Electronic Imaging Applications Research Articles

Centimeter‐Scale Growth of Unidirectional CsCu2I3 Wire Arrays for High Performance UV Photodetectors

AbstractLead‐free CsCu2I3 has attracted tremendous research interests for photonics and photoelectronics due to their nontoxicity, unique electronic structure, and excellent stability. However, it is still challenging to achieve large‐scale ordered arrays of CsCu2I3 micro/nanowires, which limits their functional applications in integrated optoelectronic devices. Herein, unidirectional CsCu2I3 wire arrays are achieved in centimeter scale through a modified microchannel‐assisted spatial confinement strategy, which can confine the precursor solution into the pre‐fabricated microchannel arrays in large area and control its evaporation. The microstructure characterizations reveal that the orthorhombic CsCu2I3 wires are grown along the c‐axis with high crystallinity. The control experiments and theoretical studies indicate that the initial CsCu2I3 nucleation at the front of the solution in the channels and the stable solute supply maintained by the movement of the coverslip determine the growth of the wires. The photodetectors based on the CsCu2I3 wires show a high responsivity (80 mA W−1 at 365 nm; 1.29 A W−1 at 330 nm) and fast response speed (trise/tdecay = 640 µs/7.1 ms). Furthermore, these CsCu2I3 wire arrays exhibit great potential in future flexible electronic and UV imaging applications. This work opens a new way to grow well‐aligned copper‐based halides nano/microwire arrays for the integrated optoelectronics applications.

Controlling the aggregation and assembly of boron‐containing molecular and polymeric materials

AbstractBoron‐containing molecules and polymers are attractive as powerful tunable Lewis acids for small molecule activation and catalysis, as luminescent materials for organic electronic device and (bio)imaging applications, and as smart chemical sensors. While the characteristics of the boron‐containing building blocks are attractive in and of themselves, their assembly into higher order supramolecular materials offers access to unique properties and emerging functions. Herein, we highlight recent achievements in the field of aggregated organoboron materials. We discuss how supramolecular interactions can be exploited to precisely control the structure of the assemblies and impact their functions as luminescent materials, recyclable and smart catalyst systems, chemical sensors, stimuli‐responsive and self‐healing materials.

Intensity-based holographic imaging via space-domain Kramers–Kronig relations

Holography is a powerful tool to record waves without loss of information that has benefited optical, X-ray and electronic imaging applications by quantifying phase delays induced by light–matter interactions. However, holographic imaging is technically demanding in that it generally requires an interferometric setup, a coherent source and long-term stability. Here, we present holographic imaging in which a phase image is obtained directly from a single intensity measurement in oblique illumination. Our approach is based on space-domain Kramers–Kronig relations that transform the spatial variation in intensity to the spatial variation in phase. We demonstrate two-dimensional holographic imaging and three-dimensional refractive index tomography of microscopic objects and biological specimens from intensity images measured with an optical microscope and illumination control. The proposed method does not require iterative processes nor strict constraints and opens up a new approach to non-interferometric holographic imaging in various spectral regimes. An intensity-based holographic imaging via space-domain Kramers–Kronig relations is presented, allowing the phase image of an object to be obtained directly from a single intensity measurement with oblique illumination.

Towards realistic image via function learning

There has been a remarkable growth in computer vision due to the introduction of deep convolutional neural network. In most electronic imaging applications, images with high resolution are desired and cannot be ignored in many crucial applications. Super-resolution is a technique that enhances the resolution of images from the low-resolution input. Even thought, the performance of pattern recognition in computer vision will be improved if high resolution image is provided. The current super-resolution models based convolutional neural network has shown great performance, and also could outpace the other models. Depth in of CNN models is crucial importance for image super-resolution. However, the deeper networks based SR techniques are more difficult to train. To address these problems we propose a very deep residual network which comprises residual in residual structure to form a very deep network. In particular, the proposed model consists of several residual units with long skip connection. The proposed model allows low-frequency information to be bypassed through multiple skip connections, and the high-frequency information will be centralized in the main network. Extensive experiments show that our proposed model achieves better performance against state-of-the-art methods.

Imaging with ghostly electrons

Electron Imaging Ghost imaging is a computational imaging approach that uses correlations between a signal beam that interacts with a sample and a reference beam that doesn't. The correlations are then used to reconstruct an image of the sample and can, in principle, be used to image samples with very weak signal beams that might otherwise be damaged with a typical probe beam. Already demonstrated for optics and atoms, Li et al. now extend the method of ghost imaging to electrons. To circumvent the difficulty of splitting an electron beam, they instead used a structured electron beam to probe the sample. They show that a reconstructed image of a sample with a lower electron dose than that used in direct imaging methods can be faithfully produced. This technique could reduce acquisition time and avoid damaging sensitive samples in electron imaging applications. Phys. Rev. Lett. 121 , 114801 (2018).

Backscattered electron imaging and electron backscattered diffraction in the study of bacterial attachment to titanium alloy structure.

The application of secondary electron (SE) imaging, backscattered electron imaging (BSE) and electron backscattered diffraction (EBSD) was investigated in this work to study the bacterial adhesion and proliferation on a commercially pure titanium (cp Ti) and a Ti6Al4V alloy (Ti64) with respect to substrate microstructure and chemical composition. Adherence of Gram-positive Staphylococcus epidermidis 11047 and Streptococcus sanguinis GW2, and Gram-negative Serratia sp. NCIMB 40259 and Escherichia coli 10418 was compared on cp Ti, Ti64, pure aluminium (Al) and vanadium (V). The substrate microstructure and the bacterial distribution on these metals were characterised using SE, BSE and EBSD imaging. It was observed that titanium alloy-phase structure, grain boundaries and grain orientation did not influence bacterial adherence or proliferation at microscale. Adherence of all four strains was similar on cp Ti and Ti64 surfaces whilst inhibited on pure Al. This work establishes a nondestructive and straight-forward statistical method to analyse the relationship between microbial distribution and metal alloy structure.

Application of low-voltage backscattered electron imaging to the mapping of organic photovoltaic blend morphologies

With organic photovoltaic (OPV) technology moving towards commercialisation, high-throughput analytical techniques are required to study the nanoscale morphology of OPV blends. We demonstrate a low-voltage backscattered electron imaging technique in the SEM that combines a solid-state backscattered electron detector with stage biasing to produce a rapid overview of the phase-separated surface morphology of an organic photovoltaic (P3HT:PCBM) blend. Aspects of obtaining the best possible results from the technique are discussed along with the possibility of probing the sub-surface morphology by altering the primary electron beam landing energy.

Comparison of optimal performance at 300keV of three direct electron detectors for use in low dose electron microscopy.

Low dose electron imaging applications such as electron cryo-microscopy are now benefitting from the improved performance and flexibility of recently introduced electron imaging detectors in which electrons are directly incident on backthinned CMOS sensors. There are currently three commercially available detectors of this type: the Direct Electron DE-20, the FEI Falcon II and the Gatan K2 Summit. These have different characteristics and so it is important to compare their imaging properties carefully with a view to optimise how each is used. Results at 300 keV for both the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are presented. Of these, the DQE is the most important in the study of radiation sensitive samples where detector performance is crucial. We find that all three detectors have a better DQE than film. The K2 Summit has the best DQE at low spatial frequencies but with increasing spatial frequency its DQE falls below that of the Falcon II.

The application of back-scattered electron imaging for characterization of pearlitic steels

The microstructures of pearlitic steel wire rods and steel wires are commonly characterized by secondary electron imaging (SEI) technique using scanning electron microscopy (SEM). In this work, a back-scattered electron imaging (BSEI) method is proposed to determine the microstructures of undeformed and deformed pearlitic steels with nanometer scale pearlite lamellae. The results indicate that BSEI technique can characterize the pearlite lamellas veritably and is effective in quantitative measurement of the mean size of pearlite interlamellar spacing. To some extent, BSEI method is more suitable than SEI technique for studying undeformed and not severely deformed pearlitic steels.

Application of Electron Paramagnetic Resonance (EPR) spectroscopy and imaging in drug delivery research – Chances and challenges

Electron Paramagnetic Resonance (EPR) spectroscopy is a powerful technique to study chemical species with unpaired electrons. Since its discovery in 1944, it has been widely used in a number of research fields such as physics, chemistry, biology and material and food science. This review is focused on its application in drug delivery research. EPR permits the direct measurement of microviscosity and micropolarity inside drug delivery systems (DDS), the detection of microacidity, phase transitions and the characterization of colloidal drug carriers. Additional information about the spatial distribution can be obtained by EPR imaging. The chances and also the challenges of in vitro and in vivo EPR spectroscopy and imaging in the field of drug delivery are discussed.

SEM characterization of silicon nanostructures: can we meet the challenge?

The current semiconductor technology road map for device scaling champions a 4.5 nm gate length in production by 2022. The scanning electron microscope (SEM) as applied to critical dimensions (CD) metrology and associated characterization modes such as electron beam-induced current and cathodoluminescence (CL) has proved to be a workhorse for the semiconductor industry during the microelectronics era. We review some of the challenges facing these techniques in light of the silicon nanotechnology road map. We present some new results using voltage contrast imaging and CL spectroscopy of top-down fabricated silicon nanopillar/nanowires (<100 nm diameter), which highlight the visualization challenge. However, both techniques offer the promise of providing process characterization on the 10-20 nm scale with existing technology. Visualization at the 1 nm scale with these techniques may have to wait for aberration-corrected SEM to become more widely available. Basic secondary electron imaging and CD applications may be separately addressed by the He-ion microscope.

The Unique Diversity of Electron and Confocal Imaging Applications in a Natural History Museum Setting

Journal Article The Unique Diversity of Electron and Confocal Imaging Applications in a Natural History Museum Setting Get access Angela V Klaus Angela V Klaus Core Imaging Facility, American Museum of Natural History, New York, NY, USA Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 8, Issue S02, 1 August 2002, Pages 182–183, https://doi.org/10.1017/S1431927602101711 Published: 01 August 2002

Active pixel sensors for mass spectrometry

Active pixel sensors (APS) are micro-fabricated CMOS amplifier arrays that are rapidly replacing CCD devices in many electronic imaging applications. Unlike the pixels of a CCD device, the sensing elements of the APS will respond to locally situated electrostatic charge, owing to the amplifier present in each pixel. We have built two small test arrays with microscopic aluminum electrodes integrated onto standard APS readout circuitry for the purpose of detecting low-energy gas-phase ions in mass spectrometers and other analytical instruments. The devices exhibit a near-linear dynamic range greater than four orders of magnitude, and a noise level of less than 100 electrons at room temperature. Data are presented for the response of the APS detectors to small ions in a miniature magnetic sector mass spectrometer and in an atmospheric pressure jet of helium. Data for individual highly-charged electrospray droplets are presented as well. Anticipated improvements suggest that in the near future APS ion detectors will posses noise levels approaching 10 electrons and will have a useful dynamic range over six orders of magnitude.

Human vision and electronic imaging

Abstract. The field of electronic imaging has made incrediblestrides over the past decade producing systems with higher signalquality, complex data formats, sophisticated operations for analyz-ing and visualizing information, advanced interfaces, and richer im-age environments. Since electronic imaging systems and applica-tions are designed for human users, the success of these systemsdepends on the degree to which they match the features of humanvision and cognition. This paper reviews the interplay between hu-man vision and electronic imaging, describing how the methods,models and experiments in human vision have influenced the devel-opment of imaging systems, and how imaging technologies and ap-plications have raised new research questions for the vision com-munity. Using the past decade of papers from the IS&T/SPIEConference on Human Vision and Electronic Imaging as a lens, wetrace a path up the ‘‘perceptual food chain,’’ showing how researchin low-level vision has influenced image quality metrics, image com-pression algorithms, rendering techniques and display design, howresearch in attention and pattern recognition have influenced thedevelopment of image analysis, visualization, and digital librariessystems, and how research in higher-level functions is involved inthe design of emotional, aesthetic, and virtual systems.

Revealing hidden structures: The application of cathodoluminescence and back-scattered electron imaging to dating zircons from lower crustal xenoliths

The use of cathodoluminescence (CL) and/or back-scattered electron (BSE) imaging techniques with in situ ion probe analyses of zircons can help unravel complex crustal histories of metamorphic rocks that otherwise might remain elusive. Using these techniques we have imaged zircons from three lower crustal xenolith suites that have previously been dated by SHRIMP (sensitive high-resolution ion microprobe). In all three cases, the zircons are featureless in transmitted light but CL and BSE reveal internal structures that correlate with distinct growth events. Generally, CL and BSE images reveal similar structures, with CL showing finer detail. Neither imaging technique is capable of delineating all growth features in every sample and the best results are obtained using a combination of the two techniques. Igneous cores in zircons commonly emit a different color CL emission. In many cases zoning in the cores is truncated, indicating that the zircons either spent time in the supracrustal environment after their initial crystallization and prior to the granulite facies event (s) or that part of the core zircon was resorbed during the subsequent metamorphic event. Metamorphic rims, when present, are commonly 10 to 30 μm thick, and are nearly always unzoned and featureless.Igneous cores and metamorphic overgrowths commonly have distinctive CL emission spectra and trace element concentrations. However, the CL spectra can only be used to qualify chemical differences, as a linear relationship has not been shown to exist between CL intensity and trace element concentration in natural zircons. In many cases the Hf, Y, P, U and the heavy rare-earth elements (HREEs) concentrations can be correlated to igneous and metamorphic growth using a combination of CL and BSE imaging techniques and in situ trace element analyses with either the electron microprobe or PIXE (particle induced X-ray emission).

Microscopy and microanalysis of calcification in the developing and adult barnacle

The barnacle begins its development in its first larval stage, the naupilus, and matures to the larval cyprid stage. Permanent attachment of the barnacle occurs between the cyprid and juvenile stages. Soon after, calcification takes place and the shells of the barnacle grow upward. The application of secondary electron imaging (SEI) and electron probe microanalysis (EPXMA) has defined the time course of calcification and shell growth in the barnacle. Freeze-dried cryosections of the larval cyprid stage can also be employed for localization of calcium at the cellular level with scanning transmission electron microscopy (STEM)/EPXMA; however these sections are unstained, thereby offering very little contrast and making the recognition of ultrastuctural compartments difficult. In an attempt to identify these structures, conventional fixation staining and transmission electron microscopy (TEM) will be used. The light microscopic study of the cyprid has been extensive, but very little ultrastructural research has been conducted. The goal of this study is twofold: to use light microscopy (LM) and TEM as guides in identifying structures of the STEM/EPXMA cryosections; and to follow the growth of the barnacle by using STEM/EPXMA to detect calcium tracers in the shell.

The technologies of electronic imaging

This article provides a brief overview of the technologies of electronic imaging as background for the other articles in this Perspectives, and focuses on technologies seen by the developer or user of electronic imaging applications. It includes a brief discussion of architectural and standards issues that arise in electronic imaging applications, and goes into more depth on issues of developing image‐oriented networked information resources. A short discussion of sources for further information on electronic imaging concludes the article. © 1991 John Wiley & Sons, Inc.