Novel light sensor to enhance digital cameras

June 19th, 2009 - 12:45 pm ICT by ANI  

Washington, June 19 (ANI): Performance of a large number of electronic devices, including digital cameras, could soon be enhanced, for researchers have now created light sensor-like a pixel in a digital camera-that benefits from a phenomenon known as multi-exciton generation (MEG).

University of Toronto (UT) scientists, who led the research, claim that they are the first group to have collected an electrical current from a device that makes use of MEG.

“Digital cameras are now universal, but they suffer from a major limitation: they take poor pictures under dim light. One reason for this is that the image sensor chips inside cameras collect, at most, one electron’s worth of current for every photon (particle of light) that strikes the pixel. Instead generating multiple excitons per photon could ultimately lead to better low-light pictures,” said Ted Sargent, professor in UT’s Department of Electrical and Computer Engineering.

In solar cells and digital cameras, particles of light called photons are absorbed in a semiconductor, such a silicon, and generate excited electrons, known as excitons.

Thus, the semiconductor chip measures a current that flows as a result.

Normally, each photon is converted into at most one exciton, which lowers the efficiency of solar cells and it limits the sensitivity of digital cameras.

When a scene is dimly lit, small portable cameras like those in laptops suffer from noise and grainy images as a result of the small number excitons.

“Multi-exciton generation breaks the conventional rules that bind traditional semiconductor devices. This finding shows that it’s more than a fascinating concept: the tangible benefits of multiple excitons can be seen in a light sensor’s measured current,” said Sargent. (ANI)

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