A planar InP/InGaAs avalanche photodiode with floating guard ring and double diffused junction

The authors discuss the fabrication, performance, and design of a novel, planar In/sub 0.53/Ga/sub 0.47/ As/InP separate absorption and multiplication region avalanche photodiode (SAM-APD) with floating guard rings and a double Zn diffused junction. The APD, grown by both vapor phase epitaxy and metalorganic vapor phase epitaxy, is observed to have a uniform gain of 85, a minimum primary dark current density of 5*10/sup -6/ A/cm/sup 2/ at 90% of breakdown, and a capacitance of 0.4 pF for a front-side illuminated device. Both experimental and analytical results show that the double-diffused floating guard ring structure prevents edge breakdown, and also greatly reduces the electric field along the semiconductor/insulator surface. The operation mechanisms and the optimum design of the planar APD based on a two-dimensional device model are discussed.>