Dome-shaped gold nanoparticles (with an average diameter of 10.5 nm) are grown on H-terminated Si(100) substrates by simple techniques involving electro- and electroless deposition from a 0.05 mM AuCl3 and 0.1 M NaClO4 solution. XPS depth profiling data (involving Au 4f core-level and valence band spectra) reveal for the first time the formation of gold silicide at the interface between the Au nanoparticles and Si substrate. UV-visible diffuse reflectance spectra indicate that both samples have surface plasmon resonance maxima at 558 nm, characteristic of an uniform distribution of Au nanoscale particles of sufficiently small size. Glancing-incidence XRD patterns clearly show that the deposited Au nanoparticles belong to the fcc phase, with the relative intensity of the (220) plane for Au nanoparticles obtained by electroless deposition found to be notably larger than that by electrodeposition.

Electrodeposition of metallic Mn films onto H-terminated Si(100) from a solution of 10 mM MnCl 2 and 2 M NH 4 Cl is studied by linear sweep voltammetry over three different potential ranges (0 to -3.0 V, -3.0 to 1.5 V, and 0 to 1.5 V). Scanning electron microscopy shows that the formation of dendritic nanostructured films on H-terminated Si(100) occurs only in the positive potential range. X-ray photoelectron spectroscopy reveals that these films consist of metallic Mn covered by Mn 7 O 13 hydrates and pyrolusite ( -MnO 2 ) as a minor surface component. Glancing-incidence X-ray diffraction shows that the Mn 7 O 13 hydrate features are of the hexagonal phase, while the metallic Mn is amorphous. A plausible mechanism involving the reduction of Mn 2+ to metallic Mn along with the oxidation of Si to SiO x on the H-terminated Si(100) substrate is proposed to account for the observed anomalous anodic electrodeposition of metallic Mn. Furthermore, by annealing the resulting metallic Mn film at 600°C in N 2 , a mixture of manganese silicides (MnSi and MnSi ∼1.7 ) covered by manganese silicate (Mn 2 SiO 4 ) is formed. Increasing the annealing temperature to 1000°C significantly reduces the amount of silicate, and MnSi appears to have completely converted to MnSi ∼1.7 .

Electrodeposition in Cr(VI) and Cr(III) aqueous electrolytes is found to produce, respectively, granular and spherical core−shell nanoparticles on H-terminated Si(100). For the granular nanoparticles obtained by electrodeposition in CrO3 and H2SO4 electrolyte solution, both the morphology and number density remain discernibly similar while the particle size increases with increasing charge transfer. In the CrCl3 electrolyte, evolution of the spherical nanoparticles to homogeneous Cr films without and with atop hexagonal microrods with increasing charge transfer is observed. The viability of producing a homogeneous Cr film on the Si substrate is therefore demonstrated. Both the granular Cr nanoparticles and the Cr film consist of predominantly Cr metallic core and Cr2O3 outer shell covered by surface CrO3, while the novel hexagonal microrods are made up of a metallic Cr core and a CrOOH shell.