Publications by authors named "Cesar Bartolo-Perez"

Since the advent of impact ionization and its application in avalanche photodiodes (APD), numerous application goals have contributed to steady improvements over several decades. The characteristic high operating voltages and the need for thick absorber layers (π-layers) in the Si-APDs pose complicated design and operational challenges in complementary metal oxide semiconductor integration of APDs. In this work, we have designed a sub-10 V operable Si-APD and epitaxially grown the stack on a semiconductor-on-insulator substrate with a submicron thin π-layer, and we fabricated the devices with integrated photon-trapping microholes (PTMH) to enhance photon absorption.

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Avalanche and Single-Photon Avalanche photodetectors (APDs and SPADs) rely on the probability of photogenerated carriers to trigger a multiplication process. Photon penetration depth plays a vital role in this process. In silicon APDs, a significant fraction of the short visible wavelengths is absorbed close to the device surface that is typically highly doped to serve as a contact.

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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.

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Theory is proposed for nanohole silicon/photodetector (PD) physics, promising devices in the future data communications and lidar applications. Photons and carriers have wavelengths of 1m and 5 nm, respectively. We propose vertical nanoholes having 2D periodicity with a feature size of 1m will produce photons slower than those in bulk silicon, but carriers are unchanged.

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