- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Dense Electron-Hole Plasma Formation and Ultra-Long Charge Lifetime in Monolayer MoS <sub/>2</sub> via Material Tuning
摘要： Many-body interactions in photoexcited semiconductors can bring about strongly-interacting electronic states, culminating in the fully-ionized matter of electron-hole plasma (EHP) and electron-hole liquid (EHL). These exotic phases exhibit unique electronic properties, such as metallic conductivity and metastable high photoexcitation density, which can be the basis for future transformative applications. However, the cryogenic condition required for its formation has limited the study of dense plasma phases to a purely academic pursuit in a restricted parameter space. This paradigm can potentially change with the recent experimental observation of these phases in atomically thin MoS2 and MoTe2 at room temperature. A fundamental understanding of EHP and EHL dynamics is critical for developing novel applications on this versatile layered platform. In this work, we studied the formation and dissipation of EHP in monolayer MoS2. Unlike previous results in bulk semiconductors, our results reveal that electro-mechanical material changes in monolayer MoS2 during photoexcitation play a significant role in dense EHP formation. Within the free-standing geometry, photoexcitation is accompanied by an unconstrained thermal expansion, resulting in a direct-to-indirect gap electronic transition at a critical lattice spacing and fluence. This dramatic altering of the material’s energetic landscape extends carrier lifetimes by 2 orders of magnitude and allows the density required for EHP formation. The result is a stable dense plasma state that’s sustained with modest optical photoexcitation. Our findings pave the way for novel applications based on dense plasma states in 2D semiconductors.
关键词： 2D materials,Dense Electron-Hole Plasma,Bandgap Renormalization,MoS2,Transition Metal Dichalcogenides,Direct to Indirect Bandgap Transition
更新于2025-09-23 15:23:52
-
[IEEE 2018 IEEE CPMT Symposium Japan (ICSJ) - Kyoto, Japan (2018.11.19-2018.11.21)] 2018 IEEE CPMT Symposium Japan (ICSJ) - Surface analysis of argon and oxygen plasma-treated gold for room temperature wafer scale gold-gold bonding
摘要： The effects of Ar and O2 plasma treatments on Au surface properties were investigated in terms of room-temperature wafer-scale Au-Au bonding. X-ray photoelectron spectroscopy analysis indicated that O2 plasma treatment formed gold oxide (Au2O3) on Au surfaces, and bonded samples treated by O2 plasma showed weak bonding strength (0.14-0.16 J/m2). It seems that Au2O3 impeded Au-Au bonding. On the other hand, strong Au-Au bonding was obtained by using Ar plasma treatment, and bonded samples were fractured at the bulk wafers during the blade test.
关键词： O2 plasma,Room-temperature bonding,Au-Au bonding,Ar plasma
更新于2025-09-23 15:22:29
-
Nitrogen Adsorption of Si(100) Surface by Plasma Excited Ammonia
摘要： Nitrogen adsorption on thermally cleaned Si(100) surfaces by pure and plasma excited NH3 is investigated by in situ IR absorption spectroscopy and ex-situ X-ray photoelectron spectroscopy with various temperatures from RT (25?C) to 800?C and with a treatment time of 5 min. The nitrogen coverage after the treatment varies according to the treatment temperature for both pure and plasma excited NH3. In case of the pure NH3, the nitrogen coverage is saturated as low as 0.13–0.25 mono layer (ML) while the growth of the nitride ?lm commenced at 550?C. For the plasma excited NH3, the saturation coverage was measured at 0.54 ML at RT and it remained unincreased from RT to 550?C. This indicates that the plasma excited NH3 enhances the nitrogen adsorption near at RT. It is found that main species of N is Si2 = NH in case of the plasma excited NH3 at RT while the pure NH3 treatment gives rise to the Si–NH2 passivation with Si–H at RT. We discuss the mechanism of the nitrogen adsorption on Si(100) surfaces with the plasma excited NH3 in comparison with the study on the pure NH3 treatment.
关键词： plasma excited NH3,Plasma,XPS,IR absorption spectroscopy
更新于2025-09-23 15:22:29
-
Direct exposure of non-equilibrium atmospheric pressure plasma confers simultaneous oxidative and ultraviolet modifications in biomolecules
摘要： Thermal plasmas and lasers are used in medicine to cut and ablate tissues and for coagulation. Non-equilibrium atmospheric pressure plasma (NEAPP) is a recently developed, non-thermal technique with possible biomedical applications. Although NEAPP reportedly generates reactive oxygen/nitrogen species, electrons, positive ions, and ultraviolet radiation, little research has been done into the use of this technique for conventional free radical biology. Recently, we developed a NEAPP device with high electron density. Electron spin resonance spin-trapping revealed ?OH as a major product. To obtain evidence of NEAPP-induced oxidative modifications in biomolecules and standardize them, we evaluated lipid peroxidation and DNA modifications in various in vitro and ex vivo experiments. Conjugated dienes increased after exposure to linoleic and α-linolenic acids. An increase in 2-thiobarbituric acid-reactive substances was also observed after exposure to phosphatidylcholine, liposomes or liver homogenate. Direct exposure to rat liver in saline produced immunohistochemical evidence of 4-hydroxy-2-nonenal- and acrolein-modified proteins. Exposure to plasmid DNA induced dose-dependent single/double strand breaks and increased the amounts of 8-hydroxy-2'-deoxyguanosine and cyclobutane pyrimidine dimers. These results indicate that oxidative biomolecular damage by NEAPP is dose-dependent and thus can be controlled in a site-specific manner. Simultaneous oxidative and UV-specific DNA damage may be useful in cancer treatment.
关键词： 8-OHdG,HNE-modified protein,non-equilibrium atmospheric pressure plasma,electron spin resonance spin-trapping,UV
更新于2025-09-23 15:22:29
-
Design status of the ITER core CXRS diagnostic setup
摘要： The Charge eXchange Recombination Spectroscopy diagnostic system on the ITER plasma core (CXRS core) will provide spatially resolved measurements of plasma parameters. The optical front-end is located in upper port 3 and the light of 460–665 nm is routed to spectrometers housed in the tritium building. This paper describes the layout of the optical system in the port plug, cell and interspace areas. The layout is a continuation of the developments described in [1] and takes into account changes in the design of the upper port plug, considerations for the system lifetime as well as internal and external tolerances on the optical chain. The layout was selected also with a number of additional criteria, including optical performance, radiation shielding, maintainability and robustness. A free-space optical chain was added pushing the optical fibres to the port cell. A line-of-sight finder imaging apertures and masks in the optical chain was added to enable determination of deviations within the optical chain and stabilise the image on the fibres. Where feasible, existing solutions for sub-systems such as the shutter were adapted to the layout.
关键词： Plasma diagnostic system,Diagnostic design,CXRS,Core Charge Exchange Recombination Spectroscopy,ITER
更新于2025-09-23 15:22:29
-
The Dependence of Resonance Frequency to Landing Angle in Reciprocal Scattering Phenomena of the Waves From an Elliptical Plasma Dielectric Antenna
摘要： Scattering of an electromagnetic plane wave in transverse electric mode which is obliquely incident to an elliptical plasma antenna with a dielectric rod is comprehensively investigated. The field solutions of the incident, transmitted, and the scattered waves will be derived in terms of Mathieu and modified Mathieu functions. Using asymptotic expansions of Mathieu functions, the scattering cross section per unit length is obtained. It will be shown that in such an elliptical plasma antenna, the backscattering cross section depends on the incident angle and the bistatic scattering cross section varies with scattering angle significantly. Such effects are not seen in antennas with circular cross section due to the circular symmetry in them. The validation of the presented formulations and numerical computation will be examined with the circular case that is an asymptotic well-known case. The graphs of backscattering cross section, scattering pattern, and their corresponding to the polarized charge densities are presented. The dependence of the backscattering cross section and the scattering pattern upon the density and geometrical dimension of the plasma and dielectric are investigated. In addition, it will be shown that the resonance frequencies, under which the plasma antenna response will be maximum, essentially depend on the incident angle of the incident wave.
关键词： dielectric rod,resonance frequency,polarized charge density,Backscattering cross section,scattering pattern,elliptical plasma antenna
更新于2025-09-23 15:22:29
-
[IEEE 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - Saint-Petersburg, Russia (2018.11.26-2018.11.30)] 2018 Wave Electronics and its Application in Information and Telecommunication Systems (WECONF) - MEMS Accelerometer with SAW
摘要： was created the model of a microaccelerometer using MEMS technology. Were investigated the sensitivity and non-linear properties of the MEMS sensor in the commercial temperature range.
关键词： microaccelerometer with SAW,slaser stimulated plasma etching,MEMS technology
更新于2025-09-23 15:22:29
-
Three-dimensional simulations of edge impurity flow obtained by the vacuum ultraviolet emission diagnostics in the Large Helical Device with EMC3-EIRENE
摘要： Edge carbon impurity flow in the stochastic layer of the Large Helical Device (LHD) has been investigated with the three-dimensional (3D) edge transport code EMC3-EIRENE. The simulated synthetic C3+ impurity flow profile from EMC3-EIRENE shows a reasonable agreement with the vacuum ultraviolet (VUV) measurements according to the CIV (1548.20 × 2 ?) Doppler-shift spectrum. The same horizontally outward C3+ impurity flows at the top and bottom edges of the stochastic layer are determined by the 3D magnetic field structure and the parallel C3+ impurity flow velocity. The observed up-down asymmetric structure of the C3+ impurity flow at the top and bottom edges is caused by the vertical displacement of the VUV spectrometer from the midplane. The horizontally outward shift of the magnetic axis position from 3.6 to 3.9 m leads to a change of the C3+ impurity flow direction at the top and bottom edges. For a high upstream plasma density, the transport of the C3+ impurity flow is mainly determined by the background parallel plasma flow, while a reversed C3+ impurity flow is obtained for a low upstream plasma density, due to the expansion of the thermal force dominant regions. The enhanced thermal force leads to a suppression of the impurity screening effect.
关键词： spectrometer,LHD,impurity flow,SOL/divertor plasma
更新于2025-09-23 15:22:29
-
[IEEE 2018 IEEE 38th Central America and Panama Convention (CONCAPAN XXXVIII) - San Salvador, El Salvador (2018.11.7-2018.11.9)] 2018 IEEE 38th Central America and Panama Convention (CONCAPAN XXXVIII) - Parallelization of a Magnetohydrodynamics Model for Plasma Simulation
摘要： Plasma simulations are inherently complex due to the numerous and intricate processes that naturally occur to matter in this state. Computer simulations and visualizations of plasma help researchers and scientists understand the physics that takes place in it. We have developed a parallel implementation of an application used to simulate and visualize the process of convection in plasma cells. This application implements a magnetohydrodynamics (MHD) approach to plasma modeling by numerically solving a fourth-order two-dimensional differential scheme. Results of experimentation with our parallel implementation are presented and analyzed. We managed to speedup the program by a factor of nearly 42× after parallelizing the code with OpenMP and using 128 cores on our Intel Xeon Phi KNL server. We also achieved an almost linear scalability of the execution time when increasing the size of the spatial and temporal domains.
关键词： plasma,physics simulation,OpenMP,MHD
更新于2025-09-23 15:22:29
-
Removal of Ethylene and By-Products using Packed Bed Dielectric Barrier Discharge with Ag Nanoparticle-Loaded Zeolite
摘要： Ethylene gas was decomposed using packed-bed type dielectric barrier discharge (PBDBD) plasma reactor to keep freshness of fruits. The ethylene gas was diluted with gas mixture of nitrogen, oxygen and carbon dioxide as simulated gas in the transportation container. The PBDBD plasma was generated by a pulse switching power supply which consisted of MOS-FET switching devices, capacitors and pulse transformers. The Ag nanoparticle-loaded zeolite as catalyst has high activity and good performance for reduction of ozone and oxidizing carbon monoxide at room temperature. The Ag nanoparticle-loaded zeolite pellets enhanced ethylene removal efficiency and reduced ozone and carbon monoxide produced by the plasma treatment. It was confirmed that the carbon monoxide in the gas simulated dry air composition was oxidized using Ag nanoparticle-loaded zeolite with plasma treatment.
关键词： plasma,catalyst,ethylene,PBDBD,carbon monoxide
更新于2025-09-23 15:22:29