Silicon photomultiplier

Every avalanche diode in a SiPM operates in Geiger mode and is coupled with the others by a metal or polysilicon quenching[clarification needed] resistor.

Compared to conventional PMTs, the photoelectron gain in SiPMs is typically more deterministic, resulting in low or even negligible excess noise factor.

Mass production of silicon electronics by multiple vendors allows SiPMs to be made very cheaply relative to vacuum tubes.

Dynamic range can be orders of magnitude larger than a PMT if large numbers of SPADs are arrayed together, enabling faster imaging rates or higher SNR without saturation.

Conventional avalanche photodiodes (APDs) also produce an amplified analog current in response to light absorption.