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Study of emission of secondary particles during ion scuttering and its effects on LEIS spectra
Malatinová, Michaela ; Johánek, Viktor (oponent) ; Průša, Stanislav (vedoucí práce)
In this thesis, we investigate the emission of secondary particles using both Low Energy Ion Scattering (LEIS) and Medium Energy Ion Scattering (MEIS) spectroscopy. LEIS utilizes a primary beam of noble gas ions with initial energies of a few keV and is particularly sensitive to the outermost surface layer. We examine the surface contamination changes on copper, platinum, and silicon, assessing the effects of sputter cleaning and annealing on both naturally occurring and induced CO gas contamination. Additionally, we employ Time-of-Flight MEIS with energy ranges up to a few hundred keV to study the desorption of surface contamination from a single-crystalline Si(100) self-supporting 50 nm thick membrane. Primary beams of He, Ne, and B were used to probe the membrane in both standard backscattering and novel transmission measurement geometries, allowing us to analyze emission from both surfaces. The desorption of surface contamination was previously attributed to electronic sputtering. However, heavier ions with higher nuclear stopping enhance the electronic energy deposition, revealing a synergy effect between them. The combined effects of increased energy deposition to the nuclear subsystem and the directional nature of the collision cascade increased the yield of secondary ions. This knowledge can significantly advance the precision cleaning and structuring of 2D materials using ion beams, enabling surface modification and control of contamination.
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