Investigation of residual impurity content in GaAs layers grown by VPE under very low pressure conditions

1991 ◽  
Vol 20 (1) ◽  
pp. 79-90 ◽  
Author(s):  
J. Camassel ◽  
J. P. Laurenti ◽  
S. Juillaguet ◽  
K. Wolter ◽  
M. Deschler ◽  
...  
Keyword(s):  
Impurity Content ◽  
Low Pressure ◽  
Residual Impurity

Synthesis and Purification of Silicon Carbide Powders for Crystal Growth

2012 ◽  
Vol 717-720 ◽  
pp. 37-40 ◽  
Author(s):  
Ta Ching Hsiao ◽  
Sheng Tsao
Keyword(s):  
Silicon Carbide ◽  
Crystal Growth ◽  
Acid Leaching ◽  
Melting Furnace ◽  
Impurity Content ◽  
Low Pressure ◽  
Free Carbon ◽  
Vacuum Induction Melting ◽  
Carbide Formation ◽  
Induction Melting

Silicon carbide powders were prepared in a vacuum induction melting furnace (VIM). Silica and silicon were used as sources of silicon, and graphite powder was used a source of carbon. Pressures of 0.1 and 0.01 atm were selected as the operation conditions, and different silicon carbide powders were prepared. Free carbon and remnant silica were removed by high-temperature baking in air and acid leaching. Low-pressure powders show better crystallinity; moreover, free carbon and silica were rarely found in the product after baking and leaching. The low-pressure grains were prismatic whereas the high-pressure grains were porous. This shows that pressure is a critical parameter in silicon carbide formation, and low-pressure makes the low-temperature synthesis of silicon carbide feasible. Glow discharge mass spectra were used to analyze the impurity content in silicon carbide powders. After baking and leaching, the purity is increased from 3N5 (99.95 wt.%) to 4N5 (99.995 wt.%). Further purification procedures will be combined to meet the quality requirements for crystal growth.

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

Low pressure improves ink jets

Nature ◽  
2005 ◽  
Author(s):  
Philip Ball
Keyword(s):  
Low Pressure

A Simple Ion Flux Estimation in a Low Pressure R.F. Plasma (13.56 MHz)

1997 ◽  
Vol 7 (4) ◽  
pp. 937-950
Author(s):  
I. Grenier ◽  
V. Massereau ◽  
A. Celerier ◽  
J. Machet
Keyword(s):  
Low Pressure ◽  
Ion Flux ◽  
Flux Estimation
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