The imperfect quality of CdZnTe (CZT) crystals for radiation detectors seriously diminishes their suitability for different applications. Dislocations and other dislocation-related defects, such as sub-grain boundaries and dislocation fields around Te inclusions, engender significant charge losses and, consequently, cause fluctuations in the detector’s output signals, thereby hindering their spectroscopic responses. In this paper, we discuss our results from characterizing CZT material by using a high-spatial-resolution X-ray response mapping system at BNL’s National Synchrotron Light Source. In this paper, we emphasize the roles of these dislocation-related defects and their contributions in degrading the detector’s performance. Specifically, we compare the effects of the sub-grain- and coherent twin-boundaries on the X-ray response maps.

We examine the potential of Bi-Ge-Se chalcogenide glass films as materials for a new type of photovoltaic devices, referred to as junctionless nanodipole PV. Glasses of a chemical composition providing a significant optical absorption were synthesized in quartz ampoules from high-purity Bi, Ge, and Se elements by a conventional melt quenching technique. This material was then used to deposit thin films with different thicknesses on various substrates by thermal evaporation under high-vacuum conditions. The original bulk glasses and the films were characterized by electron microscopy with EDS, XRD, Raman spectroscopy, differential scanning calorimetry, and spectrophotometry. Open-circuit voltage (Voc) readings under incandescent illumination were obtained from the as-deposited and annealed films. Results from this characterization work are presented and discussed. Although the efficiency of nanodipole PV material structures, based on this material remains of no practical interest, our initial results indicate a possible path for the implementation of the nanodipole PV concept.

The decorative polychrome history of a remarkable depiction of the “Guanyin of the Southern Sea” dating to the 11th-12th centuries C.E. (Nelson-Atkins Museum of Art, Kansas City, #34-10) has been studied by integrating the results of Scanning Electron Microscopy with Elemental Analysis by X-ray Spectrometry, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy and Polarized Light Microscopy. This 2.4m by 1.65m sculpture, carved almost entirely from a single Populus tree, has been attributed to Northern China and offers important points of comparison to previously studied works in the Victoria and Albert Museum and Rijksmuseum, with which it differs in certain important respects. Evidence for the original polychrome color scheme and those of at least three successive historical redecorations (two of which have been assigned ages by radiocarbon dating of paper interlayers) was found throughout the figure. By integrating the different forms of information obtainable from the methods cited above, it was possible to more fully describe complex pigment mixtures used to render different parts of the draperies. Both fracture sections and prepared cross sections serve different functions in revealing aspects of the paint preparation and its subsequent alteration. The differentiation of polymorphs of copper trihydroxychloride, made possible by Raman spectroscopy, allowed us to identify manmade botallackite with distinctive particle morphology as an important pigment of the intermediate period decorations, while elemental analysis of tin oxide traces showed that manmade atacamite used in other colors was derived from corroded bronze. Elemental analysis allowed distinctions to be made in the shade of gold leaf applied in different periods from cross sections without divesting the sculpture of later paint applications. The cross sections also provided evidence for the existence of flat gold line-work in areas subsequently redecorated with raised gilt brocades. Several combinations of the organic pigment indigo and inorganic paint constituents such as lead white, azurite, malachite and quartz reveal the means of adjusting shade and optical effects in closely-related paint applications. The results obtained by employing complementary techniques of analysis have served to greatly expand our understanding of the original use of polychrome decoration in the late Liao or Jin periods and its subsequent evolution, while alerting us to important Chinese innovations in the manufacure of pigments.

This paper reports a plasma-assisted, rapid, ambient-pressure, low-temperature one-step process for depositing conformal, non-porous nanocrystalline ZnO thin film on various substrates ranging from Si (100), fused quartz, glass, muscovite, c- and a-plane sapphire (Al2O3), to the common polymer polyimide (KaptonTM). The as-synthesized polycrystalline films range in thickness from 20nm to 200nm, deposited at a growth rate ranging from 2 nm/min to 50 nm/min. The lowest deposition temperature achieved with this method is 180°C and progress is being made in further lowering this temperature. The as-deposited films are highly oriented in the caxis, with (002) being the dominant planes.

Organosilicate glasses (OSG), also known as SiCOH or carbon-doped oxide are used as low-k inter-metal dielectrics for integrated circuits. The material must fulfill two conflicting requirements: It has to have low density to reduce the dielectric constant and be mechanically stable enough to withstand mechanical stress during subsequent production steps. Experimental advances in improving their mechanical and electrical properties have not yet been theoretically examined at the ab initio level, due to the relatively large model sizes necessary for amorphous materials. We employ the density-functional based tight-binding (DFTB) method to achieve an accurate description of OSG properties at different compositions. We analyze the influence of composition and topological defects on the density and bulk modulus of non-porous OSG. We find that the dependence of density and stiffness on chemical composition is of different nature. This difference is traced to a transition between different mechanisms of elastic deformation in silica glass and in silicon hydrocarbide, which is also the reason for different sensitivity to topological defects in the two materials.

We present the results and critical analyses of recent studies of ultrafast optical nonlinearities of liquid crystals in the isotropic and ordered phases for time scales spanning femtoseconds – microseconds. Pure undoped liquid crystals as well as liquid crystals containing plasmonic nano-particles have been investigated. Individual molecular electronic optical nonlinearities are found to be useful for femtoseconds – nanoseconds nonlinear transmission clamping applications. On the other hand, laser induced order parameter and birefringence modification in aligned nematic cells allow very rapid transmission switching of visible as well as near infrared lasers with response times in the sub-microseconds - few nanoseconds regime.

A key issue in using Polydimethylsiloxane (PDMS) based micropillars ascellular force transducers is obtaining an accurate characterization ofmechanical properties. The Young’s modulus of PDMS has been extended from aconstant in the ideal elastic case to a time-dependent function in theviscoelastic case. However, the frequency domain information is of morepractical interest in interpreting the complex cell contraction behavior. Inthis paper, we reevaluated the Young’s relaxation modulus in the time domainby using more robust fitting algorithms than previous reports, andinvestigated the storage and loss moduli in the frequency domain using theFourier transform technique. With the use of the frequency domain modulusand the deflection of micropillars in the Fourier series, the forcecalculation can be much simplified by converting a convolution in the timedomain to a multiplication in the frequency domain.

In this study, novel Si2Sb2Te6 phase change material is investigated in detail for the phase change memory application using transmission electron microscopy and X-ray photoelectron spectroscopy. The phenomenon that Te diffuses to the film surface during phase switching and successively evaporates out has been confirmed. The phase change memory cells employing Si2Sb2Te6 and Si3Sb2Te3 materials are fabricated and programmed. For the Si2Sb2Te6-based cell a data endurance of 5×105 cycles is achieved with a failure mode resembling reset stuck, which can be attributed to the migration of Tellurium during the operation cycles. It means that a thermally stable material system of SixSb2Te3 is preferred for the PCM applications.

Arrays of CdTe nanowires have been grown on conductive, flexible Mo substrates by the vapor-liquid-solid technique. A method of forming the arrays on a largely continuous CdTe film is described. For producing nanowire solar cells, this structure provides the advantage of preventing shunts. Nanowires having diameters in the range 100-500 nm and lengths up to 100 μm were generated. The influence of growth temperature, time and pressure on the morphology of deposited layers was investigated, and a mechanism for the generation of layer/nanowire combinations is postulated. Characterization by SEM, TEM and low temperature photoluminescence is presented.

Spintronic devices generally require the spin of carriers to be utilized in the storage or manipulation of data. One theoretical model for ferromagnetism in dilute magnetic semiconductors (DMS) results from the percolation of ferromagnetic regions around dilute dopants such as Mn atoms in III-V or group IV materials through the interaction of Mn atoms with carriers. Our work employed Mn implantation in Ge with subsequent rapid thermal annealing or TEM in-situ annealing to study the correlation between structure and magnetic properties. The magnetic properties of 300-350 ºC implanted Ge:Mn (which produced crystalline Ge films) varied significantly with implantation dose and annealing condition due to precipitation and transformation of different MnxGe1-x secondary phases. It was found that Mn substitution of Ge and MnxGe1-x secondary phases can both result in ferromagnetic properties. By combining TEM in-situ annealing and ex-situ magnetic characterization, we have demonstrated detailed correlation of magnetic properties with nanoscale structures in Mn implanted Ge DMS materials.

To achieve ultrasonic transducers operating above 100 MHz, square pillar shaped Pb1.1(Zr0.53Ti0.47)O3 thick film structures were fabricated using a chemical solution deposition (CSD) process. The fabricated sample showed well-saturated P-E hysteresis curve and butterfly-shaped longitudinal displacement curve. The fabricated samples generated more than 100 MHz ultrasonic waves with a pulser/receiver. Electrical impedance properties of the samples were measured with an impedance analyzer. A number of spurious resonant modes were observed in the frequency range from 40 to 300 MHz. The characteristics of the sample were investigated by finite element method (FEM). The FEM simulations were in good agreement with the experimental results. For free-standing (substrate free) 10-μm-thick PZT film models, the resonant frequency of the thickness vibration mode was estimated to be 160 MHz with the FEM simulations. These results indicate that the substrate affects the behavior of the spurious resonant modes. Therefore, a sample structure was designed using the FEM simulation. The FEM result suggests that the backside of the substrate should be removed to reduce the substrate effects. Consequently, the thickness vibration mode was observed clearly at 160 MHz. This structure is applicable to the micromachined ultrasonic transducers (MUT) operating in the thickness vibration mode above 100 MHz.

Charge injection property of organic thin film devices is a key issue tounderstand the device operation. Displacement current measurement (DCM) is apowerful technique to probe the charge injection behaviors in terms of achange in the apparent capacitance of test devices. However, it requires tosuppress actual current flowing through the device for investigating thedetails of interface phenomena. We propose here the use of ionic liquids(ILs) as a top contact insulator in organic metal-insulator-semiconductor(MIS) structures. Because of the high stability and dielectric constant ofthe ILs, the external applied voltage was applied mainly to the organiclayer with suppressing the actual current. The DCM curves of Ptwire/IL/α-NPD/ITO structure were measured, and they actually show thesignals due to the hole injection from theITO to α-NPD layer andaccumulation at the IL/α-NPD.

We present a novel ZnO:Al fabrication process consisting of room-temperature vacuum sputtering followed by an excimer laser annealing (ELA). The ELA treatment improves the optical transmission of the films, and the film resistivities (<1 mΩ·cm) remain stable or improve with increasing laser fluence up to 0.6 J/cm2, as the carrier density increases but the carrier mobility is degraded. This process is followed by a standard dilute HCl chemical texturing step, and produces substrates with suitable texture, conductivity, and transparency properties for thinfilm photovoltaic applications. Substrates resulting from this process display elevated haze levels (80% at 600 nm and 50% at 800 nm) after the wet-chemical etching step. Such substrates have been used to make single junction hydrogenated nanocrystalline silicon solar cells, and an increase in the short-circuit current of up to 2.2 mA/cm2 is observed compared to a substrate deposited by a standard room-temperature sputtering + wet-etch process. This gain is primarily due to increased photo-response in the red due to improved light-scattering, as at wavelengths greater than 600 nm, a gain in photocurrent of up to 1.7 mA/cm2 is observed.

Faience production methods include efflorescence, direct glaze application, and cementation glazing. However, similar processing has been used with a variety of other materials, such as glazed monolithic quartz, ground and re-fired faience, and steatite bodies. Furthermore, faience technology has been linked by similar processing to glass, synthetic pigment and glazing technologies. Here we reinforce these cross-craft relationships by comparing the range of similar functioning chemical elements in faience and glazed artifacts from a variety of archaeological sites that range from the Indus Valley to the Mediterranean. This broad comparative method based primarily on x-ray fluorescence analysis reveals trends in faience production, relationships with metallurgical technologies, and aspects of processing that provide areas of study that may be considered more closely in the future.

The unipolar resisitive switching properties of MOCVD deposited NiO in Ni/NiO/TiN stacks is reported. The switching quality is defined as function of RESET current and Roff/Ron ratio, and the importance of the Forming current and voltage on these parameters is discussed. The effect of structural stack variations as NiO thickness, Ti doping, and TiN thickness on the switching behavior of NiO is explained by the effect on the forming current and voltage conditions, and on Joule heating dissipation. Thinner NiO films, Ti doping, as well as thicker top electrode improve the switching quality by decreasing the RESET current and increasing the Roff/Ron ratio.

In this study we investigate how exposure to ambient air and light duringdevice processing affects the opto-electronic properties of poly-3-hexylthiophene (P3HT) : [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulkheterojunction solar cells (BHJ). The properties of pure P3HT layersprepared in an inert atmosphere, under ambient conditions, and additionallydegraded under light in ambient conditions were investigated usingphotoluminescence (PL) and photoinduced absorption (PIA). It was observedthat exposure to air during processing leads to oxygen doping of thepolymer. Exposure to air combined with light was found to significantlydecrease the PL and PIA signals. The current-voltage (I-V) and externalquantum efficiency (EQE) characteristics of solar cells fabricated in aninert atmosphere were compared to solar cells processed under ambientconditions. It was observed that processing in air leads to a reduction inthe photocurrent in the devices which is attributed to electron trapping byoxygen in the active layer.

In this study, the authors focused on children from 2-8 years of age and asked the simple question: what do engineers do? The number one response was: “I don’t know”, the number two response was “they drive a train.” While children are very familiar with professionals such as doctors, teachers, nurses, firefighters and policemen, they are rarely introduced to engineers. With this motivation, the authors developed a novel children’s book on engineering: Engineering Elephants. This book is an outreach tool that introduces children to the dynamic world of engineering design through roller coasters, fireworks, and a plethora of other exciting adventures. The book teaches children about relevant topics such as nanotechnology, renewable energy, and prosthetics by engaging them through an interactive journey of an elephant and his questioning of the world around him. The text was strategically developed using the language of science (asking questions) and introducing vocabulary relevant to science and math using a lyrical pattern. This presentation will highlight the development of this book as an instructional aid but also detail the response of various age groups to engineering activities presented as a companion to this book. In particular, an elementary school district in West Texas designed a 4-5th grade 3-week summer school curriculum around this book. Results from this study will have an impact on future generations by inspiring them to consider the exciting profession of engineering at an early age.

A study is presented on nanocrystalline diamond (NCD) growth on different substrates, including silicon with and without different metallic interlayers, on aluminum nitride (AlN), and on a Si/AlN-based cantilever. It is shown that non-diamond substrate treatment prior to NCD growth is important for achieving high nucleation densities. AFM measurements reveal that an additional Si surface pretreatment with hydrogen plasma increases the nucleation density by a factor of four. A similar effect was indirectly demonstrated with acidic pretreatment of AlN. In both cases it is believed that the surface roughening is the key factor for explaining this phenomenon.

The microstructure and compression response of a quaternary Mo-Nb-Si-B alloy has been examined in in the temperature interval 1200°C-1600°C and in the strain rate regime 10–4 s–1 to 10–6 s–1 and compared to earlier results on the ternary Mo-Si-B alloys The microstructure is composed of a three-phase microlamellar eutectic composed of the Mo-Nb solid solution phase, the T1 and the T2 intermetallic phases. Compression test confirm significantly superior creep resistance for the eutectic alloy compared to the ternary Mo-rich Mo-Si-B alloys with virtually no microstructural degradation.