Defect passivation and dark count in Geiger-mode avalanche photodiodes

An experimental study of post metal anneal conditions on dark count in Geiger-mode avalanche photodiodes (GM-APD) has been performed. The GM-APD structure will be shown to be extremely sensitive to post-metal anneals. Dark counts from measured samples decreased by a factor of two for each separate anneal in forming gas using temperatures from 425/spl deg/C to 450/spl deg/C. Conversely anneals of 250/spl deg/C in ambient increased dark count for temperature cycles up to 124 hours. Passivation and de-passivation of defect sites within the shallow junction active area are suspected as mechanisms contributing to the variations in dark count.