|Thesis abstract: |
Nowadays many optical techniques in different research and industrial fields need to detect single photons in the near-infrared (up to 1700 nm) with high efficiency, low timing jitter and high count rate. Among available single-photon detectors, SPADs (Single-Photon Avalanche Diodes) proved to be a valuable choice. However, InGaAs/InP SPADs have to be cooled in order to decrease as much as possible the dark count rate and have to be operated in gated-mode with fast active quenching in order to limit the detrimental effect of the afterpulsing (i.e. the spurious avalanche triggering due to the delayed release of carriers trapped during a preceding avalanche pulse). This PhD research activity aims to conceive, design, model and experimentally characterize novel structures for InGaAs/InP SPADs, optimized for free-running photon-counting operation, with improved quality of device hetero-structure (for reducing DCR and afterpulsing) through proper design and fabrication of epitaxial layers and Zinc diffusions. As an alternative to InGaAs/InP SPADs, Germanium-on-Silicon detectors, compatible with the silicon photonics process, will be studied and developed. Such detectors can also be integrated with waveguides for building monolithic quantum photonic circuits.