Indium was grown on Si(100)-2 X 1 at room temperature by femtosecond pulsed laser deposition. Reflection high-energy electron diffraction (RHEED) was performed in situ to study film morphology and in-plane lattice spacing. Indium was found to grow on Si(100)-2 X I by the Stranski-Krastanov mode. The initial two-dimensional In layer formed in the In-2 X I structure with a lattice constant of 3.65 angstrom. The full-width at half-maximum (FWHM) of the specular peak decreased during the growth, indicating an increase of the In islands size. Further In growth on the initial In-2 X I layer showed the formation of hexagonal, elongated, and hemispherical islands when examined ex situ by atomic force microscopy. The hexagonal islands were faceted and varied in size from similar to 170 to similar to 400 nm, with an average height of 5 nm. The elongated islands showed preferential growth orientation and had a length and height of similar to 200 and similar to 60 nm, respectively. (c) 2005 American Vacuum Society.