South Korean university develops photodiode for autonomous driving lidar

(Image source: photonics.com)

According to foreign media reports, a team of researchers at Pohang University of Science and Technology in South Korea has developed near-infrared (NIR) silicon photodiodes that are one-third more sensitive than existing photodiodes.

Existing near-infrared photodiodes are usually made of chemical materials, require separate cooling devices, and are difficult to integrate. A team of researchers led by Professor Chang-Ki Baek of Pohang University of Science and Technology used hourglass-shaped silicon nanowires to increase silicon's absorption of infrared light.

Located above the nanowires, the inverted nanocones prolong the residence time of near-infrared-shortwave infrared (SWIR) photons by generating whispering gallery resonances, while the nanocones below are able to reabsorb incident light from nearby nanowires due to their low reflectivity.

The nanowires showed a 29% increase in response to near-infrared light at a wavelength of 1,000 nanometers compared to existing planar silicon photonic diodes. The researchers used the newly developed photodiodes in a mobile heart rate measurement system and found that the new photodiodes were more sensitive than existing photodiodes with an error rate of less than 1%.

The silicon used to make photodiodes can be mass-produced at low cost, and potential applications include lidar for self-driving vehicles, medical lasers, night vision, image sensors, and more.