2D Dark-Count-Rate Modeling of PureB Single-Photon Avalanche Diodes in a TCAD Environment

Tihomir Knezevic, Lis K. Nanver, Tomislav Suligoj

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

    5 Citations (Scopus)
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    PureB silicon photodiodes have nm-shallow p+n junctions with which photons/electrons with penetration-depths of a few nanometer can be detected. PureB Single-Photon Avalanche Diodes (SPADs) were fabricated and analysed by 2D numerical modeling as an extension to TCAD software. The very shallow p+-anode has high perimeter curvature that enhances the electric field. In SPADs, noise is quantified by the dark count rate (DCR) that is a measure for the number of false counts triggered by unwanted processes in the non-illuminated device. Just like for desired events, the probability a dark count increases with increasing electric field and the perimeter conditions are critical. In this work, the DCR was studied by two 2D methods of analysis: the “quasi-2D” (Q-2D) method where vertical 1D cross-sections were assumed for calculating the electron/hole avalanche-probabilities, and the “ionization-integral 2D” (II-2D) method where cross sections were placed where the maximum ionization-integrals were calculated. The Q-2D method gave satisfactory results in structures where the peripheral regions had a small contribution to the DCR, such as in devices with conventional deepjunction guard rings (GRs). Otherwise, the II-2D method proved to be much more precise. The results show that the DCR simulation methods are useful for optimizing the compromise between fill-factor and p-/n-doping profile design in SPAD devices. For the experimentally investigated PureB SPADs, excellent agreement of the measured and simulated DCR was achieved. This shows that although an implicit GR is attractively compact, the very shallow pn-junction gives a risk of having such a low breakdown voltage at the perimeter that the DCR of the device may be negatively impacted.
    Original languageEnglish
    Title of host publicationPhysics and Simulation of Optoelectronic Devices XXVI
    Subtitle of host publicationSPIE OPTO, 27 January - 1 February 2018, San Francisco, California, United States
    EditorsBernd Witzigmann , Marek Osiński , Yasuhiko Arakawa
    Place of PublicationBellingham, WA
    Number of pages10
    Publication statusPublished - 23 Feb 2018
    EventSPIE Optoelectronics and Photonic Materials and Devices Conference, OPTO 2018 - The Moscone Center, San Francisco, United States
    Duration: 28 Jan 20182 Feb 2018

    Publication series

    NameProceedings of SPIE
    ISSN (Print)0277-786X
    ISSN (Electronic)1996-756X


    ConferenceSPIE Optoelectronics and Photonic Materials and Devices Conference, OPTO 2018
    Abbreviated titleOPTO
    Country/TerritoryUnited States
    CitySan Francisco


    • photodiode
    • single-photon avalanche diodes (SPADs)
    • detectors
    • silicon
    • pure boron
    • guard rings


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