Line width and line thickness thermal strain components in passivated Al and Cu lines were observed to relax much more than the line length strain component. Although the width-to-thickness ratios were large, 3.5 and 4.4 for Al and Cu lines, respectively, the behaviors of the thermal stresses were far from the equibiaxial. Observed changes in deviatoric strains between room temperature and 190 °C for Al and 300 °C for Cu were consistent with a model in which the changes in line width and line thickness strains were simply related to changes in line length strains by the uniaxial Poisson’s ratio. Changes in line length strains were determined by the differences in metal and substrate thermal expansion coefficients and the magnitudes of temperature changes through retained elastic strain coefficients for Al of 30% for heating and for Cu of 60% for heating and 80% for cooling, with the balance accommodated by relaxation.

Direct-write, cryogenic electron beam-induced deposition (EBID) was performed by condensing methylcyclopentadienyl-platinum-trimethyl precursor onto a substrate at −155 °C, exposing the condensate by a 15 keV electron beam, and desorbing unexposed precursor molecules by heating the substrate to room temperature. Dependencies of film thickness, microstructure, and surface morphology on electron beam flux and fluence, and Monte Carlo simulations of electron interactions with the condensate are used to construct a model of cryogenic EBID that is contrasted to existing models of conventional, room temperature EBID. It is shown that material grown from a cryogenic condensate exhibits one of three distinct surface morphologies: a nanoporous mesh with a high surface-to-volume ratio; a smooth, continuous film analogous to material typically grown by room temperature EBID; or a film with a high degree of surface roughness, analogous to that of the cryogenic condensate. The surface morphology can be controlled reproducibly by the electron fluence used for exposure.

The optical properties of N-ion-implanted diamond are evaluated. The color of implanted layer became glossy black with metallic luster, which was further enhanced after postimplantation annealing at 600 °C for 2 h in vacuum or inert gas atmosphere. Raman spectroscopy revealed that the crystalline diamond became completely disordered after irradiation, but surprisingly the crystalline nature was restored to a mixture of well-defined diamond and diamond-like carbon after annealing. When it was annealed in air at the same temperature, however, the black color disappeared, indicating a removal of the disordered or graphitized layer by oxidation. X-ray photoelectron spectroscopy and Raman analyses indicate that the black color of as-implanted diamond is associated mainly with the disordered carbon and modified band structure. Fourier transform infrared (FTIR) analysis shows that the implanted nitrogen atoms are in N–N and symmetrical 4N-vacancy bonding states, which are commonly found in the natural diamonds with yellow and brown tint.

Schottky diodes have been fabricated on metalorganic chemical vapor deposition GaN epitaxial layers grown on sapphire substrates. Carbon impurities limit the ability of these films to be used in high-power devices. Although its effect can be mitigated by growing the films at higher pressure, higher flow rates, and larger V/III ratios, it still effectively limits the net carrier concentration to ∼1016 cm−3 and therefore the breakdown voltage to ∼1200 V by acting as a compensating deep acceptor for n-type material. The net carrier concentration is smaller than the carbon concentration indicating that not all of the carbon occupies a nitrogen site acting as a deep acceptor. It is not known whether some of the carbon occupies gallium sites acting as a donor, interstitial sites creating states in the midgap region, and/or is tied up in the large number of dislocations in the films where it is not electrically active.

We demonstrate the fabrication of shadow mask (SM) patterned as well as nanoimprint lithography (NIL) patterned organic transistors and integrated complementary organic inverters (ICOIs). As active layers pentacene (p-type) and either PTCDI-C13H27 or F16CuPc (n-type) were used. The SM-patterned ICOIs with a staggered bottom gate configuration, a nanocomposite dielectric and both active layer combinations (pentacene/PTCDI C13H27, pentacene/F16CuPc) exhibited high performance (3 V operation voltage; gain around 60; high level 3 V; low level 5 mV; noise margin 0.9 V). Flexible ICOIs with transistor channel lengths of 900 nm were successfully fabricated by NIL, using a benzocyclobutene derivative as dielectric. Because of the process inherent coplanar bottom gate configuration, F16CuPc was used. The ICOIs showed proper functionality (3 V operation voltage; gain around 5; high level 2.9 V; low level 25 mV). To our knowledge, this study demonstrates the first complementary submicron inverters based on fully R2R compatible imprint processes.

Ordered nanoparticle assemblies can exhibit collective properties that are quite different from those displayed by the individual nanoparticles or their bulk counterpart. This paper reviews recent progress on the assembly of superparamagnetic nanoparticles, with emphasis on different strategies for their chemical fabrication with highly ordered nanostructures as well as their novel properties. Prospective applications of superparamagnetic nanoparticles in the fields of photonic crystals, biomedicine, and biology are also discussed.

The current-induced interfacial reactions in the Ni/Sn-3.0Ag-0.5Cu/Au/Pd(P)/Ni–P (ENEPIG) flip chip interconnects and the failure mechanism during electromigration (EM) were reported. When ENEPIG was the cathode, EM significantly enhanced the consumption of Ni–P leaving a Ni3P layer; once the Ni–P was completely consumed, the growth of Ni2SnP was accelerated. The dissolved Ni atoms from the Ni–P and the interfacial intermetallic compounds (IMCs) were driven toward the anode upon electron current stressing and precipitated as large (Ni,Cu)3Sn4 IMCs. The excessive consumption of Ni–P and the formation of voids were responsible for the EM-induced failures. When Ni was the cathode, the rapid localized dissolutions of Ni under bump metallization (UBM) and Cu pad in the current crowding region resulted in a two-stage transformation of interfacial IMCs at the opposite Ni–P/solder interface. The localized dissolutions of Ni UBM and Cu pad on chip, as well as the formation of voids, were responsible for the EM-induced failures.

The material characterization toolbox has recently experienced a number of parallel revolutionary advances, foreshadowing a time in the near future when material scientists can quantify material structure evolution across spatial and temporal space simultaneously. This will provide insight to reaction dynamics in four-dimensions, spanning multiple orders of magnitude in both temporal and spatial space. This study presents the authors’ viewpoint on the material characterization field, reviewing its recent past, evaluating its present capabilities, and proposing directions for its future development. Electron microscopy; atom probe tomography; x-ray, neutron and electron tomography; serial sectioning tomography; and diffraction-based analysis methods are reviewed, and opportunities for their future development are highlighted. Advances in surface probe microscopy have been reviewed recently and, therefore, are not included [D.A. Bonnell et al.: Rev. Modern Phys. in Review]. In this study particular attention is paid to studies that have pioneered the synergetic use of multiple techniques to provide complementary views of a single structure or process; several of these studies represent the state-of-the-art in characterization and suggest a trajectory for the continued development of the field. Based on this review, a set of grand challenges for characterization science is identified, including suggestions for instrumentation advances, scientific problems in microstructure analysis, and complex structure evolution problems involving material damage. The future of microstructural characterization is proposed to be one not only where individual techniques are pushed to their limits, but where the community devises strategies of technique synergy to address complex multiscale problems in materials science and engineering.

A catalytic technique to enhance graphite formation in nongraphitizing carbons was adapted to work with three-dimensional wood-derived scaffolds. Unlike many synthetic graphite precursors, wood and other cellulosic carbons remain largely disordered after high temperature pyrolysis. Using a nickel nitrate liquid catalyst and controlled pyrolysis conditions, wood-derived scaffolds were produced showing similar graphitic content to traditional pitch-based graphite while retaining the high-aspect ratio pores of the precursor wood microstructure. Graphite formation was studied as a function of processing time and pyrolysis temperature, and the resulting carbons were analyzed using x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, and electron microscopy techniques.

Strain evolution in 0.45-μm-thick, 2-μm-wide, and 100-μm-long Cu conductor lines with a passivation layer has been investigated using synchrotron x-ray microdiffraction. A moderate electromigration-current density of 2.2 × 105 A/cm2 was used to minimize Joule heating in the Cu conductor lines. After 120 h of current flowing in the Cu lines at 270 °C, measurements show strain relaxation and homogenization occurring in the Cu lines with current flowing, but not in Cu conductor lines without current. Stronger interaction between electrons with Cu atoms in areas with higher strains was proposed to explain the observation.

Herein we report a novel, environment-friendly approach for the reduction of graphene oxide by means of incorporating visible-light sensitive TiO2 and steady state visible-light irradiation. The surface morphology and fine structure of as-prepared composites were characterized by scanning electron microscopy and atomic force microscopy, respectively. The reduction process was evidenced by variation of conductivity. In addition, some of the electrochemical properties of the resultant graphene materials have been investigated as well.

In this work, antimony trioxide (Sb2O3) has been doped into MgB2 samples to act as an additive. The doping level varies from 2.5 to 15 wt%. The effects of Sb2O3 addition on the lattice parameters, critical temperature (Tc), critical current density (Jc), and upper critical field (Hc2) have been investigated in detail. It has been found that Sb2O3 doping results in a small depression in Tc. The Jc value is 2.4 × 103 A·cm−2 for the 2.5% Sb2O3-doped sample at 5 K and 8 T, which is more than two times higher than for the undoped sample. The significant Jc improvement at high fields is attributed to the Hc2 enhancement caused by the increased disorder.

The constituent phases, the microstructure, and the mechanical properties of a series of Fe87–xTi7Zr6Bx (x = 0, 2, 4, 6, 8, 10, and 12) alloys produced by copper mold casting were investigated. Partial substitution of iron by boron in the Fe87Ti7Zr6 ultrafine eutectic alloy induces phase/microstructural evolution and simultaneously changes the mechanical properties. In the composition range of 2 ≤ x ≤ 6, the typical lamellar structure slightly changes into a spherical cellular-type eutectic. For 8 ≤ x ≤ 12, multiphase composites containing a glassy phase form. The ultrafine eutectic composites exhibit a high compressive strength of ~2.9–3.1 GPa and a distinct plasticity of ~2–8%, whereas the glassy matrix composites show a high strength of ~3.1–3.3 GPa but no observable macroscopic plasticity before failure. These findings reveal that the plasticity of heterogeneous multiphase composites is strongly related to the length scale variables and the crystallinity of the constituent phases.

We have studied the dynamic response of Fe-doped manganites with ac susceptibility measurements in La0.65Ca0.35Mn1−xFexO3 with 0.01 ≤ x ≤ 0.10 as functions of temperature and dc magnetic field. It is observed that the in-phase part of susceptibility goes through a maximum that is removed on the application of moderate dc field. DC fields suppress both the components (real and imaginary parts) with the strongest effects being at or close to TC. Conduction and ferromagnetism have been consistently suppressed by Fe substitution. Increased spin disorder and decrease in TC with increasing Fe content are evident. The effect of Fe is seen to be consistent with the disruption of the Mn–Mn exchange possibly due to the formation of magnetic clusters. There is clear correlation between the resistivity and susceptibility. Low-temperature dissipation in high-Fe-doped samples is observed; that is, increasing the Fe leads to increased spin disorder and dissipation at low temperature. The effect of the dc field is discussed in terms of the suppression of spin fluctuations close to TC.

This work reports the continuous and large-scale production of multiwalled carbon nanotubes (MWCNTs) from xylene/ferrocene in a swirled floating catalyst chemical vapor deposition reactor using argon as the carrier gas. The concentration of ferrocene used was 0.01 g/mL of xylene. In every run, 50-mL xylene gas was used together with xylene/ferrocene mixture injected into the reactor by means of a burette. The MWCNTs produced were characterized using the transmission electron microscopy (TEM) and Raman spectra. TEM analysis showed a poor production rate at 850 °C and a good production in the range of 900–1000 °C with optimal production rate at 950 °C. Furthermore, xylene/ferrocene mixture produced more MWCNTs at 950 °C with H:Ar (1:7) as the carrier gas. The diameters of the MWCNTs in the temperatures studied ranged from 15 to 95 nm with wall thicknesses between 0.5 and 0.8 nm.

The formation of interfacial η′-Cu6Sn5 in Sn–0.7Cu/Cu solder joints at different aging temperatures was studied using x-ray diffraction (XRD). The time-temperature-formation curve was obtained and is discussed based on the phase transformation from existing η-Cu6Sn5 and interfacial reaction at temperatures below 186 °C. A minimum formation time was observed in the temperature range of 135–150 °C.

A cornerstone in the successful application of semiconductor nanowire devices is controlled impurity doping. In this review article, we discuss the key results in the field of semiconductor nanowire doping. Considerable development has recently taken place in this field, and half of the references in this review are less than 3 years old. We present a simple model for dopant incorporation during in situ doping of particle-assisted growth of nanowires. The effects of doping on nanowire growth are thoroughly discussed since many investigators have seen much stronger and more complex effects than those observed in thin-film growth. We also give an overview of methods of characterizing doping in nanowires since these in many ways define the boundaries of our current understanding.

This paper provides an overview of directed self-assembly (DSA) options that exhibit potential for enabling extensible high-volume patterning of nanoelectronics devices. It describes the current set of research requirements, which a DSA technology must satisfy to warrant insertion consideration, and summarizes the state-of-the art. The primary focus is on chemical patterning and graphoepitaxial approaches to directing block copolymer (BCP) based assembly. These options exhibit the nearest-term potential, among the emerging DSA technologies, for satisfying projected International Technology Roadmap for Semiconductors (ITRS) patterning requirements. The paper concludes with a selected set of additional challenges, which represent potential barriers to the integration of directed BCP patterning into a nanoelectronics manufacturing line, as well as a few emerging application opportunities for related functional materials. A glossary of acronyms and terms may be found at the end of this manuscript.

We report fabrication of compacted Bi0.5Sb1.5Te3 nanoplatelets using hydrothermal methods followed by cold pressing and sintering in an evacuated ampoule at various temperature of 300–380 °C. The compacted Bi0.5Sb1.5Te3 sintered at 340 °C has the highest power factor of 11.6 μW/cm·K2 and its thermal conductivity is 0.37 W/m·K at 295 K, which is very low as compared to the typical value of 1 W/m·K. The resulting dimensionless figure of merit ZT is 0.93 at 295 K.

Nanocomposite Cr–Si–N films were prepared on to Ti–6Al–4V substrates by a novel duplex surface treatment technique. Coatings consisting of a Cr3Si surface layer were deposited using a double cathode glow plasma and subsequent surface plasma nitriding. The surface topography, chemical composition, and microstructure of these treated alloys were analyzed by a variety of surface characterization techniques. The resulting Cr–Si–N films consisted of nanocrystallite CrN grains embedded in amorphous SiNx phase. Nanoindentation tests showed that with increasing nitrogen partial pressure the hardness of the Cr–Si–N films increased and the elastic modulus decreased. Wear experiments showed that the Cr–Si–N films produced at a nitrogen partial pressure of 4.5Pa and 800 °C possessed the lowest wear rate and friction coefficient. Moreover, electrochemical measurements in 5 wt% HCl solution indicated that the Cr–Si–N films acted as an effective barrier against acid attack on the alloys.