Researchers Develop Photodetector Using Graphene


Researchers developed photodetector that could improve night vision, thermal sensing, and medical imaging using graphene, according to a study published on June 28, 2018.

This study was conducted by the researchers at the UCLA Samueli School of Engineering and was published in the journal Light: Science and Applications. Photodetectors are light sensors that are capable of sensing patterns of elementary particles known as photons and creating images from those patterns. Different parts of the light spectrum are sensed using different photodetectors. The efficiency of photodetectors mainly depends on three factors: their operating speed, their sensitivity to lower levels of light, and how much of the spectrum they can sense.

Until now, photodetectors that were built did not show positive results for all the three factors. The newly developed photodetector showed major improvements in all three areas. The newly developed design has unique properties, as it is made of graphene. It is an excellent material for the detection of photons, as energy from a broad swath of the electromagnetic spectrum can be absorbed by graphene. Strips of graphene was laid over a silicon dioxide layer by the researchers to form the photodetector. Then, a series of comb-like nanoscale patterns made from gold, with ‘teeth’ about 100 nanometers wide were created.

The incoming photons are caught by graphene, by acting as a net and then, converts it into an electrical signal. The necessary information is quickly transferred into a processor by the gold comb-shaped nanopatterns. Therefore, a corresponding high-quality image is produced, even under low-light conditions.

Semih Cakmakyapan, lead author of the study said, “We specifically designed the dimensions of the graphene nanostripes and their metal patches such that incoming visible and infrared light is tightly confined inside them. This design efficiently produces an electrical signal that follows ultrafast and subtle variations in the light’s intensity over the entire spectral range, from visible to infrared.”



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