New Photodetector Design For Trillion-Sensor Era

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Researchers develop a new photosensor design that exhibits high efficiency as well as high signal to noise ratio. 

With the emerging Industry 4.0 trends, we are going towards the trillion sensor economy in which billions of sensors will be connected under the umbrella of Internet-of-things. A significant portion of these sensors will be constituted of light/photo sensors, which are tiny semiconductor-based electronic components that detect light and convert them to electrical signals. Light sensors are critical elements in various applications like optical communication systems, healthcare equipment, and automobiles.

Researchers have been trying to develop sensors that can detect a high dynamic range of lights, are easy to manufacture, and are energy efficient. Most commercially available light sensors are energy efficient but are susceptible to noise. To overcome this issue, these sensors are designed using light-to-frequency conversion circuits (LFCs) that exhibit better signal to noise ratio. However, LFCs are generally implemented by silicon-based photodetectors that can limit the range of light detection. Moreover, LFCs occupy a larger chip area.

Researchers from Incheon National University, South Korea, led by Prof. Sung Hun Jin, have developed complimentary photosensitive inverters with p-type single walled carbon nanotubes (SWNT) and n-type amorphous indium-gallium-zinc-oxide (a-IGZO/SWNT) thin film transistors.

Prof. Jin explains, “Our photodetector applies a different approach with regard to the light-to-frequency conversion. We have used components that are light dependent and not voltage dependent, unlike conventional LFCs.”

The newly developed design allows for high chip area efficiency, and moreover, experiments suggest that the photosensor system indicated excellent optical properties, including high tunability and responsiveness over a broad range of light. Also, it demonstrated high scalability and easy integration.

“LFCs based on low dimensional semiconductors will become one of the core components in the trillion sensors area. Our LFC scheme will find application in medical SpO2 detection, auto-lighting in agriculture, or in advanced displays for virtual and augmented reality” concludes Prof. Jin.

The research appeared in the journal Small.


 

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