A5103023658- Diamond and Carbon-based Materials Research
- Force Microscopy Techniques and Applications
- Radiation Detection and Scintillator Technologies
- Advanced Surface Polishing Techniques
- Electron and X-Ray Spectroscopy Techniques
- Advanced X-ray and CT Imaging
- Advanced Chemical Physics Studies
- Photocathodes and Microchannel Plates
- Electronic and Structural Properties of Oxides
- Semiconductor materials and devices
- High-pressure geophysics and materials
- Mechanical and Optical Resonators
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Semiconductor Detectors and Materials
- Advanced Optical Sensing Technologies
- Gyrotron and Vacuum Electronics Research
- Organic Electronics and Photovoltaics
- Nuclear Physics and Applications
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Hydrogen Storage and Materials
- Ammonia Synthesis and Nitrogen Reduction
- Advanced Electron Microscopy Techniques and Applications
- Molecular Junctions and Nanostructures
Brookhaven National Laboratory
2009-2024
Brookhaven College
2024
Eindhoven University of Technology
2023
Stony Brook University
2012-2022
Los Alamos National Laboratory
2020
California Institute of Technology
2020
Trier University of Applied Sciences
2015
IBM Research - Thomas J. Watson Research Center
2012
National Institute of Standards and Technology
2012
Stanford Synchrotron Radiation Lightsource
2010
Charge traps in pentacene thin-film transistors (Figure, left) have been imaged using electric force microscopy. The Figure shows a map of the trap distribution just below (middle) and well above (right) transistor threshold voltage. It is found that long-lived charge polycrystalline are distributed inhomogeneously do not appear to be associated with grain boundaries, as generally assumed (see cover).
Here we introduce time-resolved electric force microscopy measurements to directly and locally probe the kinetics of charge trap formation in a polycrystalline pentacene thin-film transistor. We find that trapping rate depends strongly on initial concentration free holes trapped is highly localized. The observed dependence hole chemical potential suggests process should not be viewed as filling midgap energy levels, but instead which very creation states requires presence holes.
Alkali-antimonide photocathodes were grown on Si(100) and studied by means of XPS UHV-AFM to validate the growth procedure morphology this material. The elements evaporated sequentially at elevated substrate temperatures (first Sb, second K, third Cs). generated intermediate K-Sb compound itself is a photocathode composition K2.4Sb close favored K3Sb stoichiometry. After cesium deposition, surface layer enriched. determined rms roughness 25 nm results in domination emittance photoinjector...
High-quality single-crystal and polycrystalline chemical-vapor-deposition diamond detectors with platinum contacts have been tested at the white-beam X28C beamline National Synchrotron Light Source under high-flux conditions. The voltage dependence of these devices has measured both DC pulsed-bias conditions, establishing presence or absence photoconductive gain in each device. Linear response consistent theoretically determined ionization energy achieved over eleven orders magnitude when...
Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode Si(100) substrates. The amorphous-to-crystalline transition for initial antimony layer was observed at film thickness 40 Å . crystalline structure dissolved upon potassium deposition,...
This study investigates the scintillation properties of polycrystalline diamond for particle detection applications, particularly in neutron and alpha radiation environments. Polycrystalline diamonds provide a cost-effective alternative to monocrystalline while retaining essential properties. Photoluminescence measurements were performed analyze emission spectra, revealing distinct characteristics based on impurity content crystallinity. Scintillation responses assessed using Silicon...
The diamond amplifier (DA) is a new device for generating high-current, high-brightness electron beams. Our transmission-mode tests show that, with single-crystal, high-purity diamonds, the peak current density greater than 400 mA/mm², while its average can be more 100 mA/mm². gain of primary electrons easily exceeds 200, and independent their within practical range DA applications. We observed emission. maximum emission measured was 40, bunch charge 50 pC/0.5 mm². There 35% probability an...
Electron emission from the negative electron affinity (NEA) surface of hydrogen terminated, boron doped diamond in [100] orientation is investigated using angle resolved photoemission spectroscopy (ARPES). ARPES measurements 16 eV synchrotron and 6 laser light are compared found to show a catastrophic failure sudden approximation. While high energy yield little information regarding NEA, low reveals for first time that NEA results novel Franck-Condon mechanism coupling electrons conduction...
A promising new concept of a diamond-amplified photocathode for generation high-current, high-brightness, and low thermal emittance electron beams was recently proposed is currently under active development. Detailed understanding physical processes with multiple energy time scales required to design reliable efficient diamond-amplifier cathodes. We have implemented models, within the VORPAL computational framework, simulate secondary charge transport in diamond order facilitate...
Hard x-ray photoelectron spectroscopy was applied to investigate the diamond-metal Schottky barrier heights for several metals and diamond surface terminations. The position of valence-band maximum determined by theoretically calculating density states applying cross section corrections. diamond-platinum height lowered 0.2 eV after thermal annealing, indicating annealing may increase carrier injection in devices leading photoconductive gain. platinum contacts on oxygen-terminated found...
Two transmission-mode diamond X-ray beam position monitors installed at National Synchrotron Light Source (NSLS) beamline X25 are described. Each monitor is constructed around two horizontally tiled electronic-grade (p.p.b. nitrogen impurity) single-crystal (001) CVD synthetic diamonds. The position, angle and flux of the white can be monitored in real time with a resolution 500 nm horizontal direction 100 vertical for 3 mm × 1 beam. first has been operation more than one year without any...
K2CsSb is a promising photocathode candidate to serve as an electron source in next-generation light sources such Free Electron Lasers (FEL) and Energy Recovery Linacs (ERL). As the traditional recipe for creation of photocathodes typically results rough surface that deteriorates beam quality, significant effort has been made explore novel growth methods photocathodes. In this paper, method ternary co-evaporation K, Cs, Sb described. By using in-situ synchrotron X-ray techniques, quality...
K-Cs-Sb bialkali antimonide photocathodes grown by a triple-element codeposition method have been found to excellent quantum efficiency (QE) and outstanding near-atomic surface smoothness employed in the VHF gun Advanced Photoinjector Experiment (APEX), however, their robustness terms of lifetime at elevated photocathode temperature has not yet investigated. In this paper, relationship between The origin significant QE degradation temperatures over $70\text{...
Bi-alkali antimonide photocathodes are one of the best known sources electrons for high current and/or bunch charge applications like Energy Recovery Linacs or Free Electron Lasers. Despite their quantum efficiency in visible light and low intrinsic emittance, surface roughness these prohibits use as emittance cathodes accelerating gradient superconducting normal conducting radio frequency photoguns limits minimum possible near threshold. Also, growth process materials is largely based on...
Cesium telluride (CsTe) photocathodes have been the primary choice for electron sources by worldwide accelerators, due to their high quantum yield, stable performance in complex operation environments and long lifetime. In this paper we compared traditional sequential newly developed coevaporation growth of CsTe describing chemical structural evolution each method, using situ, real time x-ray characterization. From codeposition were able achieve ∼2 nm surface roughness, crystallinity a...
Fabrication and testing of a prototype transmission-mode pixelated diamond X-ray detector (pitch size 60-100 µm), designed to simultaneously measure the flux, position morphology an beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on front horizontal back electronic-grade chemical vapor deposition single-crystal diamond. bias rotated through current read out at rate ∼ 1 kHz, which leads image sampling 30 Hz. This novel signal...
Doping catalytically inactive materials with dispersed atoms of an active species is a promising route toward realizing ultradilute binary catalyst systems. Beyond catalysis, strategically placed metal can accelerate wide range solid-state reactions, particularly in hydrogen storage processes. Here we analyze the role atomic Ti catalysts hydrogenation Al-based materials. We show that near Al surface activate gas-phase H(2), key step hydrogenation. By controlling placement Ti, have found...
Advanced photoinjectors, which are critical to many next generation accelerators, open the door new ways of material probing, both as injectors for free electron lasers and ultra-fast diffraction. For these applications, nonuniformity electric field near cathode caused by surface roughness can be dominant source beam emittance. Therefore, improving photocathode while maintaining quantum efficiency is essential improvement brightness. In this paper, we report demonstration a bi-alkali...
Diamond, a highly radiation-resistant material, is considered nearly ideal material for radiation detection, particularly in high-energy physics. In this study, damage from proton beams was induced diamond crystals to determine exposure lifetime detectors made material; the effects were investigated using non-destructive x-ray techniques and through FLUKA simulation package. Two irradiated by an 800 MeV beam at different fluence rates, real-time current response recorded observe degradation...
Using scanning tunneling microscopy and density functional theory, we characterize the population of low-coverage Ti atoms on Al(111) as a model surface system for transition metal doped alanate hydrogen storage compounds, such NaAlH4. When deposited at room temperature, is kinetically trapped in first-layer substitutional sites, avoids nearest-neighbor locations, preferentially forms next-nearest-neighbor pairs, similar to structure that has been predicted dissociate H2 with no energy...
Diamond X-ray detectors with conducting nitrogen-incorporated ultra-nanocrystalline diamond (N-UNCD) films as electrodes were fabricated to measure beam flux and position. Structural characterization functionality tests performed for these devices. The N-UNCD grown on unseeded substrates compared a seeded silicon substrate. feasibility of the acting was confirmed by stable performance in monochromatic beam. fabrication process is able change surface status which may influence signal...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Erik M. Muller, Mengjia Gaowei, Ilan Ben-Zvi, Dimitre A. Dimitrov, John Smedley; Carbon edge response of diamond devices. Appl. Phys. Lett. 3 March 2014; 104 (9): 093515. https://doi.org/10.1063/1.4868135 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks...