The production of quantum systems based on single atoms in a solid requires new techniques in ion implantation. A pierced atomic force microscope (AFM) tip is developed as a nanoaperture to implant single ions with nanometer resolution at kinetic energies below 10 keV to avoid ion straggling. This technique is already used for a large number of novel quantum devices in diamonds. However, to further improve the resolution, scattering at the aperture is identified as the main limiting factor of lateral placement accuracy and ion channeling effect as the main factor for depth resolution at low kinetic energy. The simulations of the scattering effects show that the fraction of scattered ions depends not only on the cone angle and shape of the hole, but also on the beam divergence and the gap between AFM tip and sample. The decrease in axial precision due to ion channeling depends mainly on the surface roughness and the incident angle of the ion beam. For a smooth (100) surface, a 12 -inclined beam that provides the best conditions for highest resolution is found.
Ion Channeling and ScatteringA nanoaperture defined by drilling in a hollow pyramidal atomic force microscope (AFM) tip is used to produce precise nitrogen vacancy (NV) center nanostructures in diamond by low energy nitrogen implantation. Ion scattering and channeling are the most important limiting factors to achieve high lateral resolution. In article number http://doi.wiley.com/10.1002/pssa.201900528 by Nicole Raatz and co‐workers, both effects are studied using iradina, crystal‐trim and corresponding experiments.
Long channels with diameter of few tens of nanometer are produced by chemical track etching of swift heavy ion irradiated muscovite sheets. Such small apertures are most suitable e.g. as beam defining apertures for focusing systems in ion beam facilities enabling beam diameters down to a few nanometers. One of the most important parameters to consider is the interaction of the ion beam with the walls of the aperture. We report angle-resolved transmission and energy-loss measurements of MeV ion beams through ion-track-etched capillaries with very high aspect ratio of about 60. For all ion energies, the angle-resolved transmission curves measured through the channels show a significant enhancement with respect to the expected pure geometrical considerations. This broadening of the acceptance angle increases further when the kinetic energy is reduced. This effect is ascribed to low-angle scattering of the ions at the surface of the muscovite capillary walls. These results are well described by simulations applying a similar approach as used for ion beam channeling in crystals.
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