Chu, Wei-Kan2015-01-042015-01-04December 22012-12http://hdl.handle.net/10657/850Morphological evolution of surfaces during the course of off-normal cluster ion beam bombardment is investigated. The objective is to realize the Ar cluster ion-induced self-assembled ripple shaped nano-pattern formation process on Si and Au surfaces. During cluster ion beam bombardment, surface atoms undergo three processes: (1) continuous sputtering into the vacuum due to high energy collisions, (2) initial re-deposition of atoms, and (3) surface diffusion of atoms. The first process is an independent of applied dosage, thus carries a minimum impact on nano-ripple pattern formation. In the second process, atoms deposit close to the collision site, which acts as a barrier for the next set of sputtering atoms. Even though this starts to develop ripples, ripples become well-ordered and grow due to surface diffusion and upstream sputtering of atoms. This investigation reveals that cluster ion-induced nano-ripple formation saturates comparatively sooner than that induced by monomer ions. Continuous bombardment creates sand dune-like nano-structures on the Si surfaces at 60o angle of incidence measured from the surface normal. However, at a grazing incidence, surface becomes smooth. Further investigation on Au surfaces conform the above mentioned three-step process of nano-ripple formation. Additionally, it was found that these nano-rippled surfaces show anisotropic properties, which are useful in directional surface wetting and surface plasmonic applications.application/pdfengThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).Nano-ripplesCluster ion beamPhysics2015-01-04Thesisborn digital