P-on-N and N-on-P silicon photomultipliers: responsivity comparison in the continuous wave regime

We report the electrical and optical comparison, in continuous wave regime, of two novel classes of silicon photomultipliers (SiPMs) fabricated on silicon P-type and N-type substrate respectively. Responsivity measurements have been performed with an incident optical power from tenths of picowatts to hundreds of nanowatts and on a broad spectrum, ranging from ultraviolet to near infrared (340-820 nm).For both classes of investigated SiPMs, responsivity shows flat response versus the optical incident power, when a preset overvoltage and wavelength is applied . More in detail, this linear behavior extends up to about 10 nW for lower overvoltages, while a shrink is observed when the reverse bias voltage increases. With regards to our responsivity measurements, carried out in the abovementioned spectral range, we have found a peak around 669 nm for the N-on-P and a peak at 417 nm for the P-on-N SiPM.