Create A Metal With Laser Light

November 2, 2021

Researchers from the Fritz Haber Institute of the Max Planck Society and the Humboldt-Universität zu Berlin have discovered that semiconductors can be converted to metals and vice versa more easily and quickly than previously thought. This discovery could increase processing speed and simplify the design of many common technology devices.

From smartphones to computer processors, much of the technology we use today has transistors. These connect many of the different materials that make up these devices and are essential for any type of data processing. Because they are so important, scientists and engineers have long tried to optimize them by modifying the properties of their materials so that they can be used more flexibly. Now, a team of researchers from the Fritz Haber Institute of the Max Planck Society and the Humboldt-Universität zu Berlin has found an important clue on how to achieve this.

Transistors are usually made up of semiconductors, that is, materials that conduct electricity, but not as well as metals. In common transistors, several semiconductors combine to control an electrical current. Unfortunately, this limits the performance and size of the device in which they are integrated. “Basically, the ideal would be to have a single material that does it all, whenever we need it,” says Professor Julia Stähler of the Humboldt Universität zu Berlin, who led the study at the Fritz Haber Institute.

Although the conductivity of semiconductors can be altered by a chemical process called ‘doping’, this technique, in which atoms of the semiconductor are replaced by others, has limitations. The properties of a material can be changed, but will remain that way permanently, whereas what is really needed is a material that can change between different properties. Julia Stähler’s group has found an answer to this question: light.

Conversion to a metal only takes 20 femtoseconds

The scientists involved in this study have investigated the popular zinc oxide semiconductor and discovered that by hitting it with a laser, simply by illuminating it, the surface of the semiconductor can turn into a metal, and vice versa. This “photodepuration” is achieved by photoexcitation: light modifies electronic properties so that electrons suddenly move freely and an electric current can flow, as it would in metal.

Once the light goes out, the material quickly reverts to a semiconductor. “This mechanism is a completely new and surprising discovery,” says Lukas Gierster, lead author and PhD student in Stähler’s group. “There are three things that have particularly surprised us: on the one hand, that photodoping and chemical doping behave so similarly despite being fundamentally different mechanisms; on the other, that gigantic changes can be achieved with a very low laser power; and finally, that the activation and deactivation of the metal occurs so quickly. ”

The conversion into a metal only takes 20 femtoseconds, that is, 20 millionth of a billionth of a second. The speed of the reconversion of the semiconductor is especially surprising, since it is orders of magnitude faster than in previous studies. In other words, zinc oxide is an ultra-fast switch that has the “power” to “do it all.”

This discovery could be very beneficial for optically controlled ultrafast transistor and high frequency device applications, increasing processing speed and simplifying device design. “Our devices could be faster and therefore smarter,” says Julia Stähler, adding: “The ultra-fast switching of driving properties will give us high speed and design flexibility.” She and her group are convinced that the same will happen with other semiconductor materials, so it is likely that their discovery goes well beyond zinc oxide.

Dr. Loony Davis5
 | Website

Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

Leave a Reply

Your email address will not be published. Required fields are marked *