We demonstrate a method for the controlled implantation of single ions into a silicon substrate with energy of sub-20-keV. The method is based on the collection of electron-hole pairs generated in the substrate by the impact of a single ion. We have used the method to implant single 14-keV 31 P ions through nanoscale masks into silicon as a route to the fabrication of devices based on single donors in silicon.

We demonstrate time-resolved control and detection of single-electron transfers in a silicon device implanted with exactly two phosphorus donors. Charge state relaxation at millikelvin temperature is shown to be dominated by phonon emission and background charge fluctuations for low energies, while higher-order processes take over at higher energies. Our results reveal relaxation times for single-donor charge states of several milliseconds, which have significant implications for single-atom nanoelectronics.