SiPM Photon Detection Efficiency (PDE) Calculator

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Choose whether to build PDE up from its physical sub-factors or to back-calculate it from a calibrated responsivity measurement.
Probability that an incident photon generates an electron-hole pair in the active silicon. Ranges from 0.3 to nearly 1 with a good anti-reflective coating; typically 0.6-0.9 in the visible band.
Fraction of the SiPM surface that is active (sensitive) area. The remainder is occupied by quench resistors, metal routing and guard rings. Typical values: 0.30 to 0.80.
Probability that a generated carrier initiates a self-sustaining Geiger avalanche. Increases with overvoltage; typically 0.5 to 0.95 at working bias.
Number of electron-hole pairs produced per fired micro-cell per detected photon. Typically 10^5 to 10^7, linear in overvoltage.
Wavelength of the incident photon. SiPMs peak in the near-UV to blue range (380-550 nm) and lose sensitivity above ~900 nm.
nm
Probability that a fired cell triggers a neighbouring cell via secondary photons, causing false multi-photon signals. Typically 0.02 to 0.20.
Probability of a delayed secondary pulse caused by carriers trapped and re-released in the silicon. Typically 0.01 to 0.10.
Photon Detection Efficiency (PDE)Moderate PDE
33.6%

Probability that one incident photon produces a counted output pulse

Expected responsivity (R)121,902.244A/W
Photon energy2.952eV
Effective detection probability0.31%
Noise inflation factor1.071
33.6%
Very low<10%Low10%-25%Moderate25%-40%Good40%-55%Excellent55%+

PDE of 33.6% is moderate - typical of small micro-cell or UV-optimised devices.

  • Of every 100 incident photons, approximately 33.6 produce an output pulse. 31.4% are true single-photon detections; the rest are inflated by crosstalk and afterpulsing.
  • Crosstalk (5%) and afterpulsing (2%) inflate the raw count rate by 7.1% above the true detection rate. This systematic excess must be subtracted in precision photon-counting applications.
  • Expected responsivity: 121.9 kA/W. This is orders of magnitude higher than a bare photodiode (typically 0.3-0.6 A/W) due to the avalanche gain of the SiPM.

Next stepTo improve PDE, focus on fill factor (larger micro-cell pitch) and triggering probability (increase overvoltage slightly). Quantum efficiency improvements require process-level changes such as anti-reflective coating optimisation.

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