Abstract

A simple separate absorption and multiplication avalanche photodiode structure (SAM APD) has been developed which utilizes a single Zn diffusion to form both the active area of the device and a unique floating guard ring structure. The first devices of this type had gains of 11 and low dark currents.¹ Recently devices with optimized ring structures have demonstrated increases in breakdown voltage over unguarded structures of at least 20 V and complete suppression of edge gain. Gains >35 at 2-µA and > 15 at 0.2- µa dark current have been observed under 1.3-/µm illumination in the devices. Total dark currents at 90% of breakdown (typically 0.9V_bis >70 V) were <10 nA. The simplicity of the fabrication process makes the device well suited to meeting the demand for high performance economical APDs for the fiber optic communications market.

© 1990 Optical Society of America