A TCAD and Spectroscopy Study of Dark Count Mechanisms in Single-Photon Avalanche Diodes

Eric A. G. Webster, Robert Henderson

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Abstract—It is shown through dark count rate spectroscopy
(DCRS) and TCAD-simulations that in single-photon avalanche
diodes (SPADs), the majority of low dark count rate (DCR)
devices in modern CMOS arrays are free of deep-level traps
and that DCR can therefore be explained by saturation current
and band-to-band tunneling (BTBT). The DCRS performed on
the Megaframe 32 × 32 show that the activation energies for
the high DCR devices are consistent with a single type of defect
at ≈0.44 eV, thought to be the E-center, in differing electric
fields. Calibrated TCAD-simulated reverse bias leakage currents
are orders of magnitude lower than those measured due to the
lack of parasitic leakage paths but give theoretical DCRS that
are close to the measured values for four different SPAD designs
and predict the voltage dependence at high fields. The coefficients
for Kane’s indirect tunneling model in the [100] direction are
determined as A ≈ 2 × 1015 cm−3/s and B ≈ 2.39 × 107 V/cm
through TCAD calibration, DCR measurement, and theory. It is
found that indirect BTBT dominates the DCR of SPADs with
low breakdown voltages.
Original languageEnglish
Pages (from-to)4014-4019
Number of pages6
JournalIEEE Transactions on Electron Devices
Volume60
Issue number12
Publication statusPublished - Dec 2013

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