Effect of sulfide-polyamide passivation on dark currents of the InAlAs/InGaAs/InP avalanche photodiodes

The paper presents a study of effect the mesa structure surface passivation on performance of InAlAs/InGaAs/InP avalanche photodiodes. The mesa passivation was made by using treatment in an aqueous solution of ammonium sulfide and subsequent protection by a layer of polyamide (sulfide-polyamide passivation). As a result, avalanche photodiodes with a photosensitive area of 32 microns reproducibly demonstrate dark current below 10-20 nA at the level of 0.9 of the breakdown voltage. A homogeneous distribution of the breakdown voltage value over the sample area at -85V, as well as long-term stability of avalanche photodiode characteristics were observed.