20,102 results
Search Results
352. A Note on the Paper 'Electrical Conduction Between Metallic Microparticles'
- Author
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R. M. Hill
- Subjects
Metal ,Materials science ,business.industry ,Electrical conduction ,visual_art ,visual_art.visual_art_medium ,General Physics and Astronomy ,Optoelectronics ,business - Published
- 1966
353. Effect of Scattering on Charge Transfer Efficiency Measurements: Comment on a Paper by Mahadevan et al
- Author
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J. R. Peterson
- Subjects
Nuclear physics ,Scattering ,Chemistry ,General Physics and Astronomy ,Atomic physics ,Charge transfer efficiency - Published
- 1965
354. Comments on the Paper 'Volume Conductivity of Borosilicate Glass' by Julius J. Muray
- Author
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A. E. Owen
- Subjects
Materials science ,Polymer science ,Borosilicate glass ,General Physics and Astronomy ,Volume conduction - Published
- 1963
355. Reply to the Comments of B. Cox on the Paper 'Use of the Nuclear Reaction 16O(d,p)17O to Study Oxygen Diffusion in Solids and its Application to Zirconium'
- Author
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B. De Gelas, G. Amsel, G. Beranger, and P. Lacombe
- Subjects
Nuclear reaction ,Zirconium ,Chemistry ,Radiochemistry ,General Physics and Astronomy ,Oxygen diffusion ,chemistry.chemical_element - Published
- 1969
356. Erratum: "Temperature dependence of avalanche breakdown in 4H-SiC devices" [J. Appl. Phys. 133, 235705 (2023)].
- Author
-
Steinmann, Philipp, Hull, Brett, Ji, In-Hwan, Lichtenwalner, Daniel, and Van Brunt, Edward
- Subjects
IMPACT ionization ,THRESHOLD energy ,TEMPERATURE ,IONIZATION energy ,APOLOGIZING - Abstract
An erratum has been issued for a paper titled "Temperature dependence of avalanche breakdown in 4H-SiC devices" published in the Journal of Applied Physics. The erratum addresses two errors in the paper that have been brought to the attention of the authors. The errors involve the unit of the quadratic temperature coefficient and the units of the threshold energies for impact ionization. The authors apologize for any inconvenience caused by these mistakes. [Extracted from the article]
- Published
- 2023
- Full Text
- View/download PDF
357. GaN-based power devices: Physics, reliability, and perspectives.
- Author
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Meneghini, Matteo, De Santi, Carlo, Abid, Idriss, Buffolo, Matteo, Cioni, Marcello, Khadar, Riyaz Abdul, Nela, Luca, Zagni, Nicolò, Chini, Alessandro, Medjdoub, Farid, Meneghesso, Gaudenzio, Verzellesi, Giovanni, Zanoni, Enrico, and Matioli, Elison
- Subjects
TWO-dimensional electron gas ,GALLIUM nitride ,PHYSICS ,NANOWIRES ,BAND gaps ,MECHANICAL properties of condensed matter ,MODULATION-doped field-effect transistors - Abstract
Over the last decade, gallium nitride (GaN) has emerged as an excellent material for the fabrication of power devices. Among the semiconductors for which power devices are already available in the market, GaN has the widest energy gap, the largest critical field, and the highest saturation velocity, thus representing an excellent material for the fabrication of high-speed/high-voltage components. The presence of spontaneous and piezoelectric polarization allows us to create a two-dimensional electron gas, with high mobility and large channel density, in the absence of any doping, thanks to the use of AlGaN/GaN heterostructures. This contributes to minimize resistive losses; at the same time, for GaN transistors, switching losses are very low, thanks to the small parasitic capacitances and switching charges. Device scaling and monolithic integration enable a high-frequency operation, with consequent advantages in terms of miniaturization. For high power/high-voltage operation, vertical device architectures are being proposed and investigated, and three-dimensional structures—fin-shaped, trench-structured, nanowire-based—are demonstrating great potential. Contrary to Si, GaN is a relatively young material: trapping and degradation processes must be understood and described in detail, with the aim of optimizing device stability and reliability. This Tutorial describes the physics, technology, and reliability of GaN-based power devices: in the first part of the article, starting from a discussion of the main properties of the material, the characteristics of lateral and vertical GaN transistors are discussed in detail to provide guidance in this complex and interesting field. The second part of the paper focuses on trapping and reliability aspects: the physical origin of traps in GaN and the main degradation mechanisms are discussed in detail. The wide set of referenced papers and the insight into the most relevant aspects gives the reader a comprehensive overview on the present and next-generation GaN electronics. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
358. Enhanced pulsed thermoacoustic imaging by noncoherent pulse compression.
- Author
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Alzuhiri, Mohand, Song, Jian, Li, Bo, Kumar, Deepak, Qiu, Zhen, Qian, Jianliang, and Deng, Yiming
- Subjects
ELECTRIC properties of materials ,SPATIAL resolution ,ULTRASONIC waves ,ELECTROMAGNETIC radiation ,TIMING circuits ,RADIO frequency - Abstract
Microwave-induced thermoacoustic imaging (TAI) is a hybrid imaging technique that combines electromagnetic radiation and ultrasonic waves to achieve high imaging contrast and submillimeter spatial resolution. These characteristics make TAI a good candidate to detect material anomalies that change the material electric properties without a noticeable variation in material density. Conventional pulsed TAI systems work by sending a single short pulse to the imaged target and then detecting the generated pressure signal; therefore, a very high peak power microwave pulse or data averaging is needed to produce images with a high signal-to-noise ratio (SNR). In this paper, we propose to enhance the SNR of pulsed TAI systems by using non-coherent pulse compression. In this approach, a predefined pulse coded signal is used to illuminate the imaged sample and the received pressure signal is cross correlated with a template that is related to the power profile of the excitation signal. The proposed approach can be easily deployed to pulsed TAI systems without the need for major system modifications to the RF source because it only requires a timing circuit to control the triggering time of the RF pulses. In this paper, we demonstrate experimentally that the proposed approach highly improves the SNR of TAI signals and images and can be used to reduce the acquisition time by lowering the number of data averaging or reduce the required peak power from RF sources. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
359. Simulation method of magneto-acousto-electrical tomography for improving computational efficiency.
- Author
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Li, Cailian, Wu, Sanxi, Bu, Shuaiyu, Li, Yuanyuan, and Liu, Guoqiang
- Subjects
COMPUTER simulation ,TOMOGRAPHY ,COMPUTERS ,TISSUES ,DEGREES of freedom ,DISCRETE Fourier transforms - Abstract
In this paper, a frequency domain simulation method of magneto-acousto-electrical tomography (MAET) was proposed. This method is based on discrete Fourier transform. With this approach, the solving degrees of freedom of the simulation model can be significantly reduced. It can greatly reduce the requirements of computer hardware and improve efficiency. At the same time, the interaction between fluid and biological tissues was considered, which makes the simulation model closer to the real model. In this paper, an MAET simulation model of acoustic–solid–electromagnetic multi-physical field coupling corresponding to the actual physical world was established. It is more reasonable to adopt the fully coupled method. However, the fully coupled method needs more computational memory. To further study the memory and time required for calculation, the segregated method was used to calculate the simulation model without affecting the accuracy and tolerance in this paper. The results show that using the segregated method can significantly reduce the memory requirement of the MAET model, but the solution time will increase accordingly. Therefore, the appropriate solution method can be selected according to the simulation computer configuration and the desired solution time. We, finally, built an experimental platform to conduct MAET experiments and verified the theoretical and simulation analyses. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
360. Reduction of g-factor due to Rashba effect in graphene.
- Author
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Shrestha, Amit, Higuchi, Katsuhiko, Yoshida, Shunsuke, and Higuchi, Masahiko
- Subjects
RASHBA effect ,SPINTRONICS ,ELECTRON paramagnetic resonance ,GRAPHENE ,ZEEMAN effect - Abstract
Graphene is a highly promising material in the field of spin electronics. Recent experiments on electron spin resonance have observed a reduction in the g-factor of graphene. In our previous paper [J. Phys. Soc. Jpn. 88, 094707 (2019)], we demonstrated that one of sources for this reduction is the diamagnetic property of graphene. However, the diamagnetic property by itself does not fully account for the magnitude of the reduction observed in the experiments. In this paper, we focus on the Rashba effect, which is caused by the work function existing near the surface of graphene. The Rashba effect tilts the spin magnetic moment to the in-plane direction of the graphene sheet, potentially reducing the g-factor. We evaluate this reduction using a simple model system incorporating the Rashba and spin Zeeman effects. We then demonstrate that the resultant g-factor is in close agreement with that observed in the prior experiments, indicating that the Rashba effect is able to account for the remaining reduction in the g-factor of graphene. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
361. Erratum: "Insulation degradation behavior of multilayer ceramic capacitors clarified by Kelvin probe force microscopy under ultra-high vacuum" [J. Appl. Phys. 113, 064103 (2013)].
- Author
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Suzuki, Keigo, Okamoto, Takafumi, Kondo, Hiroyuki, Tanaka, Nobuhiko, and Ando, Akira
- Subjects
CERAMIC capacitors ,KELVIN probe force microscopy ,ULTRAHIGH vacuum - Abstract
This electric field concentration near the anode (H-cathode) at backward bias voltage is slightly weaker than that near the anode (H-anode) at a forward bias voltage. As for sample B in the original paper, we claimed that the electric field concentration at H-cathode measured under backward bias is much higher than that at H-anode under forward bias. The electric field concentration at H-anode measured under forward bias is much higher than that at H-cathode measured under backward bias. [Extracted from the article]
- Published
- 2023
- Full Text
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362. Plasma hollow cathodes.
- Author
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Goebel, Dan M., Becatti, Giulia, Mikellides, Ioannis G., and Lopez Ortega, Alejandro
- Subjects
CATHODES ,GLOW discharges ,PLASMA-wall interactions ,PLASMA flow ,ELECTRIC propulsion - Abstract
Hollow cathode plasma discharges are a fundamental part of a large variety of applications in industry, academia, and space. From surface processing and coatings deposition to plasma–surface interaction research and electric propulsion, advances in hollow cathode modeling and performance are critically important to the progress and evolution of these and other areas of technology. This paper describes perspectives on the progress that has been made in recent years in the capabilities and modeling of hollow cathodes used in plasma discharges. While many of the developments have been driven by the demanding requirements of electric propulsion applications, the information provided applies to all thermionic hollow cathodes and their applications. In the paper, we describe the status of 2D global simulations of hollow cathode plasmas, hollow cathode plume instabilities, and the development of higher current cathodes and low-current heaterless cathode technologies. Advances in our understanding and technology in these areas and some of the challenges that still need to be addressed and solved are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
363. Respiratory droplet resuspension near surfaces: Modeling and analysis.
- Author
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Nikfar, Mehdi, Paul, Ratul, Islam, Khayrul, Razizadeh, Meghdad, Jagota, Anand, and Liu, Yaling
- Subjects
SURFACE analysis ,CONTACT angle ,HYDROPHOBIC surfaces ,SURFACE energy ,MEDICAL personnel ,SURGICAL gloves - Abstract
Knowing the environmental spreading pathway of COVID-19 is crucial for improving safety practices, particularly for health care workers who are more susceptible to exposure. This paper focuses on the possible secondary transmission due to resuspension of virus-laden droplets from common surfaces, which several studies have shown to be possible under external disturbances. Such disturbances could be body motion during walking, running, clothes removal, or airflow in the environment. In this paper, a three-dimensional two-phase model is utilized to study respiratory droplet resuspension dynamics on various surfaces due to sudden agitation. The velocity range and variation during walking, surgical glove removal, and dropping an object are studied experimentally. A parametric study is performed to characterize the effects of droplet size and surface wettability on the minimum initial droplet velocity required for detachment from surfaces. The results are reported as average droplet velocity during the detachment process, total detachment time, and detached droplet volume. The obtained results indicate that respiratory droplets larger than 200 μm can detach from typical surfaces due to normal daily activities. Droplets are partially separated from hydrophilic surfaces with contact angle ≤ 90 ° , while the entire droplet is detached from hydrophobic surfaces with contact angle > --> 90 °. Furthermore, the minimum initial droplet velocity to induce the resuspension depends on the droplet size. Droplet velocity immediately after detachment is a function of droplet size, initial droplet velocity, and surface wettability. Bigger droplets have larger detached volume percentage as well as higher velocity after detachment compared to smaller droplets. Finally, a higher initial velocity is needed to separate droplets from hydrophilic surfaces as compared to hydrophobic surfaces. In accordance with the results, the droplet minimum initial velocity to cause detachment is 2 m s
−1 , while our experiments show that surface velocity can reach up to 3 m s−1 during normal human activities. We also develop an analytical model to predict the required kinetic energy to detach droplets from different surfaces, which is in good agreement with numerical results. The mechanism of droplet detachment is dictated by a competition between droplet kinetic energy induced by surface motion and surface energy due to droplet–surface interaction as well as droplet–vapor and surface–vapor interactions. We believe that the results of this fundamental study can potentially be used to suggest proper surface wettability and safe motion that reduce respiratory droplet resuspension from various surfaces. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
364. Evanescent surface acoustic waves in 1D viscoelastic phononic crystals.
- Author
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Zhang, Shu-Yan, Wang, Yan-Feng, and Wang, Yue-Sheng
- Subjects
ACOUSTIC surface waves ,PHONONIC crystals ,FINITE element method ,SOUND waves ,CRYSTAL surfaces - Abstract
In this paper, evanescent surface waves propagating in a one-dimensional surface phononic crystal are investigated. The phononic crystal consists of elastic pillars periodically arranged on a viscoelastic substrate. By using the finite element method, the complex band structures and transmission spectra of surface waves are calculated. It is found that the evanescent wave with π phase change of the real part lies inside the resonant bandgap, and no cusp is observed for the minimum imaginary part. With the increase of frequency, the surface waves can be gradually converted to bulk waves. When the pillar height is increased, the generation mechanism of the first bandgap gradually varies from Bragg scattering to local resonance, and the evanescent waves above the sound line can be reconstructed and shifted below the sound line. When the viscosity is introduced, the minimum imaginary part inside the bandgap decreases. However, the corresponding attenuation is strengthened because the contribution of the bulk wave to the transmission gets weak. The work in this paper is relevant to the practical application of surface waves. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
365. Curvature effect of electrowetting-induced droplet detachment.
- Author
-
Xiao, Ke and Wu, Chen-Xu
- Subjects
CURVED surfaces ,CURVATURE ,VOLTAGE ,VISCOSITY ,MICROFLUIDIC devices ,WETTING - Abstract
Harnessing detachment of an aqueous droplet via electrowetting on a flat surface has been of considerable interest for potential practical applications, ranging from self-cleaning to novel optical and digital microfluidic devices, due to the wettability of the droplet on a solid substrate enhanced by applying an electric voltage between the droplet and the insulated substrate. However, a quantitative understanding of the detachment process and an accurate prediction on the thresholds of applied voltage for droplet detachment on curved surfaces are still lacking. In this paper, based on energy conservation, we derive a critical condition theoretically for electrowetting-induced droplet detachment from a hydrophobic curved surface. Furthermore, phase diagrams are constructed in terms of droplet volume, viscosity, the Ohnesorge number, friction coefficient at contact line, surface curvature, surface wettability, and electrowetting number. The deduced critical condition offers a general and quantitative prediction on when the detachment occurs, a criterion enabling us to gain more insights into how to accurately manipulate the electrowetting-induced detachment of an aqueous droplet on a curved surface. The results obtained in this paper also imply that the detachable regimes of the phase diagrams can be enlarged through increasing droplet volume and surface curvature and reducing liquid viscosity, friction coefficient, the Ohnesorge number, and wettability of substrates. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
366. Study on the nonreciprocal absorption properties of cylindrical photonic crystals embedded in graphene cascaded by periodic and Rudin–Shapiro sequences at large incident angles.
- Author
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Wang, Qian-Yu, Wang, Peng-Xiang, Wan, Bao-Fei, Ma, Yu, and Zhang, Hai-Feng
- Subjects
PHOTONIC crystals ,GRAPHENE ,ABSORPTION ,TRANSFER matrix ,CHEMICAL potential ,PHOTONIC crystal fibers - Abstract
Using the transfer matrix method, the absorption, reflection, and nonreciprocity of the cylindrical photonic crystals (CPCs) consisting of graphene and two layers of ordinary medium cascaded by a periodic sequence and a Rudin–Shapiro quasiperiodic sequence are investigated under a large incidence angle of electromagnetic wave. By comparing the cascade of two periodic structures and the case of a single periodic structure, it is concluded that the structure proposed in this paper has better nonreciprocal phenomena and wider relative absorption bandwidth at a large incidence angle, reaching 162.2%, which is also much higher than the general planar photonic crystals. The absorption performance of this structure in TE and TM modes is compared at different angles and it is found that TM mode has a wider absorption bandwidth and has an ideal bandwidth in a large range of incident angle from 20° to 80°. Meanwhile, the optimum parameters of chemical potential and medium thickness are discussed, which can meet the requirements of large absorption bandwidth and significant nonreciprocity at a large incident angle. The CPCs embedded in graphene adopted in this paper are structures that have never been studied before. The electrical conductivity of graphene can be adjusted by the chemical potential, which can more conveniently realize many optical phenomena and provide reference and application values for optical sensing, optical filtering, and optical detection. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
367. Time-domain minimum-volume cell photoacoustic of thin semiconductor layer. I. Theory
- Abstract
The model of a photoacoustic gas-microphone signal in the time domain recorded in a transmission configuration using a minimum volume cell is derived. This model takes into account the inertial thermal relaxations of both the sample and the gas filling the cell by means of the generalized hyperbolic theory of heat conduction. With the introduction of electro-thermal analogy for the thin sample and short microphone length cavity, characteristic quantities are defined, which can be used in solving the inverse problem in time-domain photoacoustic in both cases, when thermal relaxations are neglected as well as when they are considered. The derived model that includes thermal relaxation explains the experimentally observed occurrence of overshoots and undershoots as well as an oscillatory approach to the steady values of the recorded signal in high-resolution time-domain photoacoustic measurements of thin semiconductor membranes, which will be presented in detail in Paper II of the paper. © 2023 Author(s).
- Published
- 2023
368. Erratum: Validity of the Ehrenfest equation for a system with more than one ordering parameter: Critique of a paper by DiMarzio
- Author
-
Martin Goldstein
- Subjects
General Physics and Astronomy - Published
- 1976
369. Note on Paper 'On Creep and Relaxation'
- Author
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R. W. Hamming and I. L. Hopkins
- Subjects
Materials science ,Creep ,Condensed matter physics ,General Physics and Astronomy ,Relaxation (physics) - Published
- 1958
370. Comments on the Paper of Alan G. Mencher, 'Epicentral Displacement Due to Elastic Waves in an Infinite Slab'
- Author
-
Arthur S. Ginzbarg
- Subjects
Love wave ,Lamb waves ,Slab ,General Physics and Astronomy ,Displacement (orthopedic surgery) ,Mechanics ,Geology - Published
- 1954
371. Note on R. R. Newton's Paper, 'Motion of a Satellite around an Unsymmetrical Central Body'
- Author
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Theodore E. Sterne
- Subjects
Physics ,Classical mechanics ,General Physics and Astronomy ,Satellite ,Motion (physics) - Published
- 1959
372. A Comment on Dr. Vazsonyi's Paper, 'A Generalization of Nyquist's Stability Criteria'
- Author
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S. J. Mason
- Subjects
Generalization ,Stability (learning theory) ,General Physics and Astronomy ,Nyquist–Shannon sampling theorem ,Applied mathematics ,Mathematics - Published
- 1949
373. Comment on the Paper, 'Complex Modulus of a Cohesive Soil from Stress Relaxation Response using the One‐Sided Fourier Transform'
- Author
-
J. Ross Macdonald
- Subjects
symbols.namesake ,Materials science ,Fourier transform ,One sided ,Mathematical analysis ,Stress relaxation ,symbols ,General Physics and Astronomy ,Modulus - Published
- 1966
374. AGFeTe2 Semiconductor Compound: (A Remark on Papers by J. H. Wernick and R. Wolfe, and P. Manca and F. Massazza)
- Author
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E. L. Shtrum
- Subjects
Crystallography ,Compound a ,Materials science ,Manca ,General Physics and Astronomy - Published
- 1964
375. Comments on the Paper 'Use of the Nuclear Reactions 16O(d,p)17O to Study Oxygen Diffusion in Solids and its Application to Zirconium'
- Author
-
B. Cox
- Subjects
Nuclear reaction ,Zirconium ,Chemistry ,Radiochemistry ,General Physics and Astronomy ,Oxygen diffusion ,chemistry.chemical_element - Published
- 1969
376. Note on a Paper of H. Bateman
- Author
-
F. W. J. Olver
- Subjects
General Physics and Astronomy ,Mathematics - Published
- 1946
377. Papers by Hadrian D. Stahl
- Author
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G. H. Metson
- Subjects
Materials science ,General Physics and Astronomy - Published
- 1949
378. Erratum: Original Authorship of Formulas Given in Clark and Deutsch's Paper
- Author
-
M. Reiner and G. W. Scott Blair
- Subjects
Polymer science ,Philosophy ,Calculus ,General Physics and Astronomy - Published
- 1951
379. Comments on the Paper 'Hertzian Fracture Experiments on Abraded Glass Surfaces as Definitive Evidence for an Energy Balance Explanation of Auerbach's Law'
- Author
-
H. Rawson and B. Hamilton
- Subjects
Chemistry ,Energy balance ,Fracture (geology) ,General Physics and Astronomy ,Mechanics - Published
- 1970
380. Comments on the Paper 'Grain Growth during Sintering of Tungsten'
- Author
-
R. E. Mistler
- Subjects
Grain growth ,Materials science ,chemistry ,Metallurgy ,General Physics and Astronomy ,chemistry.chemical_element ,Sintering ,Crystal growth ,Tungsten ,Grain size - Published
- 1968
381. A Reply to Comments on the Paper 'Potential Distribution and Negative Resistance in Thin Oxide Films'
- Author
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T. W. Hickmott
- Subjects
Materials science ,Distribution (number theory) ,Condensed matter physics ,Negative resistance ,General Physics and Astronomy ,Thin oxide - Published
- 1966
382. Original Authorship of Formulas Given in Clark and Deutsch's Paper
- Author
-
M. Reiner and G. W. Scott Blair
- Subjects
General Physics and Astronomy - Published
- 1950
383. Nonvolatile memory based on the extension–retraction of bent ferroelastic domain walls: A phase field simulation.
- Author
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Liu, K., Song, H. J., Zhong, X. L., Wang, J. B., Tan, Congbing, Yang, Zhao, and Ta, Shi-wo
- Subjects
FERROELECTRIC thin films ,NONVOLATILE memory ,PHOTOVOLTAIC effect ,SPACE charge ,ELECTRIC fields ,THIN films - Abstract
Herein, a prototype nonvolatile bent ferroelastic domain wall (DW) memory based on extension–retraction of DWs in a top electrode/bent ferroelastic DWs/bottom electrode architecture is demonstrated and the effects of mechanical condition, electrical condition, and the material parameter on ferroelastic DWs in PbTiO
3 ferroelectric thin films are studied by phase field modeling. Misfit strain can be used to drive the bend of DWs in PbTiO3 thin film, resulting in a change of ferroelastic domain size, bending degree, and conductivity. Stable and reversible switching of DWs between the extendible state with high conductivity and the retractile state with low conductivity can be realized, resulting in an apparent resistance change with a large ON/OFF ratio of >102 and an excellent retention characteristic. The extension and retraction speed, corresponding to data writing speed, can be adjusted by the electric field magnitude and distributions. The memory speed increases by 5% under a homogeneous electric field and 6% under an inhomogeneous probing electric field, after the buildup of space charges in a ferroelectric thin film, and the fastest memory speed is obtained at tip potential φ = 1.8. Moreover, polarization orientations of a and c domains separated by bent ferroelastic DWs do not affect memory performance. This paper can guide the development of new ferroelectric domain wall memory. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
384. Dynamic hysteresis scaling behavior in polyvinylidene fluoride-trifluoroethylene ferroelectric copolymer thin films.
- Author
-
Xu, Lingfang, Song, Minghang, Yi, Wenjun, Fang, Hanshuo, Wang, Ruilong, Liang, Shiheng, Xiao, Haibo, and Yang, Changping
- Subjects
FERROELECTRIC thin films ,FERROELECTRIC polymers ,HYSTERESIS ,ELECTRIC fields ,THIN films ,TIN oxides - Abstract
In this paper, we investigated the dependence of dynamic hysteresis on the electric field amplitude E
0 and the frequency f in organic ferroelectric copolymer polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] thin films prepared by a spin-coating method on fluorine-doped tin oxide conductive glass. Three stages can be observed of the hysteresis area vs the field strength E0 . In stage I of low E0 values, the area ⟨ A ⟩ dependent on E0 follows the law of ⟨ A ⟩ ∝ E 0 1.92795 , whereas the diverse distribution of the area ⟨ A ⟩ with frequency f is found. In stage II of the intermediate E0 values, ⟨ A ⟩ ∝ E 0 β is not applicable owing to collective contributions between 180° domain and chiral domain, while a relation of ⟨ A ⟩ ∝ f − 0.18636 can be deduced, a fascinating characteristic distinguishing from the nonlinear relations of the inorganics in this section. In stage III of high E0 values, the scaling law is ⟨ A ⟩ ∝ f 0.08447 E 0 0.49394 where the chiral domain is active. The positive β in the law of ⟨ A ⟩ ∝ f α E 0 β illustrates that a growing number of chiral domains in P(VDF-TrFE) can keep pace with the variation of E0 . Especially, the negative α in the transition zone, resembling some inorganics under low electric fields, probably indicates 180° domain reversal failing to follow with the alternating velocity of the increasing periodic electric field. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
385. A design method for accurate acoustic impedance matching under coherent coupling of sound-absorbing subunits.
- Author
-
Zhang, Xiaowei, Ye, Yingrui, Lu, Yuxin, and Wang, Xiaopeng
- Subjects
IMPEDANCE matching ,ACOUSTIC impedance ,ABSORPTION of sound ,ABSORPTION coefficients ,SOUND design ,NOISE control - Abstract
Acoustic metamaterials have garnered significant attention as an effective means to control low-frequency noise. However, the accurate design of complex structures composed of multiple subunits is still a challenge due to local coupling effects. To address this issue, in this work, a new design method is proposed that accurately achieves impedance matching at the target frequency when subunits are coupled in parallel. The method is demonstrated using six Fabry–Pérot (F–P) tubes to achieve perfect sound absorption in the continuous band of 405–445 Hz and the discontinuous bands of 400–410 and 430–440 Hz. Theoretical results show an average absorption coefficient of 99.3% in the target frequency band, which is verified through an impedance tube experiment. In addition, this paper explores the stability of this method under complex design conditions and discusses the mechanism of the influence of subunit parameters on sound-absorption performance from the perspective of impedance matching. Overall, the proposed design method offers a promising approach to achieving broadband sound absorption using multiple coupled subunits. The results of this study provide valuable insights for future research and the design of acoustic metamaterials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
386. Equivalent small-signal model of InP-based HEMTs with accurate radiation effects characterization.
- Author
-
Yun, H. Q., Mei, B., Su, Y. B., Yang, F., Ding, P., Zhang, J. L., Meng, S. H., Zhang, C., Sun, Y., Zhang, H. M., Jin, Z., and Zhong, Y. H.
- Subjects
DEEP learning ,MODULATION-doped field-effect transistors ,INTEGRATED circuit design ,FEEDFORWARD neural networks ,GENERATIVE adversarial networks ,RADIATION damage ,RADIATION - Abstract
In this paper, an effective equivalent modeling technique has been proposed to describe small-signal characteristics of InP-based high electron mobility transistors (HEMTs) after proton radiation, which is composed of an artificial neural network and equivalent-circuit models. Small-signal intrinsic parameters of InP-based HEMTs are extracted from S-parameters before and after 2 MeV proton radiation as modeling objects. The deep learning model of a generative adversarial network has been explored to expand the measured finite data samples. Four feedforward neural networks are incorporated to equivalent-circuit topology to form the equivalent model, which are trained to accurately predict the radiation-induced variations of C
gs , Cgd , Rds , and gm , respectively. The prediction accuracy of the developed equivalent model has been well verified in terms of the broad-band S-parameters under radiation fluence of 1 × 1014 and 5 × 1013 H+ /cm2 . This equivalent modeling method with characterization of radiation damage effects could provide significant guidance for the aerospace monolithic millimeter-wave integrated circuit design. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
387. Analysis of the laterally bent piezoelectric semiconductor fibers with variable cross sections.
- Author
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Xu, Zelin, Fang, Kai, Yu, Mengran, Wang, Tiqing, Li, Peng, Qian, Zhenghua, and Liu, Dianzi
- Subjects
DIFFERENTIAL quadrature method ,DISTRIBUTION (Probability theory) ,STRAINS & stresses (Mechanics) ,FIBERS ,SEMICONDUCTORS - Abstract
Piezoelectric semiconductor (PS) materials have attracted much attention in recent years due to their unique properties. This paper explores the electromechanical coupling behavior of bent piezoelectric semiconductor fibers with non-uniform cross-sectional areas. The study uses the generalized differential quadrature method to numerically solve the field equations with variable coefficients derived from piezoelectric theory. The research examines the mechanical and electrical field distribution of bent variable cross-sectional fibers, comparing the performances of non-uniform fibers with different profiles. The study reveals that the variable cross-sectional profile of the fiber changes the characteristic of the uniform fiber's electrical distribution along the axis, and it exhibits a more sensitive and stronger electrical response to the same external force. The research also shows that the concavity and convexity of the radius distribution function of the non-uniform fibers determine whether there are extreme points of surface potential. Finally, the study suggests that by designing extreme points of the PS fiber profile, surface potential extreme points can be artificially created at the same location. These results offer a theoretical direction for creating advanced piezoelectric semiconductor nanodevices and present novel insights into designing higher-efficiency nanogenerators and mechanical strain sensors in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
388. Suppressed polaronic conductivity induced sensor response enhancement in Mo doped V2O5 nanowires.
- Author
-
Anson, Anakha, Mondal, Dipanjana, Biswas, Varsha, Urs MB, Kusuma, and Kamble, Vinayak
- Subjects
NANOWIRES ,FERMI energy ,GAS detectors ,VALENCE bands ,ACTIVATION energy ,CHARGE carriers - Abstract
In this paper, we show the direct correlation between the suppression of the polaronic oxygen vacancy defect (V
o ) density and gas sensor response of 1 at. % Mo-doped V2 O5 nanowires (MVONWs). Doping 1 at. % Mo5+ leads to substitution at the V5+ site in V2 O5 nanowires (VONWs) and, therefore, reduction in Vo defects. This, in turn, affects the charge carrier hopping sites and, subsequently, enhances the sensor response at lower temperatures (<320 °C). The Mo5+ dopants lead to the lowering of Fermi energy (EF ) toward valence band maxima due to the reduced Vo donor density. The polaron suppression is confirmed with the activation energy of polaron hopping, increasing from 195 to 385 meV in VONWs and MVONWs. As a result, the response to ethanol gas enhanced as the depletion width is widened for the given cross section of the nanowires. This may lead to a large depletion controlled cross-sectional area and, therefore, better sensitivity. At about 350 °C, VONWs show a change in the slope of resistance vs temperature (MIT), which is not observed in the case of MVONWs. This is attributed to the presence of the enhanced non-stoichiometry of V ion resulting in metallic behavior and accompanied by a sudden rise in the sensor response at this temperature. Moreover, the absence of MIT may be attributed to the lack of such a sudden rise in the response in MVONWs. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
389. Giant enhancement of the Goos–Hänchen shift assisted by merging bound states in the continuum.
- Author
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Chen, Shiwen, Li, Zhongfu, Mao, Yu, Dai, Xiaoyu, and Xiang, Yuanjiang
- Subjects
BOUND states ,OPTICAL devices ,QUALITY factor ,MANUFACTURING defects ,ENVIRONMENTAL indicators ,MATHEMATICAL continuum - Abstract
Bound states in the continuum (BICs) have received considerable attention in the field of nanophotonics due to their highly confined resonance and high Q factor, which effectively eliminates radiation loss. Various periodic structures have been studied to achieve BICs, with photonic crystal slabs (PCSs) being a prominent example. In PCS, multiple BICs can be merged to strongly suppress out-of-plane-scattering losses caused by fabrication imperfections. In this paper, we investigate the impact of reflection-type merging BICs on the Goos–Hänchen shift (GH shift) and demonstrate a remarkable enhancement of the GH shift, exceeding five orders of wavelength. We show the dynamic changes of the GH shifts with the isolated, merging, and merged BICs, achieving positive and negative GH shifts in different angles of peak reflectance for the same frequency. Our research highlights that even minor fabrication imperfections can result in a significant change in the GH shift, which can serve as a means for detecting manufacturing defects. Furthermore, we propose an ultrasensitive environmental refractive index sensor based on the enhanced GH shift by an isolated BIC. Our study contributes to the understanding of BICs and their potential applications in nanophotonics, including advanced optical communication devices, nanodevice fabrication, and highly sensitive sensors. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
390. An assessment of spall failure modes in laser powder bed fusion fabricated stainless steel 316L with low-volume intentional porosity.
- Author
-
Koube, K. D., Sloop, T., Lamb, K., Kacher, J., Babu, S. S., and Thadhani, N. N.
- Subjects
FAILURE mode & effects analysis ,STAINLESS steel ,POROSITY ,FRACTURE mechanics ,DISCONTINUOUS precipitation - Abstract
This paper reports on spall failure and damage modes in Laser Powder Bed Fusion fabricated Stainless Steel 316L (SS316L) with intentional levels of low-volume (1–5 vol. %) porosity and pore sizes of 200, 350, and 500 μm. The fabricated specimens were subjected to uniaxial-strain plate-impact loading at ∼4.5 GPa, to initiate incipient spall failure. Analysis of velocimetry profiles measured using multi-probe photon-Doppler velocimetry coupled with post-mortem analysis of soft-recovered samples reveals local suppression of spall failure (termed as spall-dominated) as a function of porosity, as the failure mechanism transitions from spall-centered tensile stress dominated to a pore-centered microstructure-dominated damage mode involving void/crack nucleation and growth at pre-existing pores. The critical porosity level where the suppression of spall failure is first observed, as well as the spall location, is dependent on both the volume fraction and the size of the initially fabricated pores. In samples of 500 μm pore size, the suppression of spall failure is observed with as little as 1 vol. % porosity, while samples with smaller pores (200 μm) still experience spall-centered tensile stress dominated failure with higher levels (5 vol. %) of porosity. In the case of pore-centered microstructure-dominated failure, spall damage can occur but the spall plane is shifted toward the rear free surface, or more generally in areas further away from the region with pores. Highly heterogeneous deformation twinning, shear banding, grain rotation, and cracking are observed in the vicinity of pre-existing pores and expected spall failure sites. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
391. Analysis of entropy source for random number generation based on optical PUFs.
- Author
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Chen, Kun, Wang, Pidong, Huang, Feng, Leng, Xiao, and Yao, Yao
- Subjects
RANDOM numbers ,SPECKLE interference ,ENTROPY ,PHYSICAL mobility - Abstract
In this paper, we present an in-depth analysis for entropy source based on optical physical unclonable functions (PUFs). The randomness of speckle patterns is elaborated essentially according to its statistical characteristics. Various factors affecting the source of entropy have been analyzed in detail, including wavefront modulation, sensitivity, and universality of the optical PUF, and bit-depth settings of captured speckle patterns. In view of the above considerations, we demonstrate that the entropy source can achieve an ultra-high min-entropy (>0.985 bits/bit) while maintaining a high extraction rate of 75% and also verify its independent and identically distributed nature. These results provide an in-depth and comprehensive understanding of the developed entropy source and offer a firm foundation for its practical use. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
392. Sapphire crystal growth and solid–liquid interface structure: An investigation by molecular dynamic simulation and Czochralski growth.
- Author
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Liu, Feng, Chen, Kunfeng, Peng, Chao, and Xue, Dongfeng
- Subjects
MOLECULAR structure ,CRYSTAL growth ,SOLID-liquid interfaces ,INTERFACE structures ,SAPPHIRES ,PHASE transitions ,LIQUID-liquid interfaces - Abstract
Sapphire has increasing demand toward optoelectrical devices like LED; its big challenge is to find reasonable growth mechanisms for high quality large size single crystals. In this paper, we proposed both theoretical and experimental studies to clarify multiscale behaviors within the Al
2 O3 growth system. Molecular dynamics simulation for sapphire crystal growth along c-, a-, and m-axes, and solid–liquid interface structure, and grown 2″ sapphire via the Czochralski method along the c-axis, were reported herein. Our studies show that α-Al2 O3 growth behaviors along different crystal directions are different, which is different from the amorphous Al2 O3 phase transition at the various α-Al2 O3 planes. α-Al2 O3 crystal growth in the c-axis system may be a complex process involving solid–liquid and solid–solid transformations, rather than a single solid–liquid transformation that happened in the systems growing along the a- and m-axes. Within the time scale of simulation, the crystals cannot be grown by the lattice period of the seed crystal along the c-axis and transform into γ-Al2 O3 rather than α-Al2 O3 , while it is opposite along the a- and m-axes. This may be the microscopic reason why it is difficult to grow sapphire along the c-axis in the experiment. An abrupt change in the interfacial structure is the key reason to inhibit the transformation of liquid Al2 O3 into α-Al2 O3 along the c-axis. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
393. Analytic solutions for displacements in quantum-wire structures.
- Author
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Tang, Tiezheng, Jiang, Zhizhen, Zhu, Kai, Liu, Kuanyu, Bai, Wei, Li, Pu, and Jin, Xiaoqing
- Subjects
QUANTUM dots ,GREEN'S functions ,NANOWIRES ,SEMICONDUCTOR devices ,OPTICAL properties - Abstract
Quantum wires (QWs) and quantum dots (QDs) have been widely applied in semiconductor devices due to their excellent mechanical, electronic, and optical properties. Faux and Downes [J. Appl. Phys. 82 (1997) 3754–3762] have obtained the closed-form solutions for strain distributions produced by QWs, whose cross section is composed of any combination of line elements and circular arcs. In this paper, Eshelby's inclusion model is established to simulate QWs and the closed-form solutions for the resultant displacements are obtained. By employing the method of Green's function, the displacement solutions may be formulated as area integrals and then converted into contour integrals along the boundary of the QW. The present study complements Faux and Downes' work and provides an efficient shortcut for analyzing the displacements of a QW, whose boundary may be discretized into line segments and circular arcs. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
394. Molecular dynamics simulation of mechanical response of Cu50Zr50 metallic glass under double shock loading.
- Author
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Rong, Jiacheng, Zhu, Pengzhe, and Xu, Yimeng
- Subjects
MOLECULAR dynamics ,METALLIC glasses ,SHEAR (Mechanics) ,STRESS concentration ,HIGH temperatures - Abstract
In real applications, materials are often subjected to multiple shock loadings, under which the mechanical response is rather complicated and needs in-depth studies. In this paper, molecular dynamics simulations of Cu
50 Zr50 metallic glass (MG) that has broad application prospects in various fields under double-shock loading have been carried out in order to uncover the deformation mechanism of MG in the dynamic process. By varying the velocity and the time interval from the first shock, we found that the double shock can lead to different phenomena such as recompaction, second spallation, uncompaction, or non-spallation. We further investigated the characteristics of these different phenomena through analyzing the damage area, stress distribution, density, and temperature in the shock processes. It was found that the void collapse caused high local stress and high temperature. We also found that the shear deformation resistance of the recompaction region cannot be recovered after recompaction through the quantitative statistics of the icosahedral clusters. Moreover, the material softening caused by high temperature in the recompaction region was the main reason for second spallation. In addition, a small second shock velocity could not induce the recompaction and a small interval time between two shocks inhibited the occurrence of the first spallation. The insights gained in this study contribute to a better understanding of the dynamic response of MGs under double-shock loadings. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
395. Numerical simulations of solid cerium ejecta transporting in vacuum and in non-reactive and reactive gases.
- Author
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Lyu, Sijia, Shi, Xiaofeng, Han, Dongyan, Ma, Zongqiang, Ma, Dongjun, Sun, Zhiyuan, Sun, Haiquan, and Wang, Pei
- Subjects
CERIUM ,EXOTHERMIC reactions ,SHOCK waves ,COMPUTER simulation ,TEMPERATURE control - Abstract
When a shock wave impacts a roughened metal/gas interface, metal ejecta particles emit and transport in the gas. The exchanges of momentum and energy between ejecta particles and the gas occur. If active metal particles transport in the reactive gas, the heat released by a chemical reaction could change these exchanges. In this paper, we use numerical simulations to study solid cerium ejecta transporting in a vacuum, and in non-reactive and reactive gases. In vacuum, the emitted ejecta could self-similarly expand neglecting the particle interaction. In the non-reactive gas (He), ejecta particles slow down by the gas resistance and have the exchanges of momentum and energy with the gas. In the reactive gas ( D 2 ), the ejecta particles also slow down. The exothermic reaction could induce the temperature rise of the ejecta and the gas, which could induce changes in physical property values of the gas after the shock wave and the velocity of the shock wave. The numerical result shows that the maximum temperature of the ejecta may appear in the middle of the mixture zone, which may result from the ejecta temperature being controlled by two competitive effects. Furthermore, the maximum ejecta temperature increases rapidly in the beginning and then becomes steady. Finally, the ejecta with a different initial size distribution is investigated. The ejecta with a smaller maximum size has a larger maximum particle temperature, a larger gas temperature after the shock wave, and a larger chemical reaction function of the ejecta at the same moment. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
396. Metastable and field-induced ferroelectric response in antiferroelectric lead zirconate thin film studied by the hyperbolic law and third harmonic response.
- Author
-
Nadaud, Kevin, Borderon, Caroline, Renoud, Raphaël, Bah, Micka, Ginestar, Stephane, and Gundel, Hartmut W.
- Subjects
THIN films ,LEGAL education ,FERROELECTRIC transitions ,FERROELECTRIC materials ,FERROELECTRICITY - Abstract
In this paper, the field-induced residual ferroelectricity in antiferroelectric lead zirconate thin films has been studied by impedance measurements together with a hyperbolic law analysis, which permits us to extract the different contributions to the material's complex permittivity. By measuring the Rayleigh coefficient α r , it appears that the residual ferroelectricity is considerably enhanced when the sample has been previously exposed to an electric field close to the antiferroelectric to ferroelectric transition field. This indicates that a part of the material remains ferroelectric after the antiferroelectric–ferroelectric backward transition, which constitutes an additional contribution to polarization. Consequently, a higher domain wall density and mobility can be observed. Measurements after exposition to thermal treatment show that this ferroelectric response is metastable. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
397. Analysis of the thermophysical process within the SEOP polarized 3He system.
- Author
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Wang, Bin, Zhang, Junpei, Lu, Yiping, Huang, Chuyi, Wang, Tianhao, Qin, Zecong, Dong, Yuchen, Zheng, Yujie, Li, Jun, Zhang, Wenqing, Ye, Fan, Qi, Xin, Liu, Yuntao, and Tong, Xin
- Subjects
TEMPERATURE distribution ,HIGH power lasers ,GAS distribution ,OPTICAL pumping ,LASER pumping - Abstract
Temperature is a crucial parameter in the spin-exchange optical pumping (SEOP) process of noble gas ( 3 He), but is hard to measure due to its confinement nature. In this paper, we conduct research upon the temperature and gas flow distribution within a sealed SEOP cell through computational fluid dynamics simulation. The simulation result shows that the external heat exchange of the initial heating of the cell becomes a cooling process in the presence of high pumping laser power absorbed by the alkali metal. The heat from the pumping laser would also cause the gas in the cell to reach a much higher temperature than the oven, with the hottest part appearing on the upper side of the cell. These predicted behaviors from the simulation are later confirmed by our experiment measurement, which strongly indicates that a gas flow and heat flow exist within the cell. These results help us to understand the temperature distribution of 3 He gas in the cell and provide references for the development and improvement of the future SEOP system. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
398. E–H transitions in Ar/O2 and Ar/Cl2 inductively coupled plasmas: Antenna geometry and operating conditions.
- Author
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Piskin, Tugba, Qian, Yuchen, Pribyl, Patrick, Gekelman, Walter, and Kushner, Mark J.
- Subjects
ANTENNAS (Electronics) ,PLASMA sheaths ,SEMICONDUCTOR manufacturing ,GAS mixtures ,PLASMA-wall interactions ,ELECTRON density - Abstract
Electronegative inductively coupled plasmas (ICPs) are used for conductor etching in the microelectronics industry for semiconductor fabrication. Pulsing of the antenna power and bias voltages provides additional control for optimizing plasma–surface interactions. However, pulsed ICPs are susceptible to capacitive-to-inductive mode transitions at the onset of the power pulse due to there being low electron densities at the end of the prior afterglow. The capacitive (E) to inductive (H) mode transition is sensitive to the spatial configuration of the plasma at the end of the prior afterglow, circuit (matchbox) settings, operating conditions, and reactor configurations, including antenna geometry. In this paper, we discuss results from a computational investigation of E–H transitions in pulsed ICPs sustained in Ar/Cl
2 and Ar/O2 gas mixtures while varying operating conditions, including gas mixture, pulse repetition frequency, duty cycle of the power pulse, and antenna geometry. Pulsed ICPs sustained in Ar/Cl2 mixtures are prone to significant E–H transitions due to thermal dissociative attachment reactions with Cl2 during the afterglow which reduce pre-pulse electron densities. These abrupt E–H transitions launch electrostatic waves from the formation of a sheath at the boundaries of the plasma and under the antenna in particular. The smoother E–H transitions observed for Ar/O2 mixture results from the higher electron density at the start of the power pulse due to the lack of thermal electron attaching reactions to O2 . Ion energy and angular distributions (IEADs) incident onto the wafer and the dielectric window under the antenna are discussed. The shape of the antenna influences the severity of the E–H transition and the IEADs, with antennas having larger surface areas facing the plasma producing larger capacitive coupling. Validation of the model is performed by comparison of computed electron densities with experimental measurements. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
399. Terahertz generation through optical rectification in reflection.
- Author
-
Hedegaard Kristensen, Mathias, Herault, Emilie, Zhai, Dongwei, Skovsen, Esben, and Coutaz, Jean-Louis
- Subjects
OPTICAL reflection ,HIGH power lasers ,TERAHERTZ spectroscopy ,CRYSTAL surfaces - Abstract
In this paper, we study terahertz generation through optical rectification in reflection at normal incidence in a dielectric nonlinear crystal. We first analyze, with a nonlinear optical model, the sample parameters (thickness, absorption at both laser and terahertz wavelengths, etc.) for which a terahertz optical rectification reflection scheme is preferable to the common transmission scheme. Then, we report our experimental observations of a reflected terahertz signal generated at the surface of a ZnTe crystal. The reflected terahertz signal shares all the characteristics of a signal generated in transmission but is not limited by absorption losses in the crystal, thereby providing a broader bandwidth. At high pump laser power, the signal exhibits saturation, which is caused by the decrease of the nonlinear susceptibility due to photocarriers generated by two-photon absorption. This reflection scheme could be of great importance for terahertz microscopy of opaque materials like, e.g., humid samples or samples exhibiting strong absorption bands or to study samples for which the transmitted signal cannot be recorded. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
400. All-optical logic gates using E-shaped silicon waveguides at 1.55 μm.
- Author
-
Kotb, Amer, Zoiros, Kyriakos E., and Guo, Chunlei
- Subjects
SIGNAL processing ,SILICON ,LOGIC circuits ,TELECOMMUNICATION ,WAVEGUIDES - Abstract
Owing to the advanced fabrication technology of silicon, silicon waveguides are particularly attractive for implementing all-optical signal processing devices and switches. Therefore, in this paper, a silicon-on-silica waveguide that consists of four slots arranged in the shape of letter E is proposed to be employed as the building block for simulating fundamental all-optical logic gates (AOLGs), including XOR, AND, OR, NOT, NOR, NAND, and XNOR, at 1.55 μm telecommunications wavelength. The operation concept of these logic gates relies on the constructive and destructive interference that results from the phase difference induced by optical beams that are incident on the E-shaped waveguide. The performance of the target logic gates is assessed against the contrast ratio (CR) metric. Moreover, the dependence of the spectral transmission on the device's key operating parameters is investigated and assessed. Compared to other reported designs, the results obtained by conducting simulations using the finite-difference-time-domain in lumerical commercial software show that the proposed waveguide can operate at a higher speed of 80 Gb/s and attain higher CRs of 36, 39, 35.5, 28.8, 30, 38, and 36.7 dB for logic XOR, AND, OR, NOT, NOR, NAND, and XNOR, respectively. This suggests that by using the proposed scheme, AOLGs could be realized more feasibly with greater performance and faster operation toward satisfying the present and future needs of light wave circuits and systems. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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