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Enhancing photon detection efficiency and time resolution in photodetectors in the entire visible range is critical to improve the image quality of time-of-flight (TOF)-based imaging systems and fluorescence lifetime imaging (FLIM). In this work, we evaluate the gain, detection efficiency, and timing performance of avalanche photodiodes (APD) with photon trapping nanostructures for photons with 450 nm 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 106 for the entire visible range.

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Silicon photodetectors (PDs) operating at near‐IR wavelengths with high speed and high sensitivity are becoming critical for emerging applications, such as light detection and ranging (LIDAR) systems, quantum communications, and medical imaging. However, such PDs present a bandwidth‐absorption trade‐off at those wavelengths that have limited their implementation. Photon‐trapping (PT) structures address this trade‐off by enhancing the light–matter interactions, but maximizing their performance remains a challenge due to a multitude of factors influencing their design and fabrication. Herein, strategies to improve the PT effect while enhancing the speed of operation are investigated. By optimizing the design of PT structures and experimentally integrating them in high‐speed PDs, a simultaneous broadband absorption efficiency enhancement up to 1000% and a capacitance reduction of more than 50% are achieved. Empirical equations correlate the quantum efficiency of PDs with the physical properties of the PT structures, material characteristics, and limitations of the fabrication technologies. The results that are obtained open routes toward designing cost‐effective complementary metal–oxide‐semiconductor (CMOS)‐integrated receivers.

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