HIGH TEMPERATURE RARE EARTH COMPOUNDS: SYNTHESIS, CHARACTERIZATION AND APPLICATIONS IN DEVICE FABRICATION

As the area of nanotechnology continues to grow, the development of new nanomaterials with interesting physical and electronic properties and improved characterization techniques are several areas of research that will be remain vital for continued improvement of devices and the understanding in nanoscale phenomenon. In this dissertation, the chemical vapor deposition synthesis of rare earth (RE) compounds is described in detail. In general, the procedure involves the vaporization of a REClx (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho) in the presence of hydride phase precursors such as decaborane and ammonia at high temperatures and low pressures. The vapor-liquid-solid mechanism was used in combination with the chemical vapor deposition process to synthesize single crystalline rare earth hexaboride nanostructures. The crystallographic orientation of as-synthesized rare earth hexaboride nanostructures and gadolinium nitride thin films was controlled by judicious choice of specific growth substrates and modeled by analyzing x-ray diffraction powder patterns and crystallographic models. The rare earth hexaboride nanostructures were then implemented into two existing technologies to enhance their characterization capabilities. First, the rare earth hexaboride nanowires were used as a test material for the development of a TEM based local electrode atom probe tomography (LEAP) technique. This technique provided some of the first quantitative compositional information of the rare earth hexaboride systems. Second, due to the rigidity and excellent conductivity of the rare earth hexaborides, nanostructures were grown onto tungsten wires for the development of robust, oxidation resistant nanomanipulator electronic probes for semiconductor device failure analysis.

Comparison of crystalline thin poly(vinylidene (70%)–trifluoroethylene (30%)) copolymer films with short chain poly(vinylidene fluoride) films

We compare the photoemission and electron energy loss spectra of crystalline poly(vinylidene-fluoride with trifluoroethylene: 70%: 30%), P(VDF–TrFE), films, fabricated by the Langmuir–Blodgett technique and annealed in vacuum, with in situ thermally evaporated films of poly(vinylidene-fluoride) (PVDF) in vacuum. The electronic structure and vibrational modes of the short chain PVDF films compare well with the crystalline P(VDF–TrFE) films indicating that vacuum annealed films prepared ex situ are free of significant surface contamination once vacuum annealed. The electronic structure for the short chain PVDF films exhibits, however, different temperature dependence than the crystalline P(VDF–TrFE) films. PACS: 68.47.Mn; 71.20.Rv; 63.22.+m; 73.22.-f