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The fabrication of oxide-based p-n heterojunctions that exhibit high rectification performance has been difficult to realize using standard manufacturing techniques that feature mild vacuum requirements, low thermal budget processing, and scalability. Critical bottlenecks in the fabrication of these heterojunctions include the narrow processing window of p-type oxides and the charge-blocking performance across the metallurgical junction required for achieving low reverse current and hence high rectification behavior. The overarching goal of the present study is to demonstrate a simple processing route to fabricate oxide-based p-n heterojunctions that demonstrate high on/off rectification behavior, a low saturation current, and a small turn-on voltage. For this study, room-temperature sputter-deposited p-SnOx and n-InGaZnO (IGZO) films were chosen. SnOx is a promising p-type oxide material due to its monocationic system that limits complexities related to processing and properties, compared to other multicationic oxide materials. For the n-type oxide, IGZO is selected due to the knowledge that postprocessing annealing critically reduces the defect and trap densities in IGZO to ensure minimal interfacial recombination and high charge-blocking performance in the heterojunctions. The resulting oxide p-n heterojunction exhibits a high rectification ratio greater than 103 at ±3 V, a low saturation current of ∼2 × 10-10 A, and a small turn-on voltage of ∼0.5 V. In addition, the demonstrated oxide p-n heterojunctions exhibit excellent stability over time in air due to the p-SnOx with completed reaction annealing in air and the reduced trap density in n-IGZO.

The design freedom provided by Additive Manufacturing (AM) enables the part consolidation (PC) of sophisticated mechanical assemblies. However, PC has been mainly performed for static components in assemblies with nonmoving parts. In this regard, a new approach to assembly-level Design for Additive Manufacturing (A-DfAM) considering an industrial lifeboat hook assembly with a functionally dynamic system is proposed. The methodology comprises steps starting from inputting the Computer-Aided Design (CAD) files for the 3D printing of the final assembly and evaluation. Throughout the design stages, opportunistic and restrictive natures of DfAM within our methodology direct engineers and designers to manufacture optimized products. In addition, a comparative assessment of the original and final assemblies is also illustrated. Consequently, a significant part-count reduction after PC was achieved, and the prototype of the lifeboat hook components was printed via laser-powder bed fusion (L-PBF). This shows that by incorporating the suggested A-DfAM framework, it can serve as a potential guide to whoever intends to manufacture dynamic assemblies.

We report facile growth methods for high-quality monolayer and multilayer MoS2 films using MoOCl4 as the vapor-phase molecular Mo precursor. Compared to the conventional covalent solid-type Mo precursors, the growth pressure of MoOCl4 can be precisely controlled. This enables the selection of growth mode by adjusting growth pressure, which facilitates the control of the growth behavior as the growth termination at a monolayer or as the continuous growth to a multilayer. In addition, the use of carbon-free precursors eliminates concerns about carbon contamination in the produced MoS2 films. Systematic studies for unveiling the growth mechanism proved two growth modes, which are predominantly the physisorption and chemisorption of MoOCl4. Consequently, the thickness of MoS2 can be controlled by our method as the application demands.

Oxygen (O2)-mediated controlled radical polymerization was performed on surfaces under ambient conditions, enabling on-surface polymer brush growth under open-to-air conditions at room temperature in the absence of metal components. Polymerization of zwitterionic monomers using this O2-mediated surface-initiated reversible addition fragmentation chain-transfer (O2-SI-RAFT) method yielded hydrophilic surfaces that exhibited anti-biofouling effects. O2-SI-RAFT polymerization can be performed on large surfaces under open-to-air conditions. Various monomers including (meth)acrylates and acrylamides were employed for O2-SI-RAFT polymerization; the method is thus versatile in terms of the polymers used for coating and functionalization. A wide range of hydrophilic and hydrophobic monomers can be employed. In addition, the end-group functionality of the polymer grown by O2-SI-RAFT polymerization allowed chain extension to form block copolymer brushes on a surface.

Polydimethylsiloxane (PDMS) is widely utilised as a substrate for wearable (stretchable) electronics where high fatigue resistance is required. Cyclic loadings cause the rearrangement of the basic molecular structure of polymer chains, which leads to changes in the mechanical properties of the PDMS structure. Accordingly, it is necessary to investigate reliable mechanical properties of PDMS considering both monotonic and cyclic loading conditions. This study aims to present the mechanical properties of PDMS films against both monotonic and cyclic loading. The effects of certain parameters, such as film thickness and magnitude of tensile strain, on mechanical properties are also investigated. The test results show that PDMS films have a constant monotonic elastic modulus regardless of the influence of thickness and tensile loading, whereas a cyclic elastic modulus changes depending on experimental parameters. Several material parameters, such as neo-Hookean, Mooney–Rivlin, the third-order Ogden model, and Yeoh, are defined to mimic the stress–strain behaviours of the PDMS films. Among them, it is confirmed that the third-order Ogden model is best suited for simulating the PDMS films over the entire tensile test range. This research makes contributions not only to understanding the mechanical behaviour of the PDMS films between the monotonic and the cycle loadings, but also through providing trustworthy hyperelastic material coefficients that enable the evaluation of the structural integrity of the PDMS films using the finite element technique.

The fabrication of oxide-based p-n heterojunctions that exhibit high rectification performance has been difficult to realize using standard manufacturing techniques that feature mild vacuum requirements, low thermal budget processing, and scalability. Critical bottlenecks in the fabrication of these heterojunctions include the narrow processing window of p-type oxides and the charge-blocking performance across the metallurgical junction required for achieving low reverse current and hence high rectification behavior. The overarching goal of the present study is to demonstrate a simple processing route to fabricate oxide-based p-n heterojunctions that demonstrate high on/off rectification behavior, a low saturation current, and a small turn-on voltage. For this study, room-temperature sputter-deposited p-SnO

Photoelectrooxidation of chloride ions to chlorine with co-production of hydrogen by water reduction has been proposed as a means of decreasing the net solar hydrogen production cost. So far, however, most such solar-to-chlorine production systems use cost-prohibitive materials and/or show rather small faradaic yield or stability. Here we report the development of earth-abundant, nanostructured bismuth vanadate/tungsten oxide (BiVO4/WO3) photoanode assemblies that operate in acidic sodium chloride solution (pH 1; 4 M) to produce chlorine while generating hydrogen at the dark cathode. We show that electrodeposition of 20 nm WO3 coating protects BiVO4 from harsh pH and oxidative environments while being catalytically active for chlorine evolution. The heterostructured BiVO4/WO3 photoanodes yield average photocurrent densities of 2.5 ± 0.3 mA cm−2 at 1.42 VRHE (Reversible Hydrogen Electrode) under 1 sun illumination. After two hours of continuous illumination, the best performing devices demonstrate faradaic efficiencies of 85% for chlorine production and ~100% for hydrogen production. Photoelectrochemical generation of hydrogen is of wide interest for promoting renewable energy. Here a BiVO4/WO3 photooanode is used to generate chlorine and hydrogen from acidic chloride media with Faradaic efficiency of up to 85% for chlorine and 100% for hydrogen over three hours of operation.

We report the oxygen evolution reaction (OER) catalyst composed of cobalt–calcium phosphate on reduced graphene oxide (CoCaP/rGO). Our catalyst is prepared by the anodic electrolysis of calcium phosphate/rGO mixture loaded on indium-tin-oxide (ITO) in Co2+ aqueous solution. TEM, XPS and XRD experiments confirm that the crystal phase of calcium phosphate (CaP) is transferred into an amorphous phase of calcium oxide with phosphate (5.06 at%) after anodic electrolysis. Additionally, the main cation component of calcium is replaced by cobalt ion. The current–voltage characteristics of CoCaP/rGO showed a shoulder peak at 1.10 V vs. NHE, which originated from Co2+ to higher oxidation states (Co3+ or Co4+) and a strong wave from water oxidation higher +1.16 V vs. NHE at neutral condition (pH 7). CoCaP and CoCaP/rGO showed 4.8 and 10 mA/cm2 at 0.47 V of overpotential, respectively. The enhanced OER catalytic activity of CoCaP/rGO arises from the synergetic interaction between the amorphous phase of CoCaP and electric conducting graphene sheets.

Rainfall–runoff models are not perfect, and the suitability of a model structure depends on catchment characteristics and data. It is important to investigate the pros and cons of a rainfall–runoff model to improve both its high- and low-flow simulation. The production and routing components of the GR4J and IHACRES models were combined to create two new models. Specifically, the GR_IH model is the combination of the production store of the GR4J model and the routing store of the IHACRES model (vice versa in the IH_GR model). The performances of the new models were compared to those of the GR4J and IHACRES models to determine components improving the performance of the two original models. The suitability of the parameters was investigated with sensitivity analysis using 40 years’ worth of spatiotemporally different data for five catchments in Australia. These five catchments consist of two wet catchments, one intermediate catchment, and two dry catchments. As a result, the effective rainfall production and routing components of the IHACRES model were most suitable for high-flow simulation of wet catchments, and the routing component improved the low-flow simulation of intermediate and one dry catchments. Both effective rainfall production and routing components of the GR4J model were suitable for low-flow simulation of one dry catchment. The routing component of the GR4J model improved the low- and high-flow simulation of wet and dry catchments, respectively, and the effective rainfall production component improved both the high- and low-flow simulations of the intermediate catchment relative to the IHACRES model. This study provides useful information for the improvement of the two models.

Amorphous cobalt–calcium phosphate composite (CCPC) films are electrochemically prepared on various electrodes by utilizing the solid phase of hydroxyapatite as a phosphate source. The CCPC film formation is surface process in which the dissolution of hydroxyapatite and the deposition of CCPC film concurrently occur on the electrode surface without the mass transfer of phosphate ions into the bulk solution. Elemental, crystallographic, and morphological analyses (EDX, ICP-AES, XPS, and XRD) indicate that the CCPC is composed of amorphous cobalt oxide with calcium and phosphate. The film exhibits durable oxygen evolution reaction (OER) catalytic properties under neutral and basic aqueous condition. Compared to using solution phase of phosphate source, our preparation method utilizing solid hydroxyapatite has advantage of preventing unnecessary chemical reaction between phosphate and other chemical species in bulk solution.

We report facile growth methods for high-quality monolayer and multilayer MoS

The use of electron mirrors in aberration correction and surface-sensitive microscopy techniques such as low-energy electron microscopy has been established. However, in this work, by implementing an easy to construct, fully electrostatic electron mirror system under a sample in a conventional scanning electron microscope (SEM), we present a new imaging scheme which allows us to form scanned images of the top and bottom surfaces of the sample simultaneously. We believe that this imaging scheme could be of great value to the field of in-situ SEM which has been limited to observation of dynamic changes such as crack propagation and other surface phenomena on one side of samples at a time. We analyze the image properties when using a flat versus a concave electron mirror system and discuss two different regimes of operation. In addition to in-situ SEM, we foresee that our imaging scheme could open up avenues towards spherical aberration correction by the use of electron mirrors in SEMs without the need for complex beam separators.

A Dirac fermion emerges as a result of interplay between symmetry and topology in condensed matter. Current research moves towards investigating the Dirac fermions in the presence of many-body effects in correlated systems. Here, we demonstrate the emergence of a correlation-induced symmetry-protected Dirac semimetal state in the lightly doped spin-orbit-coupled Mott insulator ${\mathrm{Sr}}_{2}{\mathrm{IrO}}_{4}$. We find that the nonsymmorphic crystalline symmetry stabilizes a Dirac line-node semimetal and that the correlation-induced symmetry-breaking electronic order further leads to a phase transition from the Dirac line-node to a Dirac point-node semimetal. The latter state is experimentally confirmed by angle-resolved photoemission spectroscopy and terahertz spectroscopy on ${\mathrm{Sr}}_{2}(\text{Ir},\mathrm{Tb}){\mathrm{O}}_{4}$ and ${(\text{Sr},\mathrm{La})}_{2}{\mathrm{IrO}}_{4}$. Remarkably, the electrodynamics of the massless Dirac carriers is governed by the extremely small scattering rate of about 6 ${\mathrm{cm}}^{\ensuremath{-}1}$ even at room temperature, which is iconic behavior of relativistic quasiparticles. Temperature-dependent changes in electrodynamic parameters are also consistently explained based on the Dirac point-node semimetal state.

In this paper, we present a review of machine health managements for the smart factory. As the Industry 4.0 leads current factory automation and intelligent machines, the machine health management for diagnostic and prognostic purposes are essential, and their importance is getting more significant for the realization of the smart factory in the Industry 4.0. After brief introductions to important concepts and definitions composing smart factory and Industry 4.0, the developments in maintenance strategies towards Prognostics and health management (PHM) of machines are summarized. The review of machine health managements is followed, classifying the references by the monitoring components, types of measurements, as well as PHM tools and algorithms. 94 existing articles are reviewed and summarized in this regard. The implementations of machine health managements within the smart factory are discussed in terms of data connectivity, communications, Cyber-physical system (CPS) and virtual factory, relating them to Internet of things (IoT), cloud computing, and big data management.

In this study, we investigated the effect of hydrocarbon species composition on carbon nanotube (CNT) growth using an iron catalyst by chemical vapor deposition. The atomic hydrogen and active carbon species from hydrocarbon affect to the nucleation and growth of CNT arrays. With increasing atomic hydrogen content, the interface layer distance of the CNTs decreased from 3.7 to 3.4 A. The shifts in the G-band in the Raman spectra of the CNTs indicated that the hydrogen atoms affected the generation of C–C bonds in graphene layers.

The present study demonstrates a simple and robust strategy for fabricating nanocomposite thin films with high quality using a multi-component ZrCuSi single target. The ZrCuSi target was produced by using computer numerical control (CNC) based direct energy deposition (i.e., 3D printing). The influence of the energy density on morphological features and porosity of the ZrCuSi target surface was closely examined at a certain range of the energy density (75–225 J/mm3). X-ray diffractometer (XRD) and scanning electron microscopy (SEM) were applied for confirming the presence of the preferable crystallographic orientation and elucidating the morphological features of the nanocomposite target. In addition, functional nanocomposite thin films deposited from the ZrCuSi target presented in the current study were characterized. A scratch test and field-emission SEM (FE-SEM) revealed the adhesion properties and the morphological features of the nanocomposite coatings. Therefore, this work is highly expected to provide a facile and robust way to fabrication of e multi-component functional targets based ZrN, thereby envisioning usefulness of the nanocomposite coatings for automotive engine parts and various other wear protection applications.

Conceptual rainfall–runoff models are widely used to understand the hydrologic responses of catchments of interest. Modellers calculate the model performance statistics for the calibration and validation periods to investigate whether these models serve as satisfactory representations of the natural hydrologic phenomenon. Another useful method to investigate model suitability is sensitivity analysis (SA), which investigates structural uncertainty in the models. However, a comprehensive method is needed, which led us to develop a model suitability index (MSI) by combining the results of model performance statistics and SA. Here, we assessed and compared the suitability of three rainfall–runoff models (GR4J, IHACRES and Sacramento model) for seven Korean catchments using MSI. MSI showed that the GR4J and IHACRES models are suitable, having more than 0.5 MSI, whereas the Sacramento has less than 0.5 MSI, representing unsuitability for most of the Korean catchments. The MSI developed in this study is a quantitative measure that can be used for the comparison of rainfall–runoff models for different catchments. It uses the results of existing model performance statistics and sensitivity indices; hence, users can easily apply this index to their models and catchments to investigate suitability.

An effect of novel path generation algorithms for focused ion beam (FIB) milling is characterized in this paper. The basic concept of the suggested paths is to distribute the directional artifacts induced by the ion beam in order to overcome or minimize the inevitable drawbacks of FIB milling. Path generation algorithms, inspired by conventional mechanical machining, were applied to the FIB scanning paths. Our results showed that the scanning path had a significant influence on the product quality with negligible time loss. Numerous paths could be generated using the suggested approach, and eight representative paths were selected for experimental characterization with regard to the surface morphology, sputter yield, and artifacts formation. Our results showed that the backstitch raster and balanced raster exhibited the best quality in terms of low roughness and high squareness of the pocket. Conventional raster and serpentine scans created a large degree of defects, due to the material redeposition and varying ion incidence angle; however, these types of scan provided a high sputter yield. The proper scanning path can be determined with respect to the required squareness, surface roughness, or productivity.

Biological materials are the result of years of evolution and possess a number of efficient features and structures. Researchers have investigated the possibility of designing biomedical structures that take advantage of these structural features. Insect shells, such as beetle shells, are among the most promising types of biological material for biomimetic development. However, due to their intricate geometries and small sizes, it is challenging to measure the mechanical properties of these microscale structures. In this study, we developed an in-situ testing platform for site-specific experiments in a focused ion beam (FIB) system. Multi-axis nano-manipulators and a micro-force sensor were utilized in the testing platform to allow better results in the sample preparation and data acquisition. The entire test protocol, consisting of locating sample, ion beam milling and micro-mechanical bending tests, can be carried out without sample transfer or reattachment. We used our newly devised test platform to evaluate the micromechanical properties and structural features of each separated layer of the beetle horn shell. The Young’s modulus of both the exocuticle and endocuticle layers was measured. We carried out a bending test to characterize the layers mechanically. The exocuticle layer bent in a brick-like manner, while the endocuticle layer exhibited a crack blunting effect. Statement of Significance This paper proposed an in-situ manipulation/test method in focused ion beam for characterizing micromechanical properties of beetle horn shell. The challenge in precise and accurate fabrication for the samples with complex geometry was overcome by using nano-manipulators having multi-degree of freedom and a micro-gripper. With the aid of this specially designed test platform, bending tests were carried out on cantilever-shaped samples prepared by focused ion beam milling. Structural differences between exocuticle and endocuticle layers of beetle horn shell were explored and the results provided insight into the structural advantages of each biocomposite structure.

Electron beams can acquire designed phase modulations by passing through nanostructured material phase plates. These phase modulations enable electron wavefront shaping and benefit electron microscopy, spectroscopy, lithography, and interferometry. However, in the fabrication of electron phase plates, the typically used focused-ion-beam-milling method limits the fabrication throughput and hence the active area of the phase plates. Here, we fabricated large-area electron phase plates with electron-beam lithography and reactive-ion-etching. The phase plates are characterized by electron diffraction in transmission electron microscopes with various electron energies, as well as diffractive imaging in a scanning electron microscope. We found the phase plates could produce a null in the center of the bright-field based on coherent interference of diffractive beams. Our work adds capabilities to the fabrication of electron phase plates. The nullification of the direct beam and the tunable diffraction efficiency demonstrated here also paves the way towards novel dark-field electron-microscopy techniques and tunable electron phase plates.

Targeted irradiation of nanostructures by a finely focused ion beam provides routes to improved control of material modification and understanding of the physics of interactions between ion beams and nanomaterials. Here, we studied radiation damage in crystalline diamond and silicon nanostructures using a focused helium ion beam, with the former exhibiting extremely long-range ion propagation and large plastic deformation in a process visibly analogous to blow forming. We report the dependence of damage morphology on material, geometry, and irradiation conditions (ion dose, ion energy, ion species, and location). We anticipate that our method and findings will not only improve the understanding of radiation damage in isolated nanostructures, but will also support the design of new engineering materials and devices for current and future applications in nanotechnology.

Various uncertainty analysis methods have been used in various studies to analyze the uncertainty of rainfall-runoff models, however, these methods are difficult to apply immediately as they require a long learning time. In this study, we propose a simple uncertainty-screening method that allows modelers to investigate relatively easily the uncertainty of rainfall-runoff models. The 100 best parameter values of three rainfall-runoff models were extracted using the efficient sampler DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, and the distribution of the parameter values was investigated. Additionally, the ranges of the values of a model performance evaluation statistic and indicators of hydrologic alteration corresponding to the 100 parameter values for the calibration and validation periods was analyzed. The results showed that the Sacramento model, which has the largest number of parameters, had uncertainties in parameters, and the uncertainty of one parameter influenced all other parameters. Furthermore, the uncertainty in the prediction results of the Sacramento model was larger than those of other models. The IHACRES model had uncertainty in one parameter related to the slow flow simulation. On the other hand, the GR4J model had the lowest uncertainty compared to the other two models. The uncertainty-screening method presented in this study can be easily used when the modelers select rainfall-runoff models with lower uncertainty.

Sublimation is an interesting phenomenon that is frequently observed in nature. The thermal behavior of InAs NWs with As-face polarity and the [1[combining macron]1[combining macron]1[combining macron]] growth direction of the zinc blende structure were studied by using in situ transmission electron microscopy (TEM). In this study, the anisotropic morphological and atomistic evolution of InAs nanowires (NWs) was observed during decomposition. Two specific phenomena were observed during the continuous heating of the NWs as observed using the TEM: the decomposition of the InAs NWs around 380 °C, much lower than the melting temperature, and the formation of particular crystallographic facets during decomposition. The low decomposition temperature is related to vaporization under the vacuum conditions of the TEM. The anisotropic decomposition of the InAs NWs during heating can be explained based on the polarity and the surface energy difference of the zinc blende structure of InAs. For example, the decomposition along the [111] direction (that is, the indium-atom-terminated plane) was continuous, resulting in a few high-index planes, for example, (022), (3[combining macron]1[combining macron]1[combining macron]), and (200), whereas that in the opposite direction (the [1[combining macron]1[combining macron]1[combining macron]] direction) occurred abruptly with the formation of ledges and steps on the (1[combining macron]1[combining macron]1[combining macron]) planes, accompanied by the generation of small grooves on the surface of the NWs. Finally, density functional theory calculations were conducted to understand the sublimation of the InAs NWs from a theoretical point of view. This study is meaningful that it provides an insight into the microstructural evolution of polar nanomaterials during heating by theoretical and experimental approaches.

Following the skyrocketing demands for micro applications, various micro-cutting tools have been investigated up to a diameter of a few μm; however, most of them are limited in terms of tool geometry due to the fabrication techniques used. In this study, we present 30-μm-diameter micro-mechanical cutting tools with 3D cutting edges fabricated using FIB systems. Their geometries were inspired by macroscale cutting tools. Tools were fabricated with one, two, four, and multiple-lattice cutting edges, and their performances were compared with a bulk cylinder tool with no pattern. A local planarization system was constructed for the nanoporous structure. To assess performances, the height and roughness of the structures were measured after the planarization. The structure height was controlled at 1 μm, and a surface roughness of 20 nm was achieved. Among the patterns, the best surface roughness was obtained with the multiple-lattice cutting edges, and surface roughness improved as the number of edges increased. The tool showed little wear at the edges after several rounds of planarization. These results will contribute to the development of an intermediate process for nanoscale 3D printing, and also to direct microscale cutting of a structure.

The change of hydrological regimes may cause impacts on human and natural system. Therefore, investigation of hydrologic alteration induced by climate change is essential for preparing timely proper adaptation to the changes. This study employed 24 climate projections from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under Representative Concentration Pathway (RCP) 4.5 scenario. The climate projections were downscaled at a station-spacing for seven Korean catchments by a statistical downscaling method that preserves a long-term trend in climate projections. Using an ensemble of future hydrologic projections simulated by three conceptual rainfall-runoff models (GR4J, IHACRES, and Sacramento models), we calculated Hydrologic Alteration Factors (HAFs) to investigate degrees of variations in Indicators of Hydrologic Alteration (IHAs) derived from the hydrologic projections. The results showed that the seven catchments had similar trend in terms of the HAFs for the 24 IHAs. Given that more frequent severe floods and droughts were projected over Korean catchments, sound water supply strategies are definitely required to adapt to the alteration of streamflow. A wide range of HAFs between rainfall-runoff models for each catchment was detected by large variations in the magnitude of HAFs with the hydrologic models and the difference could be the hydrologic prediction uncertainty. There were no-consistent tendency in the order of HAFs between the hydrologic models. In addition, we found that the alterations of hydrologic regimes by climate change are smaller as the size of catchment is larger. Copyright © 2016 John Wiley & Sons, Ltd.

One of the astounding consequences of quantum mechanics is that it allows the detection of a target using an incident probe, with only a low probability of interaction of the probe and the target. This ‘quantum weirdness’ could be applied in the field of electron microscopy to generate images of beam-sensitive specimens with substantially reduced damage to the specimen. A reduction of beam-induced damage to specimens is especially of great importance if it can enable imaging of biological specimens with atomic resolution. Following a recent suggestion that interaction-free measurements are possible with electrons, we now analyze the difficulties of actually building an atomic resolution interaction-free electron microscope, or “quantum electron microscope”. A quantum electron microscope would require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times, thus supporting high success probabilities for interaction-free detection of the specimen. Different system designs are presented here, which are based on four different choices of two-state-couplers: a thin crystal, a grating mirror, a standing light wave and an electro-dynamical pseudopotential. Challenges for the detailed electron optical design are identified as future directions for development. While it is concluded that it should be possible to build an atomic resolution quantum electron microscope, we have also identified a number of hurdles to the development of such a microscope and further theoretical investigations that will be required to enable a complete interpretation of the images produced by such a microscope., Gordon and Betty Moore Foundation

This paper investigates the charge trapping mechanism and electrical performance of CdSe nanocrystals, such as nanoparticles and nanowires in organic floating gate memory devices. Despite of same chemical component, each nanocrystals show different electrical performances with distinct trapping mechanism. CdSe nanoparticles trap holes in the memory device; on the contrary, nanowires trap electrons. This phenomenon is mainly due to the difference of energy band structures between nanoparticles and nanowires, measured by the ultraviolet photoelectron spectroscopy. Also, we investigated the memory performance with C-V characteristics, charging and discharging phenomena, and retention time. The nanoparticle based hole trapping memory device has large memory window while the nanowire based electron trapping memory shows a narrow memory window. In spite of narrow memory window, the nanowire based memory device shows better retention performance of about 55% of the charge even after 104 sec of charging. The contrasting performance of nanoparticle and nanowire is attributed to the difference in their energy band and the morphology of thin layer in the device.