Minimization of dark counts in PureB SPADs for NUV/VUV/EUV light detection by employing a 2D TCAD-based simulation environment

Tihomir Knežević*, Lis K. Nanver, Tomislav Suligoj

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

    3 Citations (Scopus)
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    PureB single-photon avalanche diodes (SPADs) were investigated with the aid of a newly developed TCAD-based numerical modeling method with which characteristics related to the avalanching behavior can be simulated. The p + region forming the anode of the PureB p + n photodiode is extremely shallow, only a few nanometer deep, which is essential for obtaining a high photon detection efficiency (PDE) for near-, vacuum- and extreme-ultraviolet (NUV/VUV/EUV) light detection but when an implicit guard ring (GR) is implemented, the dark count rate (DCR) can, despite the GR, be deteriorated at the very sharp corners of the p + -region where there is a high concentration of the electric-field. By comparing measurements to simulations, the main mechanism dominating the DCR in the PureB SPADs was identified as band-to-band tunneling (BTBT) while trap-assisted-tunneling also plays a role when the perimeter breakdown is low. Increasing the dose of carriers in the enhancement region negatively impacts the total DCR of the device, but also shifts the origin of the dominant DCR contribution from perimeter to the active region. The simulations for optimization of the SPAD geometry predict that a modification of the n-doped epitaxial region of the PureB SPADs could decrease the DCR by almost two orders of magnitude. This is achieved by increasing the n-epi-layer thickness from 1 μm to 3 μm and lowering the doping from 10 15 cm -3 to 10 14 cm -3. A high electric field at the vertical pn junction in the active region can also be minimized by modifying the implantation parameters of the n-enhancement region thus keeping the BTBT contribution to the DCR sufficiently low.

    Original languageEnglish
    Title of host publicationPhysics and Simulation of Optoelectronic Devices XXVII
    EditorsMarek Osinski, Bernd Witzigmann, Yasuhiko Arakawa
    ISBN (Electronic)9781510624665
    Publication statusPublished - 26 Feb 2019
    EventPhysics and Simulation of Optoelectronic Devices XXVII 2019 - San Francisco, United States
    Duration: 5 Feb 20197 Feb 2019
    Conference number: 27

    Publication series

    NameProceedings of SPIE - The International Society for Optical Engineering
    ISSN (Print)0277-786X
    ISSN (Electronic)1996-756X


    ConferencePhysics and Simulation of Optoelectronic Devices XXVII 2019
    Country/TerritoryUnited States
    CitySan Francisco


    • Avalanche breakdown
    • Band-to-band tunneling
    • Detectors
    • Guard rings
    • Photodiode
    • Pure boron
    • Silicon
    • Single-photon avalanche diodes (SPADs)
    • Trap-assisted tunneling


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