Charge multiplication in CdZnTe Schottky barrier diode detectors at alpha-particles registration

The planar detectors with Schottky barrier diode structure (Au/CdZnTe/In) were investigated using alpha-particle response characterisation. At irradiation of a negative In contact by alpha-particles of 5.5 MeV slow pulses with extremely large amplitude, exceeding in tens times the amplitude of the pulses when operating at the reverse bias have been found. To study this phenomenon a special charge-sensitive preamplifier with low charge sensitivity and a large decay time constant has been used. Was found that the amplitude of the output pulses obtained with detectors having Schottky barrier diode structure at the forward biases exceed in many times the amplitude of output pulses obtained with planar conductive detector (Au/CdZnTe/Au) fabricated of the same crystal. Irradiation of a negative contact of the conductive detector with a laser visible light (635 nm) leads to the similar effect.