A study was done to examine the effect of surface orientation as well as heterogeneous epitaxy at an interface between two materials with a large lattice mismatch. Silver nanoparticles of different diameters were grown in an effort to study methods of preferentially orienting the geometry of metal nanoparticles. Arrays of calcium fluoride nanorods were grown on silicon substrates using oblique angle thermal vapor deposition. The chamber operated at an ultra high vacuum pressure of 10^-10 Torr during the deposition of the rods and an oblique angle of 75° was kept between the silicon substrate normal and the direction of incident flux. A method was then developed to grow silver nanoparticles exclusively on the (111) facet of the calcium fluoride tips. This was accomplished by once again using oblique angle deposition with an angle of 75° along with the larger size of the (111) calcium fluoride tip facet. Cross sectional scanning electron microscopy and transmission electron microscopy imaging was used to verify that the nanoparticles adhered exclusively to the desired facet of the tip. Using selected area diffraction, (SAED) and dark field in the TEM, it was shown that the nanoparticles did grow at a (111) orientation at the interface between them and the calcium fluoride rods. Different thicknesses and diameters of nanoparticles were then grown to determine what an ideal size was to achieve the most (111) orientation of the nanoparticles. Thicknesses of the particles varied between 5 nanometers and 15 nanometers. Through characterization it was shown that all three of the different thicknesses grown exhibited (111) orientation of the silver nanoparticles, both at the interface and in the overall nanoparticle as well with the 10 nanometer sample being the most ideal in terms of the desired result. Lattice straining of the silver nanoparticles was also observed by characterization through diffraction and SAED.
| Identifer | oai:union.ndltd.org:vcu.edu/oai:scholarscompass.vcu.edu:etd-3729 |
| Date | 02 May 2012 |
| Creators | Auer, Mathias |
| Publisher | VCU Scholars Compass |
| Source Sets | Virginia Commonwealth University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | © The Author |
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