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Dynamic and Static Transmission Electron Microscopy Studies on Structural Evaluation of Au nano islands on Si (100) Surface
Transmission electron microscopy (TEM) study on morphological changes in gold
nanostructures deposited on Si (100) upon annealing under different vacuum
conditions has been reported. Au thin films of thickness ~2.0 nm were deposited
under high vacuum condition (with the native oxide at the interface of Au and
Si) using thermal evaporation. In-situ, high temperature (from room temperature
(RT) to 850\degreeC) real time TEM measurements showed the evaluation of gold
nanoparticles into rectangular/square shaped gold silicide structures. This has
been attributed to selective thermal decomposition of native oxide layer.
Ex-situ annealing in low vacuum (10-2 mbar) at 850\degreeC showed no growth of
nano-gold silicide structures. Under low vacuum annealing conditions, the
creation of oxide could be dominating compared to the decomposition of oxide
layers resulting in the formation of barrier layer between Au and Si.Comment: 15 pages, 4 figure
Gravity Concentration of Iron Ore
Gravity concentration process is the oldest beneficiation method known to mankind. This is a physical process and exploits the differences in densities of minerals to bring about a separation. Although with the advent of froth flotation, the relative importance of gravity concentrat-ion has declined in twentieth century but still on an average higher tonnage of material is treated by gravity
concentration than flotation. The gravity separation processes are comparatively cheap and environmentally friendly. It finds immense application in the processing of iron ores besides coal, beach sands, gold, diamonds, platinum, baryte, fluorspar, tin, tungsten ores etc
Growth of Oriented Au Nanostructures: Role of Oxide at the Interface
We report on the formation of oriented gold nano structures on Si(100)
substrate by annealing procedures in low vacuum (\approx10-2 mbar) and at high
temperature (\approx 975^{\circ} C). Various thicknesses of gold films have
been deposited with SiOx (using high vacuum thermal evaporation) and without
SiOx (using molecular beam epitaxy) at the interface on Si(100). Electron
microscopy measurements were performed to determine the morphology, orientation
of the structures and the nature of oxide layer. Interfacial oxide layer, low
vacuum and high temperature annealing conditions are found to be necessary to
grow oriented gold structures. These gold structures can be transferred by
simple scratching method.Comment: 13 pages, 3 figures, Accepted in J. Appl. Phy
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