Semiconductor devices are small components that control the movement of electrons in modern electronic devices. They are needed to power a wide range of high-tech products, including mobile phones, laptops and vehicle sensors, as well as cutting-edge medical devices. However, the presence of impurities in the material or temperature fluctuations can hinder electron flow, causing instability.

But now theoretical physicists and experimentalists from the Würzburg-Dresden cluster of excellence (ct.qmat – Complexity and Topology in Quantum Matter) have developed a semiconductor device made of aluminum gallium arsenide (AlGaAs). The electronic flow of this device, normally susceptible to interference, is protected by a topological quantum phenomenon. This groundbreaking research was recently published in detail in a respected journal Natural Physics .

“Thanks to the topological surface effect, all currents between the various contacts of the quantum semiconductor are unaffected by impurities or other external factors. This makes topological devices increasingly attractive for the semiconductor industry. Currently, there is a need for extremely high levels of material purity, which increases the cost of electronics production.” they eliminate the need,” explains Professor Jeroen van den Brink, director of the Institute for Theoretical Solid State Physics at the Leibniz Institute for Solid State and Materials Research Dresden (IFW) and principal investigator.ct.qmat.

Known for their extraordinary strength, topological quantum materials are ideal for energy-intensive applications. “Our quantum semiconductor is simultaneously stable and very sensitive; a rare combination. This positions our topological device as an exciting new option in sensor technology.”

Extremely powerful and extremely accurate

Using the topological surface effect allows the creation of new types of high-performance electronic quantum devices that can also be incredibly small. “Our topological quantum device has a diameter of about 0.1 millimeters and can be easily miniaturized,” says van den Brink. The pioneering aspect of this achievement by a team of physicists from Dresden and Würzburg is that they are the first to realize the topological skin effect in a semiconductor material on a microscopic scale. This quantum phenomenon was first demonstrated at the macroscopic level three years ago, but only in a non-natural, artificial metamaterial. Thus, a small topological semiconductor-based quantum device that is both highly reliable and ultrasensitive has been developed for the first time.

“In our quantum device, the current-voltage relationship is preserved by the topological skin effect because the electrons remain confined at the edge. The current remains constant even in the presence of impurities in the semiconductor material,” explains van den Brink. He continues: “In addition, the contacts can detect even the smallest fluctuations in current or voltage. “This makes the topological quantum device extremely suitable for building high-precision sensors and small-diameter amplifiers.”

Innovative experiments lead to discoveries

The success was achieved by creative placement of materials and contacts on the AlGaAs semiconductor device; this caused a topological effect and a strong magnetic field in ultracold conditions. “We actually eliminated the topological surface effect of the device,” explains Van den Brink. The team of physicists used a two-dimensional semiconductor structure. The contacts were arranged in such a way that electrical resistance could be measured at the edges of the contacts and the topological effect was directly revealed.

Mixed studies in different locations

Since 2019, ct.qmat has been researching topological quantum materials in Würzburg and Dresden, investigating their unusual behavior under extreme conditions such as ultra-low temperatures, high pressures or strong magnetic fields.

The latest breakthrough is also the result of long-term collaboration between scientists at two locations in the cluster. The new quantum device developed at IFW was the result of a joint effort involving theoretical physicists from the University of Würzburg as well as theoretical and experimental researchers in Dresden. After the device was produced in France, it was tested in Dresden. Jeroen van den Brink and his colleagues are now committed to further investigating this phenomenon and exploiting it for future technological innovations.