What is the photon detection efficiency (PDE) of a SiPM?
Photon detection efficiency (PDE) refers to the probability that a photon arriving on the SiPM surface is detected, an initiates the process of current pulse generation. PDE is a function of the overvoltage ΔV across the terminals of the APD and wavelength λ of the incident photon. Photon detection efficiency is one of the most important characteristics of a SiPM.
PDE is the product of three factors :- Geometrical fill factor (FF), Quantum Efficiency (QE) and Probability of a Geiger discharge. (Pt)
PDE (Vov) = Qe x Pt (Vov) x FF
Geometrical fill factor(FF)
A SiPM is a pixelated device and all the pixels(microcells) are of the same size and arranged in a tiled pattern. The total area on which the pixels of the SiPM lie is its active area. But in each microcell, only a fraction of its area is photosensitive. This fraction of the photosensitive area, equated to the active area is refferd to as the Geometrical fill factor which ranges from ∼30% to ∼80%. The larger the size of the microcell, the higher the geometrical fill factor.
Quantum efficiency (Qe) …show more content…
In the depletion region, a strong electric field exists which separates the photo-generated electron –hole pair, and is responsible for directing the charge carriers into the avalanche region. In the regions outside the depletion region, the electric field is very weak, hence photo-generated electron-hole pairs are more likely to recombine. Using Beers-Lambert law, the SiPM can be optimized to absorb light for a certain desired wavelength(or range of wavelengths) in the depletion layer. Hence depending on the range of the wavelengths set, the incident photon will initiate a Geiger discharge if it only falls within the limits. This is the principle used in fabrication of Near Ultaviolet(NUV) or Visible light (RGB)
Photon detection efficiency (PDE) refers to the probability that a photon arriving on the SiPM surface is detected, an initiates the process of current pulse generation. PDE is a function of the overvoltage ΔV across the terminals of the APD and wavelength λ of the incident photon. Photon detection efficiency is one of the most important characteristics of a SiPM.
PDE is the product of three factors :- Geometrical fill factor (FF), Quantum Efficiency (QE) and Probability of a Geiger discharge. (Pt)
PDE (Vov) = Qe x Pt (Vov) x FF
Geometrical fill factor(FF)
A SiPM is a pixelated device and all the pixels(microcells) are of the same size and arranged in a tiled pattern. The total area on which the pixels of the SiPM lie is its active area. But in each microcell, only a fraction of its area is photosensitive. This fraction of the photosensitive area, equated to the active area is refferd to as the Geometrical fill factor which ranges from ∼30% to ∼80%. The larger the size of the microcell, the higher the geometrical fill factor.
Quantum efficiency (Qe) …show more content…
In the depletion region, a strong electric field exists which separates the photo-generated electron –hole pair, and is responsible for directing the charge carriers into the avalanche region. In the regions outside the depletion region, the electric field is very weak, hence photo-generated electron-hole pairs are more likely to recombine. Using Beers-Lambert law, the SiPM can be optimized to absorb light for a certain desired wavelength(or range of wavelengths) in the depletion layer. Hence depending on the range of the wavelengths set, the incident photon will initiate a Geiger discharge if it only falls within the limits. This is the principle used in fabrication of Near Ultaviolet(NUV) or Visible light (RGB)