Detection of single photons is crucial for a number of applications. Geiger photodiodes (GPD) provide large gains with
an insignificant amount of multiplication noise exclusively from the diode. When the GPD is operated above the reverse
bias breakdown voltage, the diode can avalanche due to charged pairs generated from random noise (typically thermal)
or incident photons. The GPD is a binary device, as only one photon is needed to trigger an avalanche, regardless of the
number of incident photons. A solid-state photomultiplier (SSPM) is an array of GPDs, and the output of the SSPM is
proportional to the incident light intensity, providing a replacement for photomultiplier tubes.
We have developed CMOS SSPMs using a commercial fabrication process for a myriad of applications. We present
results on the operation of these devices for low intensity light pulses. The data analysis provides a measured of the
junction capacitance (~150 fF), which affects the rise time (~2 ns), the fall time (~32 ns), and gain (>106). Multipliers
for the cross talk and after pulsing are given, and a consistent picture within the theory of operation of the expected dark
current and photodetection efficiency is demonstrate. Enhancement of the detection efficiency with respect to the
quantum efficiency at unity gain for shallow UV photons is measured, indicating an effect due to fringe fields within the
diode structure. The signal and noise terms have been deconvolved from each other, providing the fundamental model
for characterizing the behavior at low-light intensities.