scholarly journals AlGaN/GaN asymmetric graded-index separate confinement heterostructures designed for electron-beam pumped UV lasers

2021 ◽  
Author(s):  
Eva Monroy ◽  
Sergi Cuesta ◽  
Yoann Curé ◽  
Fabrice Donatini ◽  
Lou Denaix ◽  
...  
Keyword(s):  
Electron Beam ◽  
Graded Index ◽  
Uv Lasers

Table-top Cathodoluminescence Microscopy for Geology

2020 ◽  
Author(s):  
Toon Coenen ◽  
Albert Polman
Keyword(s):  
Electron Beam ◽  
Detection System ◽  
Energetic Electron ◽  
Numerical Aperture ◽  
Graded Index ◽  
Thermo Fisher Scientific ◽  
Deformation Features ◽  
Backscattered Electron ◽  
User Friendly ◽  
Fisher Scientific

<p>Cathodoluminescence (CL) microscopy is a well-known technique for imaging geological specimens, in which the light that is generated with an energetic electron beam is collected and analyzed with a CL detector. CL provides a unique imaging contrast that can be used for visualizing growth zonation, distinguishing cement and granular detrital material, detecting trace elements, and characterizing fractures and deformation features in a large range of rocks, to name a few examples. In its simplest form CL imaging is performed with a static electron beam in an optical microscopy system (optical CL) but for more advanced experiments CL imaging is performed in a scanning electron microscope (SEM). This enables high scan speeds, high spatial resolution (< 100 nm), and correlation with other SEM based techniques such as X-ray imaging (EDS), secondary electron (SE) and backscattered electron (BSE) imaging, and more.</p><p>Currently, SEM-based CL work is mostly performed on costly floor model SEMs that require large amounts of space, complex auxiliary support systems, and an experienced operator to run the machine. In contrast, compact, affordable, and user-friendly table-top SEMs have improved substantially in the last years but they typically lack (advanced) CL imaging capabilities. Here, we will present our progress in developing a table-top SEM based CL system that can be used for geological research amongst other applications.</p><p>In particular, we have integrated a CL collection and detection system in a Thermo Fisher Scientific/Phenom XL table-top microscope, which already is equipped with SE, BSE, and EDS imaging modalities. In this SEM, electron energies of 5 – 15 keV can be used which is appropriate for most CL imaging experiments. The CL is collected using a multimode fiber optic cable connected with a graded index lens to increase the numerical aperture of the collection. Subsequently, the light is send to a spectrometer where the CL emission spectrum can be measured for every excitation point on the sample; a technique known as hyperspectral CL  imaging. To synchronize electron beam scanning with data acquisition and for data analysis we have developed dedicated software control.</p><p>We assess the potential of table-top CL by imaging representative polished zircon and quartz samples for various beam and acquisition parameters. To benchmark the system performance we compare our experimental results with results obtained from a state-of-the-art floor model SEM (Thermo Fisher Scientific Quanta 650 SFEG) system equipped with a high-end Delmic SPARC CL system. In the future, these developments may lower the threshold for using CL imaging through cost reduction and workflow simplification, making it accessible to a larger range of users within the field of geology and beyond.</p>

Degradation defects in electron-beam-pumped Zn-Cd/Se ZnSe graded-index separate-confinement 1 x x heterostructure (GRINSCH) blue and blue-green lasers

1997 ◽  
Vol 76 (3) ◽  
pp. 181-188 ◽  
Author(s):  
Jean-Marc Bonard ◽  
Jean-Daniel Ganieíre ◽  
Jens J. Paggel ◽  
Lucia Sorba ◽  
Alfonso Franciosi ◽  
...  
Keyword(s):  
Electron Beam ◽  
Graded Index

Electron-beam excitation of a Ce3+:LiCaAlF6 crystal for future high-peak-power UV lasers

2002 ◽  
Vol 74 (S1) ◽  
pp. s185-s187 ◽  
Author(s):  
T. Kozeki ◽  
Y. Suzuki ◽  
M. Sakai ◽  
H. Ohtake ◽  
N. Sarukura ◽  
...  
Keyword(s):  
Electron Beam ◽  
Peak Power ◽  
High Peak ◽  
High Peak Power ◽  
Electron Beam Excitation ◽  
Uv Lasers ◽  
Beam Excitation

ZnSe-based laser structures for electron-beam pumping with graded index waveguide

2010 ◽  
Vol 7 (6) ◽  
pp. 1694-1696 ◽  
Author(s):  
S. V. Gronin ◽  
S. V. Sorokin ◽  
I. V. Sedova ◽  
S. V. Ivanov ◽  
E. V. Zdanova ◽  
...  
Keyword(s):  
Electron Beam ◽  
Graded Index

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Temperature Dependence of the Critical Electron Dose for Fatty Acid Monolayers

1982 ◽  
Vol 40 ◽  
pp. 78-79
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Fatty Acid ◽  
Inelastic Scattering ◽  
Temperature Dependence ◽  
Structural Damage ◽  
Direct Result ◽  
Second Step ◽  
Strong Temperature Dependence ◽  
Electron Dose ◽  
Covalent Bonds

The structural damage of molecules irradiated by electrons is generally considered to occur in two steps. The direct result of inelastic scattering events is the disruption of covalent bonds. Following changes in bond structure, movement of the constituent atoms produces permanent distortions of the molecules. Since at least the second step should show a strong temperature dependence, it was to be expected that cooling a specimen should extend its lifetime in the electron beam. This result has been found in a large number of experiments, but the degree to which cooling the specimen enhances its resistance to radiation damage has been found to vary widely with specimen types.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Materials for Electron Beam Information Storage

1969 ◽  
Vol 27 ◽  
pp. 152-153 ◽  
Author(s):  
D. E. Speliotis
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Recent Literature ◽  
Electron Beams ◽  
Information Storage ◽  
The Subject ◽  
The Magnetic Field

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.

Application of Improved Voltage Compensation in the SEM to Imaging of Organic Materials

1973 ◽  
Vol 31 ◽  
pp. 444-445
Author(s):  
P.J. Killingworth ◽  
M. Warren
Keyword(s):  
Electron Beam ◽  
Organic Materials ◽  
Operating Parameters ◽  
Low Density ◽  
Beam Diameter ◽  
Incident Electron Beam ◽  
Specimen Material ◽  
Voltage Compensation ◽  
Selection Of ◽  
Scanning Electron

Ultimate resolution in the scanning electron microscope is determined not only by the diameter of the incident electron beam, but by interaction of that beam with the specimen material. Generally, while minimum beam diameter diminishes with increasing voltage, due to the reduced effect of aberration component and magnetic interference, the excited volume within the sample increases with electron energy. Thus, for any given material and imaging signal, there is an optimum volt age to achieve best resolution.In the case of organic materials, which are in general of low density and electric ally non-conducting; and may in addition be susceptible to radiation and heat damage, the selection of correct operating parameters is extremely critical and is achiev ed by interative adjustment.

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