Numerical simulation of avalanche breakdown within InP-InGaAs SAGCM standoff avalanche photodiodes

The breakdown location within a planar InP/In/sub 0.53/Ga/sub 0.47/As (InGaAs) separate absorption, grading, charge sheet, and multiplication (SAGCM) avalanche photodiode (APD), using the standoff breakdown suppression design to replace guard rings, depends on the two-dimensional (2-D) geometry of the Zn diffused well. Since the geometry of this p/sup +/ diffusion is dependent upon the surface etch, the effects of varying the etch depth (t/sub standoff/) and length of the sloped etch edge (w/sub slope/) are studied using a two-dimensional drift-diffusion simulator. It is determined that the etch depth brackets a region where center breakdown dominance is possible. To ensure center breakdown within this region it is concluded that there is a maximum value that the slope of the etch walls must not exceed.