- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Two distinct surface terminations of SrVO <sub/>3</sub> (001) ultrathin films as an influential factor on metallicity
摘要： Pulsed laser deposition-grown SrVO3 (001) ultrathin films on SrTiO3 (001) substrates were investigated by in situ low-temperature scanning tunneling microscopy and spectroscopy. SrVO3 (001) ultrathin films showed two distinct surface terminations. One termination was a ((√2 × √2)-R45° reconstruction as was previously observed for SrVO3 (001) thick films, while the other was a ((√5 × √5)-R26.6° reconstruction. Scanning tunneling spectroscopy revealed that the ((√2 × √2)-R45° surface shows a metallic electronic structure, whereas the ((√5 × √5)-R26.6° surface exhibits a significantly reduced density of states at the Fermi level. These results suggest that the surface reconstruction may be an important factor to influence metallicity in epitaxial ultrathin films of transition metal oxides.
关键词： ultrathin films,scanning tunneling microscopy,scanning tunneling spectroscopy,SrVO3,metallicity,surface terminations
更新于2025-09-04 15:30:14
-
[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - V?ster?s, Sweden (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Comparison of the Microwave Performance of Transparent Monopole Antennas Made of Different Transparent Conducting Films
摘要： The performance of four different transparent monopole antennas made from an ultrathin copper film, an ITO film, an ITO/Cu/ITO multilayer, a micrometric mesh silver film, and printed onto glass substrates is investigated. Optical transparency in the visible light spectrum, sheet resistance and microwave performance at 850 MHz of such samples are measured, compared and discussed. The micrometric mesh silver monopole antenna exhibits the best characteristics: a high level of optical transparency (higher than 80%) coupled to a sheet resistance as low as 0.054 Q/sq with a gain equal to 2.24 dBi at 850 MHz, very close to that of the reference and opaque counterpart (2.29 dBi) made of a continuous silver layer.
关键词： Mesh Metal Film,Ultrathin Metal Film,ITO/Metal Multilayer,Lozenge Monopole Antenna,ITO Film
更新于2025-09-04 15:30:14
-
Perpendicular magnetic anisotropy and its electric field effect in Co ultrathin films deposited directly on SrTiO <sub/>3</sub> (111) surface
摘要： We have investigated magnetic anisotropy and its electric ?eld e?ect in ultrathin Co with a Pt cap layer. The layers were directly deposited on SrTiO3(111) and (100) surfaces without any under layer. In as-deposited samples, a stronger perpendicular magnetic anisotropy was observed in the (111) sample. A back gate con?guration was used to apply the electric ?eld to the bottom surface of Co layer through the SrTiO3 substrate. In both samples, the coercivity was enhanced with a positive gate bias, which corresponds to the direction of the electron accumulation. The e?ciency of the change in the coercivity per modulated electron density was greater in the (111) sample over a wide temperature range including 2 K, at which the thermally activated magnetization reversal was expected to be suppressed. The results suggest that the surface orientation of the substrate a?ects both the magnetic anisotropy and its electric ?eld e?ect on Co.
关键词： perpendicular magnetic anisotropy,SrTiO3,Co ultrathin ?lms,electric ?eld e?ect
更新于2025-09-04 15:30:14
-
Real-time switching dynamics of ferroelectric tunnel junctions under single-shot voltage pulses
摘要： In ferroelectric memory devices, information is stored within the polarization direction whose reversal usually occurs by the nucleation and propagation of domains. In ultrathin ferroelectrics, ultrafast dynamics may be achieved by nucleation-limited switching, avoiding the inherently speed-limited propagation of domain walls. Here, we investigate polarization reversal dynamics in ultrathin ferroelectric films by transient current measurements. Thanks to the tunnel electroresistance, the start of polarization reversal induces sharp variations of the transmitted current under voltage pulses. These single-shot measurements show extremely fast switching with durations down to 3 ns that is only limited by the current device geometry. While the OFF-to-ON switching shows finite nucleation times that scale with the pulse amplitude, the ON-to-OFF switching speed cannot be detected under such rectangular pulses. Resorting to triangular pulse excitations allows us to detect the dynamics of this switching direction. Both cases can be interpreted by nucleation switching models following Merz’s law.
关键词： transient current measurements,nucleation-limited switching,single-shot measurements,Merz’s law,ferroelectric memory devices,ultrathin ferroelectric films,polarization reversal dynamics,tunnel electroresistance
更新于2025-09-04 15:30:14
-
Ultrathin Conductor Enabling Efficient IR Light CO2 Reduction
摘要： Concurrent transformation of carbon dioxide and water into hydrocarbons and oxygen by low-photonic-energy IR light still represents a huge challenge. Here, we design an ultrathin conductor system, in which the special partially occupied band serves as the mediator to simultaneously guarantee IR light harvesting and satisfied band-edge positions, while the ultrathin configuration improves charge separation rates and surface redox kinetics. Taking the low cost and earth abundant CuS as an example, we first fabricate ultrathin CuS layers, where temperature-dependent resistivities, valence-band spectrum and theoretical calculation affirm their metallic nature. Synchrotron-radiation photoelectron and ultraviolet-visible-near infrared spectra unveil metallic CuS atomic layers could realize a new cooperative intraband-interband transition under IR light irradiation, where the generated electrons and holes could simultaneously involve the carbon dioxide reduction and water oxidation reactions. As a result, CuS atomic layers exhibit nearly 100% selective CO production with an evolution rate of 14.5 μmol g-1 h-1 under IR light irradiation, while the catalytic performance shows no obvious decay after 96 h test. Briefly, benefiting from ultrahigh conductivity and unique partially occupied band, the abundant conductor materials such as conducting metal sulfides and metal nitrides hold great promise for applications as effective IR light responsive photocatalysts.
关键词： intraband-interband transition,ultrathin,CO2 reduction,conductor,IR light
更新于2025-09-04 15:30:14
-
Metastable crystalline phase in two-dimensional metallic oxide nanoplates
摘要： Structural phase transition in crystals induced by high-pressure or high-temperature conditions may result in the development of unusual physical and chemical properties; these properties are often difficult to stabilize under ambient conditions. Here we adopted a simple method in which ultrathin cerium oxide nanoplates (< 1.4 nm) were synthesized to increase the surface atomic content, allowing transformation from a face-centered cubic (fcc) phase to a body-centered tetragonal (bct) phase. Three types of cerium oxide nanoparticles of different thicknesses, i.e., 1.2-nm ultrathin nanoplates, 2.2-nm nanoplates, and 5.4-nm nanocubes, were examined using transmission electron microscopy and X-ray diffraction. The metastable bct phase was observed only in ultrathin nanoplates. Thermodynamic energy analysis confirmed that the surface energy of the ultrathin nanoplates is the cause of the remarkable stabilization of the metastable bct phase. The mechanism of surface energy regulation can be expanded to other metallic oxides, thus providing a new means for manipulating and stabilizing novel materials under ambient conditions that otherwise would not be recovered.
关键词： metastable phase,thickness,surface unsaturated coordination ratio,Ultrathin nanoplates,metallic oxide nanoparticles
更新于2025-09-04 15:30:14
-
Multi-inch single-crystalline perovskite membrane for high-detectivity flexible photosensors
摘要： Single crystalline perovskites exhibit high optical absorption, long carrier lifetime, large carrier mobility, low trap-state-density and high defect tolerance. Unfortunately, all single crystalline perovskites attained so far are limited to bulk single crystals and small area wafers. As such, it is impossible to design highly demanded ?exible single-crystalline electronics and wearable devices including displays, touch sensing devices, transistors, etc. Herein we report a method of induced peripheral crystallization to prepare large area ?exible single-crystalline membrane (SCM) of phenylethylamine lead iodide (C6H5C2H4NH3)2PbI4 with area exceeding 2500 mm2 and thinness as little as 0.6 μm. The ultrathin ?exible SCM exhibits ultralow defect density, superior uniformity and long-term stability. Using the superior ultrathin membrane, a series of ?exible photosensors were designed and fabricated to exhibit very high external quantum ef?ciency of 26530%, responsivity of 98.17 A W?1 and detectivity as much as 1.62 × 1015 cm Hz1/2 W?1 (Jones).
关键词： high-detectivity,single-crystalline perovskite,flexible photosensors,induced peripheral crystallization,ultrathin membrane
更新于2025-09-04 15:30:14
-
Desenvolvimento de filmes poliméricos ultrafinos e reticulados para aplica??es em sensores
摘要： A new method for producing stable films used in sensors is proposed, based on the layer-by-layer deposition of poly(o-ethoxyaniline) and phenol-formaldehyde (POEA/PF) followed by a thermal treatment to promote film crosslinking. The crosslinking process was characterized by Fourier transform infrared and ultraviolet-visible spectroscopic analyses, atomic force microscopy and desorption studies. Sensor analyses were also carried out in order to evaluate cross-linked sensor signal. Results showed that PF resin served as a curing agent, forming a semi-interpenetrating polymer network therefore producing stable films. Although there was a decrease in the sensitivity of sensors with crosslinking, such films are quite stable and can be potentially used in sensors, especially where higher stability is required.
关键词： ultrathin films,conductive polymers,sensors
更新于2025-09-04 15:30:14