Characterization of multi-segment CMOS single photon avalanche diode arrays

Abstract

Single Photon Avalanche Diodes (SPADs) are ultrasensitive semidonductor photodiodes which are increasingly becoming the preferred photodetector device in a multitude of applications. This is because of their relatively high detection rates and due to being fully integrable in standard CMOS. In optical data communication, the most important parameter of a photodetetctor is its sensitivity, which is a measure for how efficiently light from a modulated laser is converted into a useable data signal. An existing measurement system previously used to characterize four-segment SPAD receivers was extended to be used for three novel receivers fabricated in 0.35 μm HV CMOS: two distinct nine-segments receivers and on twelve-segment receiver. The twelve-segment receiver could not be characterized within scope of this thesis due to process variations making it impossible to find an utilizable operating point in the available samplews. The two nine-segment receivers performed very well, achieving peak senitivities of -56,81 dBm and -55,55 dBm respectively for Bit Error Rate (BER) limit of 2*10^(-3) at a data rate of 50Mb/s. Under these operating conditions, the better of the two 9-segment receiver designs exceeded the maximum sensitivity previously achieved by any comparable multi-segmet SPAD receiver by almost 1.5 dBm, reducing the gap to the quantum limit. Direct comparison between the distinct nine-segment receivers leads to possible implications for the most efficient geometry of such multi-segment SPAD receivers.