Nanostructure of room temperature deposited TiB2 on Si(001) by pulsed laser ablation

Ultrathin discontinuous films from a stoichiometric target of TiB2 have been deposited on Si(001) at room temperature via pulsed laser ablation. The resulting film morphology and nanostructure was studied using transmission electron microscopy. The typical results were that the films consisted of two distinct morphologies: areas of polycrystalline nanoparticles with the hexagonal TiB2 structure and smaller areas with epitaxial grains. The resulting epitaxial phase was verified to be cubic with a lattice parameter of 3.83 Å and aligned with TiBx(001) // Si(001), with x ∼ 2. We suggest that the cubic phase forms because of minimization of energy as a consequence of the excellent epitaxial matching of the film phase to Si(001).