UV-enhanced avalanche photodiode array for fluorescence applications

摘要

Abstract: We have developed avalanche photodiode (APD) arrays ofthe beveled edge type with high responsivity in theultraviolet (UV) region. A 3 $MUL 3 array with pixelsize 3 $MUL 3 mm$+2$/ was made, in which thesegmentation was done using selective diffusion in thefront surface. This technique is an improvement overprevious avalanche photodiodes, where the segmentationwas done cutting channels in the back of the detector.After the die was cut from the wafer, beveling andpassivation was performed to avoid lateral surfacebreakdown. The responsivity from 200 to 400 nm is closeto 1.1 A/W., which makes this detector suitable forflorescence applications. The gain and dark currentcoming from all pixels connected together, is the sameas a single element detector with the same area, whichindicates that the pixelization process does not reducethe performance compared to a detector withoutsegmentation. We measured high crosstalk betweenadjacent pixels (30%) which indicates that theresistance between them is too low. !12