so-called cubic diamond silicon is a key material used in the computer processors which power these electronic devices.

However, the cubic diamond structure of silicon carries a number of disadvantages, which Dr Serghiou and his fellow researchers have set out to overcome.

Energy drain

Currently, computing devices are highly energy-intensive. It is projected that by 2030, the large data centres processing a vast volume of electronic communications worldwide may consume eight percent of the world’s total energy supply.

Computer processors manufactured using cubic diamond-structured silicon are part of this problem, as they waste a large amount of energy through heat dissipation, due to resistance in their electrical circuits.

Let there be light

Light does not suffer from the same resistance issues that hamper electrical signals. A light signal can also travel further without deteriorating than an electrical signal. Researchers are therefore investigating how to create advanced light-emitting materials to enable faster and more energy-efficient processing in electronic devices.

Coupling light transmission with electrical transmission could also reduce the energy that our computing devices waste as heat, while opening the way to new technologies and applications – efficient linking with optical fibre communication networks, for example.

Cubic diamond structured silicon found in current computer processors cannot efficiently absorb and emit light. To overcome this, Dr Serghiou together with colleagues from the University of Edinburgh’s School of Geosciences and six other leading research institutions in Germany, France and the US, created a new hexagonal-structured form of silicon-germanium (SiGe) which can emit light and may therefore offer a promising alternative for the electronics industry.

Explaining the research, Dr Serghiou said, “How can we achieve light emission in computer processors since diamond-structured Si itself does not emit light? This has been a major challenge for decades.

“We can achieve this by coupling diamond-structured Si to another material. This material needs to effectively convert the electrical energy from diamond-structured Si into light. It should also be compatible with Si so that it can be snugly placed directly adjacent to Si in the computer processor without the need for power draining and space-consuming interface constructs.

“It can also contain more than one type of atom allowing for tailoring of the structural and optoelectronic properties to specific need, by varying atom proportions.”

Exciting advances

The work represents an exciting progression in this area of materials science, as the team was able to develop free-standing hexagonal SiGe and on a larger scale than had previously been possible.

The innovation that Dr Serghiou has worked on is a key step towards integrating hexagonal-SiGe with Si on the same computer chip. This could allow for efficient communication between electrons and photons, which in turn opens the way to lower energy consumption in electronic devices and applications from lasers to photodetectors and LIDAR technologies.

Importantly, Dr Serghiou and his team’s study explained the pre-conditions required to make this new form of SiGe using any proportion of Si and Ge. Combining differing proportions of silicon and germanium in the new material could allow researchers to tailor the colour of light emitted from it – making the material versatile for a wider range of applications based on the colour of light needed.

International recognition

This study was selected as a Cover Feature by Chemistry – A European Journal. It is spotlighted internationally by the Deutsches Elektronen Synchrotron (DESY), one of the world’s leading accelerator centres, as well as by the Helmholtz Research Centre for Geosciences, Germany’s National Research Centre for Earth Science. 

It was also presented at the International Cover forum of the European Synchrotron Radiation Facility in France (ESRF), a joint research facility supported by 22 countries.

Find out more

• Read the study: Hexagonal Si−Ge Class of Semiconducting Alloys Prepared by Using Pressure and Temperature, G. Serghiou, N. Odling, H-J. Reichmann, G. Ji,  M. Koch-Müller, D.  J. Frost, J. P. Wright, R.  Boehler, W. Morgenroth, Chem.  Eur. J. 2021.
• Find out more about Dr. Serghiou’s research