The application of hopping theory for the prediction of charge (hole) mobility in amorphous organic molecular materials is studied in detail. Application is made to amorphous cells of N,N’-diphenyl-N,N’-bis-(3-methylphenylene)-1,1’-diphenyl-4,4’-diamine (TPD), N4,N4’-di(biphenyl-3-yl)-N4,N4’-diphenylbiphenyl-4,4’-diamine (mBPD), 1,1-bis-(4,4’-diethylaminophenyl)-4,4-diphenyl-1,3,butadinene (DEPB), N1,N4-di(naphthalen-1-yl)-N1,N4-diphenylbenzene-1,4-diamine (NNP), and N,N’-bis[9,9-dimethyl-2-fluorenyl]-N,N’-diphenyl-9,9-dimethylfluorene-2,7-diamine (pFFA). Detailed analysis of the computation of each of the parameters in the equations for hopping rate is presented, including studies of their convergence with respect to various numerical approximations. Based on these convergence studies, the most robust practical methodology is applied to investigate the dependence of mobility on such parameters as the monomer reorganization energy, the monomer-monomer coupling and the material density. The results give insight into what factors should be controlled to develop materials with higher (or lower) charge (hole) mobility, and what will be required to improve the accuracy of predictions of mobility in amorphous organic materials.

Optimizing magnetic field sensors made by piezoelectric-magnetostrictive composites is a trade off between several parameters. Whereas large structures will cause in principle high electrical currents the mechanical coupling will lead to shear losses and therefore limit the sensitivity of the sensor and make it impossible to measure small magnetic fields. In very small structures the shear losses will decrease but the imperfections in the interfaces become more important and the typically small currents will be disturbed by, e.g., surface conductivity of the piezoelectric material and are thus difficult to measure. The best compromise is a mesoscale sensor which has relatively small losses due to shearing but still high enough electrical currents to work as a good sensor. We will present a setup which allows the use free standing ZnO micro rods as piezoelectric core material which are surrounded by a magnetostrictive layer. Since no clamping is necessary the expansion and contraction of the material is not hindered by a matrix material. The tuning of the relative layer thicknesses can be easily optimized by changing the thickness of the magnetostrictive layer so that an optimum can be achieved for different ZnO micro rods. For the growth of the ZnO a newly developed process will be presented which allows the growth of a large variety of single crystals with different aspect ratios up to needles with several millimeters in length.

ZnO has a huge potential and is already a crucial material in a range of key technologies from photovoltaics to opto and printed electronics. ZnO is being characterized by versatile metrologies to reveal electrical, optical, structural and other parameters with the aim of process optimization for best device performance. The aim of the present work is to reveal the capabilities of vacuum ultra-violet (VUV) reflectometry for the characterization of ZnO films of nominally 50 nm, doped by Ga and In. Optical metrologies have already shown to be able to sensitively measure the gap energy, the exciton strength, the density, the surface nanoroughness and a range of technologically important structural and material parameters. It has also been shown that these optical properties closely correlate with the most important electrical properties like the carrier density and hence the specific resistance of the film. We show that VUV reflectometry is a highly sensitive optical method that is capable of the characterization of crucial film properties. Our results have been cross-checked by reference methods such as ellipsometry and X-ray fluorescence.

The ability to monitor the status of a battery during charge and discharge is important for predicting its performance and life. This is typically done by measuring the voltage and resistance across the terminals, or by external characterization methods such as X-ray diffraction and Raman spectroscopy. Thermodynamics measurements based on entropy and enthalpy provide another mean to “look inside” a battery, giving us more information to determine the state of health of the battery. In particular, entropy undergoes drastic changes at boundaries of phase transitions taking place in each electrode material at defined states of charge (lithium stoichiometry). Recent work on thermodynamics study on lithium ion battery materials is summarized in this paper.

Often, mechanical properties of wood plates are accurately approximated through orthotropic characterization. However, the numerical values may show considerable variations in the case of real wood plates immersed in fluctuant environmental conditions, especially if the relative humidity of air (RH) is changing. Problems arising from the natural variations in RH have been reported on making musical instruments. In this work, the influence of changing RH on the mechanical properties of a guitar’s top plate (clamped on its contour) has been measured. Vibratory responses of the plate were experimentally obtained, through forced vibration, while data were recorded for several RH values, without any alteration in the experimental set-up devices. The six lowest natural frequencies of the structure were extracted from peaks detected in the responses. Natural frequencies depend on mass distribution and mechanical properties of the structure. For the highest sensed RH (67 %), each natural frequency of the plate decreased at least in 11 Hz compared with reference values measured at the lowest sensed RH (53 %). To determine the connection between the shift in natural frequencies and the changes in the wood elastic and shear modulus, a finite element model of the plate was performed. It was useful calculating natural frequencies through simulated modal analyses. Elastic and shear modulus were handled to match simulated results with experimental natural frequencies recorded for a RH=53% level. These elastic moduli must be decreased around 10 % to obtain a similar frequency decrease in the experimental natural frequencies obtained under a RH=67% level. The experimental results show quantitative information on an interaction scarcely researched, that is, the modification on mechanical properties of wood plates induced by RH variations. Sensed changes due this wood-air interaction are responsible of a modification in the behavior of musical instruments, as guitars and violins.

Mo fiber reinforced NiAl in-situ composites with a nominal composition Ni-43.8Al-9.5Mo (at.%) were produced by specially controlled directional solidification (DS) using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. In these composites, single crystalline Mo fibers were precipitated out through eutectic reaction and aligned parallel to the growth direction of the ingot. Mechanical properties, i.e. the creep resistance at high temperatures (HT, between 900 °C and 1200 °C) and the fracture toughness at room temperature (RT) of in-situ NiAl-Mo composites, were characterized by tensile creep (along the growth direction) and flexure (four-point bending, vertical to the growth direction) tests, respectively. In the current study, a steady creep rate of 10-6s-1 at 1100 °C under an initial applied tensile stress of 150MPa was measured. The flexure tests sustained a fracture toughness of 14.5 MPa·m1/2at room temperature. Compared to binary NiAl and other NiAl alloys, these properties showed a remarkably improvement in creep resistance at HT and fracture toughness at RT that makes this composite a potential candidate material for structural application at the temperatures above 1000 °C. The mechanisms responsible for the improvement of the mechanical properties in NiAl-Mo in-situ composites were discussed based on the investigation results.

This investigation reports the synthesis of Ni-ferrite and ZrO2 added Ni-ferrite powdered materials for H2 generation from thermochemical water-splitting reaction. NiFe2O4 was synthesized using sol-gel technique in which salts of Ni and Fe were sonicated in ethanol until a visually clear solution was obtained. To this solution, propylene oxide was added to achieve the gel formation. As-prepared gel was dried at 100oC for 1 h and calcined upto 600oC at a ramp rate of 40oC/min. The calcined sample from the furnace was removed at 600oC and cooled down at room temperature in air. To synthesize NiFe2O4/ZrO2 powdered mixture, ZrO2 nanoparticles were mixed with the calcined ferrite powder using vortex mixer. These powdered materials were analyzed using powder x-ray diffractometer (XRD), BET surface area analyzer and scanning (SEM) and transmission electron microscopy (TEM). As-prepared NiFe2O4 and ZrO2 added NiFe2O4 powdered materials were loaded in an Inconel tubular reactor to investigate H2 generation from four consecutive thermochemical cycles where water-splitting and regeneration was performed at 900o and 1100oC, respectively.

The geometries, relative energies and spectroscopic properties of α-isosaccharinate and D-gluconate complexes of uranyl(VI) are studied computationally using density functional theory. The effect of pH is accommodated by varying the number of water and hydroxide ligands accompanying gluconate in the equatorial plane of the uranyl unit. Their relative energies are found to be pH dependent, although the energetic differences between them are not sufficient to exclude the possibility of multiple speciation. The calculated uranyl stretching frequency decreases as pH increases, in agreement with previous experimental data. Three different coordination modes are studied.

Composite layers of the detonation nanodiamond/polymer type possess a spatial organization of components with new structural features and physical properties, as well as complex functions due to the strong synergistic effects between the nanoparticles and polymer [1]. Composite layers were deposited by a plasma polymerization (PP) process of the detonation nanodiamond (DND) particles added to a hexamethyl disiloxan (HMDS) monomer [1]. The incorporation of silver ions in the polymer leads to the production of materials that are highly efficient against bacterial colonization and allows better cell adhesion and spreading. [2] For cell culture processes, fibronectin (FN) treatment is one of the commonly used approaches to enhance the cell adhesion on a surface [3].

As an integrated part of our search for improved materials for life science applications such as biomaterials and biosensors, the objective of the present study is to investigate the interaction of Ag-based composite surfaces with FN protein. Two types of composite layers, Ag-ND/PPHMDS and Ag-nano/PPHMDS were obtained by plasma polymerization of HMDS and nanoparticles of Ag and Ag-DND. The composite layers are representative of the different incorporation of the Ag in the polymer net. The structures studied, consisting of composite layers with adsorbed FN were optically characterized with Ellipsometry, Fourier Transform Infrared (FTIR) and Ultra Violet (UV) Spectroscopy as well as by stylus profiling (Talysurf). The kinetic study of the FN adsorption indicates that the process depends on the FN concentration and the exposure time as well as on the surface chemistry of the composites. Compared to the reference sample, all composite layers exhibit an indication of a stronger ability to initiate the intrinsic pathway of coagulation.

We report on the materials issues involved in the hybrid floating gate (HFG) device fabrication, where the interpoly dielectric is replaced by an intermetal dielectric (IMD). Indeed, in HFG the dielectric is inserted in between two metal layers in a metal\dielectric\metal stack. The materials of choice were TiN as the metal layer and Al2O3 and HfO2 (and their combination) as IMD. The program/erase performance is discussed based on the dielectric constant and crystallinity of the IMD and the metal-IMD interface characteristics.

The demand for low cost and disposable devices has driven the development of intelligent photodiodes, especially multispectral photodiodes that were first manufactured by Rieve et al. in 2000 [1]. The most remarkable feature of these devices is the voltage-controlled spectral response. In this paper we present a-SiGe:H based bias sensitive ni3p photodiodes that have been fabricated successfully in a low temperature PECVD process. Multispectral diodes based on ni3p structures make use of an intrinsic layer divided into three regions. Further subdivision of the i-layer into different collection regions is the key to an unequivocal optical detection. In addition to the a-SiGe:H multispectral photodiodes developed at the IMT, there is an inestimable wealth of different sensor approaches that has been optimized for different applications. To optimize the separation of secondary colors (i.e. spectral signatures) it is necessary to separate only those response curves (i.e. bands) with a very high information density [2, 3]. In our case, samples of whitish powder suspected to be dangerous or illegal must be unequivocally characterized. There is need for an application specific band selection method by which various sensors can be compared and evaluated. Unfortunately it is not sufficient to optimize the spectral response only as discussed in [4]. The requirements for measuring surroundings and the mechanical handling of all parameters together form a multivariate data set. Examined were in fact more than 5,000 measurement setup combinations, fictional and real, each considering 10 parameters that partially influence each other. The influence of all these parameters has to be examined, with the awareness of multivariate analysis [5].

Optical transport through Isotactic Polypropylene (iPP) and multiwall carbon nanotubes (MWCNTs) nanocomposite thin films is important to many applications where optical transmission or polarization are used. Especially interesting is the case where the optical properties are anisotropic as in oriented thin films and the optical transport is different in the direction of orientation and perpendicular to it. Changing the orientation of the film or the polarization of the light can change the way in which the nanocomposite film interacts with light. Our polymer of choice, Isotactic Polypropylene, is one of the most widely used polymers which will increase the applicability of our results. We blended iPP with different concentration of carbon nanotubes (CNTs): 1%, 2% and 5% and oriented the thin film samples using melt-shear at 200°C and 1Hz in a Linkam microscope sharing hot stage. We measured that the index of refraction of the nanocomposites slightly decreased when CNTs are added and that when nanocomposites were shear-oriented at low loading of CNTs the index of refraction showed small difference in directions parallel and perpendicular to the direction of orientation. The extinction coefficient increased therefore it’s tuning in the nanocomposite films by the content of the carbon nanotubes can help devise new materials with the desired values of this property.

The ever-growing Internet data traffic leads to a continuously increasing demand in both capacity and performance of large-scale Information and Communication (ICT) systems such as high-capacity routers and switches, large data centers, and supercomputers. Complex and spatially distributed multirack systems comprising a large number of data processing and storage modules with high-speed interfaces have already become reality. A consequence of this trend is that internal interconnection systems also become large and complex. Interconnection distances, total required number of cables, and power consumption increase rapidly with the increase in capacity, which can cause limitations in scalability of the whole system. This paper addresses requirements and limitations of intrasystem interconnects for application in large-scale data processing and storage systems. Various point-to-point and optically switched interconnection options are reviewed with regard to their potential to achieve large scalability while reducing power consumption.

A comparison of the photocurrent spectra of organic bulk heterojunction solar cells of various thicknesses is presented. Increasing the thickness of the active layer in both MDMO-PPV /PCBM and P3HT/PCBM solar cells reduces the magnitude of the photocurrent due to the low mobility of the photogenerated holes. Measurements show that the photocurrent reduction is predominately due to a loss in carriers generated at the polymer absorption maximum, while the low energy response is relatively unaffected. In a thick enough sample, the low energy response (1.5-2 eV) dominates, and a photocurrent peak is no longer observed at the main absorption maximum (2.6 eV). The results imply that hole transport is blocked for carriers generated in the polymer at higher energy. Because these holes are generated at the absorption maximum their low mobility could be a major factor limiting solar cell efficiency.

Time of flight (ToF) is the most straightforward technique to determine polymeric semiconductor mobility for electronic applications. We demonstrate ToF limits of applicability to amorphous PPV derivatives, such as poly[2-methoxy-5-(3’,7’-dimethylloctyloxy)-1-4-phenylene vinylene] (MDMO-PPV) and poly[2-methoxy-5-(2’-ethylhexyloxy)-1-4-phenylene vinylene] (MEH-PPV), and polycrystalline poly(3-hexylthiophene) (P3HT). Hole and electron mobility (μ) in submicrometric films (200 – 500 nm) is overestimated compared to casted layers, due to reduced absorption capability, which is confirmed by Charge Extraction by Linearly Increasing Voltage (CELIV) measurements. Charge transport properties in nanometric films, such as for Field-Effect Transistors (FET), can not be studied by current-mode ToF. Hole mobility of ca. 10-5 cm2/Vs with Poole-Frenkel behavior for PPV derivatives and 10-3 cm2/Vs for P3HT is at least one order of magnitude higher than ToF results.

A couple of FeAl alloys containing up to 1.4 at.% Li have been produced by vacuum induction melting. Though previous reports indicated a significant effect of Li on the properties of FeAl, no marked changes with respect to binary FeAl are observed. Specifically, no decrease of the lattice constant and no significant increase in ductility are found by alloying with Li. If at all, there is a slight increase of the lattice constant.

1 D TiO2 nanomaterials (nanotubes, nanowires) were synthesized through hydrothermal treatment of TiO2 powder (P25) in concentrated alkaline solutions (NaOH for nanotubes, KOH for nanowires) followed by calcination at varying temperatures between 400°C and 700°C. Samples were characterized by HRTEM, XRD, Raman spectroscopy, and N2 adsorption-desorption isotherms. High surface area nanotubular TiO2 materials can maintain their 1D morphology up to a temperature of calcination of 400°C while changing their phase from hydrogenotitanate to anatase. The use of KOH leads to a retarded formation of anatase. Photocatalytic results showed that TiO2 anatase nanotubes calcined at 400°C can degrade formic acid with a rate constant four times higher than for P25. A direct correlation between surface area and photocatalytic activity explains the much higher activity of TiO2 anatase nanotubes. On the opposite, for the degradation of phenol, P25 remains more active. In the disinfection of water, contrary to P25, the high surface area of TiO2 nanotubes allows the simultaneous degradation of formic acid and the inactivation of pathogen fungus showing the interest of such materials for the treatment of wastewater.

Abrasive blade dicing is the most common technique for die separation. In this work an alternative dry and non-abrasive die separation method, which is known as "Stealth dicing", is assessed for surface-sensitive MEMS (Micro Electro Mechanical Systems) wafers. The dicing performance and capability of the system is investigated on 200mm full thickness wafers with and without MEMS structures. The diced wafers are analyzed with respect to the silicon cutting quality, possible particle contamination, the condition of functional structures and their mechanical and electrical functionality. In addition the performance and limitations of two different Stealth Dicing Engine (SDE) types, SDE01 and SDE03, are compared to each other with respect to their performance on MEMS wafer dicing.

From this work design rules and proper dimensions of the scribe line can be determined. Process integration solutions, describing steps before and after the Stealth dicing process, including the contact-less dicing tape application to the wafer back side and the final die separation method by tape stretching, are presented. It was also found that the SDE03 laser with its outstanding performance in terms of process speed and separation quality can bring a breakthrough for applying this technology for MEMS wafers.

Titanium and its alloys have been employed in bone plates/screws, and theseare often designed to be removed after recovery. Bone is known to bond tothe surface of Ti alloys. This can lead to re-fracture of newly repairedbone during operations to remove the implants, however bone does not bond toZr-based alloys. The inhibition of bone conduction on the surface ofZr-based alloys is thought to be due to the presence of a thin layer ofzirconia (ZrO2) on the surface. The purpose of the present studywas to synthesize bioinert films, including ZrO2 on pure Tisurfaces. In vitro apatite (HAp) formation and in vivo bone conduction in the tibiae of rats on the films werealso investigated.

Commercial purity Ti was chemically treated with aqueous H2O2/HNO3 at 353 K for 20 min. The diskswere hydrothermally treated with aqueous ZrOCl2/NH3/C6H8O7(citric acid) in an autoclave at 453 K for 12 h. Simulated body fluid (SBF)immersion test and implantation into tibiae of rats were carried out.

In the hydrothermal treatment with aqueous ZrOCl2/NH3,the surface product was anatase-type TiO2. On the other hand,when citric acid was added the surface of Ti was covered homogeneously witha TiO2–ZrO2 composite film though the amount of ZrO2 was very small. HAp began to form on the non-modified Tiand TiO2 surfaces after 6 days and 4 days immersion in Hank’ssolution, respectively. On the surfaces of TiO2–ZrO2,the presence of precipitates was confirmed after 6-8 days. The HAp formationwas suppressed on the surfaces of TiO2–ZrO2.Thepresent TiO2-ZrO2 surface also showed significantlylower bone-implant contact ratio in cortical bone compared with TiO2.