Single ion implantation for solid state quantum computer development

Abstract

Several solid state quantum computer schemes are based on the manipulation of electron and nuclear spins of single donor atoms in a solid matrix. The fabrication of qubit arrays requires the placement of individual atoms with nanometer precision and high efficiency. In this article we describe first results from low dose, low energy implantations and our development of a low energy (<10 keV), single ion implantation scheme for 31 P q+ ions. When 31 P q+ ions impinge on a wafer surface, their potential energy (9.3 keV for P 15+ ) is released, and about 20 secondary electrons are emitted. The emission of multiple secondary electrons allows detection of each ion impact with 100% efficiency. The beam spot on target is controlled by beam focusing and collimation. Exactly one ion is implanted into a selected area avoiding a Poissonian distribution of implanted ions.

Possible diamond-like nanoscale structures induced by slow highly-charged ions on graphite (HOPG)

“…With the recently developed single-ion implantation techniques 26,20 it becomes possible to form ordered arrays of nanodiamond (nanodiamond-like) structures which could be used in many interesting applications. We are particularly interested in forming such optically active nanodiamond centres to be used in quantum information systems for quantum cryptography or computing in connection with the Ni-N and N-V defect centres 19 .…”

Resolution of the Scanning Helium Microscope

“…Therefore, there is a problem of development of a secondary electron detector with the thickness of approximately 25 μm. However, according to [26], this problem can be solved.…”

Processing issues in top?down approaches to quantum computer development in silicon

“…11 Figure 2 a) shows an illustration of our single ion implantation system -individual ions pass through a small aperture fabricated at the end of a conventional SPM probe tip. 12 The tip can be positioned precisely with respect to substrate topography and the implantation of a single ion is detected by the burst of secondary electrons emitted when it is incident on the surface.…”

“…The high charge-state of the ion ensures that a sufficient number of secondaries are emitted with each impact to guarantee an unambiguous detection signal. 11 The small aperture size and its precise location ensure that each atom is precisely placed. Apertures with diameters as small as 4.3 nm have been formed by focused ion beam drilling in combination with local thin film deposition.…”