In this work, we present a study of epitaxial Aluminium Nitride (AlN) for thin film bulk acoustic wave (BAW) applications. Molecular beam epitaxy (MBE) was used to perform high crystalline quality AlN thin films growth on different silicon substrate preparations. A morphological study was performed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), while structural properties and acoustic wave speed were respectively assessed by X-ray diffraction and acoustic picoseconds.

Half-Heusler phases have gained recently much interest as thermoelectric materials. Screening of possible systems was performed by drawing their stability region in a three-dimensional Pettifor map. The fabrication of Half-Heusler phases requires three steps, surface activation of the raw material by ball milling, arc-melting of pressed pellets and finally long-term annealing treatment in a vacuum furnace. On doped TiCoSb specimens, Seebeck coefficients of 0.1 mV/K, on NiNbSn 0.16 mV/K were measured, although the microstructure was not yet optimized.

Alx Ga1- x N/GaN high electron mobility transistor (HEMT) structures grown by ammonia-source molecular beam epitaxy (MBE) are focused-ion-beam implanted with 300 keV Gd-ions at room temperature. The two-dimensional electron gas (2DEG) of these HEMT structures is located 27 nm underneath the sample surface. At 4.2 K, current-voltage characteristics across implanted rectangles show that the structures remain conducting up to a Gd-dose of 1×1012 cm-2. Anomalous Hall effect (AHE) is observed at T = 4.2 K for structures implanted with Gd, whose dose is 3×1011 cm-2. Measurements of AHE in the wide temperature range from 2.4 K to 300 K show that the magnetic ordering temperature of these structures is around 100 K. Therefore, these Gd-implanted HEMT structures containing the still conducting 2DEG, which is now embedded in a ferromagnetic semiconductor, open the possibility to polarize the electron spins.

Polycrystalline transparent Yb:Sc2O3 ceramics were obtained in the best conditions by a solid-state reaction route using high purity Sc2O3 and Yb2O3 powders with TEOS as a sintering aid. The as-prepared powders containing various ytterbium content were characterized by BET measurements, XRD and FEG-SEM. The sintering behaviour of the powders was investigated by dilatometry. The sintered materials microstructures were observed by FEG-SEM. EPMA allowed to characterize the repartition of the dopant Yb3+ in the Sc2O3 matrix.

Plasma etch/ash processes can induce changes in low-k film surface/bulk chemistries and topographies resulting in increased water absorption, surface roughness, and metal intrusion. After ashing, the altered surface character of the low-k can impact wetting, adhesion, and, consequently, the resistance of subsequently deposited barrier layers. In this work, we describe the use of deuterium oxide as means of measuring moisture penetration into low-k films. Film chemistries have been monitored using grazing angle attenuated total reflectance (GATR) and transmission Fourier transform infrared spectroscopy (FTIR). To study moisture absorption in porous spin-on and CVD low-k films, unashed and ashed films have been exposed to D2O liquid and vapor treatments under “dry” nitrogen. The extent of D2O uptake, removal and exchange reactions has been studied using transmission and GATR FTIR methods because the D2O and O-D adsorption peaks are distinct from water and O-H as well as other low-k adsorptions. This method can be used to study Si-OH species because deuterium can exchange with hydrogen within silanols under ambient conditions while methyl groups are much less likely to exchange. Three different low-k films, a porous spin-on MSQ (k=2.2), a porous CVD (k=2.3), and an organosilicate glass (OSG, k=2.85) have been used. In FTIR spectra, unashed low-k films show minimal D2O adsorption. In MSQ hydrogen-ashed films, the data suggest the presence of deuterium oxide and O-D peaks. Further, D2O adsorption appears to be considerably higher for ashed films as would be expected due to the hydrophobicity of these films. In the CVD films, there does not appear to be as marked a difference. This method permits the introduction of a chemical “marker” into low-k wet and ambient processes allowing one to distinguish among adsorptions from different aqueous sources.

In practical use of the SiC power MOSFETs, further reduction of the channel resistance, high stability under harsh environments, and also, high product yield of large area devices are indispensable. Pn diodes with large chip area have been already reported with high fabrication yield, however, there is few reports in terms of the power MOSFETs. To clarify the difference between the simple pn diodes and power MOSFETs, we have fabricated four pn-type junction TEGs having the different structural features. Those pn junctions are close to the similar structure of DIMOS (Double-implanted MOS) step-by-step from the simple pn diodes. We have surveyed the V-I characteristics dependence on each structural features over the 2inch wafer. Before their fabrication, we formed grid patterns with numbering over the 2inch wafer, then performed the synchrotron x-ray topography observation. This enables the direct comparison the electrical and spectrographic characteristics of each pn junctions with the fingerprints of defects.Four structural features from TypeA to TypeD are as follows. TypeA is the most simple structure as same as the standard pn diodes formed by Al+ ion implantation (I/I), except that the Al+ I/I condition conforms to that of the p-well I/I in the DIMOS. The JTE structure was used for the edge termination on all junctions. While the TypeA consists of one p-type region, TypeB and TypeC consists of a lot of p-wells. The difference of Type B and C is a difference of the oxide between the adjacent p-wells. The oxide of TypeB consists of the thick field oxide, while that of TypeC consists of the thermal oxide corresponding to the gate oxide in the DIMOS. In the TypeD structure, n+ region corresponding to the source in the DIMOS was added by the P+ I/I. The TypeD is the same structure of the DIMOS, except that the gate and source contacts are shorted. The V-I measurements of the pn junctions are performed using the KEITHLEY 237 voltage source meters with semi-auto probe machine. An active area of the fabricated pn junctions TEGs are 150um2 and 1mm2. Concentration and thickness of the drift layer are 1e16cm−3 and 10um, respectively.In order to compare the V-I characteristics of fabricated pn junctions with their defects information that obtained from x-ray topography measurements directly, the grid patterns are formed before the fabrication. The grid patterns were formed over the 2inch wafer by the SiC etching. The synchrotron x-ray topography measurements are carried out at the Beam-Line 15C in Photon-Factory in High-Energy-Accelerator-Research-Organization. Three diffraction conditions, g=11-28, -1-128, and 1-108, are chosen in grazing-incidence geometry (improved Berg-Barrett method).In the presentation, the V-I characteristics mapping on the 2inch wafer for each pn junctions, and the comparison of V-I characteristics with x-ray topography will be reported.

This work proves that a 1-D porous silicon (PSi) sensor is capable of monitoring the optical changes in a polyacrylamide (PAAm) hydrogel that correlate with swelling capacity. The PSi device was impregnated with PAAm hydrogel with varying crosslinking density and total solids. The optical response of the PSi sensor was utilized to distinguish the changes in refractive index of hydrogels with varying cross-linking densities. Refractive index values calculated by the composite hydrogel-PSi sensor response agree well (≤1% difference) with values measured using a bench-top refractometer. This work serves to build a foundation for creating a composite biochemical-responsive hydrogel-PSi sensor in which competitive binding of a target analyte would cause a reduction in hydrogel cross-linking density. Long-term goals of this work are to exploit the volume sensitivity of a PSi sensor and leverage the added optical response of the responsive hydrogel to increase target detection sensitivity in an affinity based biosensor.

Ultrasonic consolidation (UC) uses high frequency (20-40KHz) mechanical vibrations to produce a solid-state metallurgical bond (weld) between metal foils. UC as a novel layered manufacturing technique is used in this research to embed reinforcing members such as silicon carbide fibers into the aluminium alloy 6061's matrices. It is known that UC induce volume and surface effect in the material it is acting on. Both effects are employed in embedding active/passive elements in the metal matrix. Whilst the process and the two effects are used and identified at macro level, what is happening at micro level is unknown and hardly studied. In this research we are investigating the phenomena occurring in the microstructure of the parts during UC process to obtain better understanding about how and why the process works.

In this research, high-resolution electron backscatter diffraction is used to study the effects of the UC process on the evolution of microstructure in AA6061 with and without fibre elements.

The inverse pole figures (IPF), pole figures (PF) and the correlated misorientation angle distribution of the mentioned samples are obtained. The characteristics of the crystallographic orientation, the grain structure and the grain boundary are analysed to find the effect of ultrasonic vibration and embedding fibre on the microstructure and texture of the bond. The ultrasonic vibration will lead to exceptional refinement of grains to a micron level along the bond area and affect the crystallographic orientation. Additional plastic flow occurs around the fibre which leads to the fibre embedding.

Composite cements where large amounts of blast furnace slag (BFS) replace Portland cement are currently used for immobilisation of ILW. Hydration of BFS is activated by the small amount of OPC present but the amount of reaction that occurs is limited at ambient temperatures. Increasing the temperature increases the hydration of the BFS but large amounts still remain unreacted, leaving a porous matrix where the capillary pores remain filled with a highly alkaline solution. This solution causes corrosion of reactive metals giving rise to expansive reactions and hydrogen release, and it can destroy the structure of zeolites releasing the adsorbed species.

Apart from OPC, BFS hydration can be activated by other compounds such as hydroxides, sulphates, silicates, and calcium aluminate cements. The use of these alternatives gives rise to binders such as ettringite and strätlingite which have a different chemistry where the pore solution has a lower pH. Corrosion of metals does not readily occur in these binders. This may be due to the reduced pH but could also arise from the lack of pore water, as these binders bind more water in their structure so that it is not available for transport of ionic species. This extra water binding also has potential for immobilisation of sludges where high w/s ratios are necessitated by the need to transport the sludge.

This paper will review some of the alternative activators for slag hydration and present experimental results on several systems where slag has been activated with compounds other than OPC.

Cold spray is a relatively new coating technology in which coatings can be produced by powdered particles under large plastic deformation without significant heating. In this paper, nickel coatings were fabricated by cold spray process followed by heat treatment in inert gas. Structural transformation of both as-sprayed and annealed coatings was investigated by Electron Backscattering Diffraction (EBSD) in a FEG-SEM. The results show that after cold spraying sub-micron grains and subgrains with high crystal strain appear in the particle bond interface, but not shown in the center of particles. Microstructure was transformed to be uniform and stresses were released after annealing in 400°C for one hour. And ductility and formability were significantly improved due to recovery and recrystallization. Continuous recrystallization after large strain deformation could occur after cold spraying followed by annealing.

Characterization of 700-nm-thick poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)]/TiO2/Al-doped ZnO (AZO) structures on a glass substrate were investigated.In this study, the sputtered TiO2 films as insulator were used for the reduction of leakage current. The leakage current density of the fabricated Pt/P(VDF/TrFE)/AZO and Pt/P(VDF/TrFE)/170-nm-thick TiO2/AZO structures were approximately 8.7 and 3.9 nA/cm2 at the applied voltage of 10 V, respectively. In the polarization vs. voltage characteristics, the fabricated Pt/P(VDF/TrFE)/TiO2/AZO structures showed hysteresis loops caused by ferroelectric polarization. The remnant polarization (2Pr) and coercive voltage (2Vc) measured from a saturated hysteresis loop at the frequency of 50 Hz were approximately 12 μC/cm2 and 105 V, respectively. These results suggest that the insertion of TiO2 film is available for reducing the gate leakage current without changing the ferroelectric properties.

Conductive atomic force microscopy (C–AFM) in ultra high vacuum (UHV) has been used to characterize charge trapping in ultrathin as–deposited oxide films of 2–4 nm (HfO2)x(SiO2)1-x/SiO2 multilayer gate stacks. Pre– and post–stress/breakdown (BD) dielectric degradation is analyzed on a nanoscale. A systematic observation probes stress induced trap generation facilitating physical stack BD. Degradation is considered in terms of the pronounced localized leakage contribution through the high–κ and interlayer SiOx. Simultaneous nanoscale current–voltage (I-V) characteristics and C–AFM imaging illlutrates charge trapping/decay from the native or stress induced traps with intrinsic charge lateral propagation. A post–stress/BD constant voltage imaging shows effects of stress bias polarity on the BD induced topography and trap assisted nano–current variations. Physical attributes of deformed artifacts relate strongly to the polarity of electron injection (gate or substrate) so discriminating the trap generation in high–κ and interlayer SiOx revealing non–homogeneous (dynamic) nature of leakage.

Water-based polymer latexes have attracted much attention since their invention in the early 1950s. Its advantages for both general health and the environment were recognized as they emit far less volatile organic compounds (VOCs) than their solvent-based counterparts.

The performance of latex paints and coatings is directly proportional to the ease of particle deformation. This is the main driving force for the paints and coatings industry to focus its research efforts towards understanding its mechanism.

In contrast, little has been published with respect to enhancing latex's resistance against deformation despite such needs in applications such as templating porous ceramics for catalysis and biomaterial engineering. Specifically, the latex's resistance to deformation is crucial to retain a network of uniform pores for applications relating to enzyme immobilization and materials reinforcement.

The current study reports increased heat-resistance observed in latexes when synthesized using a rigid surfactant, dimethyl siloxane – ethylene oxide block copolymer (PDMS-PEO). The film formation process for this latex was deduced using atomic force microscopy and subsequent roughness analysis. A comparative study using a non-ionic long-chain hydrocarbon surfactant, morpholine oleate, was also conducted.

The microstructural development of a forged Ti-43Al-4Nb-1Mo-0.1B (in at%) alloy during two-step heat-treatments was investigated and its impact on the tensile ductility at room temperature was analyzed. The investigated material, a so-called TNM™ gamma alloy, solidifies via the β-route, exhibits an adjustable β/B2-phase volume fraction and can be forged under near conventional conditions. Post-forging heat-treatments can be applied to achieve moderate to near zero volume fractions of β/B2-phase allowing for a controlled adjustment of the mechanical properties. The first step of the heat-treatment minimizes the β/B2-phase and adjusts the size of the α-grains, which are a precursor to the lamellar γ/α2-colonies. However, due to air cooling after the first annealing step, the resulting microstructure is far from thermodynamic equilibrium. Therefore, a second heat-treatment step is conducted below the eutectoid temperature which brings the microstructural constituents closer to thermodynamic equilibrium. It was found that temperature and duration of the second heat-treatment step critically affect the solid-state phase transformations and, thus, control the plastic fracture strain at room temperature. Scanning and transmission electron microscopy studies as well as hardness tests have been conducted to characterize the multi-phase microstructure and to study its correlation to the observed room temperature ductility.

A molecular-scale interpretation of interfacial processes is often downplayed in the analysis of traditional water treatment methods; however, such a fundamental approach is perhaps critical for the realization of enhanced performance in traditional desalination and related treatments, and in the development of novel water treatment technologies. Specifically, we examine in this article the molecular-scale processes that affect water and ion selectivity at the nanopore scale as inspired by nature, the behavior of a model polysaccharide as a biofilm, and the use of cluster-surfactant flocculants in viral sequestration.

Recently, organic nonvolatile memory has attracted much interest as a candidate device for next generation nonvolatile memory because of its simple process, small device area, and high speed. To investigate electrical characteristics of small molecular organic nonvolatile memory with Ni as a middle metal layer, we developed a small molecular organic nonvolatile memory with the device structure of Aluminum tris (8-hydroxyquinolate) (Al/Alq3), Ni nanocrystals, and Alq3/Al. A high vacuum thermal deposition method was used for the device fabrication. It is critical that the fabrication process condition for Ni nanocrystals be optimized, including ∼100 Å thickness, 0.1 Å/sec-evaporation rate, and in-situ plasma oxidation for effective oxidation. The reasons we chose Ni for the middle metal layer are that Ni has a smaller grain boundary, which is beneficial for scaling down and has a larger work function (∼5.15 eV) that can make a deep quantum well in an energy band diagram, compared with that of Al. Our device showed an electrical nonvolatile memory behavior including Vth of ∼2 V, Vw (write) of ∼3.5 V, negative differential region (NDR) of 3.5∼7 V, Ve (erase) of 8 V, and symmetrical electrical behavior at reverse bias. In addition, an interesting behavior of electrical properties was that, although retention and endurance characteristics were similar to the Al device, the Ion/Ioff ratio was greater than 104 at Vr (read) of 1 V. This value of the Ni device was higher than 102 compared to that of the Al device. Also, small molecular organic nonvolatile memory with a Ni middle layer with α-NPD at same fabrication condition showed more unstable characteristics than Alq3. We can speculate that there is a relationship in fabrication condition between the middle metal material and the organic material. Finally, we conclude that our device with a Ni nanocrystals middle layer is more reliable and useful for small molecular organic nonvolatile memory.

This paper first discusses the reasons for choosing CMOS-MEMS integration, in particular integration by poly-SiGe processing above CMOS. Next the current state-of-the-art for poly-SiGe MEMS integration and the needs for the future will be addressed. Market trends are translated into two roadmaps for MEMS integration. The first roadmap is based on existing poly-SiGe deposition processes at 400 − 450 ºC. The second roadmap explores processing techniques to lower the thermal budget and widen the application field of MEMS integration by using processing techniques such as metal-induced crystallization, laser annealing or self-assembly.

Surrogates are widely used in the research and development of nuclear wasteforms, providing detailed insight into the chemical and physical behaviour of the wasteform whilst avoiding the widespread (restricted and costly) use of radiotoxic elements in the laboratory. However, caution must be exercised when dealing with surrogates since no single element or compound perfectly mimics all aspects of the behaviour of another. In this paper we present a broad discussion of the use of surrogates in waste immobilization, drawing upon and highlighting our research into glass and ceramic wasteforms for the immobilization of bulk PuO2.

The dependence of electrical resistivity on specimen temperature and imposed tensile strains was determined for shape memory polyurethane (SMPU) composites of carbon nanofiber (CNF), oxidized carbon nanofiber (ox-CNF), and carbon black (CB). The SMPU composites with crystalline soft segments were synthesized from diphenylmethane diisocyanate, 1,4-butanediol, and poly(caprolactone)diol in a low-shear chaotic mixer and in an internal mixer. The materials synthesized in the chaotic mixer showed higher soft segment crystallinity and lower electrical percolation thresholds. The soft segment crystallinity reduced in the presence of CNF and ox-CNF; although the reduction was lower in the case of ox-CNF. The composites of CB showed pronounced positive temperature coefficient (PTC) effects which in turn showed a close relationship with non-linear thermal expansion behavior. The composites of CNF and ox-CNF did not exhibit PTC effects due to low levels of soft segment crystallinity. The resistivity of composites of CNF and ox-CNF showed weak dependence on strain, while that of composites of CB increased by several orders of magnitude with imposed tensile strain. A corollary of this study was that a high level of crystallinity may cause a PTC effect and prevent any actuation through resistive heating. However, a carefully tailored compound which has reduced crystallinity and which requires minimum amount of filler may prevent PTC phenomenon and could supply necessary electrical conductivity over the operating temperature range, while offering enough soft segment crystallinity and rubberlike properties for excellent shape memory function.