Edge Breakdown Suppression of 10 Gbps Avalanche Photodiode

Abstract

We have demonstrated a high-speed avalanche photodiode (APD) for a 10 Gbps optical communication system. To achieve a high gain-bandwidth product and reliable operation, the reduction of the multiplication layer thickness and an optimum design of the internal electric eld distribution are essential. One- and two-dimensional analysis were done for this purpose. The suppression of edge breakdown can be achieved by precise control of the thickness of the multiplication layer and charge densities of the eld control layer. Furthermore we suggest a junction curvature shape having negative curvature of the equi-potential line at the device edge. This new design successfully suppressed edge breakdown. The fabricated APD shows high current gain without premature edge breakdown, and a gain-bandwidth of above 80 GHz has been obtained.