Work by the University of Utah on perovskite, a mineral discovered in Russia in the 1830s, could hold a key to the next step in ultra-high-speed communications and computing.
Researchers from the University’s Departments of Electrical and Computer Engineering and Physics and Astronomy have discovered that a special kind of perovskite, a combination of an organic and inorganic compound that has the same structure as the original mineral, can be layered on a silicon wafer to create a key component for the communications system of the future. That system would use the Terahertz spectrum, the next generation of communications that uses light instead of electricity to shuttle data allowing, for example, Internet users to transfer information a thousand times faster than today.
The new research, led by University of Utah Electrical and Computer Engineering Professor Ajay Nahata and Physics and Astronomy Distinguished Professor Valy Vardeny, was published in the latest edition of Nature Communications.
The Terahertz range is a band between infrared light and radio waves and utilises frequencies that cover the range from 100 to 10,000 Gigahertz . Scientists are studying how to use these light frequencies to transmit data because of its potential for boosting the speeds of devices such as Internet modems or cell phones.
By depositing a special form of multilayer perovskite onto a silicon wafer, Nahata and Vardeny could modulate the amplitude of Terahertz waves passing through it using a simple halogen lamp. Previous attempts to do this have usually required the use of an expensive, high-power laser. What made this particular demonstration different is that it was not only the lamp power that allowed for this modulation but also the specific colour of the light. Consequently, the team found that they could put different perovskites on the same silicon substrate, where each region could be controlled by different colours from the lamp. This is not easily possible when using conventional semiconductors like silicon.
“Think of it as the difference between something that is binary versus something that has ten steps,” is how Nahata explains the properties of this new structure. “Silicon responds only to the power in the optical beam but not to the colour. It gives you more capabilities to actually do something, say for information processing or whatever the case may be.”
Not only does this open the door to turning Terahertz technologies into a reality, but the process of layering perovskites on silicon is simple and inexpensive by using a method called “spin casting,” in which the material is deposited on the silicon wafer by spinning the wafer and allowing centrifugal force to spread the perovskite evenly.
Vardeny says what’s unique about the type of perovskite they are using is that it is both an inorganic material and also organic like a plastic, making it easy to deposit on silicon while also having the optical properties necessary to make this process possible.
Nahata reckons it’s probably at least another ten years before Terahertz technology for communications and computing is used in commercial products, but that this new research is a significant milestone to getting there.
The Nature Communications paper was co-authored by students, Ashish Chanana, Yaxin Zhai, Sangita Baniya and Chuang Zhang.
PHOTO CREDIT: Dan Hixon/University of Utah College of Engineering. (Vardeny left and Nahata)