Analogous to planar heteroepitaxy, misfit dislocation formation and stress-driven surface roughening can relax coherency strains in misfitting core-shell nanowires. The effects of coaxial dimensions on strain relaxation in aligned arrays of Ge-core/Si-shell nanowires are analyzed quantitatively by transmission electron microscopy and synchrotron X-ray diffraction. Relating these results to repo...

Fully-strained single-crystal metastable Ge12xSnx alloys were grown on Ge~001! up to their critical epitaxial thickness values tepi(x) in order to probe surface roughening pathways leading to heteroepitaxial breakdown during low-temperature molecular-beam epitaxy under large compressive strain. All films with x.0.09 have comparable roughnesses while films with x,0.09 are considerably rougher wi...

Hard-spin mean-field theory has recently been applied to Ising magnets, correctly yielding the absence and presence of an interface roughening transition respectively in d=2 and d=3 dimensions and producing the ordering-roughening phase diagram for isotropic and anisotropic systems. The approach has now been extended to the effects of quenched random pinning centers and missing bonds on the int...

Title of Document: PLASMA-SURFACE INTERACTIONS OF MODEL POLYMERS FOR ADVANCED PHOTORESIST SYSTEMS Sebastian Ulrich Engelmann, Doctor of Philosophy, 2008 Directed By: Professor Gottlieb S. Oehrlein, Department of Material Science and Engineering Plasma processing of advanced photoresist (PR) materials is a critical step in nano-manufacturing. We have studied the interactions of PRs and polymers ...

Introduction: One of the clinical problems in orthodontics is the bonding of brackets tocomposite restorations. The aim of this study was to evaluate the shear bondstrength of brackets bonded to composite restorations using Excite. Methods:Forty brackets were bonded to composite surfaces, which were embedded inacrylic resin. One of the following four protocols was employed for surfacepreparatio...

The effect of In surface segregation on the microstructure of short period superlattices ~SPSs! in two different material systems with nominally equivalent lattice misfit, AlAs/InAs and GaAs/InAs, has been investigated and compared. It was found that the quality of the SPSs and the appearance of lateral composition modulation are remarkably different in these two systems. For AlAs/InAs SPSs gro...

Dynamical roughening of interfaces has received much attention in recent years. However, experiments have been restricted to one dimensional (1d) systems. Moreover, theoretical studies of the two dimensional (2d) case have been highly inconclusive. Here we introduce an experimental 2d system, with which the theories can be tested. As is shown, the surface of a 2d pile of rice shows roughening b...

We study the growth and structure of thin films of the organic semiconductor rubrene during organic molecular beam deposition (OMBD) on silicon oxide in situ and in real time using X-ray scattering. Using in situ grazing incidence diffraction (GID) we find a small degree of local order but an otherwise largely disordered structure, consistent with out of plane scans. Monitoring the surface morp...