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A study of germanium antimonide (GeSb) phase-change nanowire as a potential candidate for programmable random access memory (PRAM) application is presented. The newly designed NW-based PRAM is expected to reduce the cell size, programming current, and intercell thermal interference, thus enabling unimpeded scalability beyond conventional thin-film PRAMs.

Developing biomaterial constructs that closely mimic the natural tissue microenvironment with its complex chemical and physical cues is essential for improving the function and reliability of implantable devices, especially those that require direct neural-electrical interfaces. Here we demonstrate that free-standing vertically aligned carbon nanofiber (VACNF) arrays can be used as a multifunctional 3-D brush-like nanoengineered matrix that interpenetrates the neuronal network of PC12 cells. We found that PC12 neuron cells cultured on VACNF substrates can form extended neural network upon proper chemical and biochemical modifications. The soft 3-D VACNF architecture provides a new platform to fine-tune the topographical, mechanical, chemical, and electrical cues at subcellular nanoscale. This new biomaterial platform can be used for both fundamental studies of material-cell interactions and the development of chronically stable implantable neural devices. Micropatterned multiplex VACNF arrays can be selectively controlled by electrical and electrochemical methods to provide localized stimulation with extraordinary spatiotemporal resolution. Further development of this technology may potentially result in a highly multiplex closed-loop system with multifunctions for neuromodulation and neuroprostheses. Index Terms--Neural electrical interface, neural stimulation, neuromodulation, vertically aligned carbon nanofibers.

Single-wall carbon nanotubes (SWCNts) are exposed to microwave-generated N2 plasma to functionalize the nanotubes. Results are strongly dependent on the distance between the discharge source and the sample as nitrogen items can be lost due to recombination.

The analysis of a plasma enhanced chemical vapor deposition process for carbon nanofiber growth is reported. A direct current (dc) plasma is employed with a mixture of acetylene and ammonia.

An oxygen plasma sustained at 13.56 MHz in a standardized reactor with a planar induction coil was used for biological decontamination experiments. Optical emission, mass spectrometry, Langmuir probe, and electrical measurements were applied to detection of chemical species and ion-energy and flux analysis. These diagnostics identified a plasma-mode transition in the range of 13-67-Pa pressure and 100-330-W power to the induction coil. At higher pressure and lower power, the plasma was sustained in a dim mode (primarily by stray capacitive coupling). A primarily inductive bright mode was attained at lower pressure and higher power. The coupling mode of plasma operation was then monitored by emission spectroscopy on an analogous, scaled-down reactor for biological degradation tests. Plasmid DNA degradation efficacies were compared in both plasma modes. DNA removal was ~25% more efficient in the inductively coupled mode than in the capacitively coupled mode at the same power. The fast degradation was attributed to synergetic mechanisms (photo- and ion-assisted etching by oxygen atoms and perhaps [O.sup.*.sub.2] metastable molecules). Volatilization rates of the decomposition products (C[O.sub.2], CO, [N.sub.2], OH, H) evolving from the microbial (Deinococcus radiodurans) and polypeptide samples exposed to the plasma were compared. A plasma sustained in Martian atmosphere is considered.

A two-dimensional axisymmetric helicon plasma source with three-dimensional wave components is modeled. Plasma fluid equations are solved self-consistently with helicon wave equations. Electron inertia is taken into account to simulate the propagation of electrostatic wave components. The purpose of this paper is to describe the model in detail and present the results to verify wave propagation characteristics, power deposition mechanisms, especially bulk versus peripheral power absorption. We also study the effect of wave absorption characteristics on discharge plasma density and temperature profiles. Index Terms--Helicon plasma, modeling, plasma discharges.

Mutiwalled carbon nanotubes are grown on various substrates by thermal chemical vapor deposition using multilayered metal catalysts. The mutiwalled carbon nanotubes towers exhibit a very strong attachment to the silicon substrate.

We present a coupled plasma and collisionless sheath model for the simulation of high-density plasma processing reactors. Due to inefficiencies in numerical schemes and the resulting computational burden, a coupled multidimensional plasma and sheath simulation has not been possible for gas mixtures and high-density reactors of practical interest. In this work, we demonstrate that with a fully implicit algorithm and a refined computational mesh, a self-consistent simulation of a reactor including both the plasma and sheath is feasible. We discuss the details of the model equations, the importance of ion inertia, and the resulting sheath profiles for argon and chlorine plasmas. We find that at low operating pressures (10-30 mtorr), the charge separation occurs only within a 0.5-mm layer near the surface in a 300 mm inductively coupled plasma etch reactor. A unified simulation eliminates the use of offline or loosely coupled and oversimplified sheath models which generally leads to uncertainties in ion flux and sheath electrical properties. Index Terms--Plasma materials-processing applications, plasma sheaths, simulation.

Research describing a model for a collisionless radio frequency biased plasma sheath is presented. The ion impact characteristics of the sheath are predicted from electrode boundary and bulk plasma conditions.

The cold ion fluid equations in the radio frequency sheath are solved numerically to show that the spatiotemporal variation of ion flux inside the sheath, commonly ignored in analytical models, is important in determining the electric field and ion energy at the electrode. A semi-analytical model that includes the spatiotemporal variation is developed for use as boundary condition in reactor simulations.

A drift-diffusion model for silane and a three-moment model for chlorine were used to study the step response of typical electronegative process gases. Three types of transients were found for silane. The step response of chlorine discharges was characterized by a smooth transition from one steady state to the next. Results suggested that the temporary extinction of the discharge and natural pulsed steady state is the effect of how the voltage is divided between the gap and blocking capacitor during the transient.

A study was done on the effect of magnetic field on a parallel-plate, radio frequency electronegative discharge. Results show that an application of a uniform magnetic field of 100 G produces an order of magnitude increase in ionization rate and five times higher densityof charged species in a 50 mTorr chlorine discharge. The sheaths in the magnetron discharge are thin and sheath electric field decreases with increasing magnetic field. The bulk ohmic heating is the dominant mechanism forpower deposition.

The effects of pillar aspect ratio, density, and spacing on carbon nanotube pillar arrays (CPAs) field emission were examined. The results showed that the pillar ratio played a significant role in the emission characteristics of the arrays, while the CPAs were found to exhibit better stability than the patterned and continuous CNT films.

A characterization of a methane/hydrogen rf plasma for carbon nanotube growth is presented. Dependencies on power and pressure are explored, indicating more efficient ionization, dissociation, and electron heating at lower pressure and higher power.

A successful fictionalization of single-walled carbon nanotubes (SWNTs), through a microwave discharge of ammonia was carried out. The results of ab initio calculations are reported to better identify the experimental products that are formed.

A tip sharpening process for multiwalled carbon nanotube (MWCNT) scanning probes is reported along with demonstrating its application in high lateral resolution imaging. The study shows that the coupling of the sharpening method and the superior mechanical properties of MWCNT results in a highly stable scanning probe with universal applications, from high lateral resolution to high aspect ratio imaging.

A combined hot filament/direct current (dc) plasma approach to chemical vapor deposition of carbon nanofibers (CNFs) is examined in an acetylene/ammonia environment. It is shown that the filament wire is primarily important in the pretreatment of the substrate, improving CNF growth quality.

A model for the dc plasma used in carbon nanotube growth is presented, and one-dimensional simulations of an acetylene/argon system are performed. Introducing a tungsten filament in the dc plasma, as in hot filament chemical vapor deposition with plasma assistance, shows negligible influence on the system characteristics.

Characterization of CF(sub 4)/O(sub 2)/Ar inductively coupled plasmas by Fourier-transform infrared spectroscopy (FTIR) and optical emission spectroscopy in a gaseous electronics conference reference cell has been carried out. The FTIR when used without the plasma on, shows that the actual partial pressures in the mixture differ slightly than expected as the residence time of the individual molecules differ from one another, and also depend on the gas composition.

A two-dimensional finite-element based microscale flow model to efficiently predict the overall flow characteristics up to the transition regime for reasonably high Knudsen number flow inside microchannels and nanopores is developed. The nanopore solutions are validated with the experimental data.

The study compares the gas phase environments of methane-based thermal and plasma chemical vapor deposition (CVD) processes for growing carbon nanotubes (CNTs). Gas phase reactions are negligible in thermal CVD until 900 degrees C while catalytic processes are responsible for CNT growth and simulations confirm presence of substantial amounts of unsaturated hydrocarbons C(sub 2)H(sub 2), C(sub 2)(H(sub 4), etc. in CH(sub 4) plasma CVD contributing to the nanotube growth.

The electrochemical study of three carbon nanotube ensemble electrodes, single walled nanotube paper, as-produced multiwalled nanotube towers, and heart-treated multiwalled nanotube towers, are reported. The carbon nanotube ensemble behaves as a three-dimensional electrode and apparent electron transfer rate was found to correlate to both the area of the exposed sidewalls and the density of graphite edge-plane-like defects

The approach of extracting rotational temperature from an inductively coupled CF4 plasma by fitting the rotational band envelope of different diatomic species in emission is examined. The results suggest that the different species have achieved different degrees of equilibrium between rotational and vibrational modes and may not be equilibrated with the translational temperatures.

A study was conducted, by using transmission electron microscopy and Raman spectroscopy, to investigate the varying inductive power, pressure, temperature, gas composition, catalyst thickness, and power to the silicon substrates. The result reveals that the power in the lower electrode holding the substrate influences the morphology and results in a transition from multiwalled carbon nanotubes (MWNTs) to nanofibers as the power is increased.

A straightforward method for interpreting dynamically averaged residual dipolar couplings (RDCs) in protein is presented. This method reduces the number of independent measurements required to characterize local motions.

The folding/unfolding kinetics of trpzip2 peptide at different tryptophan fluorescence wavelength was measured. From the range of rate observed, a lower limit for roughness of free energy was found.

The inelastic neutron scattering (INS) spectrum of crystalline H3B:NH3 to 1600 cm-1 is reported. The results of periodic density functional theory (DFT) calculations on the unit cell are also presented.

A general strategy has been developed for site-specific labeling of proteins with small molecules. Use of peptide carrier protein (PCP) tag for biotin labeling is understood to be amenable to high-throughput protein microarray preparation.

Retention time and threshold voltage shift strongly depend on the structure of the bis(terpyridine)-Fe (II) molecule. Results indicate that the presence of thiolate headgroup and/or longer ligand length increases charge retention.

The model has found a good correlation between the area increase in monolayer and the PI value of the respective proteins. It has thus successfully mimicked efficient binding of certain proteins by multipoint recognition on cell surfaces.

We have developed a self consistent fluid model that couples plasma dynamics, Navier-Stokes equations, and Maxwell's equations to analyze inductively coupled plasma reactors used in semiconductor processing. Two dimensional simulations of an [N.sub.2] plasma have been performed and found to agree well with experimental data. Images of plasma density, gas .and ion traces are provided. Index Terms - Inductively coupled plasma, gas flow, plasma reactor design, reactor model, two-dimensional model.

The influence of BCl3 magnetron ion etching on GaAs deep-level defects was investigated using deep-level transient spectroscopy. The results showed that the shallow donor concentration was not affected by the etching process when the power density was within the 0.08 to 0.4 W per square centimeter range. The etching process also had no effect on two deep defect sites with activation energies of 0.25 and 0.74 eV.

Interfacing semiconducting nanostructures with conducting or insulating substrates to attain a three-dimensional (3D) integrated platform is highly desirable for advanced nanoscale electronics and optoelectronics applications (1). As such, the assembly [...]

We have previously shown that high purity multiwalled carbon nanotubes (pristine MWNTs) can be prepared from a mixture of xylene-ferrocene (99 a%C: 1 at% Fe) inside a quartz tube reactor [...]

Research describing gas heating in inductively coupled plasma processing is presented. In particular CF4 discharges are investigated by means of a self consistent model.

The development of a a spatially averaged model of a high density power modulated high density oxygen discharge is presented.