Degradation Characteristics of Au-Si Nuclear Detectors by a Few MeV Charged Particle Irradiation

It is found that a Si surface barrier detector has been degraded after 3.2 MeV protons or 3.5 MeV 3He particle irradiation with low doses ranging from 1011 to 1012 cm-2. The degradation characteristics have been investigated through the changes in the reverse current, capacitance, alpha-particle counting response and DLTS measurements. 3He particle irradiation produces a change of the capacitance at lower reverse bias compared to that of proton irradiation, indicating the defect creation at the short penetration depth of 3He particles. Capacitance-voltage characteristics of the irradiated detectors can be simply analysed using Poisson's equation with an assumption that the charge defects are created within the depletion layers. Such kinds of defects are considered as electron traps at 0.36, 0.45 and 0.51 eV from the conduction band.