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- 摘要
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Fast 3D Microscopy Imaging of Contacts Between Surfaces Using a Fluorescent Liquid
摘要： A novel method is presented for the rapid direct 3D visualization of the contact between two surfaces by means of fluorescence microscopy using a fluorescent liquid. Distances between the surfaces of up to several hundred nanometers can be determined with sub-nanometer accuracy in 3D and within seconds of measurement time. The method opens new possibilities for research in the areas of contact mechanics, friction, wear and lubrication.
关键词： fluorescent probes,mechanical properties,3D imaging,Interfaces
更新于2025-09-10 09:29:36
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First-principles investigation of the interface magnetic anisotropy of Fe/SrTiO<sub>3</sub>
摘要： Interface effects in the magnetic nanostructures play a critical role in the magnetic properties. By using the first-principles density functional theory calculations, we investigate the electronic and magnetic properties of Fe/SrTiO3 interfaces, in which both the nonpolar surface SrTiO3(001) and the polar surface SrTiO3(110) are considered. A particular emphasis is placed on the magnetic anisotropy energy (MAE). Compare MAE of the Fe/SrTiO3 interfaces and the corresponding Fe monolayers, we find the Fe/SrTiO3(001) interface decreases MAE, while the Fe/SrTiO3(110) interface increases MAE. The interface orbital hybridization and orbital magnetic moments are detailly analyzed to understand the different interface magnetic anisotropy. Our investigation indicates that interface engineering can be an effective way to modulate the magnetic properties.
关键词： Fe/SrTiO3 interfaces,interface orbital hybridization,first-principles calculations,magnetic anisotropy energy
更新于2025-09-09 09:28:46
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Nonlinear optical susceptibility of atomically thin WX2 crystals
摘要： We have studied tungsten diselenide (WSe2) and tungsten disulfide (WS2) monolayer materials in second harmonic generation spectroscopy and microscopy experiments. Ultra-broadband continuum pulses served as the fundamental beam while its second harmonic spectrum in the visible and ultraviolet (UV) range was detected and analyzed with a better than 0.3 nm spectral resolution (< 2 meV). We provide dispersion data and absolute values for χ(2) for the materials within a photon energy range of 2.3–3.2 eV. Fine spectral features that were detected within the dispersion data for the optical nonlinearities indicate the impact of near bandgap exciton transitions. The fundamental bandgap of 2.35 eV and exciton binding energy of 0.38 eV were determined from the measurements for WS2 monolayers while the corresponding values in WSe2 monolayers were 2.22 eV and 0.71 eV. Ranges for the absolute values of the sheet nonlinearity for WS2 and WSe2 are shown to be 0.58–1.65 × 10?18 m2/V and 0.21–0.92 × 10?18 m2/V, correspondingly.
关键词： Nonlinear spectroscopy and microscopy,Transition metal dichalcogenides,Two-dimensional semiconductors,Second harmonic generation,Optical nonlinearity in semiconductors,Monolayer crystals,Optics at interfaces
更新于2025-09-09 09:28:46
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Prediction of Fundamental Properties of Semiconductors and Materials Exploration Using First-Principles Calculations
摘要： 昨今の資源?環境問題やエネルギー情勢を背景に，卓越した機能だけでなく，地球上に豊富に存在する元素により構成され，安価で高い環境調和性を示す新材料が望まれている．社会に役立つ「材料」へと昇華できる新物質を見いだすためには，的確に設計?探索の指針を立てることが重要であることは言うまでもない．そして次の関門が，いかに広い探索空間をカバーするか，その中からどのように有望な物質を絞り込むかである．最近では計算科学の進展とスーパーコンピュータの演算能力の向上により，第一原理計算等の計算科学手法を用いることで物質の安定性や特性を高精度かつ網羅的に予測できるようになってきた．これにデータ科学手法，更にはコンビナトリアル合成?評価等を連携させることで，新物質?新材料の開発を加速し，同時に膨大なデータの解析から設計?探索指針を得ようとする試みが世界各国で盛んになっている．いわゆる「マテリアルズ?インフォマティクス」によるアプローチである．
关键词： surfaces,point defects,interfaces,materials exploration,semiconductors,first-principles calculations
更新于2025-09-09 09:28:46
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Creation of Two-Dimensional Electron Gas and Role of Surface Donors in III-N Metal-Oxide-Semiconductor High-Electron Mobility Transistors
摘要： The role of surface donors at the oxide/semiconductor interface of III-N metal-oxide-semiconductor (MOS) high-electron mobility transistors (HEMTs), by creating a two-dimensional electron gas (2DEG) and the device performance, are investigated. Al2O3/GaN/AlGaN/GaN MOS HEMTs show the surface donor density (Nd,surf ) of 2.2 (cid:1) 1013 cm(cid:3)2 which is increased up to 3.4 (cid:1) 1013 cm(cid:3)2 after post-deposition annealing. In the latter, surface donors fully compensate the surface polarization charge and the HEMT threshold voltage decreases substantially with the oxide thickness. On the other hand, an open-channel drain current is found to be independent of Nd,surf, while marginal trapping is completely removed when Nd,surf increases with annealing. Consequently, ionized surface donors behave like a fixed charge and are clearly distinguishable from trapping states. Open-channel 2DEG densities of (cid:4)1.1 (cid:1) 1013 cm(cid:3)2 are extracted from capacitance–voltage measurements. Similarly, recent data on enhancement-mode HfO2/InAlN/AlN/GaN MOS HEMTs are analyzed where Nd,surf is reduced down to (cid:3)2 while 2DEG densities reach (cid:4)2.7 (cid:1) 1013 cm(cid:3)2. It is suggested that under the open-channel condition, 2DEG is supplied also by an injecting source contact if Nd,surf is lower than the QW polarization charge. Our charge quantifications are supported by calculating energy-band diagrams.
关键词： oxide-semiconductor interfaces,AlGaN/GaN high-electron mobility transistors (HEMTs),polarization
更新于2025-09-09 09:28:46
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Determination of interfacial fracture energy for 'pop-in' delaminations in a glass-epoxy system using the indentation method
摘要： The adhesion of coatings often controls the performance of the substrate-coating system. Certain engineering applications require an epoxy coating on a brittle substrate to protect and improve the performance of the substrate. Interfacial adhesion measurements of such systems provide a quantitative metric of that performance. Indentation experiments were performed to induce interfacial delaminations in a glass substrate-epoxy coating system. Delamination loads and radii were measured and applied to an analytical solution originally developed by Rosenfeld et al. (1990) to estimate the interfacial fracture energy of the substrate-coating adhesive bond. Results suggest an interfacial bond strength far exceeding that of similar previously studied glass-epoxy systems.
关键词： bonding,indentation,glass,coatings,epoxy,interfaces,fracture energy,adhesion
更新于2025-09-09 09:28:46
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Interfacing a Potential Purely Organic Molecular Quantum Bit with a Real-Life Surface
摘要： By using a multidisciplinary and multi-technique approach, we have addressed the issue of attaching a molecular quantum bit to a real surface. First, we demonstrate that an organic derivative of the pyrene-Blatter radical is a potential molecular quantum bit. Our study of the interface of the pyrene-Blatter radical with a copper-based surface reveals that the spin of the interface layer is not cancelled by the interaction with the surface and that the Blatter-radical is resistant in presence of molecular water. Although the measured pyrene-Blatter derivative quantum coherence time is not the highest value known, this molecule is known as a “super stable” radical. Conversely, other potential qubits show poor thin film stability upon air exposure. Therefore, we discuss strategies to make molecular systems candidates as qubits competitive, bridging the gap between potential and real applications.
关键词： X-ray spectroscopies,quantum bits,organic radicals,spinterfaces,interfaces
更新于2025-09-09 09:28:46
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Interfacial mechanical properties of double-layer graphene with consideration of the effect of stacking mode
摘要： The mechanical performance and the effect of the stacking mode of the double-layer graphene interface are studied. Three kinds of double-layer graphene-PET composite structure specimens with different stacking methods are designed. By combining micro-Raman spectroscopy with a micro-tensile loading device, in-situ and real-time measurements are carried out for the specimens during the uniaxial loading process. Based on mechanical analysis, a method for peak splitting of the Raman spectra of double-layer polycrystalline graphene is developed to extract the strain information for each layer of graphene. The strain distribution and shear stress distribution of graphene in each layer during the loading process are determined experimentally. The strain transfer between the two interfaces is analyzed, and the mechanical parameters of interfaces are given quantitatively; the interlayer shear stress of graphene is 0.084 MPa. Finally, double-layer graphene with different stacking modes is studied. The results show that the different lengths of the upper and lower layers of graphene lead to a stress concentration of 0.7–1 GPa at the boundary of the short layer of graphene when stacked. The stress concentration problem of double-layer graphene should be considered for the practical application in micro-electrical components.
关键词： interfacial mechanical property,Raman spectroscopy,edge effect,double-layer graphene interfaces
更新于2025-09-09 09:28:46
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Strong suppression of In desorption from InGaN QW by improved technology of upper InGaN/GaN QW interface
摘要： The aim of this work is to elucidate how di?erent growth mode and composition of barriers can in?uence the QW properties and their PL and to ?nd optimal QW capping process, to suppress the In desorption from QWs and to maintain the QW PL e?ciency. It concentrates on the technology procedure for growth of upper quantum well (QW) interfaces in InGaN/GaN QW structure when di?erent temperature for QW and barrier epitaxy is used. We have found that optimal photoluminescence (PL) results were achieved, when the growth after QW formation was not interrupted, but immediately continued during the temperature ramp by the growth of (In)GaN capping layer with small introduction of In precursor into the reactor. Optimal barrier between QW with respect to PL results was found to be pure GaN. We have shown according to SIMS and HRTEM results that by this technological procedure the InGaN desorption was considerably suppressed and three times higher In concentration and two times thicker QWs were achieved for the same QW growth parameters without deterioration of PL intensity in comparison to sample with usually used thin GaN low temperature capping protection. Additionally, for samples covered by the QW capping layer during the temperature ramp the defect band is almost completely missing, thus we can conclude that this defect band is connected with quality of the upper QW interface.
关键词： A1. Interfaces,A3. Quantum wells,B1. Nitrides,A3. MOVPE,B2. Scintillators
更新于2025-09-04 15:30:14
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<i>In situ </i>soft x-ray absorption spectroscopic study of polycrystalline Fe/MgO interfaces
摘要： In situ soft x-ray absorption spectroscopic study of polycrystalline Fe/MgO interfaces. It is found that at the interface of iron and MgO film, about two monolayers of Fe3O4 is formed. Fe3O4 being the oxide of iron with the highest heat of formation, the reaction appears to be controlled thermodynamically. On the other hand, on the interface with MgO (001) surface, FeO is formed, suggesting that the reaction is limited by the availability of oxygen atoms. Magnetic behavior of the FeO layer gets modified significantly due to proximity effect of the bulk ferromagnetic iron layer.
关键词： FeO,soft x-ray absorption spectroscopy,Fe/MgO interfaces,Fe3O4,magnetic behavior
更新于2025-09-04 15:30:14