Simulation Of Silicon Irradiation Damage Based On Geant4

With the development of aerospace industry,more and more integrated circuits are used in space vehicle, but space environment is very complex, there are a lot of different energetic particles, irradiation effect of these energetic particles can lead to failure of the semiconductor device and even the space vehicle and equipment lose their function. So research of radiation damage has a very important value.This paper mainly studies the irradiation damage of silicon material with the help of Geant4. After in-depth study of Geant4, irradiation damage model of silicon material is build, this mainly includes of the establishment of silicon material model, the definition of the particle source and the physical effect that occurs when a particle passes through the silicon material.After accomplish the simulation of 1Me V neutron in silicon material, energy spectra of PKA is got, and then study the relationship between IEL、NIEL and the geometry of silicon material, the conclusion that nanodevice has strong anti-radiation ability is obtained. By extracting the coordinate of each PKA in the silicon material, each PKA’s specific location in the silicon material can be drawn, when the size of the silicon material is much less than the mean free path of neutron in silicon material, PKA approximately uniform distribution. However, when the size of the silicon material is larger than the mean free path of neutron, the distribution of PKA exhibits obvious nonlinear.The ionization energy deposition plays an important role when 1Me V gamma particle pass through the silicon material. It is a linear relationship between the ionization energy deposition and the thickness of the silicon material when it is larger than the gamma’s mean free path in the silicon material.When high-energy electron interact with atom in silicon, PKA(primary knock-on atom) appears, however, due to the energy of PKA is relatively low, it will not form a cascade effect as neutron does. From the simulation result, it is clear that NIEL has a linear relationship with the length of silicon material when the size of the silicon material is very small, but when the size increase, clearly nonlinear relationship appeared, this is because the probability of scattering is very large, with the effect of slow down and trajectory offset, eventually it deviate from the linear relationship.Finally neutron-gamma combined radiation impact on the silicon material, the energy range is between 10 ke V to 20 Me V. From the simulation result it is known that average energy of PKA is 249.064 ke V, the peak energy is about 10 ke V, low-energy PKA occupies a larger proportion, the distribution of PKA is uniform in the silicon material. The number of SKA almost three orders of magnitude larger than the PKA, and also SKA has a uniform distribution, so it can be approximately considered that the total atoms in the material has the same distribution with SKA, that is uniform distribution.