Quantitative Correlation Between Fabrication Precision and Device Homogeneity of Single-Photon Avalanche Diodes

For single-photon avalanche diodes (SPADs), a statistical method is advanced to establish the quantitative correlation between the controllability of structure parameters in fabrication process and the homogeneity of device characteristics. With randomly varying structure parameters introduced, it is easy to learn how significant any parameter is to the device performance. By simply setting different parameters fluctuating independently and simultaneously, the collective effect of multiparameters can be obtained and a design tradeoff between various structure parameters can be straightly carried out. For a typical InGaAsP/InP SPAD, it is seen that device homogeneity with excess-bias fluctuation within 50% requires uncertainty in layer thickness and doping density to be smaller than about 3%, whereas device homogeneity better than 10% requires epitaxial precision better than 0.5%, a challenging level.