Clustering in pb thin films on bromine-passivated si(1 1 1) surfaces

Thin Pb films, deposited on clean Si surfaces at room temperature (RT), show spectral broadening in ion backscattering spectra due to clustering of Pb, when annealed [Nucl. Instr. and Meth. B 190 (2002) 641]. In order to study the dynamics of clustering on bromine-passivated Si(1 1 1) substrates, Pb thin films (~1-3 nm) were deposited from a Knudsen cell under ultrahigh vacuum conditions. Each film was deposited at RT and subsequently annealed at 100, 150 and 260 °C for about 4 h. Five Rutherford backscattering spectrometry (RBS) measurements were made at different time intervals for each annealing . Analysis of RBS spectra of as-deposited and annealed Pb films, does not show any significant spectral broadening in annealed Pb films. However, island formation has been confirmed by transmission electron microscopy on a 100 °C-annealed sample. Clustering has apparently occurred in the as-deposited film due to lower surface free energy of the passivated substrate and further detectable growth in cluster height has not occurred in annealing

Low current MeV Au<SUP>2+</SUP> ion-induced amorphization in silicon: rutherford backscattering spectrometry and transmission electron microscopy study

The amorphization due to MeV Au2+ ion implantation in Si(1 1 1) has been studied using Rutherford backscattering spectrometry/channeling (RBS/C) and transmission electron microscopy (TEM) methods. 1.5 MeV Au2+ ions were implanted into Si(1 1 1) substrates at various fluences at low currents (0.02-0.04&#956;A cm-2) while the samples were kept at room temperature. The RBS/C results for as-implanted specimen shows the onset fluence for amorphization to be &#8776;5&#215; 1013 ions cm-2 which is much lower than the fluence reported earlier. Selected area diffraction (TEM) for a sample implanted at a of 1&#215;1014 ions cm-2 confirms the occurrence of the amorphization. Earlier, amorphization studies by Alford and Theodore, using 2.4 MeV gold ions in silicon (1 0 0) reported a threshold fluence of 1.8&#215;1015 ions cm-2 for amorphization when the implantation was carried out at higher currents (0.2-5 &#956; A cm-2) [J. Appl. Phys. 76 (1994) 7265]. The nuclear energy loss (Sn) for 1.5 MeV gold ions in silicon is &#8776;13% greater than the value for 2.4 MeV and cannot be the sole reason for lower threshold fluence for the amorphization. The amorphization at a relatively lower fluence for the low current implantations could be possible due to reduction in the dynamical annealing effects

Surface phenomena involved in the formation of Co nanoparticles on amorphous Carbon and SiO₂ deposited by magnetron sputtering

High-pressure DC magnetron sputtering was used for the deposition of cobalt on amorphous carbon (a-C) and SiO. Deposition conditions, substrate surface morphology and annealing parameters are investigated in order to promote the synthesis of large arrays of nanoparticles, with regular size and shape. Uniformly distributed Co nanoparticles a few nanometers in size were formed under annealing at 700°C in H. Particle nucleation and growth are discussed based on X-ray photoelectron spectroscopy, transmission and scanning electron microscopy and kinetic Monte Carlo modeling (KMC). © Springer-Verlag 2010