Fluorinated amorphous carbon thin films (a-C:F) for use as low-dielectric-constant interlayer dielectrics are deposited by helicon-wave plasma enhanced chemical vapor deposition. To improve their thermal stability, the feasibility of adjusting the fluorine-to-carbon (F/C) ratio by changing the deposition pressure was investigated. Decreasing the pressure increased the dissociation of a source fluorocarbon material in the plasma and decreased the F/C ratio of the deposited film. Both the thermal stability and the dielectric constant of the a-C:F films were increased as the F/C ratio was decreased. Thus, there is a tradeoff relationship between a low dielectric constant and high thermal stability and the tradeoff could be optimized by the pressure during deposition. The mechanism of the pressure dependency of the dielectric constant of a-C:F films was investigated by quantifying the contribution of each polarization and found that a decrease in the dielectric constant of a-C:F films can be attributed to decreases in the orientational and electronic polarizations.

We investigated cortical responses to electrical stimulation of the retina using epi- and sub-retinal electrodes of 20-100 microm diameter. Temporal and spatial resolutions were assessed by recordings from the visual cortex with arrays of microelectrodes and optical imaging. The estimated resolutions were approximately 40 ms and approximately 1 degrees of visual angle. This temporal resolution of 25 frames per second and spatial resolution of about 0.8 cm at about 1m and correspondingly 8 cm at 10 m distance seems sufficient for useful object recognition and visuo-motor behavior in many in- and out-door situations of daily life.

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The dendrite growth of Li metal is a very severe problem for a Li metal anode used in rechargeable batteries. In this study, an ultramicroelectrode (UME) was adopted to understand the morphological variation of electrodeposited Li metal. Scanning electron microscopy (SEM) coupled with windowless electron dispersive spectroscopy (EDS) and cryo-orthogonal focused ion beam system (FIB) was utilized to observe not only the surface morphology but also the three-dimensional (3D) structure of the electrodeposited and electrochemically dissolved Li metal. The electrodeposited Li metal from the LiPF6-based electrolyte forms a very uniform column structure. The fluoride-containing solid electrolyte interphase (SEI) layer plays an important role in determining the morphological variation of the dendrite. Furthermore, the fluoride-rich SEI layer shell remains on the UME without collapse after the first cycle. The ultramicroelectrode is a very useful research platform, particularly, for studying drastic dendrite growth and electrochemical dissolution on the Li metal anode.