A theoretical study of electron-hole pair formation due to the collision of an atom with a solid surface

Electronic excitation in a semiconductor induced by the collision of energetic atoms with the solid surface is investigated theoretically. The modeling has been performed for a one-dimensional independent-electron system where the solid is described by a chain of 10-20 atoms. The time evolution of the nuclei (i.e., colliding atom and chain atoms) has been described by classical mechanics while quantum mechanical description has been used for the electronic dynamics. The two systems (i.e., the atoms and the electron) were coupled to each other and the equations of motion were solved self-consistently. Energy dissipation from the chain to the rest of the solid was included via the GLE approach. This study establishes the relationship between the probability of electron-hole formation and various parameters of the system such as collider translational energy, magnitude of the band gap, and existence of impurities in the solid. In addition, two excitation mechanisms were examined, electronic excitation due to a direct coupling between the electron and the colliding atom and an indirect mechanism due to electron-phonon coupling.