The electron elevator: excitations across the band gap via a dynamical gap state?

Abstract

We have used time-dependent density functional theory to study self-irradiated Si. We calculate the electronic stopping power of Si in Si by evaluating the energy transferred to the electrons per unit path length by an ion of kinetic energy from $1$ eV to $100$ keV moving through the host. Electronic stopping is found to be significant below the threshold velocity normally identified with direct transitions across the band gap. A structured crossover at low velocity exists in place of a hard threshold. An analysis of the time dependence of the transition rates using coupled linear rate equations enables one of the excitation mechanisms to be clearly identified: a defect state induced in the gap by the moving ion acts like an elevator and carries electrons across the band gap.

6 pages (with references), 4 figures and supplementary material (rate_equations.tex)

References in corpus (5)

• Electronic stopping power in insulators from first principles
• Electronic stopping power in gold: The role of d electrons and the H/He anomaly
• Electronic stopping power in a narrow band gap semiconductor from first principles
• Including nonlocality in exchange-correlation kernel from time-dependent current density functional theory: Application to the stopping power of electron liquids
• Incorporating non-adiabatic effects in Embedded Atom potentials for radiation damage cascade simulations

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