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We demonstrate a strategy to stabilize nanoprecipitates in Al–Cu alloys, based on computational design that identifies synergistic solutes (Sc and Fe) that simultaneously segregate to the θ′-Al2Cu/Al interface and strongly bond to one another. Furthermore, Sc and Fe are predicted to each segregate into a separate atomic plane, forming a sandwiched structure reinforcing the interface. This interfacial architecture was realized through a simple heat treatment in a Sc–Fe–Si triple-microalloyed Al–Cu model alloy. Such a back-to-back layered interface, thermodynamically stable and kinetically robust, is found to suffocate nanoprecipitate coarsening at 300°C, enabling a dramatic reduction in creep rate. IMPACT STATEMENT The segregant architecture of synergistic solute at θ′-Al2Cu/Al interface was guided by computational calculations and artificially realized at atomic scale to achieve an ultra-high thermal stability of θ′-Al2Cu, leading to a high creep resistance at 300°C.

In the paper, the influence of shape memory alloy (SMA) by varying the parameters such as volume fraction, orientation, and temperature on the hybrid-SMA composite laminate subjected to low-velocity impact is studied. A theoretical model for the composite laminated plate bonded with SMA reinforced layers is presented. The constitutive relation of the SMA layer is obtained by using the method of micromechanics. The governing relations obtained can be used for theoretical predications of thermomechanical properties of SMA plies in this paper. The analytical expressions for the hybrid SMA composite plate are derived based on Tanaka's constitutive equation and linear phase transformation kinetics presented by Liang and Rogers.The laminated plate theory, first-order shear deformation theory and minimal potential energy principle is utilized to solve the governing equations of the hybrid composite plate and calculate the absorbed energies including tensile, shear and bending.An orthogonal array and analysis of variance is employed to investigate the influence of the mentioned parameters on the energy absorption of the hybrid laminated plate. The results showed that the effects of the phase transformation temperature are more significant than the effects of the volume fraction and orientation of SMA on structural energy absorption.

Phase-change (PC) materials offer the property of thermally induced reversible change and exhibit different resistance values due to the structure changes between crystalline and amorphous phases. In this work, GeTe films with a thickness of 100 nm were deposited on the glass substrates by radio-frequency magnetron sputtering and annealed at different temperatures. The XRD analysis showed diffraction peaks corresponding to the rhombohedral structure of c-GeTe (021), (200), (202), and (220), respectively. Upon annealing at 300 and 340°C, the rhombohedral structure would transform into a rock salt structure. The Raman analysis revealed that a-Ge-Te covalent bond is the mixed structure of tetrahedron and defective octahedron changing into tetrahedral cells. The resistivity declined sharply from 0.72 to 3.8× 10−6 Ω-m, whereas the Hall mobility of holes sharply rose to 300 m2/Vs. Based on the above films, a two-port directly heated switch device was designed and fabricated in sandwich structure to verify its phase-change characteristics. Low-resistance state was converted from crystallization with a 20ns 9V voltage pulse, while high-resistance state was by passing a 2 μs 2V voltage pulse. The on/off resistance ratio of switch could reach five orders of magnitude, while the switch state remained stable after the process termination. The results obtained strongly suggest that GeTe is a promising material for RF switches.

The removal of suspended solids (SS) and color is critically important for textile wastewater treatment processes. Typically, chemical coagulation and sedimentation have been used as pretreatment processes to remove SS and color from textile wastewater. The effective removal of SS depends significantly on the particle size distribution, density, and fractal dimension. In practice, a batch settling test is used in the laboratory to evaluate the performance of chemical coagulation for the removal of SS. In this paper, we present the application of digital image analysis (DIA) for on-line and simultaneous measurement of the variations of the characteristics of particles in textile wastewater. This technology was used during a batch settling test to measure the characteristics of particles, including the mean gray value (MGV) of the captured images, particle size (i.e., equivalent diameter (ED)), total area, total volume, the fractal dimension, and the mean red/green/blue (R/G/B) values of the captured images. The on-line DIA data were used as input to regression and artificial neural network (ANN) models that predicted the efficiencies of SS removal and color removal in real textile wastewater after chemical coagulation and sedimentation. The experimental results indicated that the ANN models predicted both the SS and color removal efficiencies precisely, with correlation coefficients (R2) of 0.93 to 0.96. Thus, digital image analysis and ANN models can be used to simultaneously evaluate the removal of SS and color from textile wastewater by chemical coagulation.

Metal–oxide–semiconductor (MOS) capacitors incorporating atomic-layer-deposition (ALD) HfZrLaO high- κ gate dielectric were fabricated and investigated. The equivalent oxide thickness (EOT) is 0.68 nm and the gate leakage current density ( J g ) is only 9.3 × 10 −1 A/cm 2 . The time-dependence dielectric breakdown (TDDB) behavior agrees with the percolation model, and the TDDB characteristics are consistent with the thermochemical E -model for lifetime projection. The experimental results show that the Weibull slopes are almost independent of capacitor area and stress conditions. The field acceleration parameter ( γ ) and activation energy (Δ H 0 ) are determined around 5.9–7.0 cm/MV and 0.54–0.60 eV, respectively. At 85 °C, the maximum voltage projected for 10-years TDDB lifetime is 1.87 V.

Metal–oxide–semiconductor field-effect transistors (MOSFETs) incorporating HfSiON dielectrics with different compositions have been fabricated using atomic layer deposition (ALD) and their positive bias temperature instability (PBTI) reliability has also been investigated. The experimental results indicate that the oxide trapped charge ( N ot ) dominates the PBTI degradation process, and after PBTI stress the increment of oxide trapped charges (Δ N ot ) is about 2–3 orders of magnitude greater than the generation of interface traps (Δ N it ). Moreover, higher Hf concentration results in more pre-existing traps but slower trap creation rate. The charge pumping technique has been utilized to characterize the interfacial parameters, Δ N it , Δ N ot , and Δ D it (the generation of the density of interface trap per energy and area).

Metal-oxide-semiconductor field-effect transistors (MOSFETs) incorporating CeO2 dielectrics were fabricated and investigated. In this work, the interfacial and electrical properties of CeO2/Si were characterized by gated-diode method and charge pumping technique. The lowest density of interface traps per area and energy (Dit) of CeO2/Si interface in comparison with other high-k material is about 7.3×1010 cm-2-eV-1 due to the very low lattice mismatch at CeO2/Si interface. The density of interface trap per area (Nit) determined using gated diode method is 6×109 cm-2. The minority carrier lifetime (tFIJ), the effective capture cross section of surface state (αs) and surface recombination velocity (so) extracted using gated-diode method are 4.09×10-8 s, 7.14×10-14 cm2 and 4310 cm/s, respectively. Furthermore, a comparison with MOSFETs using the other high-k materials as gate dielectrics was also made.

Metal-oxide-semiconductor field-effect transistors (MOSFETs) in-corporating hafnium-silicate (HfSiON) dielectrics with different compositions were fabricated and investigated for hot carrier reli-ability. The experimental results reveal that the channel hot carrier (CHC) stress is worse than drain avalanche hot carrier (DAHC) stress. Moreover, the experimental results also show that the in-crease of oxide trapped charges (ΔNot) depends on Hf content and is about one order of magnitude larger than that of interface traps (ΔNit) after CHC or DAHC stress. Finally, some important interfa-cial parameters, including ΔNit, ΔDit and ΔNot, have also been characterized through the transconductance and subthrehsold swing (SS) methods.

Metal-oxide-semiconductor capacitors (MOSCs) and Metal-oxide-semiconductor field-effect transistors (MOSFETs) incorporating hafnium dioxide (HfO2) dielectrics were fabricated and investi-gated. The electrical and interfacial properties were characterized including C-V, IDS-VGS, the mean density of interface traps per unit area and energy (), energy of interface traps density distribution, interface traps density (Nit), density of near-interface oxide traps per unit area (NNIOT), effective capture cross-section area (σs), mi-nority carrier lifetime (τFIJ) and surface recombination velocity (so) were studied. Furthermore, a comparison with MOSFETs using conventional SiO2 as gate dielectrics was also made.

Metal-oxide-semiconductor (MOS) capacitors incorporating hafnium dioxide (HfO2) dielectrics were fabricated and investigated. In this work, the electrical and interfacial properties were characterized based on capacitance–voltage (C–V) and current–voltage (I–V) measurements. Thereafter the current conduction mechanism, electron effective mass (m*), mean density of interface traps per unit area and energy ( D ¯ it ), energy distribution of interface traps density and near-interface oxide traps density (NNIOT) were studied in details. The characterization reveals that the dominant conduction mechanism in the region of high temperature and high field is Schottky emission. The mean density of interface traps per unit area and energy is about 6.3 × 1012 cm−2 eV−1 by using high–low frequency capacitance method. The maximum Dit is about 7.76 × 1012 cm−2 eV−1 located at 0.27 eV above the valence band.

Metal-oxide-semiconductor capacitors (MOSCs) and metal-oxide-semiconductor field-effect transistors (MOSFETs) incorporating hafnium silicate (Hf-silicate) dielectrics were fabricated by using atomic layer deposition (ALD). The electrical properties of these Hf-silicate thin films with various postnitridation annealing (PNA) temperatures were then examined to find the best nitridation condition. It is found that the best conditions to achieve the lowest gate leakage current and best equivalent oxide thickness (EOT) are when PNA is performed at 800 °C in NH 3 ambient for 60 s. To understand the obtained film, carrier transportation mechanisms, the temperature dependence of the leakage current was measured from 300 K to 500 K for both gate injection and substrate injection. The result reveals that the leakage mechanisms involve Schottky emission at high temperature and low electrical field and Poole-Frenkle emission at low temperature and high electrical field. The barrier heights of poly-Si/Hf-silicate and Hf-silicate/Si interfaces extracted from Schottky emission are 1.1 eV and 1.04 eV, respectively. The interface traps per unit area, the mean density of interface traps per area and energy and the mean capture cross-section are determined about 8.1 x 10 10 cm -2 , 2.7 × 10 11 cm -2 eV -1 and 6.4 × 10 -15 cm -2 using charge pumping method.

A new laser machining technique for ceramic shaping, based on the concept of fracture mechanics, is proposed in this paper. The principle of fracture machining technique is investigated. A focused laser is used to scribe two groove-cracks at the two intersecting surfaces of the rectangular substrate. Then, a defocused laser beam is applied throughout the length of the groove-cracks to generate a great thermal stress, which makes the two groove-cracks link together. The material removal is due to the linkage of the groove-cracks. Conventional laser machining requires high laser power to evaporate the materials. The high temperature gradient would induce the formation of micro-cracks, which leads to a remarkable reduction in strength. The laser power required in the method proposed is only a tenth of what is required in the conventional method under the same material removal rate, and in addition, the amount of the micro-crack is smaller. The experimental specimens are alumina ceramics, and the laser sources are a CO2 laser and a Nd:YAG laser. The fracture machining technique can be successfully employed for step shaping and blind corner shaping for a thick ceramic substrate. The relationships of machining parameters such as groove-crack depth, material removal rate, laser scanning speed, and laser power are discussed. Finally, the measurement of the surface roughness and the inspection of crack defects are examined thoroughly.

The polymer dispensing technology used for a lens type LED package had been revealed in [1]. The ring type micro structure is adopted to confine the dispensed silicone encapsulant so as to form the packaged lens. To use the dispensing technology, the deviations in lens geometry are larger as comparing to that as using the silicone lens molding process. In this study herein, the dome-type UV LED and White LED packages are selected to verify the variations in the spatial radiation induced by the collimation between lens and LED chip, the height of lens and the collimation between lens and LED chip increases to 100µm, the phosphor application. Comparing to the collimating ones, as the shape of radiation pattern changes from a mountain type to a slope type at the spatial range of −75° to 75°. Furthermore, the view angle also increases 4°∼7°. The diffusive character from phosphor significantly reduces the variation in radiation pattern causing by the collimation. The view angle could reach 150° in white LED package. The view angles are 149°and 141° for the packages with the lens height of 1.3 mm and 1.5 mm, respectively. However, the radiation patterns are similar to each other in these two conditions of lens height.

This paper reports a metal-oxide RRAM with novel Defect Engineering Technology (DET) that achieves forming-free, multi-level capable, self-rectifying, large 2×104 resistance window, ultra-low 0.24nW reset power and good endurance of 10p6 cycles at the same time. Besides, by the same DET with additional forming process, we demonstrate a complementary resistive switching (CRS) on single-stack metal-oxide with large 15X resistance window, good endurance of 105 cycles and stable high-temperature disturbance.

In this study, a simple method was used to prepare a chitosan adsorbent to mix with KI and TiO2. Gravimetric analysis (TG), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the samples before and after adsorption of Hg2+. A mercury adsorption experiment was also conducted in the gypsum slurry. The results show that using hydrobromic acid as a solvent of adsorbent resulted in a better adsorption effect than using acetic acid alone. Also, the sample (CS-KI/TiO2-HBr) had a maximum mercury adsorption capacity when the pH=5 and the t=50°C. The characterization experiments showed that the thermal stability of composite materials declined and the TiO2 uniformly dispersed in the surface of the samples with a lamellar structure, generating a lot of cracks and recesses that increased the reactive sites. Furthermore, when the TiO2 reacted with CS, it resulted in Ti-C, Ti-O and Ti-N bonds. The Br- can prevent the growth of TiO2 crystal grains and strengthen the ability of I- to remove mercury. The adsorption isotherm and kinetic results indicated that the adsorption behaviour of CS-KI/TiO2-HBr as it removes Hg2+ is an inhomogeneous multilayer adsorption process. The surface adsorption and intraparticle diffusion effects are both important in the Hg2+ adsorption process.

In 1986, Bendorz and Muller1 discovered that metallic oxide with a perovskite structure in the La-Ba-Cu-O system exhibited superconductivity at 20°K. In early 1987, Chu and his co-workers2 made a YBa2Cu3O7-x compound which had a Tc higher than the temperature of liquid nitrogen. Since these discoveries, the research and development of high-Tc superconductors has aroused unpecedented attention, not only from the scientific community, but also from various industries and governments. As these new superconducting materials are in general very "brittle" and difficult to machine, it is extremely difficult to fabricate them into thin wires. In addition, practical use of new high-Tc superconductors will require materials with very high critical current density. Thus thin film preparation is particularly important for many applications of superconductors, such as electronics for the computer industry. Films with high superconducting transition temperatures have been prepared by electron beam evaporation, organometallic chemical vapor deposition, DC sputtering, molecular beam epitaxy, and laser evaporation and deposition processes. For example, Rice et al.3 used electron beam and thermal evaporation to produce Ca-Sr-Bi-Cu-O superconducting films from CaF2, SrF2, Bi, and Cu targets. Berry et al.' produced a superconductive film by organometallic chemical vapor deposition. Hellman et al.5 used molecular beam epitaxy to produce a DyBa2Cu307, film on a SrTiO3 substrate. Lynds et al.6 used a Nd-YAG laser beam to do laser evaporation and deposition to prepare a YBa2Cu307-x thin film from targets of Y203, Bat CO3, and CuO. Kwok et al.7 applied a homogeneous excimer laser to obtain a film with the right stoichiometry of YBa2Cu307,. However, most of the films in the works cited above need to be annealed in an oxygen environment in order to produce superconductivity. Recently, several research groups obtained superconductive films of YBa2Cu307, by raising the temperature of the substrate and introducing oxygen into the chamber during the thin film preparation process.8 However, no superconductive films of the Bi-Sr-Ca-Cu-O or Tl-Sr-Ba-Cu-0 systems were obtained without oxygen annealing. Nevertheless, the right ratio of various metal elements is one of the key factors in achieving superconductivity. Superconductive films are usually obtained based on repeated trials and adjustments. Venkatesan et al.9 observed two distinct components during pulsed laser deposition of high-T, superconductive film. It was pointed out that the quality of the superconductive film depends on controlling the film stoichiometry. The role of introducing oxygen into the thin film preparation chamber has never been fully understood. Thus, the need for a real-time monitor for high-Tc thin film preparation is quite critical.

The power conversion efficiencies of organic solar cells fabricated with Ag and Ti nanoparticle arrays using nanosphere lithography are studied. The Ag nanoparticle array exhibits a broad absorption spectrum peaked at 420nm, which spectrally overlaps with the absorption band of the organic absorbing layer centered at 520nm, while no peak presented for the Ti nanoparticle array. Power conversion efficiencies by the solar cells with Ag and Ti nanoparticle arrays are 2.42% and 1.68%, respectively. This efficiency improvement is proposed to originate from the strong surface plasmon resonant scattering of visible light by Ag nanoparticle arrays.

Thermal stability of fluorine-doped silicon dioxide films deposited by high-density plasma chemical vapor deposition as a function of deposition temperature were investigated in this study. Both thermal desorption spectrum and annealing test results show that SiOF films deposited above 400 °C have better thermal stability. Furnace annealing data indicate that non –Si–F– bonding fluorine does exist in low-deposition-temperature SiOF films. Furthermore, secondary-ion mass spectrometer results also reveal that the fluorine in SiOF films with a lower-deposition temperature is easily diffused out and turned into the underlayer, which results in less thermally stable SiOF films. Moreover, short-loop simulation results have been subsequently tested and it was concluded that the deposition temperature of the SiOF film is extremely important for thermal stability.

High-energy Auger and medium-energy backscattered electron diffraction are shown to be useful structural probes for ultra-thin epitaxial films. Coherent scattering of such electrons in the energy regime of 500 to 1000 eV leads to intensity modulations of the order of 50% in an angle-resolved measurement. These modulations are well accounted for by a straightforward kinematical scattering formalism in which trial geometries are employed and varied. Optimal agreement with experiment consistently results from a single geometry, leading to a unique solution to the structural problem. Atomic coordinates and elastic strain associated with lattice mismatch at the interface can be routinely determined with sub-Angstrom precision. Moreover, first layer morphology and structural rearrangement associated with intermixing can be monitored. We present results from the Cu Ni (001) , Co Ni (001) , Fe Cu (001) , Cu/Fe/Cu(001) and Fe GaAs (001) systems which illustrate these conclusions.

We have investigated the atomic structure of annealed Co/Si(111) interfaces prepared by the evaporation of one-, two-, and thirty-monolayer equivalent coverages of Co. Experimental and theoretical angular distributions of the Co LMM Auger intensity reveal that for all coverages investigated a ${\mathrm{CoSi}}_{2}$ phase forms which is rotated 180\ifmmode^\circ\else\textdegree\fi{} about the surface normal relative to the substrate. At low coverages, the ${\mathrm{CoSi}}_{2}$ phase is in the form of clusters which appear to be two to three ${\mathrm{CoSi}}_{2}$ layers in thickness and are terminated by a Si(111) bilayer. The Si(111) overlayer, which is in addition to the terminal plane of Si atoms associated with the outermost ${\mathrm{CoSi}}_{2}$ layer, also appears to be rotated 180\ifmmode^\circ\else\textdegree\fi{} about the surface normal relative to the Si substrate.

We have used high-energy Auger-electron diffraction and associated kinematical scattering calculations to determine that Co, which is hcp at room temperature and atmospheric pressure, can be grown as a stable, unstrained fcc film on Ni(001). Studies of the early stages of growth show that the first monolayer equivalent does not cover the surface uniformly but rather forms two-dimensional patches with limited amounts of a second layer. The second monolayer equivalent adds to the second layer of each patch and provides a limited number of third-layer atoms. When the total Co coverage exceeds two monolayer equivalents, the overlayer coalesces into a continuous fcc film with no detectable strain up to 30 monolayers (the highest coverage studied). For comparison, we have measured angular distributions for Cu/Ni(001) with 0.5 and 1.0 monolayer of Cu. From surface thermodynamic considerations, Cu is expected to wet the surface uniformly. However, Cu also tends to form two-layer-deep patches at a coverage of one monolayer equivalent. These results demonstrate that limited surface mobility is significant in determining the morphology of monolayer metal films, in agreement with theoretical models of overlayer growth behavior.

We present high-resolution synchrotron-radiation core-level photoemission results which show that the room-temperature deposition of Co onto GaAs(110) induces limited substrate disruption, leading to Ga and As intermixing with the metal overlayer. High-energy Auger electron diffraction and low-energy electron diffraction measurements indicate that Co orders weakly to form a metastable, epitaxial bcc matrix with principal crystallographic axes parallel to those of the substrate. Angle-dependent x-ray photoemission results show that the distribution of Ga and As in the Co overlayer varies with, and is dependent on, the Co thickness. Together, these results show that the amount of dissociated Ga and As in the overlayer decays exponentially away from the Co/GaAs interface (1/e length 3 A\r{}); that As surface segregates and its concentration profile is exponential away from the vacuum into the Co overlayer (surface concentration 5.8 at. % at 150-A\r{} Co thickness, 1/e decay length 5 A\r{}); and that the As solubility in the Co film far from either boundary is 0.26 at. %. This paper demonstrates that substrate disruption and epitaxial growth are not mutually exclusive provided that the disruption is not too severe and that conditions necessary for epitaxy exist.

We have combined high-angular-resolution Auger-electron diffraction, kinematical scattering calculations, low-energy-electron diffraction (done in a pulse-counting mode), and high-energy-resolution x-ray photoelectron spectroscopy to examine the formation of the Fe/GaAs(001)-c(8\ifmmode\times\else\texttimes\fi{}2) interface. We find that clusters of bcc Fe at least three atomic layers deep grow in registry with the substrate for coverages up to \ensuremath{\sim}4 monolayer equivalents. These clusters contain Ga and As atoms which have been liberated from the GaAs substrate. Above this coverage, the clusters coalesce into a continuous bcc Fe matrix with a lattice constant equal to half that of GaAs and with principal crystallographic axes parallel to those of the substrate. This epitaxial Fe overlayer contains Ga and As in solution in the bcc lattice with the impurity atoms occupying interstitial face-center sites. The concentration of Ga and As decreases with distance from the GaAs substrate. At the same time, we find clear evidence for surface segregation of As and enrichment of the near-surface region.

Etude du role de l'angle d'incidence du faisceau d'electrons, sur l'apparition d'anisotropies dans l'emission, a resolution angulaire, d'electrons d'Auger par des monocristaux. On montre que les distributions angulaires sont independantes de la direction du faisceau incident

Silicon on insulator (SOI) substrate is a key materials for nano-scaling IC device and the requirement for its crystal structure and quality is really high. Nanothick silicon thin film can be transferred onto a handle wafer from a donation wafer to form a SOI wafer after this process including hydrogen implantation of donation wafer, wafer bonding, and thermal treatment at moderately high temperatures of 400 to 600 degree centigrade. The expansion of the hydrogen molecular evolving from the implanted hydrogen ions interacting with silicon dangling bonds and trapped inside the microcavities located near the ion projected range resulted in exfoliation of the silicon thin film in the final heating step. The hydrogen molecules inside the microcavities tend to expand along the bonded interface rather than radially to form individual blisters. Finally, the fracture failure of ion implanted area parallel to the bonded interface near the projected ion range is formed by the sideway expansion of the cavities due to the diffusion supply of implanted hydrogen excited by thermal energy. Microwave processing can lower the activity energy to speed the chemical reaction so that it leads the format of microcavities occurring at low temperature by directly exciting the implanted hydrogen ions by microwave energy and also results in decreasing the critical dosage for layer splitting. However, microwave irradiation alone at room temperature causes the formation of lots of nucleus sites of micro-voids filled by hydrogen molecule which is immobility in silicon resulting in the issue of uniformity of transferred layer. In this study, the hydrogen implanted silicon substrate was irradiated by microwave at low temperature (200 degree centigrade) rather than microwave alone to co-activate the implanted hydrogen ions in silicon to increase not only kinetic energy but also mobility to successfully achieve a completely transferred layer in a short time.

A numerical approach is presented to evaluate the surface intensity and radiation loading on a finite cylindrical surface with a known harmonic radial velocity distribution. The approach is based on a combined FFT and Green's function method [P. Stepanishen and H. W. Chen, J. Acoust. Soc. Am. Suppl. 1 73, S22 (1983)]. Surface pressure, intensity, and radiation loading are rapidly obtained via the use of standard FFT methods. The spatial fluctuations of the surface pressure and intensity for a known velocity distribution can thus be readily investigated. Numerical results are presented to illustrate the spatial variation of surface pressure and intensity as a function of axial mode shape, circumferential mode number, and frequency. Negative intensity regions and edge effects are clearly observed in the results at low frequencies.