Epitaxial lift-off of electrodeposited single-crystal gold foils for flexible electronics.

We introduce a simple and inexpensive procedure for epitaxial lift-off of wafer-size flexible and transparent foils of single-crystal gold using silicon as a template. Lateral electrochemical undergrowth of a sacrificial SiO layer was achieved by photoelectrochemically oxidizing silicon under light irradiation. A 28-nanometer-thick gold foil with a sheet resistance of 7 ohms per square showed only a 4% increase in resistance after 4000 bending cycles.

In Situ Measurement of Voltage-Induced Stress in Conducting Polymers with Redox-Active Dopants.

Minimization of stress-induced mechanical rupture and delamination of conducting polymer (CP) films is desirable to prevent failure of devices based on these materials. Thus, precise in situ measurement of voltage-induced stress within these films should provide insight into the cause of these failure mechanisms. The evolution of stress in films of polypyrrole (pPy), doped with indigo carmine (IC), was measured in different electrochemical environments using the multibeam optical stress sensor (MOSS) technique.

Improved spatial resolution and lower-dose pediatric CT imaging: a feasibility study to evaluate narrowing the X-ray photon energy spectrum.

This feasibility study has shown that improved spatial resolution and reduced radiation dose can be achieved in pediatric CT by narrowing the X-ray photon energy spectrum. This is done by placing a hafnium filter between the X-ray generator and a pediatric abdominal phantom. A CT system manufactured in 1999 that was in the process of being remanufactured was used as the platform for this study.

Compressive stress generation in sn thin films and the role of grain boundary diffusion.

Stress evolution in high mobility Sn thin films was measured during electrodeposition and electrochemical etching to understand the roles of grain boundary diffusion and surface conditions in controlling stress. During deposition, the stress reaches a steady-state compressive value that depends on the growth rate. When the deposition or etching conditions were changed abruptly, reversible transients were observed that depend on the film thickness.

Kinetic model of stress evolution during coalescence and growth of polycrystalline thin films.

We outline a simple continuum model of the stresses that result from the coalescence and growth of islands during deposition of a polycrystalline thin film. Our model includes a detailed description of attractive forces between neighboring islands, and also accounts for mass transport along surfaces and grain boundaries. The finite element method is used to calculate the island shape changes as well as the stresses and displacements in the film during the growth process.

Transient topographies of ion patterned Si(111).

The surface of high fluence ion-sputtered Si(111) was found to exhibit a rich variety of transient one- and two-dimensional topographies that may be exploited as tunable self-organized arrays of nanostructures. Such transient effects are only partially described by analytical models of sputter patterning. However, a discrete atom kinetic Monte Carlo simulation model incorporating curvature-dependent sputtering and surface diffusion reproduces many aspects of the transient morphological evolution, and clarifies the minimal model of sputter patterning.