As computers process more data than ever before, engineers are looking for faster ways to move information inside chips. One promising solution is to use light instead of electricity. Researchers at the University of Edinburgh and European partners have now developed a new germanium–tin (GeSn) material that could help make this possible.
Modern chips rely on silicon and germanium, which are excellent semiconductors (materials that can control electrical current). However, both have what is called an indirect band gap. A band gap is the energy difference electrons must cross to conduct electricity. In an indirect band gap material, electrons cannot easily release energy as light; instead, much of it is lost as heat. This makes silicon and germanium inefficient for light-emitting devices.
Adding tin changes the electronic structure and therefore the arrangement of energy levels inside the material. With sufficient tin, germanium can move toward a direct band gap, meaning electrons can release energy directly as light. This improves light emission and absorption, which are essential for lasers, photodetectors and optical data links.
The challenge has been stability, as germanium and tin do not naturally mix well. To overcome this, the research team applied pressures of 9–10 gigapascals (around 100,000 times atmospheric pressure) and temperatures above 1200°C. Under these extreme conditions, the atoms formed a new hexagonal crystal structure. Importantly, the material remained stable when returned to normal conditions.
Alloys containing up to ~16% tin retained this hexagonal phase, while higher tin levels reverted to the usual cubic structure. Because crystal structure influences electronic behaviour, adjusting tin content provides a way to tune optical performance.
The study demonstrates a practical route to stabilising hexagonal GeSn with tuneable optical properties. By showing that tin content and crystal structure can be controlled to enhance light interaction, the research provides a clear pathway toward semiconductors that more efficiently combine electronics and photonics within existing silicon-based manufacturing systems. If integrated successfully into chips, GeSn-based photonic components could reduce data-transfer bottlenecks, lower energy losses and ultimately support faster, more energy-efficient computing performance.
For more tin technology information visit the ITA’s Tin Valley platform.
