As the scaling of complementary metal-oxide-semiconductor (CMOS) transistors proceeds, the thickness of the SiO2 gate dielectrics shrinks rapidly and results in higher gate leakage currents. High k dielectric materials are acknowledged to be the possible solutions to this challenge, as their higher k values (e.g., 15–50) raise the physical thickness of the dielectrics that provide similar equivalent thickness of a thinner SiO2 film. In order for the high k materials to be applicable in CMOS devices, there should exist deposition technologies that can deposit highly uniform films over Si wafers with diameters as large as 200 mm. This report discusses the deposition process and the correlation between the growth conditions, structural and dielectric properties of HfO2, which is one of the most promising high k dielectric materials. Judging from the thickness uniformity, surface roughness, k value, and interfacial density of state of the HfO2 films, the metalorganic chemical vapor deposition technique was identified to be suitable for growing HfO2 films targeted at applications as CMOS gate dielectrics.

The stable mechanical property polystyrene (PS) nanotubes with array structure were first prepared by filtrating a solution or melt of normal molecular weight PS (Mn ≈ 180,000) into anodic aluminum oxide (AAO) template with only 200-nm pores. The results of transmission electron microscopy and scanning electron microscopy illuminated that PS tubules were successfully obtained and the wall thickness of PS tubules prepared by the 2.5 wt%, 5.0 wt%, and 10.0 wt% PS solution were respectively 50 nm, 70 nm, and 80 nm. The structure of polymer nanotubes depends strongly on the concentration of PS solution. It was found that the wall of the nanotubes derived from melt is thicker than that of the nanotubes from solution. When the polymer solution wets AAO template, a thin polymer film will be formed on the inner porous wall. The thin film/AAO composite membrane acts as a “second-order” template and is soaked repeatedly. So PS solution wets the template and forms nanotubes according to the multi-time wetting mechanism.

A new method of dynamic nanoindentation testing is introduced in this paper. Conventional dynamic nanoindentation testing involves the superposition of a single frequency sinusoidal force or displacement onto the quasi-static load–displacement curve. However, the viscoelastic response of many materials depends upon the frequency of the deformation of the material. This paper describes a method whereby the storage and loss modulus of viscoelastic solids can be determined using a multi-frequency dynamic oscillatory motion mode of deformation. In this method, the applied load is modulated by a pseudo-random force signal comprising multiple frequencies. A Fourier analysis is then used to deconvolute the signal into frequency-dependent values of storage and loss modulus for the specimen material as a function of frequency. The instrument response is cancelled by the use of a reference transfer function using an equalization process. Established modeling equations can then be used to extract the modulus of elasticity and the viscosity of the specimen material.

Characterization of thin film solid oxide fuel-cell materials can be difficult due to the range of porosities in electrodes and electrolytes as well as the nano-sized pores and particles. In this study, optical characterization techniques such as ultraviolet–visible transmission and reflection spectrophotometry are illustrated as methods for achieving information about the film density from the film refractive index as well as the film thickness. These techniques were used to investigate the sintering process of colloidal CeO2 on sapphire substrates and polymeric precursor-derived ZrO2:16%Y (YSZ) thin films on silicon over the temperature range 400–1000 °C, and the results were compared with traditional characterization techniques such as electron microscopy, profilometry, ellipsometry, and x-ray diffraction line broadening analyses. Most of the techniques were in good agreement with the CeO2 grain size changing from 5–65 nm and the film thickness changing from 0.8–0.5 μm. Comparisons of transmission and reflection spectrophotometry with ellipsometry illustrated that scattering effects from the porous CeO2 films caused an overestimation of the refractive index from ellipsometry, but allowed for accurate grain size measurements from transmission and reflection data. Both techniques were in good agreement during the sintering of the YSZ thin films, with the density changing from 90–100% theoretical after heating between 400 and 800 °C.

The microstructure of three kinds of porous carbon–carbon preforms prepared for carbon–carbon/aluminum composites was identified by x-ray diffraction, Raman spectroscopy, and field emission scan electronic microscope. Although manufactured at same processing conditions, including the temperature, type of organic gas, and pressure of pyrolysis, the structure of the pyrolytic carbon (Cpy) in three kinds of preforms is different. The morphology of the Cpy is influence by the topology of the preforms greatly, and the crystal structure of the Cpy is influenced by the crystal structure of the carbon fiber greatly, on which surface the Cpy was deposited. The degree of graphitization of the Cpy had been enhanced and the structure of the Cpy changed to more anisotropic form when the preforms were annealed at 2773 K.

The creep behaviors of 20 vol% SiCw/2124Al, extruded with different ratios, and SiCp/2124Al, reinforced with 10–30 vol% SiC particles, were investigated to clarify the effects of aspect ratio, alignment, and volume fraction of reinforcement on creep deformation. The effective stresses on the matrix of SiC/Al composites are calculated based on the generalized shear-lag model. The minimum creep rates of SiCw/2124Al extruded with different ratios and SiCp/2124Al reinforced with different volume fractions of SiC particles are found to be similar under a same effective stress on matrix, which is calculated by the generalized shear-lag model. The subgrain sizes in matrices of crept SiC/Al composites are dependent on the effective stress on matrix but not on the applied stress on the composite. It is suggested that the role of SiC reinforcements is to increase the creep resistance of SiC/Al composite by reducing the effective stress on matrix.

A technique has been developed to facilitate analysis of the microstructural evolution of solder bumps after current stressing. Eutectic SnPb solders were connected to under-bump metallization (UBM) of Ti/Cr-Cu/Cu and pad metallization of Cu/Ni/Au. It was found that the Cu6Sn5 compounds on the cathode/chip side dissolved after the current stressing by 5 × 103 A/cm2 at 150 °C for 218 h. However, on the anode/chip side, they were transformed into (Nix,Cu1-x)3Sn4 in the center region of the UBM, and they were converted into (Cuy,Ni1-y)6Sn5 on the periphery of the UBM. For both cathode/substrate and anode/substrate ends, (Cuy,Ni1-y)6Sn5 compounds were transformed into (Nix,Cu1-x)3Sn4. In addition, the bumps failed at cathode/chip end due to serious damage of the UBM and the Al pad. A failure mechanism induced by electromigration is proposed in this paper.

Thin-film mechanical properties can be measured using nanoindentation combined with detailed finite element modeling. This technique was used for a study of very fine grained Ni films, formed using pulsed-laser deposition on fused silica, sapphire, and Ni substrates. The grain sizes in the films were characterized by electron microscopy, and the mechanical properties were determined by ultra-low load indentation, analyzed using finite element modeling to separate the mechanical properties of the thin layers from those of the substrates. Some Ni films were deposited at high temperature or annealed after deposition to enlarge the grain sizes. The observed hardnesses and grain sizes in these thin Ni films are consistent with the empirical Hall–Petch relationship for grain sizes ranging from a few micrometers to as small as 10 nm, suggesting that deformation occurs preferentially by dislocation movement even in such nanometer-size grains.

Microstructured biomaterials such as mollusk shells receive much attention at present, due to the promise that advanced materials can be designed and synthesized with biomimetic techniques that take advantage of self-assembly and aqueous, ambient processing conditions. A satisfactory understanding of this process requires characterization of the microstructure not only in the mature biomaterial, but at the growth fronts where the control over crystal morphology and orientation is enacted. In this paper, we present synchrotron microbeam x-ray diffraction (XRD) and electron microscopy observations near the nacre–prismatic interface of red abalone shell. The relative orientations of calcite and aragonite grains exhibit some differences from the idealizations reported previously. Long calcite grains impinge the nacre–prismatic boundary at 45° angles, suggestive of nucleation on (104) planes followed by growth along the c axis. In the region within 100 μm of the boundary, calcite and aragonite crystals lose their bulk orientational order, but we found no evidence for qualitative changes in long-range order such as ideal powder texture or an amorphous structure factor. XRD rocking curves determined the mosaic of calcite crystals in the prismatic region to be no broader than the 0.3° resolution limit of the beamline’s capillary optics, comparable to what can be measured on geological calcite single crystals.

The reactivity of AlN powder in an aqueous environment was studied by measuring the pH and the temperature during the hydrolysis of the powder at room and elevated temperatures. The influences of the powder concentration and the starting pH of the slurry were also investigated. The results of the measurements at room temperature show that there is an incubation time before the start of the AlN hydrolysis reactions. Once this incubation time is over, the pH and the temperature of the slurry start to increase, indicating the onset of the reactions. A higher starting temperature not only speeds up the reaction of the AlN powder with water, but it also shortens the incubation time. In addition, the starting temperature influences the morphology of the reaction product: at temperatures below 60 °C, the final product of the hydrolysis is crystalline Al(OH)3, whereas at higher temperatures (above 60 °C), crystalline AlOOH is formed. At very low pH values (pH = 1), the reaction of AlN powder with water is prevented (i.e., the incubation time is very long), whereas in an alkaline environment, the incubation time is approximately the same as in distilled water, but the reaction is accelerated.

Erbium and silicon were dual implanted into thermally grown SiO2 film on Si (110) substrates, followed by thermal treatment at 700–1200 °C for 30 min. The microstructure was studied by transmission electron microscope and x-ray diffraction. When the implanted films were annealed at T > 900 °C, the silicon nanocrystals (nc-Si) enwrapped by amorphous silicon (a-Si) could be observed. The thermal quenching behavior at λ = 1.535 μm and its relation with the annealling temperature were also investigated. With increasing annealing temperature, the portion of a-Si and the thermal quenching both decreased. Efficient luminescence from Er ions and weak intensity thermal quenching were obtained from the sample annealed at 1100 °C. The role of a-Si in non-radiative processes at T > 100 K is discussed.

Microcontact impedance spectroscopy in conjunction with conventional impedance techniques has been performed to elucidate microstructural and compositional inhomogeneities in polycrystalline Mn–Zn ferrites. Microcontact studies reveal the occurrence of oxygen stoichiometry gradients in these typically prepared ferrite ceramics together with a strong spatial resistance variation from boundary to boundary. This leads to a reinterpretation of the conventional impedance spectra of ferrites.

The kinetics of borosilicate glass film deposition on silicon using boron nitride as a solid source was investigated. Experimental data on the thickness of deposited films as a function of temperature and process times under controlled atmospheric conditions was obtained. A 33-kW rapid thermal processing infrared furnace was used to minimize temperature and gas phase transients experienced on the commercial scale. The thickness and composition of the borosilicate glass films were measured using scanning Auger spectroscopy, and the thickness of the films as a function of time for various temperatures are presented. The results suggest a rapid transition to diffusion-controlled deposition with an activation energy of 2.77 ± 0.5 eV. The partial pressure of water vapor was found to have a potentially significant effect on the rate of film growth.

The elastoplastic surface deformation of a polycrystalline graphite was studied by examining the indenter’s geometry dependence of load P versus penetration depth h relation (P–h relation) in instrumented pyramidal/spherical indentation tests. The tetrahedral pyramid indenters included inclined face angles β of 10.0°, 22.0° (Vickers pyramid), and 40.0°. The tip radius of spherical indenters used were 32 μm, 200 μm, 794 μm, 1.59 mm, and 6.35 mm. The true hardness H as a measure for plasticity was singled out of the elastoplastic loading parameter k1 in the quadratic expression of P = k1h2 and then quantitatively related to the yield stress Y that was determined from the mean contact pressure for spherical indentation at the onset of plastic yielding. The size effect of Y, decreasing with the increase in the tip radius of spherical indenter, is discussed using the model of geometrically necessary dislocations in terms of the material length scales for a plastic field with strain gradient.

The nanotopography of the surface of silicon wafers has become an important issue in ULSI device manufacturing, as it affects the post–chemical mechanical polishing (post-CMP) uniformity of the thickness deviation of dielectric films. A spectral method is proposed to examine quantitatively how the nanotopography impacts the film thickness deviation during CMP. The nanotopography impact was investigated in terms of its dependence on the characteristics of consumables, such as the polishing pad hardness and the wafer manufacturing method. In addition, the effects of the surfactant and the abrasive size in ceria slurry on nanotopography impact were investigated. It was found that the magnitude of the post-CMP oxide thickness deviation due to nanotopography increased with the surfactant concentration in the case of smaller abrasives but was almost independent of the concentration in the case of larger abrasives. These results demonstrate that the nanotopography impact can be controlled by manipulating the slurry characteristics.

A high-pressure silicon infiltration technique was applied to sinter diamond–SiC composites with different diamond crystal sizes. Composite samples were sintered at pressure 8 GPa and temperature 2170 K. The structure of composites was studied by evaluating x-ray diffraction peak profiles using Fourier coefficients of ab initio theoretical size and strain profiles. The composite samples have pronounced nanocrystalline structure: the volume-weighted mean crystallite size is 41–106 nm for the diamond phase and 17–37 nm for the SiC phase. The decrease of diamond crystal size leads to increased dislocation density in the diamond phase, lowers average crystallite sizes in both phases, decreases composite hardness, and improves fracture toughness.

Friction stir processing (FSP) has been developed as a potential grain refinement technique. In the current study, a commercial 5083 Al alloy was friction stir processed with three combinations of FSP parameters. Fine-grained microstructures with average grain sizes of 3.5–8.5 μm were obtained. Tensile tests revealed that the maximum ductility of 590 was achieved at a strain rate of 3 × 10−3 s−1 and 530 °C in the 6.5-μm grain size FSP material, whereas for the material with 8.5-μm grain size, maximum ductility of 575 was achieved at a strain rate of 3 × 10−4 s−1 and490 °C. The deformation mechanisms for both the materials were grain boundary sliding (m ∼0.5) However, the 3.5-μm grain size material showed maximum ductility of 315 at 10−2 s−1 and 430 °C. The flow mechanism was solute-drag dislocation glide (m ∼0.33) This study indicated that establishing a processing window is crucial for obtaining optimized microstructure for optimum superplasticity.

Dual cation (Yb + Y)-stabilized α-sialon ceramics with either stoichiometric composition or nonstoichiometric composition that yield less than 3 vol% of an additional intergranular liquid/glass phase were consolidated by spark plasma sintering (SPS). This process allows very fast heating and cooling, thus providing a unique possibility to monitor and manipulate the kinetics of phase transformation and grain growth during sintering. Below a temperature threshold, full densification and complete α-sialon formation are accompanied by very limited grain growth. The grain growth kinetics were investigated both by post heat-treatment of SPS pre-consolidated monophasic α-sialon bodies consisting of sub-micron sized equiaxed grains in a conventional graphite furnace using extended holding times (hours) and directly rapid annealing in the SPS apparatus above the temperature threshold (within minutes). Post heat treatment in the graphite furnace yielded in situ reinforced microstructures consisting of interlocking elongated grains only in the presence of an additional intergranular liquid/glass phase. Direct annealing by SPS process yielded in situ reinforced microstructures whether or not an additional liquid/glass was involved. The former microstructures are formed via the static Ostwald ripening mechanism whereas the latter ones are generated via a dynamic ripening mechanism. This demonstrates that the dynamic ripening provides an efficient means of developing in situ reinforced microstructure in α-sialon ceramics with improved mechanical properties.

A solid composite of desirable microstructure can be produced by curing a liquid polymeric suspension in an electric field. Redistribution effect of the field-induced forces exceeds that of centrifugation, which is frequently employed to manufacture functionally graded materials. Moreover, unlike centrifugational sedimentation, the current approach can electrically rearrange the inclusions in targeted areas. The electric field can be employed to produce a composite having uniformly oriented structure or only modify the material in selected regions. Field-aided technology enables polymeric composites to be locally micro-tailored for a given application. Moreover, materials of literally any composition can be manipulated. In this article we present testing results for compositions of graphite and ceramic particles as well as glass fibers in epoxy. Electrical and rheological interactions of inclusions in a liquid epoxy are discussed. Measurements of tensile modulus and ultimate strength of epoxy composites having different microstructure of 10 vol% graphite, ceramic particles and glass fiber are presented.

N-type nanocrystalline titania is a promising material for use in semiconductor photoelectrochemical cells and, potentially, the solar generation of hydrogen. In this study, we examined the photochemical properties of titania nanotube arrays made by anodization of a starting Ti foil in a fluoride ion containing electrolyte. The absorption properties of the titania nanotube samples were investigated using diffuse reflectance ultraviolet (UV)-visible (vis) spectroscopy, with a broadening of the absorption spectra seen as a function of material phase, nanotube diameter, and Pd sensitization. The magnitude of the anodic photocurrent obtained from the polycrystalline nanotube samples, measured under band gap UV illumination, appeared to be significantly higher than that reported for any other form of nanocrystalline titania. A maximum photoconversion efficiency (UV light exposure at 365 nm, intensity 146 mW/cm2) of 4.8% was obtained for 22 nm diameter nanotubes annealed at 500 °C and coated with a discontinuous palladium layer of 10 nm average effective thickness.