Ion Induced Particle Desorption From Self Supporting Nanomembranes : Influence of Different Geometries and Particle Types

Abstract: Nanoelectronics is a field undergoing rapid development, meaning knowledge of the materials and methods used in nano-scale systems is a driving force in the industry. Silicon is a well known material in nanoelectronics commonly used as a semiconductor and is therefore a good representative for nanomaterials in general. In this thesis work the effects of the helium and neon ions with the energies 100 keV and 200 keV respectively on surface contaminants and the bulk material of nanometer thick silicon membranes are being studied. Beyond interactions based on different incident ions, the effects are studied inboth the geometries of transmission and backscattering, giving information about the immediate effects on the surface, as well as bulk effects. Using Medium Energy Ion Scattering (MEIS), the positively charged particles on the surfaces and in the bulk of the materials, which are either sputtered or desorbed, can be detected. While the ions are different, the energies in this work are chosen to be such, that the electronic stopping power is the same, while the nuclear stopping of neon is vastly higher. From this work, it is concluded that both ions have the same qualitative effects on the membrane contaminants, consisting of hydrocarbons, which are desorbed electronically. Furthermore, neon has the effect of destructively sputtering the bulk material. A synergistic effect of electronic and nuclear deposition was also found, as quantitatively, more hydrocarbons per incident Ne+ ion were desorbed than per incident He+ ion. The change in effect based on different geometries can to a large extent be attributed to the energy loss of the ions in the material. The one change between geometries which can not be explained by energy loss in the material, is a 50% under representation of desorbed hydrogen ions in transmission geometryfor He+ incident ion. It is also concluded that the method used has the potential to be a viable, non-destructive and scalable cleaning and measuring method for contaminations on nano-scale materials, such as 2 dimensional materials.