The integration of high-density CNT bundles as via interconnects in a CNT/Cu-hybrid BEOL stack is evaluated. CNT via-conduits may greatly improve heat dissipation and as such lower interconnect resistance and improve electromigration resistance. Each carbon shell of the nanotube contributes to electrical and thermal conduction and densities as high as 5×1013 shells per cm2 are estimated necessary. CNT growth processes on BEOL compatible metals are presented with tube densities up to 1012cm−2 and shell densities approaching 1013 cm−2 on blanket substrates. Selective growth of CNT bundles with carbon shell densities around 1012cm−2 is demonstrated with high yield. Ohmic behavior of TiN/CNT/Ti contacts is shown with a CNT via resistivity of 1.2 mΩ cm.

Plasma modification of SiOCH low-k films is analyzed by means of Molecular Mechanics. It is shown that the most probable mechanism of SiOCH modification in He plasma is removal of hydrogen atoms from CH3 groups. The change of Si–O–Si bond angles depends on the amount of the formed –CH2* (CHx) groups. During the followed exposure in NH3 plasma, NH2* radicals bind CHx groups with Si forming a –CH2– Si–O–Si–O–Si–O–Si– chain. The end of this chain gets bound to its beginning through NH2. This process is the reason of pore sealing.

The polyaniline was synthesized by in situ polymerization in the presence of ¦Â-naphthalenesulfonic acid which acts as template. The structure, morphology and magnetoeletric properties of samples were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), the standard Van Der Pauw DC four-probe method and vibrating sample magnetometer (VSM) techniques. The results indicated that polyaniline exhibited the hysteresis loops of the ferromagnetic nature and the conductance is high at 53.35 S/cm which possess both magnetic properties and electrical properties.

Chemical solution deposition has been used to fabricate continuous ultrathin lead lanthanum zirconate titanate (PLZT) films as thin as 20 nm. Further, multilayer capacitor structures with as many as 10 dielectric layers have been fabricated from these ultrathin PLZT films by alternating spin-coated dielectric layers with sputtered platinum electrodes. Integrating a photolithographically defined wet etch step to the fabrication process enabled the production of functional multilayer stacks with capacitance values exceeding 600 nF. Such ultrathin multilayer capacitors offer tremendous advantages for further miniaturization of integrated passive components.

The commercial synthesis of carbon nanotube sheets will be described. This process involves the following steps: chemical vapor deposition of long CNTs from mixed hydrocarbon type fuels, creation and stabilization of the catalyst, and a large textile forming device. Movies of the growth process will be presented and described. Further the electronic properties of these textiles will be presented and discussed as: (1) A function of temperature from −4 °K to 500 °C, (2) A function frequency from 0 up to about 30 GHz and (3) In a magnetic field up to 1000 Oe. It is shown that these yarns have semiconductor properties but surprisingly exhibit apparent metallic like conduction high at high frequencies. The thermoelectric behavior of the textiles (and yarns) made of this material will be discussed as will the applications in secondary batteries. A power level of up to three watts per gram for the thermoelectric material has been demonstrated.

We study basic problems of the semiconductor film bonding technology. We propose a new releasing method for a large number of semiconductor films using the film photoresist to protect the semiconductor films. We investigated the basic process conditions. We successfully released a large number of the GaAs film and bonded them on the Si, LiNbO3 substrates and metal Au surface. We estimated the ctystallinity of semiconductor films by X-ray diffraction and Raman spectral. The results clarified that these process were effective. As an application of the semiconductor film bonding technology, we fabricated a two-axis Hall sensor with planar structure. The two-axis hall sensor can measure axial and radial magnetic filed components (Bx and Bz) with a sensitivity of about 9.2 Ω/G for Bz and 4.5 Ω/G for Bx respectively.

The garnet Ca3Sc2Si3O12 (CSSO) and the silico-carnotite Ca3Y2Si3O12 (CYSO) and Ca3Lu2Si3O12 (CLSO) materials, both undoped and doped with Pr3+, have been synthesized by solid state reaction at high temperature. The luminescence spectroscopy and the excited state dynamics of the materials have been studied upon VUV and X-ray excitation using synchrotron radiation. All doped samples have shown efficient 5d-4f emission upon direct VUV excitation of 5d levels, but only CSSO:Pr3+ shows luminescence upon interband VUV or X-ray excitation. The VUV excited emission spectra of CYSO:Pr3+ and CLSO:Pr3+ show features attributed to emission from two distinct sites accommodating the Pr3+ dopant. The decay kinetics of the Pr3+ 5d-4f emission in CSSO:Pr3+ upon VUV excitation across the conduction band are characterized by decay times in the range 25-28 ns with no significant rise after the excitation pulse. They appear to be faster upon X-ray irradiation than for VUV excitation. Weak afterglow components are attributed to defect luminescence.

The use of nanosized Silicon powders in nanoelectronics and photovoltaics enables new technologies and promises to reduce the production costs of devices like solar cells and printable electronics significantly. However, to understand their electrical behavior and mechanical properties, such systems must be examined carefully. In porous systems like powders, the macroscopic electrical properties result from transport mechanisms such as hopping and tunneling between particles as well as from structural properties such as the amount and shape of particle contacts. Theoretical approaches like the strongest stresses network or the brick layer model can only describe this complex relation in a simplyfied way and need to be accompanied by suitable experiments. Nanosized pure and doped Silicon powders, synthesized in a microwave supported plasma reactor, were characterized by determining in-situ the conductance, impedance, and the change of porosity while applying a uniaxial mechanical pressure ranging from 7.5 to 750MPa. The porosity change of the powder during electrical measurements was characterized by means of a laser interferometer to determine the mechanical properties of the powder more accurately. Conductance measurements as a function of the applied pressure show an exponential dependence for nanosized particles and a power law for microsized particles. Simple scaling considerations in respect of the particle size cannot explain this fundamentally different behavior. Therefore a more sophisticated model is needed. A time dependent change in conductance together with a decrease in porosity was observed while applying a constant pressure, suggesting friction limited compaction of the powder. For a constant external force, the comparison of different samples leads to a clear power law dependence between the conductance of pressed samples and their mean particle diameter. This size effect spans seven orders of magnitude of the conductance while the particle size changes by only a factor of ten, and it clearly exceeds any influence of the doping concentration and the variation of the sample mass. To separate the contributions of the particle cores, particle-particle, and particle-electrode contacts to the complex conductance and capacitance, impedance spectroscopy was performed. In agreement with the observed compaction of the powder, the spectra show a strong increase of the sample capacitance and conductance as a function of the applied pressure.

We are developing the technique of spin-polarized photoelectron spectroscopy as a probe of electron correlation with the ultimate goal of resolving the Pu electronic structure controversy. Over the last several years, we have demonstrated the utility of spin polarized photoelectron spectroscopy for determining the fine details of the electronic structure in complex systems such as those shown below.

We develop a physical model to describe the kinetic behavior in cell-adhesion molecules. Unbinding of non-covalent biological bonds is decomposed into entropic and energetic controlled debonding. Such a treatment on debonding processes is a space decomposition of bond breaking events. Entropy controlled dissociation under thermal fluctuation is non-directional in a 3-dimensional space, and its energy barrier to escape may be not influenced by a tensile force but the microstates which can lead to dissociation are changed by the tensile force; An applied force effectively lowers the energy barrier to escape along the force direction. Such energetic effect will accelerate dissociate mainly along directions parallel to the loading direction. The lifetime of the biological bond, due to the superimposition of two concurrent off-rates, may grow with increasing tensile force to moderate amount and decrease with further increasing load, as debonding events dominated by entropy transit to those controlled by an applied force. We hypothesize that a catch-to-slip bond transition is a generic feature in biological bonds. The model also predicts that catch bonds in compliant molecular structure have longer lifetimes and may be activated at lower forces [1].

The reaction of CO2 gas with OPC, OPC-BFS and OPC-PFA composite cement systems were studied using XRD, SEM and TG to investigate the applicability of these materials to immobilise carbon arising from graphite waste. XRD results suggested that calcite formed in OPC system after the carbonation reaction, whereas calcite and vaterite were observed in OPCBFS and OPC-PFA systems. In OPC system, nearly half of Ca(OH)2 was consumed to form CaCO3. In OPC-BFS and OPC-PFA systems, the amount of CaCO3 formed, corresponded to the consumption of greater than 100% of Ca(OH)2 initially present, suggesting that other hydration products e.g. C-S-H were also consumed, either directly or indirectly during the carbonation process. The OPC-BFS system became more porous after carbonation. OPC-PFA system indicated a high efficiency on the conversion of Ca in the system into CaCO3.

Metallic clusters show excellent performance as catalysts because of their high surface-to-volume ratio. An inert-gas aggregation source is an experimental method by which clusters are produced. In such a method, cluster coalescence is one of growth modes of clusters. Bimetallic clusters also attract much attention of researchers because of their novel physical and chemical properties. At coalescence of two metallic clusters of different species, alloying or core-shell structuring tends to occur spontaneously. Resulting alloyed clusters or core-shell clusters will behave as unique catalysts. In this paper, morphological evolution of two metallic clusters of different elements at coalescence is investigated using molecular-dynamics simulation. All pair combinations of the elements Au, Ag, Pt, and Pd are considered. The interactions between such metallic atoms are calculated by using generic embedded-atom method (GEAM) potential. Two clusters of icosahedral structure are equilibrated at specified temperature beforehand. The two clusters are put close to each other, where the nearest two atoms belonging to the two clusters, respectively, start to interact with each other. After coalescence the original surfaces of the two clusters decrease, and the surface energy is transformed into the kinetic energy. Consequently, the temperature of the united cluster rises. If this temperature is higher than the melting temperature, melting and local alloying at the interface occur. If alloying spreads into the united cluster, an alloyed bimetallic cluster is synthesized. If melting occurs only in one of the two clusters, and the atoms in liquid phase gradually cover the surface of the other cluster, a core-shell cluster appears. The morphological evolutions in the two modes of coalescence are followed, and under what conditions each mode of coalescence occurs is discussed.

The results show that the surface energy and atom size of two clusters determine which mode is selected at coalescence.

Epitaxial growth on Si-face nominally on-axis 4H-SiC substrates has been performed using horizontal Hot-wall chemical vapor deposition system. The formation of 3C inclusions is one of the main problem with growth on on-axis Si-face substrates. In situ surface preparation, starting growth parameters and growth temperature are found to play a vital role in the epilayer polytype stability. High quality epilayers with 100% 4H-SiC were obtained on full 2″ substrates. Different optical and structural techniques were used to characterize the material and to understand the growth mechanisms. It was found that the replication of the basal plane dislocation from the substrate into the epilayer can be eliminated through growth on on-axis substrates. Also, no other kind of structural defects were found in the grown epilayers. These layers have also been processed for simple PiN structures to observe any bipolar degradation. More than 70% of the diodes showed no forward voltage drift during 30 min operation at 100 A/cm2.

Silicon-based photovoltaics typically convert less than 30% of the solar spectrum into usable electric power. This study explores the utilization of CdSe based quantum dots as spectral converters that absorb the under utilized UV portion of the solar spectrum and fluoresce at wavelengths near the band-gap of silicon-based solar cells. A flexible 1 mm thick thin-film structure that contains an array of microfluidic channels is designed and fabricated in polydimethylsiloxane (PDMS) using soft-lithographic techniques. The channels are approximately 85 microns wide by 37 microns tall and are filled with a solution containing the quantum dots. The thin-film structure can easily be attached to the surface of a single-junction solar cell. As a result, solar energy striking the coated solar cell with wavelengths less than 450 nm, which would normally experience low conversion efficiency, are absorbed by the quantum dots which fluoresce at 620nm. The high energy photons are converted to photons near the band-gap which increase the overall conversion efficiency of the solar cell. The quantum dots employed in this study are fabricated with a CdSe core (5.2 nm) and a ZnS outer shell and they exhibit a 25 nm hydrodynamic diameter. The UV-VIS spectral transmission properties of PDMS, along with its refractive index, are determined in order to characterize the spectral conversion efficiency of the thin-film structure. A model is developed to predict the optimum path length and concentration of quantum dots required to improve the power output of an amorphous silicon solar cell by 10%.

Spherical submicrometer-sized titanium dioxide (TiO2 or titania) particles were prepared by the sol-gel method from hydrolysis and condensation of titanium butoxide Ti(OC4H9)4 using ammonia as a catalyst in ethanol/acetonitrile and annealing in air at 100°C. Subsequently, they were deposited onto silicon substrates, in order to form a monolayer of TiO2 particles. Then these samples were irradiated at room temperature with Si2+ ions at 4, 6 and 8 MeV, with fluences in the 2×1014-2×1015 Si/cm2 range, under an angle of 45° with respect to the sample surface. The titania particles were characterized by scanning electron microscopy to determine their size and shape before and after the ion irradiation. After the Si irradiation the spherical silica particles turned into ellipsoidal particles, as a result of the increase of the particle dimension perpendicular to the ion beam and the decrease in the direction parallel to the ion beam. This deformation effect increases monotonically with the ion fluence, and depends on the electronic energy loss of the impinging ion.

Heterogeneous, one-dimensional (1D) nanomaterials, such as nanorods and nanowires, have been utilized for a variety of different biomedical applications because they offer a unique combination of properties and provide a material platform for integrating multiple functions. In this paper, we propose a template-assisted wetting approach to fabricate segmented polymer nanorods using biodegradable polymers for controlled drug delivery. Our previous work with polystyrene (PS) and poly(methyl methacrylate) (PMMA) heterogeneous, segmented nanorods is described briefly to introduce our current preliminary work with the fabrication of homogeneous biodegradable nanorods and drug release from polymer thin films. Since the template-assisted fabrication approach provides us unprecedented control over the size, spacing, and length of the heterogeneous polymer nanorods, this technique will provide for the opportunity to evaluate drug release kinetics as a function of the segment spacing, size of the nanorods, and aspect ratio in the future.

The functionalization of polymers and nano-materials with 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) groups provides materials suitable for a variety of preconcentrator and sensor applications. These are especially useful in high vapor pressure, hydrogen-bond basic vapor collection. These specific interactions lead to high efficiency collection of basic analytes such as DMMP (organophosphonates), DNT, and TNT (nitroaromatics). The lower vapor pressure analytes such as RDX have a larger dependence on surface interactions without specific (hydrogen bond) interactions. The use of carbosilane polymers with HFIP pendant groups offers dramatic improvements over fluoropolyol (FPOL) and siloxane polymers in sensor and precon applications. The sorbent capacity and thermal stability are both dramatically improved. In this work we will demonstrate the use of Carbon Nanotube (CNT) composites with HFIP polymers as sorbent coatings and evaluate their use as SPME coatings.

Many-body polarizable force field has been developed and validated for a wide class of ionic liquids. Classical molecular dynamics (MD) simulations have been performed on 29 ionic liquids. This presentation will focus on ability of developed force fields to predict condensed phase properties and on understanding the influence of many-body polarizable interactions on the ionic liquid structure and transport.

Post annealing of Hf-silicate thin film grown by ALD was done with different kind of nitrogen gas and order of annealing. Annealing conditions are as follows: (1) NO gas only, (2) NH3 gas only, (3) NO gas + NH3 gas, and (4) NH3 + NO gas. With these conditions, the physical and electrical properties of nitrided Hf-silicate films were analyzed. Content of nitrogen is decreased with post NO gas annealing. In case of NH3, content of nitrogen is much higher than NO case. Most nitrogen atoms were distributed between Si substrate and Hf-silicate film for NO gas annealing. However, with NH3 gas annealing, nitrogen atoms were distributed in the whole Hf-silicate film evenly. Leakage current was decreased with post NO gas annealing and flat band voltage was also decreased.

Many researchers have investigated organic nonvolatile memory devices as one of candidates device for next generation nonvolatile memory because of their low-cost, flexible and simple fabrication. The memory phenomenon in these devices is based on the electrical bistability of the material, which has two resistance states. We report memory effect in organic molecules based on electrical bistability of the materials and the bistable phenomenon was observed in poly(N-vinylcarbazole) (PVK) layer, containing a high density of Au nanocrystals and sandwiched between Al electrodes. The device was fabricated on cleaned SiO2. First, Al for the bottom electrode was deposited on SiO2 substrate by thermal evaporation in a vacuum chamber (pressure ∼10−6 torr). The PVK was dissolved with chloroform, spin-coated on the Al electrode, and baked at 120¡ÆC for 2 min to evaporate the solvent away. Subsequently, a 5-nm-thick Au film was deposited on the PVK. Additional PVK was then spin-coated on the Au film and baked. Next, the device was cured at 300¡É for 2 h in air to produce the Au nano-crystals. This device showed good nonvolatile memory characteristics. It was confirmed that it shows several region of current levels, (ION, IOFF, IINTER). When the voltage increased from zero in the OFF state (low conductivity state), the current increased rapidly at the threshold voltage (Vth), and presented a regime of negative differential resistance (NDR) after writing. Moreover ON and OFF states could be set at voltages at Vprogram (or Vp) and Verase (or Ve), respectively, and could be read at 1 V. After the device was programmed by sweeping the voltage from 0 to Vp, the current followed the high conductivity state and stayed in the ON state. And the device was programmed by sweeping the voltage from 0 to Ve, the current followed the low conductivity state and stayed in the OFF state. Furthermore, they exhibited seven different reversible current paths (intermediate states) capable for approving electron charge or discharge on surface of Au nanocrystals by sweeping the voltage from 0 to VNDR. Our results demonstrate that the fundamental parameters of the device were stable; the values of Vth, Vp, and Ve were ∼2.8, ∼4, and ∼8 V, respectively. In particular, this device exhibited excellent nonvolatile memory behavior, with bistability (ION/IOFF) of >1×102 and an intermediate state for multi-bit operation. We suggest that the current conduction mechanism clearly follow space-charge-limited(SCLC) for low conductivity state, thermionic field emission for electron charge(writing) or discharge(erasing), and F-N tunneling after erasing.