APD with Photon Trapping

University of California – Davis and W&WSens Devices publish a paper "Avalanche Photodetectors with Photon Trapping Structures for Biomedical Imaging Applications" by Cesar Bartolo-Perez, Soroush Ghandiparsi, Ahmed S. Mayet, Hilal Cansizoglu, Yang Gao, Wayesh Qarony, Ahasan Ahamed, Shih-Yuan Wang, Simon R. Cherry, M. Saif Islam, and Gerard Arino-Estrada.

"In this work, we evaluate the gain, detection efficiency, and timing performance of avalanche photodiodes (APD) with photon trapping nanostructures for photons with 450 and 850 nm wavelengths. At 850 nm wavelength, our photon trapping avalanche photodiodes showed 30 times higher gain, an increase from 16% to >60% enhanced absorption efficiency, and a 50% reduction in the full width at half maximum (FWHM) pulse response time close to the breakdown voltage. At 450 nm wavelength, the external quantum efficiency increased from 54% to 82%, while the gain was enhanced more than 20-fold. Therefore, silicon APDs with photon trapping structures exhibited a dramatic increase in absorption compared to control devices. Results suggest very thin devices with fast timing properties and high absorption between the near-ultraviolet and the near infrared region can be manufactured for high-speed applications in biomedical imaging. This study paves the way towards obtaining single photon detectors with photon trapping structures with gains above 10^6 for the entire visible range."