Researchers from the University of Utah’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 vital component for future communications systems.
The next generation of communications bandwidth is expected to use the terahertz spectrum that uses light instead of electricity to move data, allowing users to transfer information a thousand times faster that is the case today.
The research, led by University of Utah electrical and computer engineering professor Ajay Nahata and physics and astronomy Distinguished Professor Valy Vardeny, appeared in the latest edition of Nature Communications.
The terahertz range is a band between infrared light and radio waves and uses frequencies that cover the range from 100 gigahertz to 10,000 gigahertz (a typical cellphone operates at just 2.4 gigahertz). Scientists are studying how to use these light frequencies to transmit data because of its tremendous potential for boosting the speeds of devices.
The research undertaken at Utah found that by depositing a special form of multilayer perovskite onto a silicon wafer, it is possible to modulate terahertz waves passing through it using a simple halogen lamp. Modulating the amplitude of terahertz radiation is crucial because it is how data in such a communications system would be transmitted.
Previous attempts have used expensive, high-power lasers, this demonstration is different ii that it is not only the lamp power that allows for this modulation but also the specific colour of the light. As a result different perovskites can be placed on the same silicon substrate, where each region could be controlled by different colours from the lamp.
“Think of it as the difference between something that is binary versus something that has 10 steps,” Nahata explains about what this new structure can do. “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.”
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 like rock but also organic like a plastic, making it easy to deposit on silicon while also having the optical properties necessary to make this process possible.
According to Nahata it will probably be at least another 10 years before terahertz technology for communications and computing is used in commercial products, but this new research is a significant milestone to getting there.