New research explores graphene-silicon devices for photonics applications

If you use a smartphone, laptop, or tablet, then you benefit from research in photonics, the study of light. At the University of Delaware, a team led by Tingyi Gu, an assistant professor of electrical and computer engineering, is developing cutting-edge technology for photonics devices that could enable faster communications between devices and thus, the people who use them.

The research group recently engineered a silicon-graphene device that can transmit radiofrequency waves in less than a picosecond at a sub-terahertz bandwidth—that's a lot of information, fast. Their work is described in a new paper published in the journal ACS Applied Electronic Materials.
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"In this work, we explored the bandwidth limitation of the graphene-integrated silicon photonics for future optoelectronic applications," said graduate student Dun Mao, the first author of the paper.

Silicon is a naturally occurring, plentiful material commonly used as a semiconductor in electronic devices. However, researchers have exhausted the potential of devices with semiconductors made of silicon only. These devices are limited by silicon's carrier mobility, the speed at which a charge moves through the material, and indirect bandgap, which limits its ability to release and absorb light.

Now, Gu's team is combining silicon with a material with more favorable properties, the 2-D material graphene. 2-D materials get their name because they are just a single layer of atoms. Compared to silicon, graphene has better carrier mobility and direct bandgap and allows for faster electron transmission and better electrical and optical properties. By combining silicon with graphene, scientists may be abletocontinue utilize technologies that are already used with silicon devices—they would just work faster with the silicon-graphene combination.