The local spin configuration and band structure of chromium doped boron carbide calculated by density functional theory suggests local magnetic ordering. While the long range dopant position appears random in the boron carbide semiconductor, the local position and initial empirical/computational results suggest the promise of large magneto-resistive effects. The chromium doped boron carbide thin films, fabricated by boron carbide-chromium co-deposition, were studied by current-voltage (I-V) characteristics measurements. The results provide some reason to believe that magneto-resistive effects are indeed present at room temperature.

We study the switching characteristics of nanoscale junctions between a metallic tip and a silver film covered by a thin Ag2S ionic conductor layer. Resistive switching phenomena are studied on samples of various Ag2S layer thicknesses. Metallic and semiconductor behavior are distinguished by current-voltage characteristics measured at room temperature and at 4.2 K.

In order to make innovative curriculum materials more accessible to instructors, a set of teaching, learning, and assessment resources have been created to implement more student-centered pedagogy for many topics in an introductory materials course. The resource development has been based on major principles for effective learning described in the book, How People Learn. The book states that, for more effective teaching and learning, instructors need pay attention to three major principles. One is that they should be aware of students’ prior knowledge and experience and misconceptions in order to inform classroom instruction and materials. As such, we have created tools to assess prior knowledge including the Materials Concept Inventory and Pre-Post Topical Concept Question Sets. Eliciting such information is critical in informing creation of innovative and misconception-informed teaching materials. A second principle is that instructors should create opportunities for student engagement with one another in order to promote conceptual change with deeper content understanding. This will help students build a conceptual framework that facilitates recall and transfer of concepts to new applications. As such, we have created visually-rich, contextualized content to promote student interest and link abstract concepts to concrete applications. The constructivist materials and activities that have been created include: Misconception-Informed Mini-Lecture Slide Sets, topical concept-context maps, a variety of classroom engagement activities, and homework that includes just-in-time preview problems to prepare students for the next class. A third principle is that instructors should promote student reflection so they become more metacognitive learners who can develop their own expertise by defining learning goals and monitoring their own progress. This need was addressed with a Daily Reflection Points sheet that requested students to write down their own class Points of Interest, Muddiness, and Learning. Most of these resources are available on the web at http://concept.asu.edu/. Assessment results showed significant gains on specific course topics using the innovative materials and an increase in persistence of students completing the class that rose from 85% to 95% compared with earlier lecture-based classes.

A major challenge for scanned probe microscopy is to identify structures and chemical species on a surface, which have not already been inferred from other analytical techniques. Progress is impeded by the fact that in general the structure and composition of the tip atom is not known. To illustrate some of the issues involved, we report simultaneous scanning tunneling microscopy/atomic force microscopy (STM/AFM) of the TiO2 (110) surface. The use of small amplitudes enabled the simultaneous acquisition of force gradient and barrier height images during standard STM imaging. Surprisingly, we find most STM images exhibit a corrugation contrast inverse to that usually reported in the literature. However, regardless of the contrast in STM, force gradient images always showed greater attraction over O rows. Barrier height images also show this consistency, always being greater over O rows. This supports the theoretical model of the electronic structure of the surface, but shows that the tip structure and interaction cannot be ignored in modeling STM images. We conclude that there is a fine balance between topography and local density of states (LDOS) in STM imaging of this surface; which of them dominates the STM image is determined by the tip. Simultaneous multi-parameter imaging is useful in interpreting images reliably, particularly on multi-component surfaces.

The damage accumulation behavior of different grain boundary structures in Inconel 690 (Ni-29wt%Cr-9wt%Fe) was investigated in the presence of large, localized plastic strains induced by nanoindentation. Spatially-resolved hardness was measured as a function of lateral distance from ‘random’ high-angle grain boundaries and twin boundaries. The confinement of induced defects between the indenter tip and grain boundaries did not lead to significant differences in measured hardness between high angle and twin boundaries. Critical “pop-in” loads indicating the onset of incipient plasticity were lower within 1μm of grain boundaries, but were statistically equivalent for random and twin boundaries. These results suggest a comparable extent of dislocation mobility and absorption at the different grain boundary types in Inconel 690 under ambient conditions.

Dual two-phase intermetallic alloys based on the Ni3Al-Ni3V pseudo-binary alloy system have been reported to display high phase and microstructure stabilities and good mechanical properties at high temperature and are therefore considered to be used as a next generation type of high temperature structural materials. The microstructure of the dual two-phase intermetallic alloys is composed of primary Ni3Al and the channel (eutectoid) regions consisting of Ni3Al+Ni3V. In this study, the microstructure of the channel regions was investigated by a transmission electron microscope (TEM). The contrasts of the channel regions showed a complicated microstructure in bright-field images. However, the electron beam diffraction consisted of a single set of patterns and the spots did not accompany streaks, indicating that crystallographic coherency among the constituent phases or the domains is very high. It was also shown that the lattice misfit between the a-axis of Ni3Al and the c-axis of Ni3V is larger than that between the a-axis of Ni3Al and the a-axis of Ni3V. From the dark-field observation, it was found that the c-axis of Ni3V domains in the channel regions is oriented perpendicular to the interface between primary Ni3Al and Ni3V. Therefore, it is suggested that the crystallographic orientation of Ni3V in the channel regions is aligned in the manner of lowering an internal stress caused by the lattice misfit between primary Ni3Al precipitates and Ni3V domains.

We present a versatile and facile route for highly sensitive detection ofanalytes through coupling the enlargement of gold nanoparticles (Au NPs)with fluorescence decrease. The fluorescence intensity of dye molecules(e.g., fluorescein or rhodamine B) significantly decreased with theincreasing concentration of reducing agents, such as hydrogen peroxide andhydroquinone. The sensitivity for the detection of reducing agents was muchhigher than other detection methods based on the absorbance measurement ofenlarged gold nanoparticles or quantum dot-enzyme hybridization. We couldsuccessfully detect acetylthiocholine with the detection limit of several nMorders, using an enzymatic reaction by acetylcholinesterase, a key route forthe detection of toxic organophosphate compounds. The fluorescencedecreasing approach described in this work requires only a simple additionof fluorescence dye to the reaction solution without any chemicalmodification. The strategy of fluorescence decrease coupled withnanoparticle growth will be applied on the fluorescent substrate to developdetection templates for highly sensitive optical biosensor.

CuO and CuGaO2 thin films have been grown on Si (100) substrates using a sol-gel spincoating method. CuO films were successfully fabricated by the annealing around 700°C. At higher temperatures (>800°C), pyramidal CuO islands with 1~2μm in width and 0.4~0.8μm in height were observed. They arranged structures as a straight line parallel to the <110> and <010> directions, which suggests the self-organized growth of CuO pyramidal islands. Delafossite CuGaO2 films were fabricated as well, using Cu-Ga-O mixed solutions with Ga/(Cu+Ga) atomic ratio of 0.5. These results indicate that Cu-based compounds were fabricated by the sol-gel spincoating method.

Low-pressure MOCVD, with tris(2,4-pentanedionato)aluminum(III) as the precursor, was used in the present investigation to coat alumina on to cemented carbide cutting tools. To evaluate the MOCVD process, the efficiency in cutting operations of MOCVD-coated tools was compared with that of tools coated using the industry-standard CVD process.

Three multilayer cemented carbide cutting tool inserts, viz., TiN/TiC/WC, CVD-coated Al2O3 on TiN/TiC/WC, and MOCVD-coated Al2O3 on TiN/TiC/WC, were compared in the dry turning of mild steel. Turning tests were conducted for cutting speeds ranging from 14 to 47 m/min, for a depth of cut from 0.25 to 1 mm, at the constant feed rate of 0.2 mm/min. The axial, tangential, and radial forces were measured using a lathe tool dynamometer for different cutting parameters, and the machined work pieces were tested for surface roughness. The results indicate that, in most of the cases examined, the MOCVD-coated inserts produced a smoother surface finish, while requiring lower cutting forces, indicating that MOCVD produces the best-performing insert, followed by the CVD-coated one. The superior performance of MOCVD-alumina is attributed to the co-deposition of carbon with the oxide, due to the very nature of the precursor used, leading to enhanced mechanical properties for cutting applications in harsh environment.

We report on the realization of high precision hollow structures directly on silicon suitable for liquid and gas/vapor transport. The formation of hollow structures requires high aspect ratio etching combined with bulk back-side micro-machining to realize silicon-based membranes. The use of a slant angle deposition method has been used as an alternative method for three-dimensional lithography. The transfer of acetone vapor through such tiny holes shows an anomalous behavior where a sharp rise is observed followed by an exponential and gradual decay. These structures can be eventually used as mass ion separation devices.

Chemical Mechanical Polish (CMP) is one of the key technologies for the development of modern high performance integrated circuits. The requirements for the CMP uniformity get extremely demanding in order to meet the litho requirements for 32nm technology node and beyond. In this paper, two kinds of orders related to the stressor films that affect the CMP uniformity are revealed. The first is the stressor films deposition order according to the CMP polish rate of each stressor film. The second is the stress gradients order that formed inside the films sitting on top of the stressors. Through the optimization of the order, we show successfully removal of couple hundreds angstroms stressor step heights within 300mm wafer range. The method developed here can also find applications in microelectromechanical systems and 3D integration circuits.

To reduce time-to-knowledge and costs associated with wafer scale processing a laboratory scale copper electrochemical deposition (ECD) system was developed for screening new organic additives which promote bottom-up fill in interconnect trenches and vias. This new setup enables working process conditions and functionality trends to be identified for open source and proprietary suppressors and levelers at leading edge feature sizes (sub 50nm). The laboratory results can then be compared to the in-line wafer scale plating tool results to ensure their compatibility. A reliable laboratory setup that can mimic the dynamic conditions found inside the wafer scale plating tool will enable the main objective of this work to be efficiently realized. The main objective is to test two previously published models describing copper fill inside the trenches by bridging the gap between fundamental electrochemical measurements and wafer scale plating results. To date this work will focus on the reliability and transferability of plating results between the laboratory setup and a wafer scale plating tool and present preliminary data using gap fill and bottom-up growth ratio as performance metrics.

We have fabricated high performance amorphous IGZO TFTs and integrated circuits on flexible kovar (Ni-Fe 42 alloy) foils. Excellent dimensional stability on kovar foils is obtained by a pre-anneal process at 800°C that limits the thermal run-out to within 100ppm. After substrate annealing, Ni-Fe 42 alloy retains high yield strength and good flexibility with the re-crystallized structure containing large isotropic grains between 20-50μm. Amorphous IGZO TFTs and circuits with a staggered, bottom-gate architecture are fabricated and tested. Non-flexed TFTs have field effect mobility of 12 cm2/V.s, threshold voltage around 2 V and sub-threshold swing of 0.6 V/decade and ON/OFF current ratio exceeding 107. Under prolonged uniaxial tensile strain upto 0.8%, TFTs exhibited minimal change in performance which augers well for use of Ni-Fe foil as flexible substrates. To demonstrate the viability of oxide-based device integration, n-type pseudo logic ring oscillator circuits are also evaluated. Sub 300 ns propagation delay is confirmed at a rail-rail supply voltage of 40 V. The results suggest that device integration on such a highly flexible substrate is amenable to roll-to-roll processing of future electronics.

For the first time, a new AFM mode is presented that simultaneously allows the measuring of adhesion and friction forces at different constant and continuous sliding velocities. Our methodology consists of implementing a circular relative displacement of the contact to reach a constant sliding velocity, with no stop periods. Some of the main advantages of performing a circular displacement is that continuous and high sliding velocities (more than 1 mm/s) can be reached compared to the low sliding velocities (up to 10 μm/s) available when using commercial AFM. Also, a stationary state is reached when doing measurements. Moreover, the circular mode can be coupled with the classical operating mode, for instance, force spectrum. Main applications of this circular mode are related to metrological measurements in physics that require high speed displacements. As an example, we report the evolution of friction and adhesive forces measured in air at different high sliding velocities.

We present materials development in fabricating thin film devices for the conversion of wind energy as a sustainable energy source. We demonstrate the feasibility of piezoelectric polymer thin film devices to harvest wind energy in a miniature wind tunnel. Using an example of prototype device based on polyvinylidene fluoride (PVDF) thin film devices, we are able to obtain electrical power from the wind’s energy through the mechanical deformation of PVDF, such as that obtained from the films flapping in the wind. We have obtained a preliminary result of 1 mW power (at 15 mph wind) with a single layer of PVDF of 4 x 2 inches and 50 μm in thickness sandwiched between two thin gold electrode films. Additionally, the fracturing of metallic electrodes over time from the induced strain of this application lead to the significance of examining carbon nanotubes as compliant electrodes offering better mechanical properties while maintaining necessary electrical properties.

Planar NAND technology is rapidly approaching its fundamental limits and will likely transition to a three dimensional structure. The scaling challenges facing NAND will be reviewed. Emerging memory technologies, such as the cross-point, will be discussed. The materials challenges facing emerging memories will be reviewed.

Conventional silicon sensors provide insufficient capability for color reproduction by producing three color signals (RGB) to fit their pixel sensitivities to that of the human eye. Photo detector devices based on a-SiC:H and a-SiGe:H offer the opportunity to shift spectral sensitivity continuously by varying external bias voltages. Based on the measurement results of Rieve et al. [2] we determined the absorption coefficients of a group of a-SiC:H and a-SiGe:H layers to simulate the penetration depth of photons at different energies into the device structure [3]. Knowing the indices of absorption, refraction and extinction, it is possible to engineer diodes in such a way that accumulations of charge carriers are generated at varying device depths. The use of common chromium (Cr) cathodes avoids a sharp falling edge of the sensitivity towards longer wavelengths. The use of low reflective and highly conductive aluminum-doped zinc oxide (ZnO:Al) as a material for the back contact of the diodes suppresses Fresnel reflections and has been verified experimentally. A dynamic range of more than 100 dB at 1000 lux could be obtained by I-/V- measurements of a-Si:H pin diodes fabricated between two ZnO:Al contacts. Optically the detectors show maxima between 440 nm and 630 nm with reduced Fresnel reflections and a very low leakage current of 10-8A/cm2 at -5 V bias voltage. Present research efforts concentrate on the verification of the optical properties and exact thicknesses of the chosen layers as well as on the development of a front and back illumination device structure which ensures a continuous spectral shift of the photosensitivity. This work requires extensive bandgap engineering and offers good prospects to improve security imaging tools as well as chemical analysis systems.

Mesoporous cobalt oxide-tungstophosphoric acid composite frameworks have been synthesized by structure replication from cubic mesoporous KIT-6 silica. The products possess a regular structure with uniform wall thickness (~7 nm) and large internal BET surface area (~87-141 m2/g). The pore walls of these materials consist of nanocrystalline Co3O4 and 12-tungstophosphoric acid (HPW) components with different HPW content, i.e. 6, 15 and 36 wt. %. Total X-ray scattering analysis and UV/vis spectroscopy confirmed the Keggin structure of HPW into the mesoporous frameworks. Preliminary catalytic experiments found that Co3O4-HPW composites exhibited a remarkable activity in the direct decomposition of nitrous oxide into N2 and O2.