In/sub 0.53/Ga/sub 0.47/As/InP floating guard ring avalanche photodiodes fabricated by double diffusion

In/sub 0.53/Ga/sub 0.47/As/InP separate absorption and multiplication region avalanche photodiodes (SAM-APDs) with doubly diffused floating guard rings have been demonstrated. The planar, front-side illuminated devices are easily fabricated and incorporate strong guarding against edge and surface breakdown. Edge gain is suppressed both by the action of the floating guard rings and by the grading of the p-n junction at the outer edges of the active region that results from the second diffusion. Uniform gains as high as 85 have been measured at multiplied dark currents <100 nA. Multiplied dark currents below 5 nA have been measured at 90% of breakdown, with capacitances below 400 fF for front-side illuminated devices. The low values of dark current and capacitance, as well as the ease of fabrication, make the devices well suited for fiber-optic applications.<>