Deep Level Promotion Mechanism in Sputtering

TL;DR

This paper models the surface effects on ionized sputtered atoms using a localized level Hamiltonian, revealing a power law relation between charge state and velocity at low energies, validated against experimental data.

Contribution

It introduces a novel application of the Anderson-Newns Hamiltonian to analyze charge states in sputtering, incorporating electronic excitations and multiple time scales.

Findings

Power law dependence of charge state on velocity at low energies.

Agreement with previous theoretical results at zero temperature.

Validation against SIMS experimental data.

Abstract

We have applied a double decoupled localized level Anderson-Newns Hamiltonian to the analysis of surface effects upon the ionized fraction $\mathcal{R}_{+}$ of sputtered atoms from a metal surface. Electronic excitations, induced in the conduction band by the transient formation of quasi molecular systems, between substrate and emitted atoms, in the collision cascade generated by the primary incident beam, have been explicitly included into an instantaneous transition matrix peaked at the Fermi level of the material. The interaction dynamics seem to take place over two different time scales, one related to sputtered atom trajectories and the other to recoiled substrate particles. Finite temperature calculations have suggested, at very low ejection energies, a power law dependence of the final charge state of the sputtered beam on its detected velocity. This result is in agreement, in the zero temperature limit, with some previously published papers and its validity has been compared to other theoretical outcomes and tested on SIMS data.