Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Engineering
Laser – Induced Nanostructures In Silicon, Jason Fowlkes
Laser – Induced Nanostructures In Silicon, Jason Fowlkes
Doctoral Dissertations
This dissertation addresses the formation of nanostructures induced by the laser irradiation of silicon. A KrF (248 nm) pulsed excimer laser was used as the irradiation source. Irradiating micro – structured substrates in a reactive O2 atmosphere produced SiO nanostructures. Si nanoparticles were formed by irradiating both flat and micro – structured silicon surfaces in an inert gas ambient. On flat surfaces, low energy density irradiation (Ed < 1 J/cm2) induces the formation and clustering of a thin silicon film pulsed – laser deposited on silicon into nanoparticles that grow to 2 – 80 nm in diameter. Control over the Si nanoparticle diameter to within ± 1 nm could be obtained by optimizing the laser beam energy density, the inert gas pressure, and the number of laser pulses. The nanoparticles in the surface plane will self – organize into periodically spaced lines, if a periodic or quasi – periodic, microstructure is present at the surface.
A film of silicon nanoparticles was formed on the surface of a silicon target following pulsed laser irradiation in an inert, background gas. Silicon species generated during laser ablation were backscattered by the …
The Effect Of Implantation Temperature And Ionizing Radiation On The Microstructure Of Ion Implanted Sapphire, Lawretta Chineze Leaticia Ononye
The Effect Of Implantation Temperature And Ionizing Radiation On The Microstructure Of Ion Implanted Sapphire, Lawretta Chineze Leaticia Ononye
Doctoral Dissertations
Single crystalline specimens of aluminum oxide (Al2O3) were irradiated with boron, nitrogen and iron ions at room temperature and 1000oC to fluences of 1×1017 B+/cm2, 3×1016 N+/cm2 and 1×1017 Fe+/cm2 respectively with 150 keV of energy. Following irradiation, the structures were examined by several experimental techniques: transmission electron microscopy (TEM), Rutherford backscattering - ion channeling (RBS-C) spectroscopy, optical absorption measurements, x-ray diffraction (XRD) technique, and x-ray photoelectron spectroscopy (XPS). The samples implanted at room temperature were then annealed for one hour at 1000oC in a reducing (Ar-4%H2) gas and the microstructures examined.
The implantation temperature significantly influenced the …