CRYSTAL ANISOTROPY INFLUENCE ON THE FORM OF THE LIQUID INCLUSION MOVING IN THE GRADIENT FIELD IN TECHNOLOGIES OF SYNTHESIS OF SEMICONDUCTOR MATERIALS

Author(s):  
Anatoly Blagin
2016 ◽  
Vol 843 ◽  
pp. 145-150
Author(s):  
A.V. Blagin ◽  
N.A. Nefedova ◽  
B.M. Seredin

The paper analyzes the features of a liquid zones thermomigration process in a crystal for the formation of semiconductor materials with the required substructure, carried out in comparison with a diffusion method. The primary factors defining and accompanying the thermomigration process of liquid inclusion in a crystal are considered. The geometrical, concentration, temperature-time and other conditions at which the choice of the thermomigration effect as a local doping method is preferable are revealed and described. It is shown, that the thermomigration method possesses considerable advantages, in particular, the possibilities of decreasing doping process temperature, increasing process speed, increasing the distribution uniformity of the doping impurity and improves the crystal perfection of the doped layers. The quantitative estimations related to the revealed conditions, are illustrated with an aluminium-silicon example.


Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.


2020 ◽  
Vol 64 (1-4) ◽  
pp. 19-29
Author(s):  
Shuting Ren ◽  
Yong Li ◽  
Bei Yan ◽  
Jinhua Hu ◽  
Ilham Mukriz Zainal Abidin ◽  
...  

Structures of nonmagnetic materials are broadly used in engineering fields such as aerospace, energy, etc. Due to corrosive and hostile environments, they are vulnerable to the Subsurface Pitting Corrosion (SPC) leading to structural failure. Therefore, it is imperative to conduct periodical inspection and comprehensive evaluation of SPC using reliable nondestructive evaluation techniques. Extended from the conventional Pulsed eddy current method (PEC), Gradient-field Pulsed Eddy Current technique (GPEC) has been proposed and found to be advantageous over PEC in terms of enhanced inspection sensitivity and accuracy in evaluation and imaging of subsurface defects in nonmagnetic conductors. In this paper two GPEC probes for uniform field excitation are intensively analyzed and compared. Their capabilities in SPC evaluation and imaging are explored through simulations and experiments. The optimal position for deployment of the magnetic field sensor is determined by scrutinizing the field uniformity and inspection sensitivity to SPC based on finite element simulations. After the optimal probe structure is chosen, quantitative evaluation and imaging of SPC are investigated. Signal/image processing algorithms for SPC evaluation are proposed. Through simulations and experiments, it has been found that the T-shaped probe together with the proposed processing algorithms is advantageous and preferable for profile recognition and depth evaluation of SPC.


2003 ◽  
Vol 8 (5-6) ◽  
pp. 30-32
Author(s):  
B.E. Paton ◽  
◽  
E.A. Asnis ◽  
S.P. Zabolotin ◽  
P.I. Baranskii ◽  
...  

2002 ◽  
Vol 97 ◽  
pp. 563-568 ◽  
Author(s):  
Paul Jursinic ◽  
Robert Prost ◽  
Christopher Schultz

Object. The authors report on a new head coil into which the Leksell aluminum localization frame can be easily and securely mounted. Mechanically, the head coil interferes little with the patient. Methods. The head coil, which is for magnetic resonance (MR) imaging, is a 12-element quadrature transmitand-receive high-pass birdcage coil with a nominal operation frequency (63.86 MHz). The coil was built into a plastic housing. This new head coil minimizes patient motion and provides a 20% increase in signal/noise ratios compared with standard head coils. An MR image test phantom was mounted in the coil and this allowed quantification of image distortion due to inhomogeneities in the main magnetic field, nonlinearity in the gradient field, and paramagnetism of the aluminum headframe. There were no significant differences in geometric distortion between the new head coil and the standard coil. Conclusions. The new head coil has advantages for reducing patient movement artifacts and has a better signal/noise ratio with no reduction in geometric accuracy.


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