Researchers recently discovered a snowflake shaped fractal design that has a similar pattern repeating itself at smaller and smaller scales. They believe that this can enhance graphene’s inherent low optical absorption. This resulted in development of graphene photodetectors that have an order-of-magnitude enhancement in photovoltage, ultrafast light detection, and other such benefits. The research team working on this project hails from the Purdue University in Indiana where two graduate students named Di Wang and Jeiran Fang worked under the guidance of professors Amexendra Boltasseva, Alex Kildshev, and Vlad Shalaev and their collaborating professors.
Technically, photodetectors are those devices that detects light when it converts photons into electric current. These have several applications along with X-ray telescopes, TV remote controls, video cameras, robotic sensors, wireless mice, and so forth. The present range of photodetectors is mainly formed from common semiconducting materials, germanium, silicon and a few others. But recent researches are being carried out to make graphene the basic component of all semiconductors. The only challenge lies with its low optical absorption and in order to address this problem, the Purdue researchers team created a graphene photodetector instilled with gold contacts in a snowflake form like a fractal metasurface. They were successful in showing that fractal patterns perform better when it comes to photons collection across a wide range of frequencies as compared with plain edge of graphene gold. This enables the new design to produce 10 times better photovoltage than the progonal one.
Figure: Graphene Photodetector Enhanced With Fractal Golden “Snowflake”
The new version comes with numerous benefits like it is highly sensitive to light that comes from any angle, it also has a broader broadband which enhances light detection across the complete visible spectrum. Along with, the fast electron speed of these allows the photodetector to detect light much quickly. Wang adds, “In this work, we have solved a vital problem of enhancing the intrinsically low sensitivity in graphene photodetectors over a wide spectral range and in a polarization-insensitive manner, using an intelligent self-similar design of a plasmonic fractal metasurface. To our knowledge, these two attributes were not achieved in previously reported plasmonic-enhanced graphene photodetectors.”
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