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Light-sensitive device paves the way for optical computers

Physicists have invented a light-sensitive device that can generate binary optical signals resembling binary digits (1 and 0), making it potentially useful for developing light-based computing systems1. Being light-sensitive, it could also be used to enhance the efficiency of solar cells.

In separate recent experiments, researchers had made a number of light detectors that were capable of generating binary optical signals. These devices, however, generated optical signals only in the presence of ultraviolet and visible light.

In search of a device that is sensitive to a wide range of light, scientists from CSIR-National Physical Laboratory in New Delhi, India, led by Prabir Pal and Suraj P. Khanna, fabricated the light-sensitive device by embedding nanosheets of graphitic carbon-nitride in silicon. They then tested its light sensitivity by exposing it to a wide range of light.

The device displayed excellent light sensitivity to the entire spectrum of light, including ultraviolet, visible and near-infrared light. It retained its good light sensitivity up to the near-infrared region of light. Exposure to light led to a change in the current from positive to negative at small externally applied voltage. Positive and negative current are equivalent to binary digits 1 and 0, respectively.

This successfully demonstrates the ability of the device to function as an optical binary switch at room temperature. Being a highly sensitive light detector, it could harness its own power from light, shunning the need for connecting it to any external energy source.



  1. Prakash, N. et al. Binary multifunctional ultrabroadband self-Powered g-C3N4/Si heterojunction high-performance photodetector. Adv. Optical. Mater. 1800191 (2018)

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