Suppression of avalanche gain at the junction periphery by floating guard rings in a planar InGaAs/lnGaAsP/lnP avalanche photodiodes

Summary form only given. Planar type InGaAs/InP based avalanche photodiodes (APDs) are widely used for 2.5 Gbit/s optical communication system have also been recently developed for 10-Gbit/s applications. There exists a critical problem of edge breakdown in a planar APD. To overcome this problem, they make a smooth junction front using etching process so that the curvature become large or employ guard rings to disperse dense equipotential lines at the periphery. Floating guard rings (FGRs) were studied extensively by Y. Liu and S.R. Forrest (1992). But, there is lack of accordance between experimental and calculated optimum FGR´s dimension and also lack of experimental data showing why and how well FGR´s suppress the peripheral electric field. We fabricated various planar APDs with FGRs of different dimensions to systematically see the role of FGRs and to determine optimized condition.