Synthesis of Al-B system nanostructures by interaction of disperse aluminium with boron and diborane in arc discharge plasma

2020 ◽  
pp. 11-18
Author(s):  
A.G. Astashov ◽  
◽  
A.V. Samokhin ◽  
N.V. Alekseev ◽  
V.A. Sinayskiy ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Phase ◽  
Thermal Plasma ◽  
Gas Flow ◽  
Arc Discharge ◽  
Experimental Studies ◽  
Plasma Chemical ◽  
Aluminum Boride ◽  
Disperse Aluminum ◽  
Boride Phases

Experimental studies of aluminium boride synthesis as a result of interaction of disperse aluminum with diborane B2H6 and disperse boron in a flow of thermal plasma of different composition generated in electric arc plasma torch have been carried out. Experimental work on the synthesis of aluminium boride nanoparticles from elements (a mixture of disperse aluminum and boron) has shown the possibility of obtaining in thermal plasma arc discharge of such phases of the boride as AlB12 and AlB31. The specific surface of the powders obtained is from 3 to 27 m2/g. According to X-ray phase analysis, the powders obtained, except for aluminum boride phases, also contain boron, aluminum, aluminum nitride and boric acid phases. The greatest yield of aluminum boride phases is provided by using the nitrogen plasma with hydrogen and enthalpy 4.5 kWt∙h/m3 in the reactor with increased high-temperature zone. The use of gaseous diborane made it possible to eliminate restrictions on the evaporation of boron particles but did not provide an opportunity to obtain aluminum borides in the plasma-chemical process. It was concluded that it is necessary to perform quenching of high-temperature gas flow containing boron and aluminum vapor to form aluminum borides from the gas phase in plasma-chemical synthesis. Such an approach should ensure that the temperature is reduced to the values at which aluminum borides are stable and that the formation of aluminum boride nanoparticles will occur as a result of condensation from the gas phase under these conditions.

Comparative Study of GaN Growth Process by MOVPE

1999 ◽  
Vol 572 ◽  
Author(s):  
Jingxi Sun ◽  
J. M. Redwing ◽  
T. F. Kuech
Keyword(s):  
High Temperature ◽  
Comparative Study ◽  
Gas Phase ◽  
Residence Time ◽  
Gas Flow ◽  
Flow Sheet ◽  
Flow Zone ◽  
High Quality ◽  
Phase Temperature ◽  
High Temperature Gas

ABSTRACTA comparative study of two different MOVPE reactors used for GaN growth is presented. Computational fluid dynamics (CFD) was used to determine common gas phase and fluid flow behaviors within these reactors. This paper focuses on the common thermal fluid features of these two MOVPE reactors with different geometries and operating pressures that can grow device-quality GaN-based materials. Our study clearly shows that several growth conditions must be achieved in order to grow high quality GaN materials. The high-temperature gas flow zone must be limited to a very thin flow sheet above the susceptor, while the bulk gas phase temperature must be very low to prevent extensive pre-deposition reactions. These conditions lead to higher growth rates and improved material quality. A certain range of gas flow velocity inside the high-temperature gas flow zone is also required in order to minimize the residence time and improve the growth uniformity. These conditions can be achieved by the use of either a novel reactor structure such as a two-flow approach or by specific flow conditions. The quantitative ranges of flow velocities, gas phase temperature, and residence time required in these reactors to achieve high quality material and uniform growth are given.

Application and Characterization of 12-Phase AC Arc for Glass in-Flight Melting

2012 ◽  
Vol 443-444 ◽  
pp. 637-642
Author(s):  
Yao Chun Yao ◽  
Takayuki Watanabe ◽  
Kazuyuki Yatsuda
Keyword(s):  
High Temperature ◽  
Flow Rate ◽  
Temperature Region ◽  
Gas Flow ◽  
Arc Discharge ◽  
Melting Behavior ◽  
Raw Material ◽  
Gas Flow Rate ◽  
High Temperature Region ◽  
Ac Arc

A stable 12-phase AC arc was successfully generated and applied in the field of glass in-flight melting, the arc behavior was characterized by image analysis. The effects of electrode configuration and sheath gas flow rate on arc and melting behavior of granulated glass raw material were investigated. Results show that different electrode configurations leads to various arc discharge and high-temperature region. The luminance area with high-temperature region and its fluctuation reflect the change of arc discharge behavior. The vitrification degree of glass raw material is mostly dependent on the center temperature of arc. As the sheath gas flow rate increases, the ratio of luminance area decreases and the center temperature of arc increases.

scholarly journals Experimental studies of two-phase liquid metal-gas chain flow with ultrasonic echo pulse method and in the magnetic field of permanent magnets

2018 ◽  
Vol 240 ◽  
pp. 03003
Author(s):  
Artur Andruszkiewicz ◽  
Kerstin Eckert
Keyword(s):  
Magnetic Field ◽  
Gas Phase ◽  
Gas Flow ◽  
Permanent Magnets ◽  
Liquid Metals ◽  
Experimental Studies ◽  
Pulse Method ◽  
Phase Flow ◽  
Ultrasonic Echo ◽  
Echo Pulse

Metallurgical processes of refining and degassing liquid metals are related to the blowing-in neutral gasses like for example argon. Effectiveness of the process depends on the flowing gas parameters like: dimensions, velocity, distribution amd gas phase flow zone. These parameters can be changed under the influence of outside magnetic field and formed by it a Lorentz’ force. In order to get full information of rising bubbles essential are certain measuring methods. Among many of these the ultrasonic echo pulse method is likely to be the most intensive developed in the past few years. That method enables estimation of gas phase flow parameters in a range from individual bubble flow up to full continuous gas flow at the inlet nozzle. In this paper a measurement principle has been described for an ultrasonic echo method and there also submitted and discussed results of obtained results for diphase flow of GaInSn-argon.

EFFECT OF PASSIVATING COATINGS ON METALLIZATION TOPOLOGY IN PRODUCTION OF SEMICONDUCTOR DEVICES

2021 ◽  
Vol 0 (4) ◽  
pp. 30-34
Author(s):  
M.V. POTAPOVA ◽  
◽  
M.YU. MAKHMUD-AKHUNOV ◽  
V.N. GOLOVANOV ◽  
K.E. IMESHEV ◽  
...  
Keyword(s):  
Gas Phase ◽  
Silicon Oxide ◽  
Semiconductor Device ◽  
Semiconductor Devices ◽  
Experimental Studies ◽  
Chemical Deposition ◽  
Aluminum Film ◽  
Single Crystal Substrate ◽  
Plasma Chemical ◽  
Aluminum Metallization

The surface quality of the metallized contact pads on the crystal plays an important role in the production of semiconductor devices. This paper presents experimental studies of the effect of a protective passivation film of silicon oxide on the surface structure of aluminum metallization in the field of forming contact pads. Plasma chemical deposition of passivation layer SiO2 from gas phase (PECVD method) was carried out on prepared samples of silicon with aluminum metallization using a high-frequency power source with a frequency of 13.56 MHz. After that, chemical etching of precipitated silicon oxide was carried out to simulate the process of forming contact areas of semiconductor device crystals. The resistance of the metallization surface to plasma processes was studied by raster electron microscopy. It is shown that as a result of the process cycle, defects of the dislocation type are generated in the applied film Al. The nature of the observed defects has been found to be different. The revealed large square-shaped pits with a size of ~ 1 μm at the places where dislocations come to the surface are of a single nature and appear independently of the processes of applying passivation coatings, which is determined by the orienting action of a single-crystal substrate having some low dislocation density. While the second type of defects, shown by the presence of etching pits measuring ~ 100-300 nm, is characterized by a higher surface density. Moreover, the exclusion of the passivation process with silicon oxide did not lead to the appearance of this type of defects, which determined their nature associated with the ion bombardment of the Al layer during the plasma chemical deposition of silicon oxide from the gas phase. It is also shown that a feature of this type of defects is their disorientation both with respect to the first type of defects and with respect to each other. Detection of the structure of the metallization layers was carried out by X-ray diffraction, the results of which show the polycrystallinity of the formed aluminum metallization. The preferred orientation of the aluminum film corresponds to the substrate Si (111).

scholarly journals Predicting performance of a thermal shield of a spacecraft in a high-temperature gas flow

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Lyudmila Ivanovna Gracheva
Keyword(s):  
High Temperature ◽  
Gas Flow ◽  
Experimental Studies ◽  
Theory Of Elasticity ◽  
Operating Conditions ◽  
Stress Distributions ◽  
Thermal Shield ◽  
Predicting Performance ◽  
Temperature Heating ◽  
High Temperature Gas

A fundamental understanding of the mechanism of material interaction with a medium is based on correspondence between experimental studies and actual operating conditions of a given model or a structure. We estimated performance of thermal shield structures based on computations brought about considering physical properties of materials obtained under conditions simulating re-entry of a spacecraft into the atmosphere.A thermal shield is considered of a layered type shell, made of fiber glass with phenol-phormaldehide matrix. Both elastic and thermo-physical characteristics are varied depending on the temperature change.A thermal-stressed state of a cylindrical shield subjected to action of a high-temperature gas flow, is defined based on solving a 3D problem simultaneously using equations of theory of elasticity, thermal conductivity, and numerical analysis. Results are given as dependencies of stress distributions through the thermal coating, taking into account such parameters of atmosphere in re-entry as temperature, heating rate, pressure of a gaseous medium.

Fast 4H-SiC Crystal Growth by High-Temperature Gas Source Method

2014 ◽  
Vol 778-780 ◽  
pp. 55-58 ◽  
Author(s):  
Norihiro Hoshino ◽  
Isaho Kamata ◽  
Yuichiro Tokuda ◽  
Emi Makino ◽  
Jun Kojima ◽  
...  
Keyword(s):  
Crystal Growth ◽  
High Temperature ◽  
Growth Rates ◽  
Gas Flow ◽  
Computational Simulation ◽  
Experimental Studies ◽  
High Growth ◽  
Source Method ◽  
Gas Source ◽  
High Temperature Gas

Possibilities of very fast 4H-SiC crystal growth using a high-temperature gas source method are surveyed by computational simulation and experimental studies. The temperature range suitable to obtain high growth rates are investigated by simulating temperature dependences of growth rates for H2+SiH4+C3H8 and H2 +SiH4+C3H8+HCl gas systems. Simulation and experimental results demonstrate that an increase in source gas flow rates as well as gas-flow velocities enhance growth rates. High growth rates exceeding 1 mm/h are experimentally obtained using both gas systems. Single crystal growth on a 3-inch diameter seed crystal is also demonstrated.

scholarly journals Application of RF (13.56 MHz) Arc Discharge for Plasma Chemical Conversion of Volatile Chlorides of Silicon and Germanium.

2019 ◽  
Vol 6 (2) ◽  
pp. 127-130 ◽  
Author(s):  
R. Kornev ◽  
P. Sennikov ◽  
V. Nazarov ◽  
A. Sukhanov ◽  
L. Shabarova
Keyword(s):  
Gas Flow ◽  
Hydrogen Reduction ◽  
Arc Discharge ◽  
Reduction Process ◽  
Chemical Conversion ◽  
Temperature Fields ◽  
Chemical Transformations ◽  
Plasma Chemical ◽  
Exchange Processes ◽  
Silicon And Germanium

The processes of hydrogen reduction of silicon and germanium chlorides are studied under RF conditions (40.68 MHz) of contracted atmospheric pressure arc discharge stabilized between two rod electrodes. The main gas-phase and solid products of plasma-chemical transformations are determined. Using the hydrogen reduction of SiCl<sub>4</sub> as an example, the numerical simulation of gas-dynamic and heat exchange processes for this type of discharge was performed. The studies were carried out for the optimal conditions for obtaining trichlorosilane using modern computational technologies of fluid dynamics which made it possible to detail the velocity and temperature fields, the gas flow rates in the plasma region, and also determine the main temperature zones affecting the hydrogen reduction process.

scholarly journals Extreme high temperature redox kinetics in ceria: exploration of the transition from gas-phase to material-kinetic limitations

2016 ◽  
Vol 18 (31) ◽  
pp. 21554-21561 ◽  
Author(s):  
Ho-Il Ji ◽  
Timothy C. Davenport ◽  
Chirranjeevi Balaji Gopal ◽  
Sossina M. Haile
Keyword(s):  
High Temperature ◽  
Thermodynamic Properties ◽  
Gas Phase ◽  
Gas Flow ◽  
Solid Phase ◽  
Oxygen Release ◽  
Flow Rates ◽  
Redox Kinetics ◽  
Extreme High Temperature ◽  
Relaxation Experiments

Overcoming influences of oxygen release or uptake from the solid phase in relaxation experiments requires large gas flow rates, as dictated by the thermodynamic properties of the solid.

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