Sputtering of Mo and Ag with xenon ions from a radio-frequency ion thruster

Abstract

The goal of this work was the setup of an electric propulsion (EP) sputtering test section as a feasibility study for ground-based sputter testing of spacecraft materials with a radio-frequency ion thruster (RIT). Such experiments deliver valuable data which are scarce but highly desired to model EP-based space missions, for example with SPIS (Spacecraft Plasma Interaction System), in order to predict the performance and lifetime of spacecraft components. This study assessed if sufficient testing conditions can be met to produce reliable experimental material data in the future. Therefore, the thruster was operated at ion energies of 1.5 keV and 1.8 keV, and a quartz crystal microbalance (QCM) was installed to detect sputter deposition rates. Molybdenum (Mo) and silver (Ag) were chosen as sputter targets. Wafer substrates served as a passive sampling method to characterize the composition of sputtered material by Rutherford Backscattering Spectrometry (RBS). Additionally, sputtering simulations matching the experimental conditions were conducted with the software SDTrimSP. We obtained comparable experimental and computational data, as measured sputter deposition rates lie within the simulated order of magnitude and to some extent show the predicted angular dependence. Analysis of deposited sputter material revealed the formation of metal oxides which requires a future adaption of the material specific QCM settings. Furthermore, the cooling system of the QCM sensor head was not sufficient, limiting the comparability of results.

Low energy ion-solid interactions: a quantitative experimental verification of binary collision approximation simulations

“…Low energy ion irradiation and ion implantation of solids becomes increasingly important due to the advances in ultra-low energy ion implantation of two-dimensional (2D) materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], implantation of shallow junctions [17][18][19][20] and the broad applied field of ion erosion [21][22][23][24][25]. Ion energies required for doping of 2D materials are as low a 20 eV.…”