Electronic stopping power and transient charge dynamics of low-energy H, B, and N ions penetrating through 4H-SiC

The microscopic mechanisms of electronic energy loss and charge redistribution induced by slow ions in wide-bandgap semiconductors are central to ion implantation and radiation-tolerant device design. Using real-time time-dependent density functional theory, we investigate the electronic stopping power and transient charge dynamics of neutral H, B and N projectiles channeled along the <001> direction in 4H-SiC over velocities of 0.1-0.6 a.u. The energy deposition profiles display pronounced oscillations that follow the periodic modulation of the crystal's electron density, while the overall stopping scales linearly with velocity and increases systematically with projectile atomic number. The calculated stopping powers are in good quantitative agreement with stopping and range of ions in matter data in the pre-Bragg-peak regime. The longitudinal force on the projectiles and nearby host atoms shows pronounced oscillations, with amplitudes mainly determined by the projectile species. Hirshfeld charge analysis shows that the carbon atom experiences transient electron depletion, the silicon atom tends to accumulate electrons, and the projectiles develop strongly species- and velocity-dependent effective charges, most pronounced for N. Real-space charge-density-difference maps further demonstrate that the induced nonequilibrium response is highly localized around C-2p orbitals and tracks the ion on sub-femtosecond time scales. These results provide a coherent microscopic picture of ultrafast, nonadiabatic electronic stopping processes in 4H-SiC under low-velocity ion irradiation.