Numerical Modeling of Structural and Spectral Changes in a Textured Silicon Wafer after Shock Compression

Abstract This study investigates structural and spectral changes in a single–crystalline silicon plate subjected to mild laser–induced shock–wave compression. X-ray diffraction and Raman spectra of silicon in the initial and post–shock states are analyzed experimentally. To interpret the experimental results, numerical simulations of the shock loading process and subsequent relaxation of the atomic structure are performed using classical molecular dynamics with the Tersoff interatomic potential, as well as a simplified finite element model employed to estimate the macroscopic loading parameters. A range of moderate shock pressures on the order of one gigapascal is considered, for which the fraction of irreversibly rearranged atoms remains below one percent. Analysis of coordination characteristics and radial distribution functions reveals no evidence of phase transformations, but indicates the development of non–affine deformation of the crystalline lattice. Examination of bond angle distributions demonstrates local distortions of the tetrahedral configuration characteristic of silicon, accompanied by an increased angular spread and the formation of irreversible local rearrangements corresponding to plastic deformation. Shock–induced local restructuring of the atomic configuration, breaking of centrosymmetry, and the emergence of residual elastic stresses result in observable peak shifts in the X-ray diffraction and Raman spectra in the post–shock state. It is shown that the employed numerical approach provides an adequate atomistic description of post–shock structural relaxation in silicon and the associated spectral changes, thereby bridging the gap between experiment and theory and may be useful for applications in laser processing and micro- and nanoelectronics.