Single Ion Implantation for Solid State Quantum Computer Development
  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 efficieny. In this article we describe first results from low dose, low energy implantations and our development of a low energy (<10keV), single ion implantation scheme for 31P(q+) ions. When 31P(q+) ions impinge on a wafer surface, their potential energy (9.3 keV for P15+) 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. 
T. Schenkel, J. P. Holder, J. W. McDonald, J. Meijer, A. Persaud, D.   H. Schneider