Epitaxial NiSi layers on 〈111〉-oriented Si obtained by pulsed laser irradiation

Abstract

Thermally grown NiSi layers on (111) Si substrates have been irradiated by 35-ns Nd laser pulses in the energy density range of 0.3–2.0 J/cm2. The duration of the laser-induced melt was monitored in situ by transient reflectivity measurements. Samples have been subsequently analyzed by Rutherford backscattering in combination with channeling and by transmission electron microscopy. It is shown that laser irradiation in a narrow energy density range results in the formation of a novel epitaxial NiSi phase on (111) Si. Electron microscopy studies show that this silicide phase could have a cubic symmetry with a lattice constant very similar to that of Si. This phase is, however, metastable and it transforms into the orthorhombic one upon thermal annealing at about 300 °C.