Current stability to improve AMS precision for cosmogenic 10Be applications

2021 ◽  
Author(s):  
Ana Carracedo Plumed ◽  
Derek Fabel ◽  
Richard Shanks
Keyword(s):  
Metal Matrix ◽  
Ion Beam ◽  
Beam Current ◽  
Ion Sources ◽  
Precipitation Process ◽  
Case Scenario ◽  
Series Of Experiments ◽  
Counting Statistics ◽  
Beam Currents ◽  
Cosmogenic 10Be

<p>With the present AMS <sup>10</sup>Be uncertainties (~2% best case scenario) and the increasing need for more precise cosmogenic <sup>10</sup>Be data it has become imperative to improve AMS measurements. Precision depends on counting statistics which in turn depend on ion beam current stability and sample longevity. The ion beam currents are dependent on the metal matrix in which BeO is dispersed; the matrix:BeO ratio; homogeneity of the mixture and the packing of the AMS cathode. We aim to understand the effect of cathode homogeneity in generating stable beam currents. We have performed a series of experiments using different metal matrices (Nb, Ag, Fe) in different forms (solid and in solution). The metals have been added to different stages of the sample precipitation process and both BeO and Be(OH)<sub>2</sub> have been pressed into AMS cathodes and analysed at SUERC. We will discuss results of these experiments and introduce an innovative use of polyoxometalates (molibdanate and niobate) to create a homogeneous compound that has the potential to generate stable ion beam currents from sputter ion sources.</p>

scholarly journals Developing Ultra Small-Scale Radiocarbon Sample Measurement at the University of Tokyo

Radiocarbon ◽  
2010 ◽  
Vol 52 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Yusuke Yokoyama ◽  
Mamito Koizumi ◽  
Hiroyuki Matsuzaki ◽  
Yosuke Miyairi ◽  
Naohiko Ohkouchi
Keyword(s):  
Ion Beam ◽  
Measurement Techniques ◽  
Beam Current ◽  
Ion Source ◽  
Small Samples ◽  
Small Scale ◽  
Target Holder ◽  
Vacuum Line ◽  
The Difference ◽  
Beam Currents

We have developed accelerator mass spectrometry (AMS) measurement techniques for ultra small-size samples ranging from 0.01 to 0.10 mg C with a new type of MC-SNICS ion source system. We can generate 4 times higher ion beam current intensity for ultra-small samples by optimization of graphite position in the target holder with the new ionizer geometry. CO2 gas graphitized in the newly developed vacuum line is pressed to a depth of 1.5 mm from the front of the target holder. This is much deeper than the previous position at 0.35 mm depth. We measured 12C4+ beam currents generated by small standards and ion beam currents (15–30 μA) from the targets in optimized position, lasting 20 min for 0.01 mg C and 65 min for 0.10 mg C. We observed that the measured 14C/12C ratios are unaffected by the difference of ion beam currents ranging from 5 to 30 μA, enabling measurement of ultra-small samples with high precision. Examination of the background samples revealed 1.1 μg of modern and 1 μg of dead carbon contaminations during target graphite preparation. We make corrections for the contamination from both the modern and background components. Reduction of the contamination is necessary for conducting more accurate measurement.

Ion Beam Deposition, Film Modification and Synthesis

MRS Bulletin ◽  
1988 ◽  
Vol 13 (12) ◽  
pp. 40-45 ◽  
Author(s):  
S.M. Rossnagel ◽  
J.J. Cuomo
Keyword(s):  
Thin Film ◽  
Ion Beam ◽  
Thin Film Deposition ◽  
High Energy ◽  
Film Deposition ◽  
Ion Sources ◽  
Chamber Pressure ◽  
Fusion Plasmas ◽  
Angle Of Incidence ◽  
Beam Currents

Ion beam processing for thin film deposition is rapidly overtaking some of the more conventional plasma-based thin film processing techniques. This is due to strong improvements in the types and reliabilities of the sources available as well as a growing understanding of the advantages and capabilities of using ion beams.An ion beam process can be differentiated from a plasma-based process in that the plasma in an ion beam is generated away from the sample and a beam of ions is directed at the sample. In a plasma-based process, the sample is usually immersed in the plasma. This highlights the fundamental advantage of ion beam processing—control of the flux and energy of the ions incident on either a sample or a target (for sputter deposition). It is this control which is missing in plasma-based processing, where the ion flux (current), ion energy, chamber pressure, and gas species are all hopelessly intertwined. In addition, certain aspects of the ion bombardment—angle of incidence, complications of gas scattering, etc. —are essentially fixed in plasma-based processing, leaving no room to vary parameters, and in conjunction, film properties.A wealth of different types of ion sources cover a broad range of beam currents and energies. At the high energy end (0.1 – 20 MeV) are the implantation sources, typically used for doping semiconductors and treating surfaces (hardening, for example) and for various types of nuclear chemical analysis. These sources, however, tend to be very low current (μA). At slightly lower energies (tens of kilo-electron volts), but significantly higher currents (50 A), are the ion sources used for heating fusion plasmas.

Further Inquiry into Xe Primary Ion Species for Circuit Edit Application

2017 ◽  
Author(s):  
Valery Ray ◽  
Ali Hadjikhani ◽  
Joseph Favata ◽  
Seyedeh Ahmadi ◽  
Sina Shahbazmohamadi
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Beam Current ◽  
Ion Sources ◽  
Advanced Technology ◽  
Semiconductor Materials ◽  
Beam Current Density ◽  
Fundamental Limitations ◽  
Technology Nodes ◽  
Ion Species

Abstract Widespread adoption and significant developments in Focused Ion Beam technology has made FIB/SEM instrumentation a commonplace sample preparation tool. Fundamental limitations inherent to Ga ion species complicate usage of Ga+ FIB instruments for the modification of semiconductor devices on advanced technology nodes. Said limitations are fueling interest in exploring alternative primary species and ion beam technologies for circuit edit applications. Exploratory tests of etching typical semiconductor materials with Xe ion beams generated from two plasma ion sources confirmed advantages of Xe+ as a potential ion species for gas-assisted etching of semiconductor materials, but also revealed potential complications including, swelling of metal and Xe+ retention within the material arising from excessive Xe ion beam current density.

The Characterization of CIGS Thin Films Prepared by Ion Beam Sputtering Deposition from a Quaternary Target

2013 ◽  
Vol 734-737 ◽  
pp. 2545-2548
Author(s):  
Chao Ming Chen ◽  
Ping Fan ◽  
Guang Xing Liang ◽  
Zhuang Hao Zheng ◽  
Dong Ping Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Ion Beam ◽  
Hall Effect Measurement ◽  
Beam Current ◽  
Chalcopyrite Structure ◽  
Ion Beam Sputtering ◽  
Sputtering Deposition ◽  
X Ray ◽  
Beam Sputtering ◽  
Beam Currents

This study reports the successful preparation of Cu (In, Ga)Se2(CIGS) thin film solar cells by ion beam sputtering with a chalcopyrite CIGS quaternary target. The films were fabricated with different beam currents. The thin films were characterized with X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and hall effect-measurement system to study the microstructures, composition, surface morphology and electrical properties, respectively. Experimental results show that both the films are chalcopyrite structure, the Ga/(In+Ga) ratio, Cu/(In+Ga) ratio and Se/(Cu+In+Ga) ratio are decrease with the beam currents increase, the surfaces morphology of the films are dense, and the resistivity of the film deposited with the beam current of 40mA is 0.56Ωcm, with a carrier concentration of 4.11Χ1018cm-3and mobility of 2.73cm2V-1s-1. The resulting film exhibited p-type conductivity.

Development of high-current ionic liquid ion source toward surface modification

2013 ◽  
Vol 1575 ◽  
Author(s):  
Mitsuaki Takeuchi ◽  
Takuya Hamaguchi ◽  
Hiromichi Ryuto ◽  
Gikan H Takaoka
Keyword(s):  
Ionic Liquid ◽  
Surface Modification ◽  
Flow Rate ◽  
Ion Beam ◽  
Beam Current ◽  
Ion Source ◽  
Ion Sources ◽  
Ion Current ◽  
High Current ◽  
Beam Characteristics

ABSTRACTIonic liquid (IL) ion sources with different emitter tip materials and tip numbers were developed and examined on ion beam characteristics with respect to its ILs wettability. As a result of ion current measurements, the most stable emission current was obtained for the graphite emitter tip and the ion current increased with increase of the tip number. The results indicate that the emitter wettability corresponding to the supplying flow rate and the number of emission site play an important role to stabilize and increase the beam current.

Effects of secondary γ-electrons from accelerator grid under ion impingement in gridded ion sources

2021 ◽  
Author(s):  
Sheng Hui Fu ◽  
Li Cheng Tian ◽  
Zhen- Feng Ding
Keyword(s):  
Electron Cyclotron Resonance ◽  
Voltage Drop ◽  
Ion Beam ◽  
Energetic Electron ◽  
Underlying Mechanism ◽  
Beam Current ◽  
Ion Source ◽  
Ion Sources ◽  
Direct Excitation ◽  
Screen Grid

Abstract Thus far, effects of secondary γ-electrons emitted from accelerator grids of gridded ion sources on ionization in discharge chambers have not been studied. The presence and induced processes of such secondary electrons in a microwave electron cyclotron resonance gridded ion source are confirmed by the consistent explanations of: (1) the observed jump of ion beam current (Ib) in case of a low-density plasma appearing at the chamber’s radial center due to the microwave skin effect; (2) the evolution of glow images recorded from the end-view of the ion source during the jump of Ib; (3) the over-large jump step of Ib with the increasing microwave power; (4) the pattern appearing on the temperature sticker exposed to the discharge operated in the regime where the arrayed energetic-electron beamlets are injected into the discharge chamber; (5) the measured step-increment in the voltage drop across the screen grid sheath. A positive feedback loop composed of involved processes are established to elucidate the underlying mechanism. Energetic γ-electrons from the accelerator grid and warm δ-electrons from the opposite antenna do not produce direct excitation and ionization, but they enhance the electrical confinement of cold electrons by elevating the voltage drop across the sheaths at the antenna and screen grid, thus leading to the jump of Ib. The energetic γ-electrons-based model can be also modified to explain abnormal results observed in the other gridded ion sources. Energetic γ-electrons from accelerator grids should be taken into account in understanding gridded ion sources.

Effects of Ion Beam Milling on Surface Topography

1973 ◽  
Vol 31 ◽  
pp. 84-85
Author(s):  
P.G. Pawar ◽  
P. Duhamel ◽  
G.W. Monk
Keyword(s):  
Surface Topography ◽  
Ion Beam ◽  
Solid Material ◽  
Beam Current ◽  
Atomic Mass ◽  
Micro Milling ◽  
Ion Milling ◽  
Controlled Atmospheres ◽  
Milling Operations ◽  
Sufficient Energy

A beam of ions of mass greater than a few atomic mass units and with sufficient energy can remove atoms from the surface of a solid material at a useful rate. A system used to achieve this purpose under controlled atmospheres is called an ion miliing machine. An ion milling apparatus presently available as IMMI-III with a IMMIAC was used in this investigation. Unless otherwise stated, all the micro milling operations were done with Ar+ at 6kv using a beam current of 100 μA for each of the two guns, with a specimen tilt of 15° from the horizontal plane.It is fairly well established that ion bombardment of the surface of homogeneous materials can produce surface topography which resembles geological erosional features.

Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

1990 ◽  
Vol 48 (1) ◽  
pp. 442-442
Author(s):  
Galen Powers ◽  
Ray Cochran
Keyword(s):  
Low Voltage ◽  
Beam Current ◽  
Microchannel Plate ◽  
Normal Operation ◽  
Microscopy Imaging ◽  
Backscatter Signal ◽  
Vacuum Interface ◽  
Width Measurements ◽  
Working Distance ◽  
Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

Quantitative Electrical Analysis of FIB Prepared Vias on BiCMOS and CMOS090 Designs

2006 ◽  
Author(s):  
B. Domengès ◽  
P. Poirier
Keyword(s):  
Ion Beam ◽  
Beam Current ◽  
Kelvin Probe ◽  
Metal Line ◽  
Cross Sectional ◽  
Probe Technique ◽  
Cross Sectional Analysis ◽  
Controlling Parameter ◽  
Electrical Analysis ◽  
Sectional Analysis

Abstract In this study, the resistance of FIB prepared vias was characterized by the Kelvin probe technique and their physical characteristics studied using cross-sectional analysis. Two domains of resistivity were isolated in relation to the ion beam current used for the deposition of the via metal (Pt). Also submicrometer vias were investigated on 4.2 µm deep metal lines of a BiCMOS aluminum based design and a CMOS 090 copper based one. It is shown that the controlling parameter is the shape and volume of the contact, and that the contact formation is favored by the amount of over-mill of the via into the metal line it will contact.

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