  We demonstrate single dopant implantation into the channel of a silicon
nanoscale metal-oxide-semiconductor field-effect-transistor. This is achieved
by monitoring the drain current modulation during ion irradiation.
Deterministic doping is crucial for overcoming dopant number variability in
present nanoscale devices and for exploiting single atom degrees of freedom.
The two main ion stopping processes that induce drain current modulation are
examined. We employ 500~keV He ions, in which electronic stopping is dominant,
leading to discrete increases in drain current and 14~keV P dopants for which
nuclear stopping is dominant leading to discrete decreases in drain current.
