Electronic transport along atomically placed P ribbons in Si*

Atomically precise placement of dopants in Si permits creating P nanowires by design. High-resolution images show that these wires are few atoms wide with some positioning disorder with respect to the Si structure sites, which is expected to lead to electronic localization. Experiments, however, report good transport properties in quasi-1D P nanoribbons. We investigate their electronic properties using an effective single-particle approach based on a linear combination of donor orbitals (LCDO), keeping the ground state donor orbitals' oscillatory behavior due to interference among the states at the Si conduction band minima. Our model for the P positioning errors accounts for the presently achievable placement precision.

Transport properties are inferred from the calculated localization length ζ at the half-filling. For 1 to 3 atoms thick wires,ζ shows a rich non-monotonic behavior with respect to placement target parameters. We consider different systems widths and disorder scenarios to explore how transverse and longitudinal aimed interdonor distances can be chosen to optimize and contro ζ for specific device applications.