Radial Uniformity Research Articles

The impact of electric field strength on the accuracy of boron dopant quantification in silicon using atom probe tomography

This study investigates the impact of the surface electric field on the quantification accuracy of boron (B) implanted silicon (Si) using atom probe tomography (APT). The Si Charge-State Ratio (CSR(Si) = Si2+/Si+) was used as an indirect measure of the average apex electric field during analysis. For a range of electric fields, the accuracy of the total implanted dose and the depth profile shape determined by APT was evaluated against the National Institute of Standards and Technology Standard Reference Material 2137. The radial (non-)uniformity of the detected B was also examined. At a higher surface electric field (i.e., a greater CSR(Si)), the determined B dose converges on the certified dose. Additionally, the depth profile shape tends towards that derived by secondary ion mass spectrometry. This improvement coincides with a more uniform radial B distribution, evidenced by desorption maps. In contrast, for lower surface electric fields (i.e., a lower CSR(Si)), the B dose is significantly underestimated, and the depth profile is artificially stretched. The desorption maps also indicate a highly inhomogeneous B emission localized around the center of the detector, which is believed to be an artifact of B surface migration on the tip of the sample. For the purposes of routine investigations of semiconductor devices using APT, these results illustrate the potential origin of quantification artifacts and their severity at different operating conditions, thus providing pathways towards best practices for accurate and repeatable measurements.

A measurement method for zero-degree thermostat

Thermocouple thermometers are widely used in laboratories and industry, the ice-water mixture is usually used as cold end compensation for thermocouple thermometer measurement. However, the ice-water mixture has disadvantages, such as complex manufacturing process, short use time, and unstable internal temperature field. The zero-temperature thermostat can replace the traditional ice water mixture to provide a stable temperature field environment. However, there is no suitable measurement method that can evaluate the zero-degree thermostat to meet the measurement requirements of thermocouple thermometer. Therefore, comparative experiments on temperature deviation, volatility, axial temperature field uniformity, radial temperature field uniformity, and load characteristics of the ice-water mixture and the zero-temperature thermostat are evaluated. In addition, the uncertainty of the zero-temperature thermostat and the ice water mixture is also proposed. The results reveal that the measurement results of temperature deviation, volatility, axial temperature field uniformity and load characteristic of the zero-temperature thermostat is smaller than that of the ice water mixture. Meanwhile, the uncertainty results also reveal that the zero-temperature thermostat is more stable than the ice water mixture. This study provides a comprehensive method for evaluating the performance of zero temperature thermostats, which can be used to verify the accuracy of the instrument and ensures the reliability of the thermocouple thermometers measurement, and promotes the development of zero temperature thermostat in temperature measurement field.

Effects of coil frequency on the carbon transport in the top-seeded solution growth of SiC single crystal

The flow pattern and carbon transport in the solution for the solution growth of silicon carbide (SiC) in an induction-heating system can be effectively controlled by adjusting the coil frequency to obtain a relatively uniform distribution of growth rate. In this paper, a global heat and mass transfer model was first verified by the SiC crystal growth experiment results at the coil frequency of 8 kHz. Then, the influence of coil frequency on the fluid flow, carbon concentration, and growth rate for the growth of SiC crystals was numerically investigated. The results indicated that electromagnetic convection (at low frequencies) greatly enhances the upward convection beneath the crystal and weakens the adverse effects of Marangoni convection, resulting in a uniform distribution of radial temperature along the growth interface. Consequently, the carbon transport from the crucible wall to the crystal center is strengthened, leading to a uniform region of high carbon supersaturation with a lower coil frequency. The optimal radial uniformity of the growth rate along the growth interface is achieved at the coil frequency of 3 kHz.

Effect of coil and chamber structure on plasma radial uniformity in radio frequency inductively coupled plasma

Enhancing plasma uniformity can be achieved by modifying coil and chamber structures in radio frequency inductively coupled plasma (ICP) to meet the demand for large-area and uniformly distributed plasma in industrial manufacturing. This study utilized a two-dimensional self-consistent fluid model to investigate how different coil configurations and chamber aspect ratios affect the radial uniformity of plasma in radio frequency ICP. The findings indicate that optimizing the radial spacing of the coil enhances plasma uniformity but with a reduction in electron density. Furthermore, optimizing the coil within the ICP reactor, using the interior point method in the Interior Point Optimizer significantly enhances plasma uniformity, elevating it from 56% to 96% within the range of the model sizes. Additionally, when the chamber aspect ratio k changes from 2.8 to 4.7, the plasma distribution changes from a center-high to a saddle-shaped distribution. Moreover, the plasma uniformity becomes worse. Finally, adjusting process parameters, such as increasing source power and gas pressure, can enhance plasma uniformity. These findings contribute to optimizing the etching process by improving plasma radial uniformity.

Effect of horizontal magnetic field position on oxygen distribution in CZ silicon crystal growth

The horizontal magnetic field-assisted Czochralski(CZ) method is gaining significant popularity in the semiconductor industry for producing 200 mm semiconductor-grade silicon wafers. In this study, the impact of the horizontal magnetic field position on the oxygen content and radial uniformity of semiconductor-grade silicon crystals produced by the CZ method was investigated. Three-dimensional simulations were conducted using finite element software to calculate the melt convection and oxygen content before and after adjustment of the magnetic field position, respectively. The simulations results predicted a decrease in the oxygen content of the crystals following the adjustment of the magnetic field position from 0 to 75 mm below the free surface, and this was experimentally verified. The velocity distribution of the free melt surface exhibits better uniformity when lowering the magnetic field position. The influence of the magnetic field position on the temperature distribution and Marangoni flow in the melt was investigated, and the result of oxygen concentration difference identified the adjustment of the magnetic field position promoted the greater Marangoni flow below the free melt surface, which promoted the volatilization of SiO gas and thus reduced the oxygen concentration in the silicon ingot. Therefore, adjusting the position of the magnetic field is an effective way to increase the Marangoni flow and to obtain semiconductor-grade silicon crystal with lower oxygen content and better oxygen radial homogeneity.

Optimization of bulk microdefect performance in epitaxial silicon wafer

Bulk microdefects (BMDs) in epitaxial silicon wafers are pivotal for advanced node integrated circuits, offering enhanced mechanical strength and metal gettering capabilities. This study introduces two heat treatment procedures to optimize BMD density and radial uniformity in lightly doped wafers, addressing the challenges associated with large-diameter crystal growth and the thermal budget constraints of advanced node processes. We demonstrate that Rapid Thermal Annealing (RTA) at temperatures exceeding 1175 °C significantly improves BMD uniformity. A post-RTA stabilization step, when performed prior to epitaxial growth, enhances BMD density by retaining nuclei generated by RTA. Conversely, when the RTA with stabilization step follows epitaxial growth, a higher BMD density and larger BMD size are achieved. Light Scattering Tomography (LST) analysis confirms the optimal conditions for these treatments. The findings contribute to the semiconductor industry by optimizing wafer properties for high-performance ICs.

Role of gas composition in weakened nonlinear standing wave excitation and improved plasma radial uniformity in very-high-frequency asymmetric capacitive Ar/CF4 discharges

The higher harmonics generated by nonlinear sheath motion would enhance the standing wave effect, and thus lead to center-peaked plasma density profile in very-high-frequency (VHF) capacitive discharges. In this work, a nonlinear transmission line (NTL) model introduced in Zhou et al (2021 Plasma Sources Sci. Technol. 30 125017) has been extended, with radial transport of various particles and nonlinear sheath motion into account, to investigate the effects of CF4 fraction α on the nonlinear standing wave excitation and plasma radial uniformity in VHF (60 MHz) capacitively coupled Ar/CF4 plasmas at 3 Pa. The results indicate that for pure Ar discharges (i.e. α= 0%), the nonlinearly excited harmonics with short wavelength significantly enhance the electron power absorption at the radial center, resulting in a pronounced central-high plasma density profile. As α increases, the high-order harmonics are gradually damped due to the increase of resistance, as well as the longer wavelength caused by thicker sheath thickness. Thus, the radial profile of the electron absorbed power density shifts from center-peak to edge-high. Besides, at the radial center, the electron density and Ar+ ion density decrease with α , CF3 + ion density shows an increasing trend, while F− ion density initially rises and then decreases. Moreover, the density profiles of all the species become more uniform at higher CF4 fraction, due to the suppressed nonlinear standing wave excitation and the longer wavelength of the nonlinear harmonics.

Enhancing radial strain uniformity of thin-walled cylinder by the dual asymmetric active counter-roller spinning process

Aiming at the problem of uneven forces on the inner and outer surfaces during counter-roller spinning (CRS) of thin-walled cylinders, which affects the spinning stability and forming quality, a new dual asymmetric active counter-roller spinning (DAACRS) process is proposed. It enhances the radial strain uniformity through more consistent contact of the inner and outer rollers and the material flow on the inner and outer surfaces. The theoretical analytical model of the influence of the spinning structural and process parameters on the contact condition and the oriented relationship is established. On this basis, the Kriging predictive surrogate model under the coupling influence of these parameters is established, and the spinning parameters optimized by the multi-objective particle swarm optimization (MOPSO) algorithm in the global continuous variables are obtained. The radial strain gradient effect of traditional spun parts is basically eliminated under this process parameters. Additionally, an active counter-roller spinning (ACRS) machine is independently developed and a comprehensive macro-micro quality evaluation method is proposed. The ACRS process can transform the material from dispersed {001}<110> low-strength plate texture to more standard {001}<100> high-strength plate texture, and obtain balanced axial and circumferential tensile strengths. Moreover, the new DAACRS process resulted in more balanced forming accuracy, inner and outer surface grain size, texture strength, and isotropic mechanical properties due to the high radial strain uniformity. Compared with the traditional completely symmetric active counter-roller spinning (CSACRS), the L̅, O̅, UD, UT{100}, UT{110}, and UT{111} are improved by 0.08265 mm, 0.00335 mm, 4.83%, 10.55%, 11.54%, and 16.34%, respectively. Further analysis provides that the allowable values of strain uniformity for the higher quality thin-walled cylinders are [Uε(PEEQ)]=0.365 and [Uε(Max Principal)]=0.438. These results increase the understanding of the strain change, microstructure evolution, and mechanical properties change mechanism of the CRS process, thereby providing important guidance for improving the CRS process and forming quality.

Explore the growth mechanism of high-quality diamond under high average power density in the MPCVD reactor

Investigating the mechanism behind the high-efficiency deposition of high-quality diamond has always been a prominent topic in related research. This paper investigates the CH4-H2 plasma characteristics and related chemical reaction kinetics in the average power density range of 18–100 W·cm−3, which is a typical range for large-area diamond film deposition. The number densities of H, CH3 and C2H2 increase linearly with the average power density. C2H2 is the main hydrocarbon in the discharge, and CH3 is the main single-carbon hydrocarbon. The number density and radial uniformity of CH3 and C2H2 increase with the average power density, which is necessary for the high rate and uniform deposition of diamond films. The plasma's optical emission spectra indicate an acceleration in the C2 production rate at high power density. The diamond film deposition experiment demonstrates the efficacy of high average power density in achieving high-quality diamond deposition at a high growth rate.

Numerical simulation of inductively coupled Ar/O&lt;sub&gt;2&lt;/sub&gt; plasma

In the inductively coupled plasma (ICP) discharge, surface processes, such as reflection, de-excitation, and recombination, can occur when active species arrive at material surfaces, which accordingly influences the plasma properties. In this work, a fluid model is used to study the Ar/O&lt;sub&gt;2&lt;/sub&gt; plasma generated by ICP reactors made of different materials. In simulation, sticking coefficient is employed to estimate the surface reactions on different materials. As the reactor material changes from stainless steel to anodized aluminum to Cu, the sticking coefficient of surface reaction O→1/2O&lt;sub&gt;2&lt;/sub&gt; decreases accordingly. It is found that the reactor material has a great effect on species density. In the stainless steel reactor, the density of O atoms at grounded state and excited state are much lower because more O&lt;sub&gt;2&lt;/sub&gt; molecules are generated from the surface reaction, yielding a much higher density of &lt;inline-formula&gt;&lt;tex-math id="M5"&gt;\begin{document}$ {\text{O}}_2^ + $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M5.jpg"/&gt;&lt;graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M5.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; molecular ions which are mainly created from the ionization process of O&lt;sub&gt;2&lt;/sub&gt; molecules. Similarly, the high density of O&lt;sub&gt;2&lt;/sub&gt; molecules also enhances the production of &lt;inline-formula&gt;&lt;tex-math id="M6"&gt;\begin{document}${{{\mathrm{O}}} _2}\left( {{{\mathrm{a}}^1}{\Delta _{\mathrm{g}}}} \right)$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M6.jpg"/&gt;&lt;graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M6.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; molecules through the excitation process and O&lt;sup&gt;–&lt;/sup&gt; ions through the dissociation attachment reaction. On the contrary, more electrons are consumed via the collisions between electrons and O&lt;sub&gt;2&lt;/sub&gt; molecules or &lt;inline-formula&gt;&lt;tex-math id="M7"&gt;\begin{document}$ {\text{O}}_2^ + $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M7.jpg"/&gt;&lt;graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M7.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; molecular ions. Therefore, the electron density obtained in the Cu reactor is highest. The density of Ar&lt;sup&gt;+&lt;/sup&gt; ions and Ar&lt;sub&gt;m&lt;/sub&gt; atoms also increase with sticking coefficient decreasing. The density of O&lt;sup&gt;+&lt;/sup&gt; ions and &lt;inline-formula&gt;&lt;tex-math id="M8"&gt;\begin{document}$ {\text{O}}_2^ + $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M8.jpg"/&gt;&lt;graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M8.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; molecular ions peak below the coil in the stainless steel reactor, whereas the radial uniformities are improved in the Cu reactor. In the three reactors, the electrons distribute evenly at the reactor center region. The O density and &lt;inline-formula&gt;&lt;tex-math id="M9"&gt;\begin{document}${{{\mathrm{O}}} _2}\left( {{{\mathrm{a}}^1}{\Delta _{\mathrm{g}}}} \right)$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M9.jpg"/&gt;&lt;graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M9.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt; density significantly peak at the reactor center, while the maximum value of Ar&lt;sup&gt;+&lt;/sup&gt; density and Ar&lt;sub&gt;m&lt;/sub&gt; density are below the coil. As for O(&lt;sup&gt;1&lt;/sup&gt;D), the maximum density below the coil region moves toward the reactor center as the reactor material changes from stainless steel to Cu. Finally, the effect of sticking coefficient of O→1/2O&lt;sub&gt;2&lt;/sub&gt; is studied. The results show that the O atom density decreases with the sticking coefficient increasing, but the opposite trend is observed in O&lt;sub&gt;2&lt;/sub&gt; molecular density. It is noticed that the sticking coefficient has little effect on species density when it is higher than 0.5.

Effect mechanism of multi-phase coupling on particle behaviors in magnetorheological foam plane finishing process

In this study, the effect mechanism of multi-phase coupling on particle behaviors in magnetorheological foam plane finishing (MRFPF) was researched to realize the collaborative control of particle distribution uniformity and polishing quality. To reach the goal, particle behaviors in MRFPF under the effect of fluid-solid coupling in magnetorheological foam were numerically studied by molecular dynamics (MD) simulation based on the force analysis that considering pressure drop due to fluid flow in foam pores. According to the simulation results, the influence law of different processing parameters on the radial distribution uniformity of particles was analyzed based on experimental analysis method. The results show that the polishing disk rotation speed and foam porosity have a positive effect on the radial distribution uniformity of particles, while the foam aperture affects little, and the greatest influence is produced by foam porosity which followed by polishing disk rotation speed and foam aperture. What's more, an optimal parameter combination with foam porosity 0.7, polishing disk rotation speed 30 rpm, and foam aperture 1 mm was determined by comprehensively considering the fluidity of MRPF and self-excited characteristics of abrasive particles in MRPF. Moreover, the advantages of MRFPF in improving the particle distribution uniformity and surface finishing quality to that of magnetorheological finishing were verified from numerical simulations and experiments.

Technical note: The Graetz problem at small Peclet number and its application to sizing condensation particle counters

We extend to small Peclet number Pe the familiar high-Pe solution to the Graetz problem of heat/mass transfer in a tube with parabolic flow with a wall temperature discontinuity at an axial position z = 0. Retaining diffusion in the axial direction results only in slight shifts in the eigenfunctions describing the problem. This enables the characterization of the saturation field S by separation of variables, which we implement for Pe = 0, 0.1, 0.25. Calculations based on discretization of the transport partial differential equations are also used to analyze the problem at Pe up to 5. As Pe tends to 0, the heat and mass transfer problems are both described by the same dimensionless function θ(z,r) of the axial and radial coordinates z and r. S then depends on the single quantity θ, and its maximum value Smax is exactly the same along all streamlines. This would result in sharp activation curves in a hypothetical low-Pe condensation particle counter, similarly as in the special circumstance when the ratio Le between heat and mass diffusivities is unity. Calculations are run to determine how the radial uniformity of Smax is degraded at increasing Pe. When accounting for axial diffusion, Smax at the wall is independent of Pe or Le. The commonly considered high Pe limit fails to satisfy this requirement, and therefore predicts an incorrect Smax at distances from the wall discontinuity small compared to Pe−1/2.

Applied Plasma Physics Experiments in Linear (APPEL) device for plasma surface interaction studies

The APPEL device (Applied Plasma Physics Experiments in Linear Device), recently commissioned at the Institute for Plasma Research (IPR), is an intermediate setup towards building a Plasma Material Interaction (PMI) facility. A particular application of this device is to develop and test high-density, low-pressure plasma sources that can be operated under magnetic fields; optimize the plasma sources for working under various magnetic field configurations; and perform physics experiments relevant to electron heating and plasma interactions with external electrodes. The setup consists of 16 electromagnets that provide a flexible, steady-state axial magnetic field in excess of 0.4 T over an axial distance of 3.5 m, with 2 % radial uniformity across 32.0 cm diameter. This paper gives a brief overview of the APPEL device, emphasizes on the APPEL magnet system, and presents the characteristics of a 3.5 m long, high-density (1017–1018 m−3) helium plasma column, using a hollow cathode plasma source obtained in the pressure range below i.e., p < 2.0 Pa. The corresponding ion flux is found to be in the range of 1021 -1022 m−2s−1, similar to other linear systems currently in use for plasma surface interaction studies. A qualitative discussion is given to explain the characteristics of the plasma column.

Measuring Cardiac Dyssynchrony with DENSE (Displacement Encoding with Stimulated Echoes)-A Systematic Review.

In this review, we introduce the displacement encoding with stimulated echoes (DENSE) method for measuring myocardial dyssynchrony using cardiovascular magnetic resonance (CMR) imaging. We provide an overview of research findings related to DENSE from the past two decades and discuss other techniques used for dyssynchrony evaluation. Additionally, the review discusses the potential uses of DENSE in clinical practice. A search was conducted to identify relevant articles published from January 2000 through January 2023 using the Scopus, Web of Science, PubMed and Cochrane databases. The following search term was used: (DENSE OR 'displacement encoding with stimulated echoes' OR CURE) AND (dyssynchrony* OR asynchron* OR synchron*) AND (MRI OR 'magnetic resonance' OR CMR). After removing duplicates, researchers screened a total of 174 papers. Papers that were not related to the topic, reviews, general overview articles and case reports were excluded, leaving 35 articles for further analysis. Of these, 14 studies focused on cardiac dyssynchrony estimation with DENSE, while the remaining 21 studies served as background material. The studies used various methods for presenting synchronicity, such as circumferential uniformity ratio estimate (CURE), CURE-singular value decomposition (SVD), radial uniformity ratio estimate (RURE), longitudinal uniformity ratio estimate (LURE), time to onset of shortening (TOS) and dyssynchrony index (DI). Most of the dyssynchrony studies concentrated on human heart failure, but congenital heart diseases and obesity were also evaluated. The researchers found that DENSE demonstrated high reproducibility and was found useful for detecting cardiac resynchronisation therapy (CRT) responders, optimising CRT device settings and assessing right ventricle synchronicity. In addition, studies showed a correlation between cardiac fibrosis and mechanical dyssynchrony in humans, as well as a decrease in the synchrony of contraction in the left ventricle in obese mice. DENSE shows promise as a tool for quantifying myocardial function and dyssynchrony, with advantages over other cardiac dyssynchrony evaluation methods. However, there remain challenges related to DENSE due to the relatively time-consuming imaging and analysis process. Improvements in imaging and analysing technology, as well as possible artificial intelligence solutions, may help overcome these challenges and lead to more widespread clinical use of DENSE.

A Compact Broadband Monopole Tapered Slot Antenna With High Field Uniformity for Vehicle EMC Test From 20 to 220 MHz

A compact broadband monopole tapered slot antenna (MTSA) for vehicle electromagnetic compatibility (EMC) tests in the semi-anechoic chambers (SAC) is proposed and investigated. The proposed MTSA takes the metal ground of the SAC as part of an antenna. With the mirroring effect of the ground plate in the SAC, the proposed MTSA acts as a conventional tapered slot antenna (TSA) but with only a half size of the conventional TSA, and also avoids the adverse effect of the ground reflections on the field uniformity effectively. Moreover, the MTSA has a slot on its flaring plate that reduces its weight by 30%. Both the simulated and the measured results show that the proposed MTSA achieves a standing wave ratio (VSWR) below 2:1 from 20 MHz to 220 MHz, and a good uniformity, with radial uniformity better than 3 dB, transverse uniformity better than 4 dB. The simulated gains are from 6 dBi to 13.5 dBi with radiation efficiencies over 90% across almost the entire bandwidth.

Experimental study on the effect of injection schemes on fuel spray and combustion characteristics in a compact combustor

Fuel injection schemes based on close-coupled injection are usually used in compact combustor design. In this paper, an experimental method is adopted to study the fuel spray Sauter mean diameter (SMD) and combustion characteristics when different fuel injection schemes, strut cavity structures, and fuel/air jet momentum flux ratios are applied. Four fuel injection schemes based on close-coupled injection schemes and premixed injection schemes are proposed for use in a compact integrated combustor to compare the effects of the fuel injection schemes. Three struts are designed to study the influence of the cavity on the close-coupled fuel injection scheme. The results show that the spray and combustion characteristics of the close-coupled injection scheme differ from those of premixed injection schemes. Specifically, the SMD in the close-coupled scheme is in the range of 70-150 μm, which is larger and more uneven than that of the premixed scheme (15-40 μm), and the close-coupled scheme has better ignition performance at a temperature of 450 K. The flame structure of the close-coupled injection schemes with reverse mainstream inside the cavity has better radial uniformity, but more fuel is attached to the strut surface, resulting in a lower flame intensity and increased diffusion flame. The cavity on the strut sidewall can effectively promote fuel atomization by approximately 25% when the jet momentum flux ratio is low, make the fuel more uniform in the strut radial direction, increase the flame intensity, and reduce diffusion flame zone. In the close-coupled injection scheme, the large jet momentum ratio will lead to the collision and fusion of multiple fuel streams downstream of the struts, thus increasing the fuel droplet size and limiting the promoting effect of the strut wall structure. In summary, this paper provides further understanding of the combustor spray and combustion characteristics of different fuel injection schemes.

MODELING OF THE SUBSTRATE COOLING SYSTEM IN THE INSTALLATION FOR THE DEPOSITION OF COATINGS BY THE GAS PLASMA METHOD

The efficiency of diamond coating synthesis depends on both the parameters of the plasma flow and the uniform temperature distribution on the surface of the substrate on which the coating is synthesized. Mathematical modeling of the substrate cooling system in the installation for the deposition of coatings by the gas plasma method was carried out in order to find optimal parameters at which high density and radial uniformity of energy and chemically active particle flows are simultaneously achieved on the substrate in the process of synthesis of diamond coatings. The task was solved by direct search methods using the FlowSimulation module of the SolidWorks package.

Modulation of the plasma radial uniformity in pulsed dual-antenna inductively coupled plasmas

Pulse modulation in inductively coupled plasmas (ICPs) has been proven as an effective method not only to restrain the charging effect in etching trenches but also as a potential approach to ameliorate the plasma uniformity. In this paper, a two-dimensional fluid model is employed to systematically study the modulation of the radial uniformity in pulsed dual-antenna Ar ICPs. The inner four-turn coils are connected to a continuous wave at the current of 5.0 A, and the outer three-turn coils are pulse modulated at various duty cycles and currents. The results indicate that when the outer coil current is fixed at 7.0 A, the electron density always shows an off-center distribution during the active-glow period when the duty cycle increases from 20% to 60%, due to the stronger electric field induced by the higher outer coil current. Although the ionization mainly happens at the reactor center during the after-glow period, the electron density distribution evolves from a center-high profile to a rather uniform distribution as duty cycle increases. Under the combined influence, the time-averaged electron density over one pulse period shifts from center-high over uniform to edge-high. When the pulse duty cycle is fixed at 50%, the time-averaged electron density distribution shifts from a center-high profile over uniform to an edge-high profile, as the outer coil current increases from 5.7 to 7.7 A. The results obtained in this work could help to optimize the plasma radial uniformity, which plays a significant role in improving the large-area plasma processing.

Alloy Disordering Effects on the Thermal Conductivity and Energy Gap Temperature Dependence of Cd1-xZnxSe Ternary Crystals Grown by the Bridgman Method.

Investigated in this work, Cd1-xZnxSe-mixed ternary compounds were grown by the Bridgman method. Several compounds with zinc content varying in the range 0 < x < 1 were produced between two binary parents, CdSe and ZnSe crystals. Using the SEM/EDS technique, the accurate composition of formed crystals was determined along the growth axis. Thanks to that, the grown crystals' axial and radial uniformity were determined. Characterization of the optical and thermal properties was undertaken. The energy gap was measured using photoluminescence spectroscopy for different compositions and temperatures. The bowing parameter describing the behavior of the fundamental gap with composition for this compound was found to be 0.416 ± 0.06. The thermal characteristics of grown Cd1-xZnxSe alloys were systematically studied. The thermal diffusivity and effusivity of the crystals under investigation were experimentally determined, allowing the calculation of the thermal conductivity. We applied the semi-empirical model that Sadao Adachi developed to analyze the results. Thanks to that, it was possible to estimate the contribution arising from chemical disorder to the crystal's total resistivity.

Study on the Influence of the Pulling Rate on the Axial and Radial Uniformity of Gallium in Czochralski Monocrystalline Silicon Crystal

Study on the Influence of the Pulling Rate on the Axial and Radial Uniformity of Gallium in Czochralski Monocrystalline Silicon Crystal