The smart people at MIT, Columbia University and IBM’s T. J. Watson Research Center have apparently succeeded in increasing the responsivity (the amount of light that is actually converted into an electrical current) of graphene in photodetectors that convert optical signals to electrical signals in integrated optoelectronic computer chips. (Optoelectronic computer chips use light rather than electricity to move data, drastically reducing their power consumption and heat production.) When graphene is used integrated in a silicon chip, the optoelectronic devices become much simpler in design than those made from other materials and could lead to optoelectronic chips that are simpler and cheaper to manufacture.
The standard way to increase a photodetector’s responsivity is to apply a voltage across it but the voltage will inevitably induce a slight background current that adds “noise” to the detector’s readings. The new design uses a “waveguide” (a silicon channel) etched into the surface of a chip to increase the responsivity without requiring the application of a voltage. The researchers hope that, with even better engineering — thinner electrodes, or a narrower waveguide — they can manufacture a photodetector with still higher responsivity.
Read the article at: mitnews.
Editor’s note: Just wondering: Would the use of graphene and “waveguide” technology eventually migrate to image sensors? By simplifying the design and increasing the responsivity of the sensor, could the issue of noise at high ISOs become a moot point — irrespective of image sensor size? An intriguing thought.