ABSTRACTComposite nanowires with typical diameters of 30-100nm, which consisted of Si, β-SiC, amorphous carbon were converted from Si nanowires by ion beam deposition. The Si nanorods were exposed to broad low energy ion beams. The low energy hydrocarbon, argon and hydrogen ions, generated in a Kaufman ion source, reacted with Si nanowires and formed the composite nanowires. It has been assumed that the reaction pathway to form the composite nanowires were driven by both thermal diffusion and kinetic energic of interacting particles.
ABSTRACTA low-energy ion beam deposition system has been developed at Oak Ridge National Laboratory and has been applied successfully to the growth of epitaxial films at low temperatures for a number of different elements. The deposition system utilizes the ion source and optics of a commercial ion implantation accelerator. The 35 keV mass- and energy-analyzed ion beam from the accelerator is decelerated in a four-element electrostatic lens assembly to energies between 10 and 500 eV for direct deposition onto a target under UHV conditions. Current densities on the order of 10 A/cm are achieved with good uniformity over a 1.4 cm diameter spot. The completed films are characterized by Rutherford backscattering, ion channeling, cross-section transmission electron microscopy, and x-ray diffraction. The effects of substrate temperature, ion energy, and substrate cleaning have been studied. Epitaxial overlayers which show good minimum yields by ion channeling (3–4%) have been produced at temperatures as low as 375°C for Si on Si(100) and 250°C for Ge on Ge(100) at growth rates that exceed the solid-phase epitaxy rates at these temperatures by more than an order of magnitude.
Ion beam deposition provides an additional control of ion beam energy over the chemical vapor deposition methods. We have used a low energy ion beam of hydrogen and carbon to deposit carbon films on Si(100) wafers. We found that graphitic films, amorphous carbon films, and oriented diamond microcrystallites could be obtained separatedly at different ion beam energies. The mechanism of the formation of the oriented diamond microcrystallites was suggested to include three components: strain release after ion bombardment, hydrogen passivation of sp3 carbon, and hydrogen etching. Such a process can be extended to the heteroepitaxial growth of diamond films.
AbstractThe technique of ion beam deposition (IBD) is utilized to investigate low-energy, ion-induced damage on Si and Ge; to study reactive ion cleaning of Si and Ge; to fabricate amorphous isotopic heterostructures; and to fabricate and study the low-temperature epitaxial deposition of 74Ge on Ge(100), 30Si on Si(100), and 74Ge on Si(100). The techniques of ion scattering/channeling and cross-sectional TEM are combined to characterize the deposits.
Low-energy mass-selected ion beam deposition of silicon carbide with Bernas-type ion source using methylsilane
