Temperature Facilitated ECR-Etching for Isotropic SiC Structuring

2010 ◽  
Vol 645-648 ◽  
pp. 849-852 ◽  
Author(s):  
Florentina Niebelschütz ◽  
Thomas Stauden ◽  
Katja Tonisch ◽  
Jörg Pezoldt
Keyword(s):  
Substrate Temperature ◽  
Gas Flow ◽  
Electron Cyclotron Resonance ◽  
Three Dimensional ◽  
Etching Process ◽  
Free Standing ◽  
Working Pressure ◽  
Isotropic Etching ◽  
Set Up ◽  
Ar Gas

In order to realize complex three dimensional or free standing structures on SiC substrates, an undercut, i.e. a selective isotropic etching process of SiC, is required. This was realized using an electron cyclotron resonance etching set up with pure SF6 and a SF6/Ar gas composition at elevated substrate temperatures. Above 350°C a significant lateral etch component was observed, which rose to a value of 50-70 nm/min increasing the substrate temperature up to 570°C during the etching process. Depending on substrate temperature the etching profiles and surface roughness were studied. Based on an analysis of the influence of microwave power, working pressure, bias voltage, gas flow and gas mixture on the etching behavior a novel isotropic, high selective, residue free etch process for SiC was developed, which allows for example the fabrication of piezoelectric actuated AlGaN/GaN resonators grown on SiC substrates.

A 3D Numerical Investigation on Droplets Distribution in a Wave-Plate Separator

2013 ◽  
Vol 842 ◽  
pp. 522-529
Author(s):  
Yong Lei Qu ◽  
Shi Bu ◽  
Bo Wan
Keyword(s):  
Gas Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Geometrical Model ◽  
Turbulent Dispersion ◽  
Liquid Loading ◽  
Wave Plate ◽  
Gas Liquid Flow ◽  
Set Up ◽  
Plate Separator

The gas-liquid flow in a wave-plate separator is extremely complex due to its three-dimensional characteristic. Numerical simulation accomplished by former investigators using two-dimensional model may be appropriate for the iteration of pressure drop, but they were far from accurate in prediction of removal efficiency. To fill the gap, a three dimensional geometrical model of wave-plate separator is set up in this paper, RNG k-ε model is employed to compute the gas phase flow field, and the droplet trajectories were predicted applying the Lagrangian method. The turbulent dispersion of droplets were simulated by discrete random walk model. Using the assumption of a constant liquid loading of gas flow, simulation were accomplished for six different inlet velocities and two different droplet sizes. The influence pattern of gravity together with gas velocity on droplets distribution and the overall removal efficiencies were obtained.

scholarly journals Electrical, thermal and optical characteristics of plasma torch

2019 ◽  
Vol 13 (27) ◽  
pp. 151-156
Author(s):  
Ali A-K. Hussain
Keyword(s):  
Atmospheric Pressure ◽  
Gas Flow ◽  
Low Cost ◽  
Argon Plasma ◽  
Maximum Value ◽  
Gas Plasma ◽  
Ac Power ◽  
Set Up ◽  
Ar Gas ◽  
Plasma Electrode

Non thermal argon plasma needle at atmospheric pressure was constructed. The experimental set up was based on simple and low cost electric components that generate electrical field sufficiently high at the electrodes to ionize various gases which flow at atmospheric pressure. A high AC power supply was used with 9.6kV peak to peak and 33kHz frequency. The plasma was generated using two electrodes. The voltage and current discharge waveform were measured. The temperature of Ar gas plasma jet at different gas flow rate and distances from the plasma electrode was also recorded. It was found that the temperature increased with increasing frequency to reach the maximum value at 15 kHz, and that the current leading the voltage, which demonstrates the capacitive character of the discharge. The electron temperature was measured at about 0.61 eV, and we calculated the electron number density to be 4.38×1015 cm-3.

scholarly journals Postdeposition Annealing Effect on Cu2ZnSnS4Thin Films Grown at Different Substrate Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Samia Ahmed Nadi ◽  
Puvaneswaran Chelvanathan ◽  
Zaihasraf Zakaria ◽  
Mohammad Mezbaul Alam ◽  
Zeid A. Alothman ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Gas Flow ◽  
Hall Effect Measurement ◽  
Soda Lime ◽  
Rf Magnetron Sputtering ◽  
Soda Lime Glass ◽  
Secondary Phases ◽  
Working Pressure ◽  
Czts Thin Films

Cu2ZnSnS4(CZTS) thin films were deposited on top of Molybdenum (Mo) coated soda lime glass (SLG) substrates using a single target rf magnetron sputtering technique. The sputtering parameters such as base pressure, working pressure, rf power, argon (Ar) gas flow rate, and deposition time were kept consistent throughout the experiment. The effect of different substrate temperatures, for example, room temperature (RT), 300°C, 350°C, 370°C, 400°C, and 450°C, was analyzed by studying their structural, electrical, and optical properties. As-sputtered films were then annealed at 460°C. X-ray diffraction (XRD) measurement revealed the structure to be kesterite with peak of (112) plane in both annealed and as-sputtered CZTS thin films. The crystallinity of the films improved with the increasing substrate temperature until 370°C. Secondary phases of MoS2,CuxMoSx,CuxSnSx,CuxS, and Cu6MoSnS8(hemusite) were also observed in the annealed CZTS films. Scanning electron microscopy (SEM) shows crystallite size of deposited CZTS thin film to be proportionally related to deposition temperature. The highest surface roughness of 67.318 nm is observed by atomic force microscopy (AFM). The conductivity type of the films was found to be p-type by Hall effect measurement system.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

Real gas flow fields about three dimensional configurations

1983 ◽  
Author(s):  
A. BALAKRISHNAN ◽  
C. LOMBARD ◽  
W.C. DAVY
Keyword(s):  
Gas Flow ◽  
Three Dimensional ◽  
Flow Fields ◽  
Real Gas

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

Optimum Design for the Frame of Open Type Abrasive Flow Polish Machine

2012 ◽  
Vol 497 ◽  
pp. 89-93
Author(s):  
Liang Liang Yuan ◽  
Ke Hua Zhang ◽  
Li Min
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Finite Element Methods ◽  
Optimization Design ◽  
Low Cost ◽  
Three Dimensional ◽  
Force Model ◽  
Optimization Analysis ◽  
Open Type ◽  
Set Up

In order to process heterotype hole of workpiece precisely, an open abrasive flow polish machine is designed, and the optimization design of machine frame is done for low cost. Firstly, basing on the parameters designed with traditional ways, three-dimensional force model is set up with the soft of SolidWorks. Secondly, the statics and modal analysis for machine body have been done in Finite element methods (FEM), and then the optimization analysis of machine frame has been done. At last, the model of rebuild machine frame has been built. Result shows that the deformation angle value of machine frame increased from 0.72′ to 1.001′, the natural frequency of the machine decreased from 75.549 Hz to 62.262 Hz, the weight of machine decreased by 74.178 Kg after optimization. It meets the strength, stiffness and angel stiffness requirement of machine, reduces the weight and cost of machine.

scholarly journals Modeling of three-dimensional exciplex pumped fluid Cs vapor laser with transverse and longitudinal gas flow

2021 ◽  
Vol 9 ◽  
Author(s):  
Chenyi Su ◽  
Xingqi Xu ◽  
Jinghua Huang ◽  
Bailiang Pan
Keyword(s):  
Wall Temperature ◽  
Laser Power ◽  
Gas Flow ◽  
Particle Density ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Heat Accumulation ◽  
Vapor Laser ◽  
Output Laser Power ◽  
Output Laser

Abstract Considering the thermodynamical fluid mechanics in the gain medium and laser kinetic processes, a three-dimensional theoretical model of an exciplex-pumped Cs vapor laser with longitudinal and transverse gas flow is established. The slope efficiency of laser calculated by the model shows good agreement with the experimental data. The comprehensive three-dimensional distribution of temperature and particle density of Cs is depicted. The influence of pump intensity, wall temperature, and fluid velocity on the laser output performance is also simulated and analyzed in detail, suggesting that a higher wall temperature can guarantee a higher output laser power while causing a more significant heat accumulation in the cell. Compared with longitudinal gas flow, the transverse flow can improve the output laser power by effectively removing the generated heat accumulation and alleviating the temperature gradient in the cell.

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