silicon photomultipliers (SiPM)
Silicon photomultipliers (SiPM) are single-photon sensitive semiconductor devices, more specifically arrays of hundreds to tens of thousands of integrated SPADs implemented on a common silicon substrate, each capable of individually and independently detecting photons.
All microcells are read in parallel. This makes it possible to generate signals in a dynamic range from a single photon to 1000 photons for a device with an area of only one square millimeter.
Compared to conventional PMTs, there is a low or even negligible additional noise factor. In addition, the bias voltages are 10 to 100 times lower, which simplifies the electronics. In the red to near-infrared they have a significantly higher quantum efficiency than available PMTs and a significantly larger dynamic range when a large number of SPADs are placed together. This enables faster imaging rates or a higher signal-to-noise ratio.
Please note: Unlike PMTs, SiPM may require sub-ambient cooling and may be difficult to obtain large active areas as the dark numbers per area are higher than PMTs.