We propose an efficient optically actuated THz modulator based on an ultrathin epsilon-near-zero (ENZ) slab photogenerated in an InAs semiconductor. We experimentally demonstrate a modulation depth of 90% at 1 THz obtained with a continuous laser at irradiation lower than 10   W   cm − 2. Beyond the strong attenuation of the THz transmission provided by the ENZ absorption effect, we also report a broadband

Deep UV-LEDs (DUV-LEDs) emitting at 233 nm with an emission power of (1.9 ± 0.3) mW and an external quantum efficiency of (0.36 ± 0.07) % at 100 mA are presented. The entire DUV-LED process chain was optimized including the reduction of the dislocation density using epitaxially laterally overgrown AlN/sapphire substrates, development of vanadium-based low resistance n-metal contacts, and employment

In this work, the high-performance transparent Al:InZnSnO/InZnO/Al:InZnSnO tri-layer thin-film phototransistors are reported. They show a high field-effect mobility of 40.1 cm2/V·s and an excellent high photoresponsivity of 25 000 A/W, a photosensitivity of 3.3 × 107, a specific detectivity of 4.3 × 1017 cm·Hz1/2·W−1 under the illumination at 460 nm with an intensity of 140 μW/cm2. The persistent photoconductivity

Quantum dot light-emitting diodes (QD-LEDs) are expected to be used in wide-color-gamut displays because the emission colors from QDs are highly saturated. InP-based QDs are one of the most promising candidates for low-toxicity QDs. Here, we report an efficient green QD-LED whose emitting layer was composed of InP-based QDs and an organic electron-transporting material (ETM). To investigate ETMs suitable

We experimentally demonstrate the controllable laser output of cylindrical vector (CV) beams, which feature flexibility, high efficiency, and good beam quality. Particularly, the CV laser beams have negligible radial components, distinguishing themselves from the extra-cavity-generated CV beams. The output state is controlled by an intra-cavity vortex half-wave plate (VWP). By changing the topological

Sub-wavelength periodic arrays exhibit narrow near-unity reflection bands that arise from guided mode resonances. These resonances have extremely high quality factor (i.e., narrow band features) and are ideal for filtering applications. A high quality factor requires many periods, causing large lateral footprints that limit an imaging system's spatial resolution. We present a 1D ultra-thin (<100 nm)

Ultraviolet laser-induced etching is a method of machining and nanostructuring diamond surfaces in which carbon is removed from the surface via a photochemical process involving oxygen. We show here that using a dry source of oxygen at pressures in the range of 0.01–1 Torr leads to a 10-fold increase in the etch rate compared to etching in atmospheric air. The enhanced etch rate is also found to be

Black phosphorus (BP) has potential for fabricating p-type transistors in ultra-thin 2D-material complementary circuits. However, as the synergetic effect of water and oxygen leads to performance degradation under an ambient atmosphere, it is urgent to develop a passivation strategy for robust stability. Herein, a scalable superhydrophobic passivation layer is designed to improve the stability of BP

Epitaxial metal/semiconductor superlattice heterostructures with lattice-matched abrupt interfaces and suitable Schottky barrier heights are attractive for thermionic energy conversion, hot electron-based solar energy conversion, and optical hyperbolic metamaterials. HfN/ScN is one of the earliest demonstrations of epitaxial single-crystalline metal/semiconductor heterostructures and has attracted

Ultrasonic phased-array (PA) systems have been widely adopted in the field of nondestructive evaluation for material characterization and imaging of internal defects. Whereas many defects exhibit complex three-dimensional structures, most PA systems provide only two-dimensional images. In this Letter, we demonstrate the ability to create high-resolution 3D images of internal defects using a PA system

Rutile-related (tetragonal rutile and monoclinic distorted rutile) ReO2 epitaxial thin films were grown on rutile TiO2 single crystalline substrates by reactive pulsed laser deposition of the Re metal target under a N2O atmosphere. The ReO2 film underwent structural phase transition from the monoclinic to tetragonal phase with the decreasing film thickness, driven by compressive lattice strain from

Ultrasound directed self-assembly (DSA) enables noninvasively aligning high aspect ratio particles in three-dimensional (3D) user-specified orientations, which finds application in a myriad of engineering applications, including manufacturing engineered materials. However, the number of ultrasound transducers and their spatial arrangement limit the accuracy of the particle alignment with any 3D user-specified

ScxAl1−xN (x = 0.18–0.40) thin films of ∼28 nm thickness grown on metal polar GaN substrates by molecular beam epitaxy are found to exhibit smooth morphology with less than 0.5 nm roughness and predominantly single-phase wurtzite crystal structure throughout the composition range. Measurement of the piezoelectric d33 coefficient shows a 150% increase for lattice-matched Sc0.18Al0.82N relative to pure

Heteroepitaxial growth is critical for large-scale synthesis of diamond (111) substrates. In this study, the local initial epitaxial growth of diamond (111) on Ru/c-sapphire was investigated. As the economic viability of ruthenium (Ru) is more than that of iridium (Ir), a 150-nm Ru (0001) thin film was sputter-deposited on an Al2O3 (0001) substrate using a RF/DC magnetron sputtering system. X-ray diffraction

Carrier compensation traps in n−-GaN drift layers grown on Si substrates were investigated using high-temperature deep-level transient spectroscopy (DLTS). The upper limit of the temperature range (700 K) allows for the study of deeper levels in the bandgap than those previously reported by conventional DLTS. Three trap states were revealed to be responsible for carrier compensation. Besides the residual

This paper studies spin–orbit torque (SOT) switching behaviors in synthetic antiferromagnet (SyAF) structures of Ta/[Pt/Co]m/Ru/[Co/Pt]n, which are asymmetric between the upper multilayer (UML) and the bottom multilayer (BML). The SOT-induced magnetization switching loops show multiple transitions of switching orientations between clockwise and anticlockwise with an increasing in-plane magnetic field

Here, we have investigated the spin pumping effect of Y3Fe5O12 (YIG)/Cu (tCu nm)/Cr heterostructures at room temperature with the thickness of the Cu interlayer varying from 0.4 nm to 5.0 nm. A huge charge signal Ic = 0.239 μA is observed in a YIG/Cr bilayer with direct contact, whereas Ic drops dramatically by two orders of magnitude when thin Cu interlayers down to 0.4 nm are inserted between YIG

We demonstrate the formation of metastable Néel-type skyrmion arrays in Pt/Co/Ni/Ir multi-layers at zero-field following the ex situ application of an in-plane magnetic field using Lorentz transmission electron microscopy. The resultant skyrmion texture is found to depend on both the strength and misorientation of the applied field as well as the interfacial Dzyaloshinskii–Moriya interaction. To demonstrate

Reversible, thermally controlled, spontaneous magnetization switching (reversible TCSMS) is demonstrated in the absence and presence of an external magnetic field in polycrystalline perovskite-type CaMn0.95Sb0.05O3. The spontaneous magnetization value is retained throughout a cyclic process even in bias magnetic fields. Neutron diffraction and theoretical studies indicate that two weak ferromagnetic

Polymers with electrically charged internal air cavities (ferroelectrets) reveal a pronounced piezoelectric response and are regarded as soft electroactive multi-functional materials. This work presents preliminary results on the preparation and piezoelectric effect of ferroelectrets based on the polylactic acid (PLA) polymer. A distinctive feature of the manufactured films is that they are biodegradable

Linear dielectrics are promising candidates for high-performance energy storage applications with high efficiency, excellent thermal stability, and high reliability due to their low loss, high dielectric breakdown strength, and stable dielectric properties, which are independent of the electric field and temperature. However, their low dielectric constant or polarization restricts the stored electrical

Optimizing the combination of dielectric and magnetic properties has become an important issue for electrical and electronic devices. Compared to single-function materials, multifunctional materials have the advantages of increasing device response speed, reducing costs, and increasing stability while reducing the device size. In this work, Janus structure polyvinylidene fluoride (PVDF) composites

Self-assembled Cd(Se,Te) quantum dots with various Se compositions embedded in the ZnTe matrix are grown by molecular beam epitaxy. A huge redshift of the near band edge emission, from 2.1 eV to 1.5 eV, with an increasing Se content in the dots is observed. It is accompanied by an increase in the excitonic lifetime by the factor of 10. We associate these effects with a gradual change from the direct

Bright emission from non-classical light sources is a key requirement for their practical use in quantum optics. In this Letter, we report on an alternative approach to realize high-brightness nanowire emitters in the telecom band. We discuss the growth and optical properties of a single InA s 0.68 P 0.32 quantum dot in an InA s 0.50 P 0.50 quantum rod, all embedded in an InP nanowire waveguide. Modifying

We have measured the electrochemical capacitance in a quantum coherent capacitor consisting of a quantum dot connected to an electron reservoir by a gate tunable quantum point contact and Coulomb coupled to a gate. The results show that for a weak transparent channel, the capacitance exhibits sharp Coulomb blockade oscillations with gate voltage related to the oscillations of the dot density of states

In this work, we have predicted a giant thermal magnetoresistance for the thermal photon transport based on the tunable magnetoplasmon of graphene. By applying an external magnetic field, we find that the heat flux can be modulated by approximately three orders of magnitude. Accordingly, both negative and giant relative thermal magnetoresistance ratios are achieved for magnetic fields with a maximum

We investigated microstructural deformations and Bi segregation in GaAs/GaAsBi/GaAs core–multishell heterostructures, which were triggered by the existence of twin defects. We observed Bi segregation at the interface of the twin defect interface in the GaAsBi shell. The phenomenon produced a horizontally spread Bi-accumulated nanostructure in the nanowire, which is probably induced by the large lattice

Three-dimensional tubular origami, fabricated by the self-rolling of functional nanomembranes, is of great interest due to its numerous opportunities for applications in photochemical sensing, intelligent actuators, microrobots, electronics, and many others. A continuing opportunity of this area is in the development of strategies for fabricating tubular origami, in solvent-free and low-cost conditions

Higher-order topological insulators (HOTIs) capable of hosting multi-dimensional topological states have been considered as a significant platform for wave regulation. Here, based on a “breathing” kagome lattice composed of coupled tube resonators, we demonstrate the topological phase transition induced by tuning the nearest-neighbor interactions of the tubes. Crucially, beyond the nontrivial bulk

Investigating the mechanical properties of soft biological samples on the single-cell level is of great interest as cell mechanics play a central role in many physiological processes in health and disease. Scanning ion conductance microscopy (SICM) is an emerging technique for measuring cell stiffness on the micro- and nanometer scale in a non-contact fashion. However, as SICM stiffness measurements

A complex quantum dot circuit based on a clean and suspended carbon nanotube embedded in a circuit quantum electrodynamic (cQED) architecture is a very attractive platform to investigate a large spectrum of physics phenomena ranging from qubit physics to nanomechanics. We demonstrate a carbon nanotube transfer process allowing us to integrate clean carbon nanotubes into complex quantum dot circuits

We report detection and coherent control of a single proton nuclear spin using an electronic spin of the nitrogen-vacancy (NV) center in diamond as a quantum sensor. In addition to determining the NV–proton hyperfine parameters by employing multipulse sequences, we polarize and coherently rotate the single proton spin and detect an induced free precession. Observation of free induction decays is an

Recent technological innovations in organic light-emitting diodes (OLEDs) have enabled their applicability to be expanded to not only displays but also the lighting industry. In addition, the high scalability and flexibility of OLEDs render them promising candidates for next-generation displays. However, their insufficient lifetime and low uniformity/stability are challenging issues, mainly because

Spin current represents a flow of spin angular momentum and does not require movement of charges. Magnetic insulators can therefore work as a source as well as a medium of spin currents, which has been established in ferrimagnetic insulators. Here, we report recent progress in the generation and electrical detection of spin currents in uniaxial antiferromagnetic insulators carried by antiferromagnetic

We generate frequency-tunable narrow-band intense fields in the terahertz (THz) range by optical rectification of a temporally modulated near-infrared laser pumping a nonlinear organic crystal. Carrier-frequency tunability between 0.5 and 6.5 THz is achieved by changing the modulation period of the laser pump. This tunable narrow-band THz source allows the selective coherent excitation of adjacent

An optical method for the sensitive detection of excited energy levels in rare-earth luminescent materials is developed based on the magnetic field induced photoluminescence (PL) enhancement phenomenon observed in Er3+:YVO4 crystals. Since the PL intensity of rare-earth luminescent materials is sensitive to the excitation efficiency, continuous tuning of the excitation laser wavelength under a magnetic

Chiral nature of an enantiomer can be characterized by circular dichroism (CD) spectroscopy, but such a technique usually suffers from weak signal even with a sophisticated optical instrument. Recent demonstrations of plasmonic metasurfaces showed that chiroptical interaction of molecules can be engineered, thereby greatly simplifying a measurement system with high sensing capability. Here, by exploiting

Scanning-probe-assisted mid-infrared nano-spectroscopy is employed to reveal the polaritonic dispersion of individual MIM (metal-insulator-metal) square patch antennas whose modes can be strongly coupled to a mid-infrared intersubband transition. The patch antenna side length L sets the resonances between λ = 5.5 μm and 12.5 μm. The active region consists of a highly doped AlInAs/InGaAs/AlInAs single

Vibrational properties and ultrafast photocarrier dynamics of 2H–TaS2 under pressures are studied by the experiments of Raman scattering and femtosecond time resolved spectroscopy. With increasing pressure, the linewidth of two-phonon Raman mode broadens, especially features with a sudden rapid increase above 10 GPa. Meanwhile, the ultrafast dynamics show that the fast decay through optical phonon

Pd crystals grown in ultrahigh vacuum (UHV) on nanostructured SrTiO3(001) and anatase TiO2(001) thin film substrates were studied using scanning tunneling microscopy. The crystals have the equilibrium shape of a truncated octahedron with a {111} top facet, {111} and {001} side facets, and a {111} interface. A consistent crystal shape is reached only after annealing the samples in UHV at 450 °C or above

We report the temperature-dependent phonon modes and interband electronic transitions of InSe films on SiO2/Si substrates prepared by pulsed laser deposition. The microstructure results proved the ε phase structure and monochalcogenide phase composition with well-defined hexagonal InSe sheets. The temperature effects on lattice vibrations were discovered by Raman spectra from 123 K to 423 K. The frequency

Ni/Al2O3/GaN structures with vicinal GaN surfaces from the c- or m-plane were formed. Then, electrical interface properties of the structures were systematically investigated. It was found that interface state density (Dit) at the Al2O3/GaN interface for the c-plane is higher than that for the m-plane, and post-metallization annealing is quite effective to reduce Dit for both c- and m-planes. As a

The band alignment and the chemical bonding at the β-Ga2O3/AlN and β-Ga2O3/GaN interfaces are studied through hybrid functional calculations. We construct realistic slab models with III–O (III = Al, Ga) bonds dominating the chemical bonding at both interfaces. The epitaxial relationships between β-Ga2O3 and wurtzite AlN and GaN determined from experiments are adopted in our slab models. These models

In this Letter, we report on the evolution of electronic properties governed by epitaxial misfit strain in cubic In2O3 epilayers grown on sapphire. At elevated growth temperature, the competition between the film/substrate lattice mismatch and the thermal expansion mismatch alters the macroscopic biaxial strain from compressive to tensile. Simultaneously, the electron concentration is tuned from degeneration

Interfacial properties and energy-band alignment of annealed AlN dielectric films on Si-face 4° off-axis 4H–SiC substrates were characterized and demonstrated by x-ray photoelectron spectroscopy (XPS) and current-electric field (I–E) measurements. The XPS results reveal that the Al–O bonds and the silicon suboxides can convert into more stable Al–N bonds and Al–O–Si bonds at the AlN/4H–SiC interface

Power electronics seek to improve power conversion of devices by utilizing materials with a wide bandgap, high carrier mobility, and high thermal conductivity. Due to its wide bandgap of 4.5 eV, β-Ga2O3 has received much attention for high-voltage electronic device research. However, it suffers from inefficient thermal conduction that originates from its low-symmetry crystal structure. Rutile germanium

We investigate carrier localization in Al-rich AlGaN/AlN quantum well (QW) structures. Low temperature time-resolved photoluminescence (PL) experiments reveal a strong variation of the carrier decay times with detection photon energy, suggesting a strong impact of carrier localization, which is found to depend primarily on the QW width. In combination with time-integrated PL measurements and numerical

This work presents the results of magnetotransport measurements performed on a 156 nm-thick Bi2Te3 epitaxial film in the temperature range of 1.9–300 K, showing Shubnikov–de Haas oscillations for temperatures below 50 K. A detailed analysis of oscillations as a function of temperature provides the main transport parameters, including the Landé g-factor and cyclotronic masses. A systematic analysis

Gallium nitride is an increasingly technologically relevant material system. While donor doping GaN to low and intermediate dopant concentrations using silicon and germanium has become routine, compensation mechanisms activate under very high donor doping, limiting the maximum electron concentration achievable with either dopant in the degenerate doping regime. This effect, and how it differs between

Growth of Mg-doped GaN on trench-patterned GaN films consists of competing lateral and vertical growth fronts that result in regions with different electronic properties. Under typical growth conditions, lateral growth from the trench sidewall occurs at a faster rate than vertical growth from the trench base. When the trench width is sufficiently narrow, the growth fronts from opposite sidewalls coalesce

We study the effects of asymmetrical magnetization and an optoelectronic tunable band structure on the transmission of particles in a MoS2 tunnel junction. Based on the results, we propose a model for a multifunctional coupler as a single system incorporating giant magnetoresistance, a spin–valley filter, and a spin–valley valve. The device is made up of ferromagnetic/ferromagnetic/normal junctions

We propose a class of metamaterials in which the propagation of acoustic waves is controlled magnetically through magnetoelastic coupling. The metamaterials are formed by a periodic array of thin magnetic layers (“resonators”) embedded in a nonmagnetic matrix. Acoustic waves carrying energy through the structure hybridize with the magnetic modes of the resonators (“Fano resonance”). This leads to a

We report on the experimental observation of short, exchange-dominated spin waves (EDSW) generation by a thickness step in the ferrite waveguide under microwave pumping. This effect was explored both experimentally (using mirco-Brillouin light scattering technique) and theoretically (by micromagnetic simulation) for the sample magnetized along the step and for two cases of pumping: a uniform microwave

Macroscopic polarity and its dynamic response to external electric fields and temperature in the nominally ergodic relaxor phase of pristine lead magnesium niobate crystals and ceramics, Pb(Mg1/3Nb2/3)O3 (PMN), were investigated. Dynamic pyroelectric measurements provide evidence for persistent macroscopic polarity of the samples. Annealing experiments below and above Burns temperature of polarized

Designing two-dimensional materials with magnetic and topological properties has continuously attracted intense interest in fundamental science and potential applications. Here, on the basis of first-principles calculations, we predict the coexistence of antiferromagnetism and Dirac nodal loops (NLs) in monolayer MnB, where the band crossing points are very close to the Fermi level. Remarkably, a moderate

We show that ideal memristors—devices whose resistance is proportional to the charge that flows through them—can be realized using spin torque-driven viscous magnetization dynamics. The latter can be accomplished in the spin liquid state of thin-film heterostructures with frustrated exchange, where the memristive response is tunable by proximity to the glass transition, while current-induced Joule

A method based on cyclic gate bias stress followed by a single point drain current measurement is used to probe the interface or near-interface traps in the SiO2/4H-SiC system over the whole 4H-SiC bandgap. The temperature-dependent instability of the threshold voltage in lateral MOSFETs is investigated, and two separated trapping mechanisms were found. The experimental results corroborate the hypothesis

Organic–inorganic lead halide perovskites have attracted great attention for use in solar cells, because of their efficient solar power conversion, along with compatibility with simple solution processing. To evaluate the operational stability of perovskite solar cells (PSCs), measurements on their current density–voltage (J−V) curves are periodically repeated in most literature studies. However, how

Vacancies in oxides play important roles in material performances of electronic devices, and they are recently considered to be a source of the bistable resistance switching effects of amorphous oxides. Here, we show theoretically that an O vacancy in amorphous alumina has two distinct types of atomic and electronic structures with an energy barrier between them when neutrally charged, acting to be

Dielectric resonators made of high permittivity materials with low losses have been extensively studied for application in magnetic resonance imaging (MRI) and magnetic resonance spectroscopy. They can focus, redistribute, and enhance the radio frequency magnetic field in a controlled way. In this Letter, we investigate coupled very-high permittivity dielectric resonators for clinical bilateral breast