Sputtering of silicon by low‐energy oxygen bombardment studied by MD simulations

Abstract

In the field of secondary ion mass spectrometry, ion-matter interactions have been largely investigated by numerical simulations. For molecular dynamics simulations related to inorganic samples, mostly classical force fields assuming stable bonding structure have been used. In this paper, we will use a reactive force field capable of simulating the breaking and formation of chemical bonds. Important features of this force field for simulating systems that undergo significant structural reorganisation are (i) the ability to account for the redistribution of electron density upon ionization, formation, or breaking of bonds, through a charge transfer term, and (ii) the fact that the angular constraints dynamically adjust when a change in the coordination number of an atom occurs. In this work, we present results obtained for the simulation of low-energy oxygen bombardment of crystalline and amorphous silicon. Information on variation of sputtering yields, energy, and angular distributions as well as the emission of clusters are studied. Compared to normal force fields, ion-matter interactions as well as the sputtering of matter should be described more accurately, especially when using reactive primary ions (oxygen or cesium) at low impact energies.