A PLANAR INP/INGAAS AVALANCHE PHOTODIODE WITH FLOATING GUARD RING AND DOUBLE DIFFUSED JUNCTION

We discuss the fabrication, performance, and design of a novel, planar In0.53Ga0.47As/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 x 10(-6) A/cm2 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.