Study of irradiation damage in silicon at different scales

In this work we focus on the simulation of radiation effects on silicon under proton irradiation at different scales. Two models of the Monte Carlo displacement damage calculation method in the Particle and Heavy Ion Transport code System (PHITS) were first used: the Torrens displacements per atom (NRT-DPA) model and a thermal recombination corrected dpa (arc-DPA), the prediction result of the final arc-DPA model is about 1/3 lower than the traditional NRT-DPA model; we also compared the difference between the two calculated values at the same dose of irradiation. When presenting a molecular dynamics study of the generation and evolution of silicon defects under irradiation, we simulated a 10 keV displacement cascade at room temperature. By postprocessing the simulation results, the changes in the distribution and number of defects, as well as the evolution of defect clusters, were analyzed, where both the number of point defects and vacancy clusters show a tendency to increase and then decrease. Finally, first -principles were used to simulate and analyze the energy band structures, DOS, effective mass, the dielectric function, reflection and transmission spectra of silicon after introduction of defects. In order to obtain more accurate value of the bandgap, the HSE06 hybridization generalization is used so that the bandgap is not underestimated, while the clear bandgap facilitates fine analysis of the band structures of the defect states. We found that although the width of the energy band is reduced, which will lead to a increase of intrinsic carrier concentration. At the same time, the effective mass of the electron and hole are greatly reduced, which ultimately leads to a reduction of carrier mobility, and this will finally cause series of performance degradations.