An Estimation of Single Photon Avalanche Diode (SPAD) Photon Detection Efficiency (PDE) Nonuniformity

An analytical expression estimating the photon detection efficiency (PDE) nonuniformity of single-photon avalanche diodes is derived. The estimation relies upon well-established semiempirical and analytical models and is useful for medium- to high-resolution arrays, as well as for wafer-to-wafer variations. While the only explicit example presented so far is for 1-D estimation based on breakdown voltage variation, the proposed PDE nonuniformity estimation algorithm can be expanded to additional dimensions so as to incorporate spread in technological parameters such as junction depth, well depth, and local defects.