Optimization of floating guard ring parameters in separate-absorption-and-multiplication silicon avalanche photodiode structure

In this paper, the effect of the floating guard ring (FGR) parameters, such as number of FGRs and the distances between the FGRs, on the prevention of the breakdown at the multiplication layer edge for a given avalanche photodiode (APD) structure has been analyzed. Four structures are examined: APD without FGR and APDs with one, two and three FGRs. The width and depth of the boron-doped FGRs is 1 μm with peak concentration of 1018 cm^-3. The intrinsic breakdown voltage in the active region of the APD is 371 V and the epitaxial layer is fully depleted at 14 V. The breakdown occurs in the active area of the APD structure by using three FGRs. The optimal position of three FGRs are determined and the breakdown voltage of 409 V is achieved at the multiplication edge, which is higher by 38 V than in the active region. In contrast, the edge breakdown voltage is 170 V, 270 V and 348 V for structures without floating guard rings, with one FGR and with two FGRs, respectively. Spectral responsivity of the structure is analyzed in the range of 400 to 1000 nm showing that such APD can be effectively used for detection of the visible light.