Gamma-ray sensor based on an iron chloride tetraphenyl porphyrin/p-silicon heterojunction diode
An Au/Fe(III)ClTPP/p-Si/Al heterojunction diode was constructed. The I–V characteristics of
the sensor under dark and illumination conditions were studied before and after -irradiation.
C–V measurements were also carried out at 1MHz before and after -irradiation. Two
conduction mechanisms are operating in the device depending on the applied potential.
Thermionic emission conduction is operating up to 0.6V and space charge limited current
conduction is operating at voltages >0.6 V. The rectification ratio, built-in potential and
density of defect states in the interfacial layer increase with increasing the irradiation dose.
Increasing the irradiation dose decreases the quality factor, the dark current, the capacitance at
zero bias potential and the carrier density in the depletion region. These changes are attributed
to an increase in the density of defect states in the interfacial layer and energy gap of a
semiconductor upon -irradiation.