Geant4 simulation of neutron displacement damage effect in InP

As the second-generation compound semiconductor material, indium phosphide (InP) has strong irradiationresistance and high photoelectric conversion efficiency. It has advantages in the field of photonics and radiofrequency. In atmospheric space, high-energy cosmic rays enter into the earth's atmosphere and interact withnitrogen (N), oxygen (O) and other elements to produce secondary cosmic rays. The irradiation particles in theatmosphere are mainly neutrons because the penetration of charged particles is weak. The InP semiconductordevices are affected by atmospheric neutron irradiation of various energy from all directions, which results inthe internal defects in InP crystals, the degradation of device performance and the reduction of device lifetime.In this paper, Monte Carlo simulation software Geant4 is used to simulate the neutron irradiation effect, andthe initial state distribution of displacement damage caused by neutrons with different energy is obtained,including the distribution of non-ionized energy loss (NIEL) with depth, the relationship between NIEL and theenergy of incident neutrons, and the type, number and energy of primary knock-on atoms (PKA). The resultsshow that 1) the NIEL is uniformly distributed when material thickness is on the order of mu m and for thematerial thickness on the order of cm and more, the NIEL decreases as the depth increases and can be reducedto zero when the target material is thick enough; 2) by analyzing the NIEL produced by 1-20 MeV neutronsincident on 3-mu m InP and their distribution with depth, it is found that the NIEL first increases and thendecreases with incident neutron energy increasing. This trend is caused mainly by PKA produced through theinelastic scattering reaction; 3) by analyzing the type and the energy of PKA produced by 1-20 MeV neutronsincident on 3 mu m InP, it is found that the PKA of In/P accounts for a large proportion, which causesdisplacement damage mainly, and the higher the neutron energy, the richer the variety of PKA is and thegreater the maximum kinetic energy of PKA, but the PKAs mainly distribute in the low energy part. Thepresent research has theoretical and guiding value for the long-term application of InP-based 5G devices inatmospheric neutron irradiation environment