The observed results are promising for realization of memory devices, compatible with the silicon complementary-metal-oxide-semiconductor technology. Electrically driven single-photon sources are essential for building compact, scalable, and energy-efficient quantum information devices. Recently, color centers in SiC emerged as promising candidates for such nonclassical light sources.
However, very little is known about how to control, dynamically tune, and trigger their single-photon electroluminescence SPEL , which is required for efficient generation of single photons on demand. This time is shorter than the lifetime of the excited state of the SiC-SF center, which gives the possibility to trigger single-photon generation by applying short electric pulses.
The high contrast ratio between the ON and OFF states combined with short characteristic times creates a solid foundation for the development of on-demand high-repetition-rate single-photon sources. Joint motion is a very common activity which involves tensile or compressive bending motions. Distinguishing and monitoring of joint motions are important for an interactive human—machine interface or rehabilitation of human joints.
Here, we present an asymmetric structure based, liquid metal embedded, resistive strain sensor, which is prepared by a stereolithography-based 3D printing process. Electromechanical characterization results of sensors confirm that the current sensor can monitor the angle and direction of joints even if the angle amplitude remains the same.
Sensor performance is enhanced with the increase of its thickness, which is due to an additional deviation produced at the center. This deviation causes the resistance of the sensor to change greatly during both compressive and tensile bending.
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Our sensor paves a way for real-time continuous monitoring of human or artificial robot joint motions. Detecting and discriminating chemical vapors are essential for environmental monitoring and medical diagnostics. In this study, highly sensitive chemical vapor sensors fabricated from fluorinated thiophene—isoindigo donor—acceptor conjugated polymers are realized through understanding the interaction of the fluorine functional group and different chemical vapors.
The polymers possess the merits of facile synthesis for high quality materials, good field-effect transistor performance, and stability in air and humid environments. The transistor exhibits extremely high detecting capability for minute chemical vapor down to the ppb range. The detecting sensitivity of the transistor depends on the chemical structure of the polymer and the nature of analytes.
Polar molecules such as amines with potential hydrogen bond donor can adsorb in close vicinity to conducting channels due to the formation of a hydrogen bond with fluorine atoms, enhancing the sensitivity significantly. Chemical vapors such as acetone and xylene interacting with the polymers via dipolar and van der Waals forces, respectively, have to accumulate sufficient amounts in the polymer films or at the dielectric interface.
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Through understanding functional group—analyte interactions, polymers can be designed for multiparameter sensing, paving ways toward ultrasensitive sensors and accurate discrimination of different kinds of chemical vapors. Vanadium pentoxide V2O5 is known to have natural n-type conductivity but transitions from n- to p-type conductivity when grown in a hydrated amorphous phase via atomic layer deposition.
This increased internal electric field strengthens the electron—hole separation across the heterojunction interface, which in turn improves the photocatalytic and photoelectrochemical performance of the structure. Using first-principles calculations, we found that when H2O molecules are incorporated into the amorphous V2O5 matrix, delocalized empty states are freshly formed above the valence band maximum in the hydrated amorphous V2O5, playing a crucial role in the transition of electrical conductivity within V2O5.
This approach provides a simple and efficient way to discover new p-type materials and apply them to future p—n junction devices in terms of process simplicity and cost effectiveness. Significant heat generation in modern high-speed electronic devices requires elevated thermal conductivity of electrically conductive adhesives ECAs , but the gap between discrete filler materials significantly interrupts the pathway of heat transport. The silver—organic complex is capable of molecule-scale blending and forming ultrafine Ag particles 13—47 nm well-distributed in the epoxy matrix, enabling gap-filling and bulky network sintering to achieve thermal conductivity enhancement.
Two-dimensional 2D materials, such as graphene, are seen as potential candidates for fabricating electronic devices and circuits on flexible substrates. Inks or dispersions of 2D materials can be deposited on flexible substrates by large-scale coating techniques, such as inkjet printing and spray coating. One of the main issues in coating processes is nonuniform deposition of inks, which may lead to large variations of properties across the substrates.
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Here, we investigate the role of surface morphology on the performance of graphene ink deposited on different paper substrates with specific top coatings. Substrates with good wetting properties result in reproducible thin films and electrical properties with low sheet resistance. The correct choice of surface morphology enables high-performance films without postdeposition annealing or treatment. Scanning terahertz time-domain spectroscopy THz-TDS is introduced to evaluate both the uniformity and the local conductivity of graphene inks on paper.
A paper-based strain gauge is demonstrated and a variable resistor acts as an on—off switch for operating an LED. Customized surfaces can thus help in unleashing the full potential of ink-based 2D materials. Topological insulators TIs are a class of materials that can exhibit robust spin polarizations at the surfaces and have attracted much attention toward spintronic applications. Solution chemistry provides high quality nanoplates of TIs with options to manipulate the surface states.
The 2D electron carrier concentration for Sb-doped Bi2Se3 nanoplates is lowered to 5.
At 2 K, the pronounced ambipolar field effect is observed on the low-carrier-density Sb-doped Bi2Se3 nanoplates, further demonstrating the flexible manipulation of carrier type and concentration for these single-crystal nanoplates. Large out-of-plane magnetoresistance is measured, with a gate tunable phase coherence length. Besides the advantages of owning a significant amplification on photocurrent, the detector has a wide detection zone and a strong immunity to temperature variation.
Demonstrated in experiments, these properties are mainly contributed by the combination of applied electric voltage and local electromagnetic field enhancement at structure surface. Because of the merits of low cost and high photoelectric performance, this structure is considered to be a promising prospect in photodetection. We study magnetotransport in a rare-earth-doped topological insulator, Sm0. It is found that that the crystals exhibit Shubnikov—de Haas SdH oscillations in their magnetotransport behavior at low temperatures and high magnetic fields. The SdH oscillations result from the mixed contributions of bulk and surface states.
We also investigate the SdH oscillations in different orientations of the magnetic field, which reveal a three-dimensional Fermi surface topology. By fitting the oscillatory resistance with the Lifshitz—Kosevich theory, we draw a Landau-level fan diagram that displays the expected nontrivial phase.
In addition, the density functional theory calculations show that Sm doping changes the crystal structure and electronic structure compared with those of pure Sb2Te3. This work demonstrates that rare-earth doping is an effective way to manipulate the Fermi surface of topological insulators. Our results hold potential for the realization of exotic topological effects in magnetic topological insulators. Achieving large magnetoelectric coupling is of interest for memory and communication applications.
In multiferroic hybrid structures combining ferroelectric and magnetic materials in the presence of a magnetoelectric coupling, the ferroelectric properties can be modulated by a magnetic field. This is called the direct magnetoelectric effect. Measuring the ferroelectric properties in multiferroic materials most commonly requires using metallic electrodes that sandwich the ferroelectric material.
We will show that the variations are fully reversible and more apparent at high frequencies; thus, of particular interest for applications, where high commutation rates are required. The III—V compound semiconductor quantum dot QD photonic devices have attracted considerable attention due to their stable operation at high temperature, low threshold current, and high-speed modulation.http://blacksmithsurgical.com/t3-assets/fantasy/segel-master-technique.php
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The photoluminescence PL energy of QDs depends on the dot sizes and the energy height of barriers. It is difficult to encourage the growth of low indium content QDs because of small lattice distortions between the InGaAs well regions and GaAs barrier regions. In conventional self-organized QD devices produced by Stranski—Krastanow growth methods, the injected carriers are first captured by the wetting layers and then dropped to the QDs with relaxation to the ground state for QD devices. Our proposed unique quantum disk structures have no wetting layers because the quantum well QW region is fully etched by using a low-damage dry etching process.
We observed the InGaAs nanodisks via scanning electron microscopy and measured their photoluminescence PL. To confirm the quantum confinement effects of InGaAs nanodisks, their energies and transient PL behaviors were measured as a function of temperature. The combined low-damage dry etching and MOVPE regrowth processes form an important technique, as they promise a low-damage interface and regrowth ability. This unique technology is attractive for carrier transportation dynamics and spintronics of hybrid QDs and QW nanostructures, and it is easy to adapt for industrial production systems.
We demonstrate the effect of the crystallinity of ceramic targets on the electronic properties of LaNiO3 thin films epitaxially grown by pulsed laser deposition PLD. We prepared two kinds of LaNiO3 targets with different crystallinity by manipulating calcination temperature i. Intriguingly, the electrical transport properties of the as-grown LaNiO3 thin films are quite different depending on crystallinity of the LaNiO3 ceramic target used for film deposition.
This difference in degree of charge disproportionation can induce a discrepancy in the metal-to-insulator transition temperature of ultrathin LaNiO3 films and in their electrical conductance. We report several molecules based on a central pyrazino[2,3-g]quinoxaline unit which is substituted with eight peripheral flexible tails of varying length. The out-of-plane conformation of the phenyl moieties made the self-assembly very sensitive to minute variation in the molecular structure. The compounds with very short and branched peripheral chains did not stabilize any liquid crystalline phase, while the medium- to long-chain homologues exhibited columnar phases.
All the compounds exhibited high extinction coefficient and good greenish-yellow emission behavior in solution and solid state. Solvent-dependent aggregation behavior was noticed, and they could form long fibers of several micrometers in length. One of the columnar liquid crystalline materials was utilized to realize organic light-emitting diodes OLEDs either as the sole emissive material or as a dopant at low concentration in different host materials. High-performance and thermally stable phosphors play an important role in high-quality white light-emitting diode pc-WLED lighting.
The photoluminescence intensity can be increased by 6. The internal quantum efficiency IQE can achieve Based on Rietveld refinement results, the corresponding enhancement mechanism is ascribed to the local lattice modification and the improved structure rigidity.