  The avalanche breakdown and Geiger mode of the silicon p-n junction is
considered. A precise physically motivated method is proposed for determining
the avalanche breakdown voltage of silicon photomultipliers (Si PM). The method
is based on measuring the dependence of the relative photon detection
efficiency (PDErel ) on the bias voltage when one type of carriers (electron or
hole) is injected into the avalanche multiplication zone of the p-n junction.
The injection of electrons or holes from the base region of the Si PM
semiconductor structure is performed using short-wave or long-wave light. At a
low overvoltage (1-2 V) the detection efficiency is linearly dependent on the
bias voltage; therefore, extrapolation to zero PDErel value determines the Si
PM avalanche breakdown voltage with an accuracy within a few millivolts.
