The modelling and simulation of the performance parameters of single-photon avalanche diode
(SPAD) is carried out with the help of MATLAB. The model is applied on a sample SAM SPAD
device which consists of a multiplication region made of InP and an absorber region of InGaAs. A
generalized theory for breakdown probability is implemented which takes into account the
generation of photocarriers at random locations among each layer. The study reveals that by
increasing the multiplication region width, the number of dark carriers due to field-assisted
generation mechanisms is reduced which are counteracted by an increase in the number of GR dark
carriers. Thus, the photon detection efficiency (PDE) and Dark count rate (DCR) is of utmost
importance before the fabrication of a device. In this work we have simulated a SPAD device
incorporating dead space effects and history dependent ionization coefficient to generate the electric
field profile, dead space profile, ionization coefficient profile, breakdown profile and avalanche
probabilities. Finally, we have extracted the PDE vs overbias voltage and PDE vs DCR curves of
the simulated device under different multiplication region widths to demonstrate the effect of
multiplication region width on the performance parameters of a SPAD.
