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Diamond/Ag-Ti composites were fabricated by pressureless sintering. The minor addition of Ti effectively ameliorated the wettability between diamond and the silver matrix. Transmission electron microscopy indicated that the interface structure of the diamond (100) plane of the diamond/Ag-Ti composites was Ag/TiC/TiC-Ag/diamond. The thermal conductivity of the 300 μm 60 vol% diamond/Ag-1.5 at% Ti composite reached 953 W/m·K – approximately 98% of the theoretical thermal conductivity calculated by the differential effective medium model in conjunction with the diffuse mismatch model. The composites possessed compatible coefficients of thermal expansion, and excellent thermal cycling performance under long-term operation and stringent joining packages condition. The excellent thermal properties and low cost of the diamond/Ag-Ti composites make them promising as thermal management materials in integrated electronic devices.

The superior mechanical properties of high-entropy alloys (HEAs) have made an outstanding success in materials science and engineering. Studies to date have been devoted to what the severe lattice distortion induces. However, most researchers focus on its stimulation to plastic deformation instead of scrutinizing the variations on elasticity. Compared with conventional alloys, HEAs may perform disproportionate elasticity with uneven local lattice strain resulting from the severe lattice distortion. Therefore, it is necessary to survey its influence on the mechanical properties of HEAs systematically. In this study, the Lennard-Jones (LJ) potential, the embedded atom method (EAM) potential, and the modified embedded atom method (MEAM), are respectively conducted to investigate the lattice distortion effect on Young’s modulus E (hkl) and Poisson’s ratio ν (hkl, θ) along [100], [110], and [111] loading directions for several fcc metals composed of 1 ∼ 5 atomic types, including Ni, Ni98W2, Ni96W4, FeCrNi, and CoNiCrFeMn HEAs. Also, a method is used to analyze the performance of the individual element on the elastic properties in the HEA environment. As a result, it can be unveiled that the effect of electron density inconsistency is more dominant than the effect of lattice distortion associated with the atomic size difference. The electronic configuration in the HEA environment plays a major role in elastic anisotropy while the difference of the atomic radii does the minor one. The anisotropy of CoNiCrFeMn HEA analyzed by this work is also consistent with in-situ neutron diffraction measurements.

Texture evolution during tension test was investigated on three face-centered cubic (FCC) metals, namely, Ni (unary), equiatomic CrFeNi (ternary), and equiatomic CoCrFeMnNi (quinary) with small and large grain sizes of ~20 and ~100 μm, respectively. The microtextures for 18%, 36% and 54% engineering strains of a tension-interrupted specimen were characterized on the same area. The three metals exhibited a similar texture evolution, which the fraction of {001}//ND remains constant. However, the fraction of {011}//ND decreases, whereas that of {111}//ND increases. On the other hand, the fraction of //RD also remains constant, that of //RD decreases, and that of //RD increases. However, the several differences still were found during plastic deformation. Fine-grained Ni initiated a significantly crystallographic rotation (CRo) at the lower strain, increased with strain and then remained nearly unchanged as strain was higher than 18%. Coarse-grained Ni delayed this rotation and slowly developed the trend at large strains. As for CrFeNi, the comparison between fine-grained and coarse-grained structure does not have obvious difference. As for fine-grained CoCrFeMnNi, it can be seen that an obvious CRo develops under 36% strain, and maintains constant over 36% strain. But the coarse-grained CoCrFeMnNi reveals that the significant CRo develops continuously from 0% to 54% strain. The mechanisms for the effects of number of element and grain size in the present study are elucidated.

Although refractory high-entropy alloys have exceptional strength at high temperatures, they are often brittle at room temperature. One exception is the HfNbTaTiZr alloy, which has a plasticity of over 50% at room temperature. However, the strength of HfNbTaTiZr at high temperature is insufficient. In this study, the composition of HfNbTaTiZr is modified with an aim to improve its strength at high temperature, while retaining reasonable toughness at room temperature. Two new alloys with simple BCC structure, HfMoTaTiZr and HfMoNbTaTiZr, were designed and synthesized. The results show that the yield strengths of the new alloys are apparently higher than that of HfNbTaTiZr. Moreover, a fracture strain of 12% is successfully retained in the HfMoNbTaTiZr alloy at room temperature.

Diamond/Ag–Ti composites were fabricated by a low-cost liquid sintering technique. The Ti addition can effectively improve wetting and promote penetration in composite pores during liquid sintering. The interface structure of the diamond/Ag–Ti composite was identified as Ag/TiC/Ag–Ti/diamond. A high thermal conductivity of 719 W/mK was obtained for the 50 vol.% diamond/Ag-1 at.% Ti composite. Using a bimodal mixture (60 vol.% 150 μm + 10 vol.% 50 μm diamond/Ag-2 at.% Ti composite), a low coefficient of thermal expansion of 6.3 × 10 − 6 /K still with high thermal conductivity of 687 W/mK was achieved. These composites have potential applications for thermal management of high integration electronic devices.

Degenerately Sn-doped In2O3 (ITO) nanowires were synthesized via an Au-catalyzed vapor–liquid–solid (VLS) method at 750 °C. The Au seed layer provided sites with a high surface energy for the selected-area growth of ITO nanowires. Morphology and crystal structures confirmed by field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), and X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) was employed to obtain the chemical compositions of the ITO nanowires as well as the ratio of Sn/In and oxygen concentrations. Under the photo-excitation the ITO nanowires emit ultraviolet light, which can be ascribed to transitions related to donor levels. Moreover, photoluminescence (PL) spectrophotometer and UV–VIS spectrum analysis revealed a blue shift peaks in the degenerately ITO nanowires. This phenomenon can be explained by Burstein–Moss effect.

Enhanced field emission properties of Sn-doped In2O3 (ITO) nanowires (NWs) after the formation of a heterostructure core–shell configuration, namely ZnO nanoparticle-decorated HfO2/Sn-doped ITO NWs, by the atomic layer deposition (ALD) process were reported and investigated in detail. Island growth of a ZnO layer on the ITO NWs, with a low density, after the ALD process was observed while for the growth of the ZnO layer on the HfO2/ITO core–shell NWs, a ZnO layer with very tiny nanoparticles (NPs) can be achieved along the axial direction throughout the whole nanowire. A turn-on field of ∼10.8 eV with a field enhancement factor (β) of 409 can be found for the ITO NWs while the turn-on field decreases from 10.8 to 6 V μm−1 with an increase in the field enhancement factor (β) from 409 to 753 after the ZnO nanoparticle growth on the ITO NW. By combining the two materials utilizing surface modification engineering, a highly dense ZnO NP decorated on HfO2/ITO core–shell NWs can be achieved, resulting in a significant reduction of the turn-on field to 3.7 V μm−1 with an excellent field enhancement factor of 1677. The findings provide an effective way of improving the field emission properties for nanodevice applications.

The hardening in Al 0.3 CrFe 1.5 MnNi 0.5 high-entropy alloy not only nearly triples the hardness of the alloy, but also shows a quick hardening response and the absence of overaging. However, the crystal structure, morphology, and composition of the hardening phase have not yet been confirmed. Here, such information regarding the hardening phase is investigated. It was found that the hardening phase is a Cr–Mn–Fe ternary sigma phase. Unlike in conventional engineering alloys, the sigma phase is not precipitated from the matrix, instead, the whole BCC matrix transforms to sigma phase almost without changing its composition. Therefore, the hardening phenomenon is not a precipitation hardening reaction as suggested before.

An Al 0.3 CrFe 1.5 MnNi 0.5 multi-component alloy with a very effective surface hardening ability attributed to intrinsic ρ phase precipitation and applicable to complex tool components was developed. Under a conventional aging treatment in a normal atmosphere at 550 °C for 2 h, the alloy with the surface precipitation hardening layer of 74 μm thick exhibited markedly enhanced surface hardness from HV 338 to HV 840 and efficiently improved wear resistance to 1.4 times the values of SUJ2 and SKD61 steels, while high fracture toughness close to that of ductile SKD61 steel was effectively retained. Precipitation thermodynamics and growth kinetics of the surface hardening layer were also investigated. The growth of the surface hardening layer was much faster than that of the precipitation in the bulk matrix; it did not follow typical long-distance diffusion kinetics but behaves more similar to a self-induced or reaction-accelerated short-range decomposition with a thickness increase proportional to the cube of aging time. On the surface, a lower heterogeneous nucleation energy and a reduced strain energy (total 55 kJ/mol) than the regular nucleation energy in the bulk matrix (78 kJ/mol) dominated the rapid formation and growth of the intrinsic surface precipitation with significant strain relaxations.

(AlCrMoTaTiZr)Nx high-entropy films were deposited on silicon wafer and cemented carbide substrates from a single alloy target by reactive RF magnetron sputtering under a mixed atmosphere of Ar and N2. The effect of nitrogen flow ratio RN on chemical composition, morphology, microstructure, and mechanical properties of the (AlCrMoTaTiZr)Nx films was investigated. Nitrogen-free alloy film had an amorphous structure, while nitride films with at least 37 at.% N exhibited a simple NaCl-type FCC (face-centered cubic) structure. Mixed structures occurred in films with lower nitrogen contents. Films with the FCC structure were thermally stable without phase decomposition at 1000 °C after 10 h. The (AlCrMoTaTiZr)N film deposited at RN = 40% exhibited the highest hardness of 40.2 GPa which attains the superhard grade. The main strengthening mechanisms for this film were grain-size and solid-solution strengthening. A residual compressive stress of 1.04 GPa was small to account for the observed hardness. The nitride film was wear resistant, with a wear rate of 2.8 × 10− 6 mm3/N m against a loaded 100Cr6 steel ball in the sliding wear test. These high-entropy films have potential in hard coating applications.

Thermal management in microelectronic technology has become an important issue due to the increase of device power and integration levels. Diamond and silver were selected for the fabrication of composites with high thermal conductivity and low coefficient of thermal expansion (CTE). Diamond reinforcement powders with varied types, shapes and sizes were electroless plated by silver. Then these powders were hot-pressed in air at 600 °C, 500 MPa for 30 min to produce bulk silver matrix composites. The thermal conductivity and the CTEs of the composite at 20 vol.% are 420 W/m K and 12 ppm/K, respectively. These diamond/Ag composites have potential applications for the high integration electronic devices.

Multi-element (AlCrTaTiZr)N films were deposited on cemented carbide and M2 steel substrates by reactive RF magnetron sputtering. Prior to nitride film deposition, an interlayer between the film and the substrate was introduced to improve adhesion property. The influence of interlayer materials (Ti, Cr, and AlCrTaTiZr alloy) and interlayer thickness (0–400 nm) on the adhesion and tribological properties of films was investigated. In this study, the nitride film deposited at RN = 20% exhibited the highest hardness (35.2 GPa) and the lowest residual compressive stress (− 1.52 GPa), and was prepared as the top layer for further testing. The interlayer materials can effectively improved the film adhesion onto the cemented carbide substrates, and the adhesive failure was not observed even under the normal load of 100 N. For M2 steel substrates, only the Cr interlayer can slightly improve the film adhesion, and the cohesive and adhesive failure can be found at relatively lower applied load. The optimal interlayer thickness was 100–200 nm for the 1 µm-thick (AlCrTaTiZr)N film and can be related to the stress evolution. The friction coefficient and wear rate for the (AlCrTaTiZr)N film were 0.82 and 4.9 × 10− 6 mm3/Nm, respectively, and almost kept constant under different interlayer materials and thickness. The worn-through event of the nitride film during tribological test occurred easily owing to its poor adhesion behavior, and can be improved by interlayer additions.

This work studies the effect of the sized silver (Ag) nanoparticles on the optical property of SPR. Nanoparticles were prepared on fluorine-doped-tin-oxide (FTO) coated glass substrates by RF magnetron sputtering with various deposition times and the subsequent rapid thermal annealing (RTA) to control the particle size. To make the Ag films, Ag films of different thicknesses were first deposited on either glass or FTO substrate by a vacuum sputtering technique. Some of the samples founded nanoparticles by rapid thermal annealing. The substrates with and without nanoparticles were then sensitized by immersing them in a 0.2 mM N719 dye solution. Finally, the effect of the absorption coefficient was investigated by adsorbing it on fine silver Ag islands. The surface plasmon resonance enhanced the absorption by the sample with Ag nanoparticles above that of the sample without nanoparticles. In this study, the peak position of the surface plasmon characteristic absorption increased with the grain size of the nanoparticles in a red-shift. The structure and the quantity of Ag particles were very critical to the surface plasmon resonance effect.

Multi-element (AlCrTaTiZr)N coatings are deposited onto Si and cemented carbide substrates by reactive RF magnetron sputtering in an Ar + N2 mixture. The influence of substrate bias voltage, ranging from 0 to − 200 V, on the microstructural, mechanical and tribological properties of these nitride coatings is studied. A reduction in concentration of N and Al is observed with increasing substrate biases. The (AlCrTaTiZr)N coatings show the face-centered-cubic crystal structure (B1–NaCl type). The use of substrate bias changes the microstructure of the (AlCrTaTiZr)N coating from the columns with microvoids in boundaries to the dense and less identified columns. The compressive macrostress increases from − 0.9 GPa to − 3.6 GPa with an increase of substrate bias. The hardness and adhesion increase to peak values of 36.9 GPa and 60.7 N at the bias voltage of − 150 V, respectively. The tribological properties of the (AlCrTaTiZr)N coatings against 100Cr6 steel balls are evaluated by a ball-on-disc tribometer with a 10 N applied load. With an increase of substrate bias, the wear rate reduces while the friction coefficient almost keeps constant at 0.75. The lowest wear rate of 3.65 × 10− 6 mm3/Nm is obtained for the (AlCrTaTiZr)N coating deposited at the bias voltage of − 150 V.

Multi-element (AlCrTaTiZr)N coatings are prepared by reactive RF magnetron sputtering for a constant argon and nitrogen flow. The influence of the substrate temperature (100 to 500 °C) on the chemical composition, microstructure and mechanical properties of these coatings is investigated. A reduction of the nitrogen concentration is observed with increasing the substrate temperature. X-ray diffraction (XRD) shows that these coatings are of a single-phase face-centered-cubic structure. Furthermore, it is determined from XRD analysis that there is an increase in (200) peak intensity and the decrease in crystallite size and lattice parameter, for increasing substrate temperature. An increase in substrate temperature results in a monotonic decrease of compressive internal macrostress from 3.2 to 2.0 GPa. High hardness and elastic modulus around 35 and 350 GPa, respectively, were obtained nearly independent of the substrate temperature.

Effect of pre-nucleation techniques on enhancing nucleation density and the adhesion of ultra-nanocrystalline diamond (UNCD) deposited on the Si substrates at low temperature were investigated. Four different pre-nucleation techniques were used for depositing UNCD films: (i) bias-enhanced nucleation (BEN); (ii) pre-carburized and then ultrasonicated with diamond powder solution (PC-U); (iii) ultrasonicated with diamond and Ti mixed powder solution (U-m); (iv) ultrasonicated with diamond powder solution (U). The nucleation density is lowest for UNCD/U-substrate films (∼ 10 8 grains/cm 2 ), which results in roughest surface and poorest film-to-substrate adhesion. The UNCD/PC-U-substrate films show largest nucleation density (∼ 1 × 10 11 grains/cm 2 ) and most smooth surface (8.81 nm-rms), whereas the UNCD/BEN-substrate films exhibit the strongest adhesion to the Si substrates (critical loads = ∼ 67 mN). Such a phenomenon can be ascribed to the high kinetic energy of the carbon species, which easily form covalent bonding, Si–C, and bond strongly to both the Si and diamond.

The AlxCoCrCuFeNi alloys with different aluminum contents prepared by arc melting were investigated on their adhesive wear behaviors. With increasing aluminum content, both the volume fraction of BCC phase and the hardness value increase, and thus the wear coefficient decreases. Moreover, the wear mechanism changes from delamination wear to oxidative wear. For low aluminum content, x = 0.5, the microstructure is of simple ductile FCC phase and the worn surface is deeply grooved and undergoes a periodic delamination which produces big debris. For medium aluminum content, x = 1.0, the microstructure is a mixture of FCC and BCC phases, and the worn surface is deeply grooved in FCC region but smooth in BCC region. Delamination wear is still dominant although oxidative wear occurs in the smooth region. For high aluminum content, x = 2.0, the microstructure is of BCC phase and the worn surface is smooth and yields fine debris with high oxygen content. The high aluminum content gives a large improvement in wear resistance. This improvement is attributed to its high hardness, which not only resists plastic deformation and delamination, but also brings about the oxidative wear in which oxide film could assist the wear resistance. © 2005 Elsevier B.V. All rights reserved.

Continuous fluorinated amorphous carbon (a-C : F) films doped with nitrogen (a-C : F : N) were deposited by plasma enhanced chemical vapor deposition using CF4 and C2H2 gases as precursors with the addition of N2 gas. The surface morphologies, chemical compositions, deposition rates, thermal stability and mechanical properties of these films varied with the deposition parameters, including CF4 and N2 feed gas concentrations, processing pressure, plasma power and substrate temperature. With increasing N2 feed gas concentration, the nitrogen content of the a-C : F : N films increased to about 6 at.% and contributed to higher mechanical properties. After thermal annealing, the a-C : F films with higher fluorine contents exhibited more obvious fluorine release and extensive film thickness shrinkage, whereas the a-C : F : N films with higher contents of nitrogen doping yielded less composition variations, smaller thickness shrinkages, higher mechanical properties, and conclusively better thermal stability.

Nanodiamond films containing uniformly small diamond grains (

Ultrananocrystalline diamond (UNCD) films, which possess very smooth surface, were synthesized using CH4/Ar plasma. When the nucleation process was carried out under methane and hydrogen (CH4/H2) plasma with negative DC bias voltage, no pretreatment on substrate was required prior to the formation of diamond nuclei. The average grain size of BEN induced diamond nuclei is about 20∼30 nm, with the nucleation site density more than 1011 sites/cm2. The growth rate of UNCD is markedly enhanced due to the application of BEN induced nuclei. Moreover, the growth rate of UNCD films was more significantly affected by the substrate temperature, but was less influenced by the microwave power. All of these UNCD films showed similar morphology, i.e., with grain size less than 10 nm and surface roughness around 10 nm. They also possess similar Raman spectra, i.e., similar crystallinity. However, the deposition rate can be increased from ∼0.2 to 1.0 μm/h when substrate temperature increased from 400 to 600 °C.

Nano-diamond films having grain size around 20 nm were deposited by bias enhanced growth (BEG) method. Different surface treatments were carried out to increase their field emission properties and their effects are clearly noticed. Surface morphology of different surface treated nanodiamond films was examined. There was no significant change in the curve of Raman spectra of different surface treated samples. Raman spectra were typically of similar nature to nano-diamond film. Field emission results were more interesting. Biased in hydrogen plasma treated nanodiamond film has shown best electron emission behavior and low turn-on-field (E0). The turn-on-field of bias-treated nano-diamond film was 19.5 V/Am. The decrease of turn-on-field (¨6V/Am) of biasedtreated nano-diamond film from as-grown BEG film was attributed to the formation ofthin sp 2 layer and more defects on the surface of film by hydrogen ion bombardment. Moreover, hydrogen-plasma treated nano-diamond film was also found to be good for electron emission but there was no improvement in electron emission as in the case of air plasma treated nano-diamond films. D 2005 Published by Elsevier B.V.

The preparation of near stoichiometric spinel and alumina-rich spinel composites from Al2O3and MgO powders with the addition of Na3AlF6up to 4 wt% in the temperature range 700°–1600°C was studied; 98 wt% spinel containing 72 wt% Al2O3can be produced from the mixture of 72 wt% (50 at.%) Al2O3+ 28 wt% (50 at.%) MgO powders with the addition of 1 wt% Na3AlF6fired at 1300°C for 1 h. Spinels containing 81–85 wt% Al2O3can be produced from either the mixture of 90 wt% (78 at.%) Al2O3+ 10 wt% (22 at.%) MgO or the mixture of 95 wt% (88 at.%) Al2O3+ 5 wt% (12 at.%) MgO powders with the addition of 4 wt% Na3AlF6in the temperature range 1300°–1600°C by using a torch-flame firing for 3 min, followed by quenching in water, while the same system under slow cooling in a furnace results in spinel containing 74–76 wt% Al2O3. Microscopic studies indicate that the alumina-rich spinel composites consist of a continuous majority spinel phase and an isolated minority corundum phase, regardless of slow cooling in a furnace or quenching in water.

The properties and thermal stability of porous organic low-dielectric-constant films (version 8 and version 9) have been studied in this research. These porous films were obtained by spin coating, followed by baking and furnace curing. Both porous films exhibit very low dielectric constants of only approximately 2.1 and good physical and electric properties. Thermal decomposition and further shrinkages occur in these as-cured films during heat treatments, indicating the release of residual poragens and some structural changes of these films; whereas the properties of the version 9 porous organic films remain at the same levels after heat treatments and exhibit better thermal stability. Residual compressive stresses of approximately 40 MPa exist in both films and decrease after heat treatments, revealing some film degradation and stress relaxation.

The mechanical properties of porous low-dielectric-constant (low-k) thin films have been investigated for the stability evaluation of multilevel-interconnect structures using nanoindentation, microscratch, and four-point bending tests. Stress–strain curves of these films are proposed to predict their strengths and to explain their deformation behaviors. Real stress–strain behaviors are analyzed and confirmed by combining the experimental data obtained from nanoindentation and microscratch tests. Soft low-k films exhibit large plastic deformation, while hard and brittle films fracture early. The interfacial adhesion strengths and delamination behaviors between thin-film layers have been also studied using microscratch and four-point bending tests. The mechanical failure of interconnect structures depends on the inferiority of film strength or interfacial adhesion. 2004 Elsevier B.V. All rights reserved.

Modification on microwave dielectric properties of (Ba0.6Sr0.4)TiO3 (BST) materials due to the incorporation of Ba4Ti13O30 (B4T13) materials was investigated. The dielectric constant of the BST materials was lowered from KBST = 600 to KCOMP = 100, whereas the quality factor of the materials was increased markedly from (Q ×} f)BST = 80 to (Q ×} f)COMP = 2,000, due to the addition of B4T13 materials. Evanescent microwave probe (EMP) measurements indicate that the thick films prepared from the mixture contain two phases. The low-K and high-Q particulates, which are presumably B4T13 phase, are distributed uniformly among the high-K and low-Q matrix, resulting in a tunable materials with improved microwave dielectric properties.

Growth behavior of Ba(Mg1/3Ta2/3)O3/Pb(Zr, Ti)O3/Ba(Mg1/3Ta2/3)O3, BMT/PZT/ BMT, heterostructure on Pt-coated silicon substrate (Pt(Si)) by using in-situ pulsed laser deposition process was systematically examined. The crystallographic orientation and microstructure of heterostructure were observed to vary with deposition parameters markedly. The BMT seeding layer enhanced the growth of PZT films, which started to crystallize at a substrate temperature as low as 350°C. The ferroelectric properties of BMT/PZT/BMT/Pt(Si) films can be optimized when the films were synthesized at 400°C substrate temperature with 0.3 mbar ambient oxygen pressure during deposition of BMT seeding layer (Pr = 29.7 μ C/cm2 & EC = 82.5 kV/cm). Fatigue of the heterostructure showed no degradation and the hysteresis loops showed essentially no change even after 1011 fatigue cycles.

Growth behavior of (Pr2/3Ca1/3)MnO3, PCMO, thin films deposited by pulsed laser deposition (PLD) process on uncoated or Pt-coated silicon substrates was investigated. Perovskite phase of PCMO thin films can be formed directly on Si-substrate only in a very narrow range of deposition parameters. Using PCMO thin films as buffer layer markedly enhances the crystallization kinetics for the subsequently grown Pb(Zr0.52Ti0.48)O3 (PZT) thin films, which were prepared by metallo-organic-deposition technique. The perovskite phase of PZT films can be obtained at lower post-annealing temperature (550°C) and sustain higher heat treatment temperature (700°C) without inducing significant degradation. The presence of PCMO-buffer layer markedly suppresses the leakage currently density for the PZT films, but insignificantly alters their ferroelectric properties.

(100) textured Pb(Zr0.48Ti0.52)O3 (PZT) films were prepared on silicon substrates by MOD process and laser lift-off technique. Textured PZT films were first grown on (001) Sapphire substrate, using Ba(Mg1/3Ta2/3)O3 (BMT) materials as buffer layer. The (100) textured PZT/BMT/Sapphire films were attached to Si substrate using a transient-liquid-phase Pd-In bonding process, and then were separated from Sapphire substrates by a laser lift-off process, in which, a 38 ns pulse from excimer laser (248 nm) at 600 mJ/cm2 fluence melted BMT buffer layer, expelling the Sapphire. The crystallinity of the surface of films was further improved by laser annealing. X-ray diffraction analysis of the PZT films showed that the crystallographic structure of films is maintained during laser lift-off process. Electrical testing of the films after laser lift-off process followed by laser annealing demonstrated that the ferroelectric properties are retained for the transferred films (Pr = 9μ C/cm2 and Ec = 74 kV/cm).

Ba(Mg1/3Ta2/3)O3 (BMT) microwave dielectric thin films were successfully synthesized by a modified pulsed laser deposition (PLD) process, which includes low temperature (200°C) deposition and high temperature (>500°C) annealing. Crystalline structured BMT thin films were obtained when the PLD-deposited films were post-annealed at a temperature higher than 500°C in oxygen atmosphere. The characteristics of BMT thin film, including crystallinity, grain size, film roughness, and dielectric properties were improved with annealing temperature, achieving dielectric constant K = 23.5 and dissipation factor tan δ = 0.015 (at 1 MHz) for the 800°C-annealed films.

Copper nanowires with multiwall carbon nanotubes (MWNTs) encapsulated inside were prepared via surface modification of MWNTs followed by chemical deposition of copper on surfaces. These MWNTs-encapsulated copper nanowires were investigated as a reinforcement to improve the mechanical strength of the Y−Ba−Cu−O superconductor. TEM and SEM reveal that MWNTs are uniformly coated by copper and the diameters of the prepared MWNTs-encapsulated Cu nanowires range from 50 to 150 nm and the lengths are up to several micrometers. These MWNTs-containing Cu nanowires could effectively improve the hardness of the Y−Ba−Cu−O without sacrificing its superconductivity. The Vicker's hardness of the Y−Ba−Cu−O is reinforced by ∼20% after 5 wt % of MWNTs incorporation. This study presents the first result that demonstrates the feasibility of the reinforcement of brittle YBaCuO superconductor by using MWNTs.

The hot properties of the Al2O3–MgO castables containing 5.5 wt.% MgO and 1.36 wt.% CaO with and without the addition of 0.75 wt.% microsilica and the Al2O3–spinel castables containing 20 wt.% Al2O3–rich spinel of 90 wt.% Al2O3 and 1.70 wt.% CaO, respectively, were investigated. The thermal shock damage test using the prism quench into water technique indicated that the retained modulus of rupture of the Al2O3–MgO castables after three cycles was down to 5%, while that of the Al2O3–spinel castables was 51%. The combined test of slag and thermal shock attack on castables using the rotary slag test furnace showed that the Al2O3–MgO castables had 0% penetration and 24% erosion, while the Al2O3–spinel castables had 10% penetration and 30% erosion. The field trials confirmed that Al2O3–MgO castables have better slag resistance and a longer service life for use in steel ladles, compared to Al2O3–spinel castables. The importance of thermal shock damage resistance of castables for use in steel ladles should be deemphasized, based on the lab and field tests. There is no correlation between hot strengths and slag resistance for castables. The magnitude of specific surface area of pores is more important than pore size and porosity for governing the slag resistance of Al2O3– MgO castables, with and without microsilica addition. # 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.

The cavitation erosion of FeMnAl alloys and 304 stainless steel in both distilled water and 3.5% NaCl solution was studied by an ultrasonic vibration system. In distilled water, the cavitation erosion resistance of solution heat treated FeMnAl alloys are superior to that of 304 stainless steel. The solution heat treated alloys with higher hardness shows better cavitation resistance. But, cavitation resistance could not be improved by age hardening. Grain boundary or twin boundary in the material were preferential sites for cavitation attack. The weight loss in cavitation was due to detachment of small chips between slip bands and the loss of whole surface grains by the growth of grain boundary cracks underneath surface grains. In 3.5% NaCl solution, the cavitation erosion resistance of FeMnAl alloys was degraded by corrosion. But, little change of the FeMnAl alloy that contains 2.6% Cr was observed and it was more cavitation resistant than 304 stainless steel. In the dual phase FeMnAl alloy (Alloy A), the ferrite phase was harder and more cavitation resistant than the austenite phase in distilled water. In contrast, it was more easily attacked than the austenite phase in 3.5% NaCl solution. The weight loss was increased by brittle fracture occurred along grain boundaries and in the ferrite phase. The addition of 0.3 M NaNO 2 that could inhibit the corrosion was found to reduce the cavitation damage of dual phase FeMnAl alloy in 3.5% NaCl solution to the level obtained in distilled water.

The debris and the worn surface after dry sliding wear were studied by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffractometry (XRD). A pin-on-disk method, in which the pin was the 15%Al2O3(p)-6061Al composites and the disk was a 52100 steel, was used. The microstructural features for severe wear appeared to be much coarser than those for mild wear. According to the EDS and XRD results, the chemical compositions of the debris for mild wear were different from those for severe wear. The debris for mild wear mainly consisted of ferric oxide (Fe2O3), while the debris for severe wear was composed of Al2O3, Al and α-Fe. Cross-sectional SEM images showed that Al2O3 particles near the composite surface did not suffer obvious deformation. Thus, it seemed to be the Al2O3 particles which make the composite more wear resistant under the mild wear conditions. However, in the severe wear conditions, many Al2O3 particles near the surface were broken off, which prevented them from resisting wear.

One-dimensional oxide-based nanostructures have been intensively studied because of their excellent optoelectronic properties. Due to the drawbacks of vapor-phase or aqueous solution growth, including complex processes, high synthesis temperatures, expensive precursors, and also preceding patterned seeding or subsequent patterning processes, there is an urgent need to grow patterned nanostructures by a simple and direct process at low temperatures. In the present study, stress-induced growth of one-dimensional single-crystalline ZnO and TiO2 nanostructures directly from ZnO and TiO2 films, respectively, in an ambient atmosphere at room temperature were developed by indentation or scratching without the use of any reaction precursors. Under large applied stresses, oxide bonds were broken, assisted by hydrolysis in the presence of moisture, and subsequently were reconstructed (defined as a bond breaking–hydrolysis–reconstruction mechanism) leading to the spontaneous growth of one-dimensional nanocrystals. The direct growth at controlled locations provides an opportunity for the simple preparation of patterned nanostructures of oxide-based materials.

Thermal evaporation made trigonal-phase Al2O3 nanowires are coated with amorphous TiO2 using atomic layer deposition and subsequent annealing results in crystallization of the coating and creation of abundant oxygen deficient states at the interface. Interfacial states behave as electron acceptors upon charging and capacitance density has been measured to be three orders of magnitude greater than existing data.

In this study, the interface chemistry and adhesion strength between a porous SiOCH extra-low-dielectric-constant film and SiCN etch stop layers were investigated with different plasma treatments. An interlayer of ∼6 6 nm thick between the porous SiOCH film and SiCN layers was found to be composed of Si, N, C, and O. The SiOCH/SiCN interface was constructed by mixing bonds, including Si-C-N, Si-N-C, Si-O-C, Si-O 2 , etc. Under H 2 and NH 3 plasma treatments, a large amount of weak Si-CH 3 and SiO-CH 3 bonds were broken, and more Si-O related bonds of high binding energy formed at the interfaces. Moreover, under the accumulation of sufficient shear stresses around the indented regions during nanoindentation tests, interface delamination between the porous SiOCH film and SiCN layers occurred. The interface adhesion energy between untreated porous SiOCH film and SiCN layers was accordingly measured as 1.68 J/m 2 . After plasma treatments, especially NH 3 plasma, the adhesion strength was effectively improved to 2.13 J/m 2 .

Spiral alumina nanowires, doped with Cr and Si, are directly and reliably produced in bulk quantities via annealing of high entropy alloys.

Continuous fluorinated amorphous carbon (a-C:F) films with low dielectric constants (low-k), relatively low surface roughness, and low refractive indices were deposited by plasma-enhanced chemical vapor deposition using CF 4 and C 2 H 2 gases as precursors. A uniform composition was obtained except surface fluorination with an F-rich layer. The deposition rates, fluorine contents, and refractive indices of these films varied with the deposition parameters, including CF 4 feed gas concentration, processing pressure, plasma power, and substrate temperature. The a-C:F films with higher fluorine contents had lower refractive indices but possessed smaller hardnesses and elastic moduli. During thermal annealing, fluorine was released from these films, but the interface adhesion to the substrates was improved. Plasma post-treatment altered the surface compositions of the films, while the interior compositions, refractive indices, and mechanical characteristics remained unchanged.

An electrochemical deposition process for copper (Cu) metallization has been developed and investigated by the integration of nanoscaled palladium (Pd) catalyzation, electroless plating of Cu seed layers, and electroplating of Cu films in this study. Following surface cleaning and etching, sensitization and activation of Si/SiO 2 /TaN substrates were performed to obtain uniformly distributed Pd catalysts of only about 10 nm. Smooth and continuous 30 nm thick Cu seed layers with low electrical resistivity were electrolessly deposited using the nanosized Pd catalysts as nucleation sites. Copper metallization with high purity small surface roughness, low electrical resistivity of 1.77 μΩ cm, low residual stresses, and good adhesion to substrates was achieved using the subsequent electroplating on the electroless seed layers and postannealing. Good gap-filling capability on finely patterned structures was performed and exhibited the great application potential of low-temperature integrated electrochemical deposition process for next-generation Cu metallization of ultralarge-scale integrated circuits.

The curing process window and properties of both nitrogen (N 2 ) and ammonia (NH 3 ) cured porous methyl silsesquioxane (MSQ) based low-dielectric-constant (low-k) spin-on dielectric (SOD) films are comprehensively explored and compared in this research. Higher curing temperatures, longer curing time, and an NH 3 atmosphere provide more complete poragen removal and H-OR/ H-OH hydration, and thus achieve higher degrees of cross-linking and volume shrinkage of these films. The desorption of water and ethylic organics confirms the release of hydrated ROH/H 2 O and is dominated by the curing temperatures. Smaller refractive indexes, better electrical properties, and stronger mechanical properties are obtained with NH 3 curing and increased curing temperatures and time because of more complete hydration. With consideration of total thermal budget, the appropriate curing process window locates at 350°C for only 10 min or 300°C for 20-30 min with N 2 /NH 3 flows of 10/0.1-10/2.0 slm. All the properties do not degrade with extended thermal-cycle treatments, exhibiting good thermal stability.

Agglomerations composed of Cu nanocrystallites are observed in the electroless Cu films deposited on Pd-activated TaN/SiO 2 /Si substrates. They were found to in situ recrystallize as large grains when exposed to the electron-beam of scanning electron microscopy (SEM). This observation not only confirms the self-induced repeated nucleation involved in electroless crystallization, but indicates that low-angle grain boundaries form during repeated nucleation of Cu nuclei in the Cu film. The rotation of Cu nanocrystallites by slipping away the boundary dislocations in low-angle boundaries is responsible for the recrystallization induced by the electron-beam under SEM observation.

The preparation of nanoscaled palladium (Pd) particles for catalyzation of electroless copper (Cu) plating has been investigated in this research. Nanosized Pd catalysts were electrochemically deposited on Si/SiO 2 /Ta x N substrates using displacement activation and sensitization activation, and their formation and microstructures were characterized. By displacement activation, large Pd particles with nonuniform size distribution from 20 to 200 nm are observed, resulting in subsequent rough and discontinuous Cu films electrolessly deposited on these Pd catalysts. In comparison, tremendous, small, and uniform Pd nanoparticles of about 10 nm are obtained by sensitization activation as fine nucleation sites for following electroless deposition of smooth and conformal Cu films. Nucleation, growth, coalescence, and then connection and film growth steps are observed in the formation process of Cu films. No preferred orientation of both electrolessly deposited Cu films is found. Well-controlled, electrochemically deposited nanoscaled Pd catalysts and uniform Cu films can be used as 65 nm Cu interconnect metallization.

The effect of electroless nickel coating on the interfacial shear strengths of silicon carbide continuous fiber reinforced AA 7075 aluminum matrix composites (SiC f /7075Al) was investigated using a push-out method with a tungsten carbide (WC) cone indenter. During indentation, no rupture of fibers was observed. This showed that the push-out test can measure the interfacial shear strength of SiC f /7075Al precisely. The 160 MPa interfacial shear strength of the specimen without coating decreases to 120 MPa for the specimen with 0.5 μm nickel coating, even to 20 MPa with 0.8 μm nickel coating, and then slightly increases with increasing coating film thickness. Nickel film reacted with aluminum matrix to form porous nickel aluminide intermetallic compounds during processing and to lower the interfacial shear strength.

The catalyzation of TaN/SiO 2 /Si substrates was carried out by immersion in SnCl 2 /HCl and PdCl 2 /HCl solutions for electroless Cu deposition. The sizes and morphologies of the catalytic sites on the TaN layers were found to be a function of catalyzation conditions, including solution temperature, immersion time, and the surface oxides. The appropriate formula for catalyzation was obtained by considering both the quality and efficiency. The catalytic sites were composed of Sn and Pd, and the ratio of Sn/Pd was about 1.3. During electroless Cu deposition on the catalyzed TaN/SiO 2 /Si substrates. Cu nuclei first formed at the catalytic sites in the early stage, gradually agglomerated into dense islands, and finally merged to continuous deposition films. The Cu films were uniformly and smoothly deposited with a surface roughness of 6.2 nm under a film thickness of 210 nm. The lowest electrical resistivity of the Cu films was 2.5 μΩ cm, and the residual resistivity contributed to the participation of Sn-Pd catalyst and internal defects. Good gap-filling capability of electroless Cu deposition on Sn/Pd catalyzed, patterned substrates exhibited its high potential to act as a seed layer for Cu electrodeposition and even to completely fill submicrometer gaps in ultralarge-scale integrated metallization.