Electrical and structural properties of nanoscaleNiSi2precipitates in silicon

Structurally well-defined ${\mathrm{NiSi}}_2$ platelets of two {111}-silicide lattice planes thickness and 37 nm diameter form after in-diffusion of nickel in n-type silicon at 900 °C followed by rapid quenching. These platelets are bounded by a dislocation ring and exhibit in deep-level-transient-spectroscopy (DLTS) measurements a line that can be attributed to bandlike electronic states at the extended defect. We exploit internal ripening of individual precipitates upon additional annealing at 320 °C in order to study the temporal evolution of their electrical and structural properties. Within a short time of about 1 min one observes a continuous transmutation of DLTS line characteristics, finally revealing localized states at the defect. Structural changes towards a compact shape become observable by means of transmission electron microscopy on a significantly larger time scale of several minutes. We conclude that the bounding dislocation ring determines the electrical activity of platelets as-quenched. Due to its particular core structure, the dislocation exhibits characteristics of a quantum wire. A specific core defect that allows us to construct curved dislocation line segments causes meandering, which has been shown to be the weakest perturbation of ideal one-dimensional behavior.