A High Performance Energy Analyzer for Use in Electron Scanning Microscopy

1969 ◽  
Vol 27 ◽  
pp. 14-15
Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
High Performance ◽  
Vertical Plane ◽  
Median Plane ◽  
Electron Gun ◽  
Uniform Field ◽  
Loss Mechanism ◽  
Electron Scanning Microscopy ◽  
Sector Type ◽  
Double Focusing ◽  
Electron Energy Loss

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).

Structural and ferromagnetic properties of Cu-doped GaN

2007 ◽  
Vol 22 (5) ◽  
pp. 1396-1405 ◽  
Author(s):  
B. Seipel ◽  
R. Erni ◽  
Amita Gupta ◽  
C. Li ◽  
F.J. Owens ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Electron Gun ◽  
Superconducting Quantum Interference Device ◽  
X Ray Diffraction ◽  
Calcination Process ◽  
X Ray ◽  
Lattice Constants ◽  
Gan Crystal ◽  
Electron Energy Loss ◽  
Atomic And Electronic Structure

The wurtzite polymorph of GaN was calcined with CuO in flowing nitrogen. As a result of this processing, both superconducting quantum interference device magnetometry and ferromagnetic resonance studies showed ferromagnetism in these samples at room temperature. These magnetic results are qualitatively consistent with very recent first-principle calculations [Wu et al., Appl. Phys. Lett.89, 062505 (2006)] that predict ferromagnetism in Cu-doped GaN. We focus in this paper on analyzing changes in the GaN atomic and electronic structure due to calcination with CuO using multiple analytical methods. Quantitative powder x-ray diffraction (XRD) showed changes in the lattice constants of the GaN due to the incorporation of copper (and possibly oxygen). Energy-dispersive x-ray spectroscopy proved the incorporation of copper into the GaN crystal structure. Electron-gun monochromated electron energy loss spectroscopy showed CuO calcinations-induced GaN band gap changes and indicated changes in the atomic arrangements due to the calcination process. The fine structure of the N K-edge showed differences in the peak ratios with respect to higher nominal CuO contents, corresponding to an increase in the c-lattice constant as confirmed by XRD.

scholarly journals Energy Loss in a MEMS Disk Resonator Gyroscope

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 493 ◽  
Author(s):  
Xie ◽  
Hao ◽  
Yuan
Keyword(s):  
Energy Loss ◽  
Bias Voltage ◽  
High Performance ◽  
Resonance Structure ◽  
Dissipated Energy ◽  
Thermoelastic Damping ◽  
Disk Resonator ◽  
Loss Mechanism ◽  
Energy Loss Mechanism ◽  
Anchor Loss

Analysing and minimizing energy loss is crucial for high performance disk resonator gyroscopes (DRGs). Generally, the primary energy loss mechanism for high vacuum packaged microelectromechanical system (MEMS) resonators includes thermoelastic damping, anchor loss, and electronic damping. In this paper, the thermoelastic damping, anchor loss, and electronic damping for our DRG design are calculated by combining finite element analysis and theoretical derivation. Thermoelastic damping is the dominant energy loss mechanism and contributes over 90% of the total dissipated energy. Benefiting from a symmetrical structure, the anchor loss is low and can be neglected. However, the electronic damping determined by the testing circuit contributes 2.6%–9.6% when the bias voltage increases from 10 V to 20 V, which has a considerable impact on the total quality factor (Q). For comparison, the gyroscope is fabricated and seal-packaged with a measured maximum Q range of 141k to 132k when the bias voltage varies. In conclusion, thermoelastic damping and electronic damping essentially determine the Q of the DRG. Thus, optimizing the resonance structure and testing the circuit to reduce energy loss is prioritized for a high-performance DRG design.

High Performance of 5.7kV 4H-SiC JBSs with Optimized Non-Uniform Field Limiting Rings Termination

2016 ◽  
Vol 858 ◽  
pp. 986-989 ◽  
Author(s):  
Hao Yuan ◽  
Qing Wen Song ◽  
Xiao Yan Tang ◽  
Yu Ming Zhang ◽  
Hui Guo ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Schottky Diode ◽  
High Performance ◽  
Figure Of Merit ◽  
Doping Concentration ◽  
Reverse Current ◽  
Uniform Field ◽  
Forward Current

In this paper, a 5.7kV 4H-SiC Junction Barrier Schottky diode(JBS) with non-uniform field limiting rings termination is simulated and fabricated successfully based on a epitaxial thickness of 49μm and the doping concentration about 1.04×1015cm-3 respectively. The reverse breakdown voltage could reach to 5.7kV at least at reverse current of 200μA. And the on-state voltage is 3V at the forward current of 2A, corresponding to an on-resistance of 32mΩ•cm2. The corresponding figure-of- merit of VB2/ RSP-ON for our fabricated device is 1.026 GW/cm2, which is closing to the optimal levels among several reported SiC JBS.

A Combined Scanning Electron Microscope/Electron Microprobe Analyzer

1968 ◽  
Vol 26 ◽  
pp. 368-369
Author(s):  
V.G. Macres ◽  
O. Preston ◽  
N.C. Yew ◽  
R. Buchanan
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Microprobe ◽  
High Performance ◽  
Electron Gun ◽  
Objective Lens ◽  
Condenser Lens ◽  
X Ray ◽  
Low X ◽  
Scanning Electron

The instrument described here is the Materials Analysis Company Model 400S combined scanning electron microscope/electron micro-probe analyzer. It was designed specifically to incorporate the most advanced features of a high performance electron microprobe analyzer with those of a medium resolution (1000A°) scanning electron microscope. The high effective x-ray take-off angle of the instrument (38.5°) offers low x-ray absorption, and thus allows the analysis of fairly rough specimens. The large depth of focus of the scanned electron images further enhances the capability of examining rough specimens.The electron-optical column comprises a triode electron gun, double condenser lens and objective lens. The electron gun uses a conventional hairpin filament, autobiased Wehnelt cylinder and anode. An externally controlled filament/Wehnelt cylinder height adjustment is provided for optimizing gun performance at all operating potentials. The double condenser lens is unitized and has two lens regions and a common energizing coil.

Local Structure of High Performance TiO x Electron-Selective Contact Revealed by Electron Energy Loss Spectroscopy

2018 ◽  
Vol 6 (3) ◽  
pp. 1801645 ◽  
Author(s):  
Takeya Mochizuki ◽  
Kazuhiro Gotoh ◽  
Yasuyoshi Kurokawa ◽  
Takahisa Yamamoto ◽  
Noritaka Usami
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Local Structure ◽  
High Performance ◽  
Electron Energy Loss

scholarly journals FEI Titan G2 80-200 CREWLEY

2016 ◽  
Vol 2 ◽  
Author(s):  
András Kovács ◽  
Roland Schierholz ◽  
Karsten Tillmann
Keyword(s):  
Dark Field ◽  
Electron Gun ◽  
Atomic Scale ◽  
Fourth Generation ◽  
High Brightness ◽  
Transmission Electron ◽  
Wide Range ◽  
Schottky Type ◽  
Technical Specifications ◽  
Electron Energy Loss

<p>The FEI Titan G2 80-200 CREWLEY is a fourth generation transmission electron microscope which has been specifically designed for the investigation of a wide range of solid state phenomena taking place on the atomic scale of both the structure and chemical composition. For these purposes, the FEI Titan G2 80-200 CREWLEY is equipped with a Schottky type high-brightness electron gun (FEI X-FEG), a Cs probe corrector (CEOS DCOR), an in-column Super-X energy dispersive X-ray spectros-copy (EDX) unit (ChemiSTEM technology), a post-column energy filter system (Gatan Enfinium ER 977) with dual electron energy-loss spectroscopy (EELS) option allowing a simultaneous read-out of EDX and EELS signals at a speed of 1000 spectra per second. For data recording the microscope is equipped with an angular dark-field (ADF) scanning TEM (STEM) detector (Fischione Model 3000), on-axis triple BF, DF1, DF2 detectors, on-axis BF/DF Gatan detectors as well as a 4 megapixel CCD system (Gatan UltraScan 1000 XP-P). Typical examples of use and technical specifications for the instrument are given below.</p>

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