Locating the avalanche structure and the origin of breakdown generating charge carriers in silicon photomultipliers by using the bias dependent breakdown probability

Understand

We present characterization results of two silicon photomultipliers; the Hamamatsu LVR-6050-CN and the Ketek PM3325 WB.

• With our measurements of the bias dependence of the breakdown probability we are able to draw conclusions about the location and spatial extension of the avalanche region.
• For the KETEK SiPM we find that the avalanche region is located close to the surface.
• In the Hamamatsu SiPM the high-field region is located $0.5\,\mu$m below the surface, while the volume above is depleted almost until the surface.