Investigation of Ion Channeling and Scattering for Single‐Ion Implantation with High Spatial Resolution

Abstract

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.

Scalable creation of silicon-vacancy color centers in diamond by ion implantation through a 1-$μ$m pinhole

“…The foil thickness around it was measured optically to d foil = (27.5 ± 1.1) µm, which is important to evaluate a possible effect of a pinhole tilt on the ion throughput. We emphasize here, that for our 1 µm hole, this issue is not as critical as in the case of nano-apertures 19 . Nonetheless, the relatively thick frame of the pinhole demands a precise perpendicular mounting relative to the incoming ion beam.…”

“…Color centers can be obtained either during diamond growth 14 or by ion implantation followed by thermal annealing 15 . Only in the second case their position can be laterally controlled, for instance by focused ion-beam techniques [16][17][18] or by aperture-type AFM tips 19 , which is crucial for device fabrication. Although these techniques have demonstrated very high lateral resolution (down to about 10 nm), so far they have only been investigated at low ion energies (a few keV), which limits the implantation depth to only a few nanometers.…”

Near-Surface Electrical Characterisation of Silicon Electronic Devices Using Focused keV Ions

“…Precision localisation of single ions has already been demonstrated with the use of an atomic force microscope nanostencil placed directly above the device [54]. However, adapting this approach below the 30 nm level may be technically challenging due to expected lateral and axial ion aperture straggling effects [55]. Such concerns do not apply in this approach, given the lack of a mechanical mask.…”

Charge‐Assisted Engineering of Color Centers in Diamond

“…It is furthermore possible to avoid ion channeling by implanting with an incidence angle a few degrees off from any main crystal axis. A detailed study of the channeling effect for low energy ions is found in the study by Raatz et al [ 28 ] Several methods were thus developed to reach high lateral resolution as well and to obtain a full 3D nm positioning. The implantation of nitrogen into diamond to form NV centers was an ideal playground.…”