  We demonstrate the controlled incorporation of P dopant atoms in Si (001)
presenting a new path toward the creation of atomic-scale electronic devices.
We present a detailed study of the interaction of PH3 with Si (001) and show
that it is possible to thermally incorporate P atoms into Si (001) below the H
desorption temperature. Control over the precise spatial location at which P
atoms are incorporated was achieved using STM H-lithography. We demonstrate the
positioning of single P atoms in Si with ~ 1 nm accuracy and the creation of
nanometer wide lines of incorporated P atoms.
