David D. Allred received Alumni Professorship Award

Abstract: This paper has provided details on the LE of the data on magnetic tape, hard-disc drives, flash memory, and optical discs. For archival purposes, only the M-DISC presently meets the requirement of long-term data retention (more than 100 years). This disc has been rigorously tested, and the results are very positive. The main weakness of the M-DISC is its relatively small capacity. This weakness is being addressed by our current research on a permanent solid-state solution, one whose density will enable a capacity of several terabytes in the format of a solid-state drive. Though it will be much more expensive than an M-DISC, the convenience of having several terabytes in a single, removable form of storage should be very attractive to the archival community.

Abstract: Dielectrophoresis has been used as a technique for the parallel localization and alignment of both semiconducting and metallic carbon nanotubes (CNTs) at junctions between electrodes. A variation of this technique known as floating potential dielectrophoresis (FPD) allows for a self-limiting number of CNTs to be localized at each junction, on a massively parallel scale. However, the smallest FPD geometries to date are restricted to conductive substrates and have a lower limit on floating electrode size. We present a geometry which eliminates this lower limit and enables FPD to be performed on non-conducting substrates. We also discuss experiments clarifying the self-limiting mechanism of CNT localization and how it can be used advantageously as devices are scaled downwards to smaller sizes.

Abstract: This paper examines the effect of iron catalyst thickness on the straightness of growth of carbon nanotubes (CNTs) for microelectromechanical systems fabricated using the CNT-templated-microfabrication (CNT-M) process. SEM images of samples grown using various iron catalyst thicknesses show that both straight sidewalls and good edge definition are achieved using an iron thickness between 7 and 8 nm. Below this thickness, individual CNTs are well aligned, but the sidewalls of CNT forests formed into posts and long walls are not always straight. Above this thickness, the CNT forest sidewalls are relatively straight, but edge definition is poor, with significantly increased sidewall roughness. The proximity of a device or feature to other regions of iron catalyst also affects CNT growth. By using an iron catalyst thickness appropriate for straight growth, and by adding borders of iron around features or devices, a designer can greatly improve straightness of growth for CNT-MEMS.

Abstract:

Paper and ink-based records, followed by photographs printed on photographic paper, have provided personal and institutional historians access to original documents dating back hundred and even thousands of years. However, the age of digital documents has raised the alarming specter of a “digital dark age” – an era characterized by a complete absence of original sources due to the lack of permanence of digital data. Research at BYU has culminated in the first truly permanent digital data storage option, which at least has addressed the persistence issue. Needed are additional permanent media, and this need is being met by research on a permanent solid-state storage medium and a permanent ½-inch tape storage medium, both at BYU. This paper provides an update on progress on this research.

Abstract: Crystalline films and isolated particles of vanadium dioxide (VO2) were obtained through solid phase crystallization of amorphous vanadium oxide thin films sputtered on silicon dioxide. Electron back-scattered diffraction (EBSD) was used to study the crystals obtained in the thin films, to differentiate them from different vanadium oxide stoichiometries that may have formed during the annealing process, and to study their phase and orientation. EBSD showed that the crystallization process yielded crystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated particles, and did not show evidence of other vanadium oxide stoichiometries present. Indexing of the crystals for the orientation study was performed using EBSD patterns for the tetragonal phase of vanadium dioxide, since it was observed that EBSD patterns for the monoclinic and tetragonal phases of vanadium dioxide are not distinguishable by computer automated indexing. Using the EBSD patterns for the tetragonal phase of vanadium dioxide, orientation maps showed that all VO2 crystals that were measurable (approximately the thickness of the film) had a preferred orientation with the c-axis of the tetragonal phase parallel to the plane of the specimen. (C) 2011 Elsevier B.V. All rights reserved.

Abstract: Self-assembly of organic thiols is the most common S H way to introduce functional groups onto gold surfaces. Although the gold-sulfur (Au-S) bond is moderately strong (similar to 45 kcal/mol), it is also prone to oxidation, which substantially weakens the Au-S interaction. In this work, we describe the creation of more robust molecular assemblies on gold. As a first step, a thiolated monolayer is prepared on gold with an a,alpha,omega-dithiol. Experiments are also reported for a mercaptosilane monolayer on silicon dioxide. An oligomer of polybutadiene (PBd) was then tethered to these surfaces using thiol-ene chemistry. Residual groups on the PBd are then reacted with thiols, including octadecanethiol (ODT), 1H,1H,2H,2H-perfluoroalkanethiol, and a thiol-terminated 25-mer of DNA. Little nonspecific adsorption of a non-thiolated DNA oligomer was observed. Surface characterization was performed with X-ray photoelectron spectroscopy (XPS), contact angle goniometry, time-of-flight secondary ion mass spectrometry (ToF-SIMS), and spectroscopic ellipsometry. A thiol-gold monolayer and an analogous assembly of the same thiol tethered to gold through PBd on a dithiol monolayer were both exposed to air and light for 2 weeks and then rinsed with water. The monolayer on gold was removed in this process, while the thiol in the assembly appeared unaffected.