Germanium-Tin Alloy Paves New Way for High-Efficiency LEDs

Silicon has long dominated the competition among semiconductor materials, but its "innate shortcomings" in the optoelectronic field have limited its development potential. Recently, researchers have developed a new semiconductor material composed of germanium and tin, which features higher light absorption and emission efficiency than silicon semiconductors and is expected to become a new generation of high-performance semiconductors.

Silicon is the cornerstone of the modern electronics industry. Most chips for electronic products such as computers and mobile phones are mainly made of silicon, which is still difficult to replace with other materials.

Despite its mature technology and low cost, silicon suffers from low luminous efficiency due to its indirect bandgap property, far lower than direct bandgap materials such as gallium arsenide (GaAs). It cannot be directly used as high-efficiency laser or LED light source devices, making it hard to excel in optoelectronics.

To realize optical communication on chips-which is faster and more energy-efficient than electronic transmission-engineers usually need to heterogeneously integrate expensive Ⅲ-Ⅴ materials (e.g., gallium arsenide), involving complex processes and high costs. Therefore, scientists have long been committed to developing alternatives among group Ⅳ materials, among which germanium-tin alloy (GeSn) is regarded as the "Holy Grail" in the semiconductor field.

Unlike Ⅲ-Ⅴ materials, germanium and tin are both group Ⅳ elements. Doping a specific proportion of tin into the germanium lattice can alter its band structure, turning it into a direct bandgap material with higher carrier mobility. Meanwhile, group Ⅳ elements are highly compatible with existing silicon integrated circuit processes, making them highly attractive for optoelectronic applications.

In the past, the main challenge for germanium-tin alloys was that the two elements were difficult to react chemically under normal conditions. Until recently, a research team from the University of Edinburgh heated a mixture of germanium and tin to 1200 °C and applied pressure as high as 10 GPa, finally successfully synthesizing germanium-tin alloy stable at room temperature and atmospheric pressure.

Both next-generation electronic devices and data centers with growing power demand are expected to improve energy efficiency through optical transmission in the future. The new material is promising to make devices run faster with lower power consumption.