Preparation and characterization of C54 TiSi2 nanoislands on Si (1 1 1) by laser deposition of TiO2

We present the preparation of C54 TiSi2 nanoislands on Si (1 1 1) with a method of the pulsed laser deposition of titanium oxide thin films. The TiO2 thin films with nominal thicknesses of 1 nm on Si (1 1 1) were annealed at 850 8C for about 4 h in situ. The X-ray diffraction patterns and the X-ray photoelectron spectra indicate that the nanoislands are in C54 TiSi2 phase. The characterization using a scanning tunneling microscope shows that the nanoislands with triangular, polygonal and rod-like shapes on Si (1 1 1) exhibit the Volmer–Weber growth mode. The sizes of the polygonal islands distribute in two separated ranges. For the small islands, they have a narrow lateral size distribution centered at 4 nm and a height range in 0.6–3.6 nm, while for the large islands, their lateral sizes are in the range of 12–40 nm and the heights in the range of 4–9 nm. The sizes of the well-shaped triangular islands are intermediate with the lateral sizes in range of 5–20 nm and the heights of 2–3.5 nm. The rod-like islands are about 50–200 nm in length, 5 nmin height and about 15–20 nm in width. The origination of the various shapes of the nanoislands is attributed to the symmetry of Si (1 1 1) substrate and the lattice mismatch between the C54 TiSi2 and the Si (1 1 1) surface.