Nokia’s PureView technology is already at the forefront of smartphone imaging. What may come next to make it even better?
How about graphene based photo sensors?
I am not sure how far along on the way to commercialization this technology is, but Nokia R&D is busy developing a graphene photo-detector, and already filed a patent for it.
The patent describes photo-detector/pixel with graphene photon collecting layer, a number of finger shaped electrodes placed above it to collect electrons-holes generated by passing light photons, a graphene nano-ribbon acting as field effect transistor to amplify the resulting current and transfer it to the connected control electronics. Several light detecting and amplifier layers can be stacked on top of each other, with color filters in between, so different colors can easily be detected by each pixel in the sensor.
Why use graphene for the sensor? The main reason is the transparency. This single layer of carbon cells absorbs only 2.3% of the passing light, and does it very evenly across the whole light spectrum (infrared, visible, ultraviolet). So, according to Nokia, it will should perform much better than traditional CMOS sensors in low light conditions.
Then there is a question of size. Graphene based photo-sensor can be made much thinner than its traditional counterpart, so your next 41 megapixel PureView handset won’t need that huge lump, that the back of Nokia 808 has.
Also, when they finally iron out all the graphene performance issues, the sensor manufacturing process itself should be more simple then current CMOS production, and it will use cheaper materials.
Easier to make, cheaper and better performance. What’s not to like about the new graphene image sensors, and why we don’t have them yet?
Unfortunately, for all the magical properties and devices graphene is promising in the future – it is still not there yet. Very few commercial graphene products are getting out from R&D labs into the real world for now, for various reasons. In this particular case, compared to advanced CMOS, graphene sensors still lack enough photo responsivity and generate too much noise for practical applications.
So where is Nokia in solving practical graphene sensor development problems. Who knows? Probably only their R&D guys and partner companies.
But let’s hope they are pretty close, because thinner sensors with bigger megapixel count could really help all those coming PureView devices.
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