The Silicon Photomultiplier (SiPM) is a novel device for low level light detection in various applications, for example scintillator-and fiber readout. 1,2 The SiPM is insensitive to magnetic fields and has a high photon detection efficiency. Current devices have a high optical crosstalk probability, which causes a significant increase of the excess noise factor. 3 It may replace traditional Photo Multiplier Tubes (PMT) when the optical crosstalk is reduced to a lower level of below 10%.Depending on the quantity of hot electrons in the Geiger discharge approximately three to fifty secondary photons (in average three photons per 10 5 avalanche electrons 4 ) with a wavelength range from 450nm to 1600nm are emitted from the excited cell in all directions. 5 Some of those secondary photons cause the discharge of the neighboring cell. 6,7 The different mechanism of optical crosstalk are categorized as direct and indirect crosstalk.To reduce direct crosstalk an optical barrier has to be implemented between the single micro cells. 8 Thus, we have investigated different technological concepts with regard to the trench shape, the trench etching process as well as the trench fill material.

Abstract. Despite several advantages of Silicon Photomultipliers (SiPM) over Photomultiplier Tubes (PMT) like the increased photon detection efficiency (PDE), the compact design and the insensitivity to magnetic fields, the dark count rate (DCR) of SiPM is still a large drawback. Decreasing of the SiPM dark count rate has become a modern task, which could lead to an enormous enhancement of the application range of this promising photo-detector. The main goal of this work is to gain initial information on the dark generation and identify the dominating contributions to dark currents. The chosen approach to fulfill this task is to extract characteristic activation energies of the contributing mechanisms from temperature dependent investigations of dark currents and DCR. Since conventional methods are not suited for a precise analysis of activation energies, a new method has to be developed. In this paper, first steps towards the development of a reliable method for the analysis of dark currents and dark events are presented. IntroductionThe dark count rate (DCR) of the Silicon Photomultiplier (SiPM) is still a limiting factor for the extension of its application range and requires a significant reduction. In order to achieve this requirement, a distinction of contributions determining the DCR is needed to be able to identify the dominating mechanisms. As reported in [1,3,4,5] the extraction of characteristic activation energies from the temperature dependence of the dark current is able to provide information on the dominating mechanisms. Unfortunately these methods are not suited for a precise determination of the needed energy levels, since the investigated dark currents are determined by a mixture of effects depending on voltage on the one hand (e.g. generation current, electric field effects) and overvoltage on the other hand (e.g. gain, crosstalk, afterpulsing). In this paper, we propose a new method to separate the mentioned effects using the responsivity of the detector as an appropriate reference for the measured dark current. This approach allows us

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