Researchers at the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in South Korea and the University of Basel in Switzerland have developed a new graphene-based photodetector, that is regarded as the world's first graphene-based microwave photodetector. The sensor can reportedly detect 100,000 times less light energy than any existing graphene photodetector and may be useful in applications like wearable devices and flexible displays.
The teams studied the microwave absorption capabilities of bilayer graphene arranged into p-n junctions. Previous attempts to study the microwave range in photodetection met a considerable obstacle - the microwave on the detector itself had much smaller energy than the surface potential difference caused by the surrounding environment. This included residues on the surface of graphene that were left behind during its fabrication.
To overcome this issue, the researchers separated the graphene-based p-n junction from the substrate by creating a bridge-like structure that suspended the p-n junction above the substrate. This bridge basically allows the electrons to flow without hitting the obstacles created by the residues on the device.