We report on the development of a low-energy x-ray phase-based microscope using intensity-modulation masks for single-shot retrieval of three contrast channels: transmission, refraction, and ultra-small-angle scattering or dark field. The retrieval method is based on beam tracking, an incoherent and phase-based imaging approach. We demonstrate that the spatial resolution of this imaging system does

Field-effect transistors (FETs) combined with a microfluidic system allow for the electrical detection of charged materials moving in a microfluidic channel. Here, we demonstrate trench-shaped silicon FETs with the combination of a microfluidic channel that can be used for simultaneous electrical and optical detection of charged fluorescent beads. The n-channel silicon trench FETs have a maximum transconductance

We report on a time-domain polarimetry (TDP) system for generating and detecting broadband terahertz (THz) waves of different polarization angles. We generate THz waves from two-color laser filaments and determine their polarization states with a detection bandwidth of up to 8 THz using a spinning gallium phosphide crystal. The polarization of THz emission can be controlled by adjusting the position

We propose an elliptical-tube off-beam quartz-enhanced photoacoustic spectroscopy (EO-QEPAS) method in which an elliptical tube is employed as an acoustic resonator, instead of a circular resonator in QEPAS, to match the stripe-like beam emitted from a high-power multimode laser diode (MLD). A lower noise level than that of conventional QEPAS is achieved due to the optimal matching between the elliptical

Recently, organic light-emitting diodes (OLEDs) are becoming increasingly attractive to information security, wearable healthcare, and other fields. These fields propose different requirements for performances of OLEDs, especially for voltage-controlled color tunability. In this study, it is proposed to use an ultrathin layer consisting of thermally activated delayed fluorescence (TADF) material as

We report on a GaN/AlGaN quantum cascade detector operating in the terahertz spectral range. The device was grown by metal organic chemical vapor deposition on a c-sapphire substrate and relies on polar GaN/AlGaN step quantum wells. The active region thickness is in micrometer range. The structural, electrical, and optical investigations attest of high structural quality of the synthetized nitride

In this work, we present a GaN-based blue LED construction utilizing bottom tunnel junction (TJ) grown by plasma-assisted molecular beam epitaxy. The setup allows for N-polar-like built-in field alignment while being grown on a Ga-polar substrate. In this study, we present an efficient bottom TJ LED in which the distance between the quantum well and device surface is only 25 nm. This is achieved by

Single-mode operation while maintaining a high-quality factor have always been key factors for building high-performance semiconductor lasers. Here, single CsPbBr3 perovskite microwire with a width of ∼3 μm is served as an active microresonator in which a typical single-mode laser output with a quality factor of 3000 is realized through the intrinsic self-absorption effect in success. Simultaneously

We demonstrate the generation of intense, sub-cycle terahertz (THz) pulses with variable elliptical polarization and peak fields above 80 kV/cm from large aperture photoconductive antennas using a specific interdigitated structure. The latter is composed of horizontal and vertical electrodes, which allow the generation of two quasi-half-cycle THz pulses with orthogonal polarization. A time delay between

Springs are ubiquitous in a variety of scientific and engineering fields. However, the comprehensive study on mechanical properties of micro-spring has not been fully conducted yet due to a lack of reliable productions of varied-shaped micro-springs. Here, we report the design and manufacturing of triple-helix-shaped springs employing two-photon polymerization (TPP) technologies and present a systemic

Despite graphene being an attractive transparent conductive electrode for semiconductor deep ultraviolet (UV) light emitting diodes (LEDs), there have been no experimental demonstrations of any kind of semiconductor deep UV LEDs using a graphene electrode. Moreover, although aluminum gallium nitride (AlGaN) alloys in the format of nanowires are an appealing platform for surface-emitting vertical semiconductor

Interband cascade lasers are power-efficient mid-infrared laser sources which usually exhibit a spectral linewidth of hundreds of kHz. However, narrower linewidth lasers are more desirable for high-resolution molecular spectroscopy applications. This work narrows the spectral linewidth of an interband cascade laser from about 530 kHz down to about 30 kHz by applying optical feedback from an external

Recent development on Ge1−xSnx nanowires with high Sn content, beyond its solid solubility limit, makes them attractive for all group-IV Si-integrated infrared photonics at the nanoscale. Herein, we report a chemical vapor deposition-grown high Sn-content Ge–Ge0.92Sn0.08 core–shell based single nanowire photodetector operating at the optical communication wavelength of 1.55 μm. The atomic concentration

The search for materials with high thermal resistance has promising applications in thermoelectric devices and boiling crisis retardation. In this paper, we study the interfacial heat transfer between water and gold, nanostructuring the gold surface and coating it with graphene. By trapping air (or vacuum in our simulations) between graphene and the nanopatterned surface, we observe a considerable

Highly energetic ions have been previously used to modify the shape of metal nanoparticles embedded in an insulating matrix. In this work, we demonstrate that under suitable conditions, energetic ions can be used not only for shape modification but also for manipulation of nanorod orientation. This observation is made by imaging the same nanorod before and after swift heavy ion irradiation using a

Taking advantage of the flexible customization of dynamic and Pancharatnam–Berry phases on meta-atoms, spin-decoupled multifunctional metasurfaces have been realized for optical beams of orthogonal circularly polarized lights, which promotes the diverse development of nanophotonic devices. To date, spin-decoupled metasurfaces can only spatially split and deflect beams in coplanar directions not in

Plasmonic metasurfaces form a convenient platform for light manipulation at the nanoscale due to their specific localized surface plasmons. Even despite high intrinsic Joule losses, plasmonic nanoparticles are very effective for light manipulation. Here, we show the lattice of plasmonic nanoparticles onto a dielectric waveguide that efficiently couples oppositely propagating guided modes to circularly

In this work, we propose and demonstrate a scheme to realize broadband coherent perfect absorption of spoof surface plasmon polaritons (SPPs) using an ultrathin conductive film vertically placed on a plasmonic metasurface that supports spoof SPPs. When the conductive film possesses an appropriate sheet resistance, two incident coherent beams of spoof SPP waves can be simultaneously absorbed over a

Passive radiative cooling, radiating energy from objects to the outer space through the Earth's atmospheric window, offers promising solutions for passive building cooling and renewable energy harvesting. However, static passive radiative cooling systems with a fixed thermal emissivity cannot automatically regulate emission in response to varying ambient temperature. Here, we propose an intelligent

A solid state phase transformation of Ti-6Al-4V was studied using high speed in situ x-ray diffraction measurements made during rapid cooling of a cold metal transfer arc weld bead deposited onto a water cooled substrate. Analysis of body centered cubic (BCC) and hexagonal close packed (HCP) lattices revealed an abrupt, nonlinear shift in the lattice parameters of both phases just after the HCP phase

Development of blue quasi-2D lead halide perovskite LEDs is key to the perovskite based full-color displays and white-light illumination. It is still quite challenging to accurately enlarge the bandgap to achieve high performance and stable blue Quasi-2D perovskite LEDs. The lattice strain due to the deformation of lead-bromide octahedra is a critical factor leading to the energy band adjustment and

In this work, we report a study of the temperature dependent pulsed current voltage and RF characterization of β-(AlxGa1−x)2O3/Ga2O3 hetero-structure FETs (HFETs) before and after silicon nitride (Si3N4) passivation. Under sub-microsecond pulsing, a moderate DC-RF dispersion (current collapse) is observed before passivation in gate lag measurements, while no current collapse is observed in the drain

In this study, n-type SiC Schottky barrier diodes (SBDs) with various doping concentrations (Nd=4×1015–1×1019cm−3) were fabricated, and their forward and reverse current–voltage (I–V) characteristics were analyzed focusing on tunneling current. Numerical calculation with the fundamental formula of tunneling current gives good agreement with experimental forward and reverse I–V curves in the heavily

Exciton–phonon interactions strongly affect photocarrier dynamics in two-dimensional materials. Here we report on resonant Raman experiments based on a graded composition WxMo1–xS2 alloy with tunable exciton energy without changing the energy of excitation laser. The intensities of the four most pronounced Raman features in the alloy are dramatically enhanced due to the resonance derived from the energy

Pulsed laser deposition is employed to fabricate as-grown amorphous and post-growth annealed crystalline β-Ga2O3 films. The films annealed at temperatures above 600 °C are found to exhibit a pure monolithic phase with a bandgap of 4.7 eV. The thermally activated donor ionization and dielectric relaxation of these films are systematically investigated by temperature-dependent DC and AC conductivity

The ultra-wide bandgap of Al-rich AlGaN is expected to support a significantly larger breakdown field compared to GaN, but the reported performance thus far has been limited by the use of foreign substrates. In this Letter, the material and electrical properties of Al0.85Ga0.15N/Al0.6Ga0.4N high electron mobility transistors (HEMT) grown on a 2-in. single crystal AlN substrate are investigated, and

This paper proposes a math-physical correlative method that monitors deep defect response by electrical measurement and calculates the state density by designed mathematical processing. The extracted Gaussian distribution of deep defects was discussed according to the theoretical model for the density of states. The accuracy of this method was also verified through 1/f low frequency noise analysis

Ultra-wide bandgap (UWBG) semiconductors have great potential for high-power electronics, radio frequency electronics, deep ultraviolet optoelectronic devices, and quantum information technology. Recently, the two-dimensional UWBG GaPS4 was first applied to the solar-blind photodetector in experiments, which was found to have remarkable performance, such as high responsivity, high quantum efficiency

In this Letter, we unveil the high-temperature limits of N-polar GaN Schottky contacts enhanced by a low-pressure chemical vapor deposited (LPCVD) SiN interlayer. Compared to conventional Schottky diodes, the insertion of a 5 nm SiN lossy dielectric interlayer in-between Ni and N-polar GaN increases the turn-on voltage (VON) from 0.4 to 0.9 V and the barrier height (ϕB) from 0.4 to 0.8 eV. This modification

Single femtosecond-pulse toggle switching of ferrimagnetic alloys is an essential building block for ultrafast spintronics. It is believed that for switching to occur in these ferrimagnets, the individual sublattices must have very different (element-specific) demagnetization dynamics. This suggests that ferrimagnets composed of two different elements, such as rare-earth transition-metal alloys, are

In a perpendicularly magnetized (PM) material with the interfacial Dzyaloshinskii–Moriya interaction (iDMI), a chirality-induced effective magnetic field (EMF) acts on a magnetic domain wall, which is a naturally formed in-plane magnetized (IM) region sandwiched by perpendicular (PM) regions. In this study, we artificially created a Pt/Co/MgO system with the regions exhibiting different anisotropy

Magnetic systems exhibiting spin-canted states have garnered much attention recently for their promising rich exotic properties driven by the real-space spin textures and competing magnetic orders. In this study, we present the structural and magnetic properties of hexagonal 60 nm MnPtGa epitaxial thin films grown by magnetron sputtering on Al2O3(0001) single-crystalline substrates. The MnPtGa film

Strong-field terahertz (THz) light-matter interaction provides various nonlinear control approaches in condensed matter physics, energy and material sciences, electron acceleration, and manipulation. Recently developed spintronic THz emission with minimum complexities has been demonstrated to have the capability for generating high field strengths. Up to now, nonlinear applications based on the spintronic

We perform hysteresis-loop measurement and domain imaging for (11¯00)-oriented D019-Mn3+xSn1-x (−0.11≤x≤0.14) thin films using the magneto-optical Kerr effect (MOKE) and compare it with the anomalous Hall effect (AHE) measurement. We obtain a large Kerr rotation angle of 10 mdeg, comparable with bulk single-crystal Mn3Sn. The composition x dependence of AHE and MOKE shows a similar trend, suggesting

The spin Hall effect appears in nature in two forms. Its intrinsic form is highly dependent on the crystal symmetry while its extrinsic form stems from impurity scattering. Its efficiency is defined by the spin Hall angle, θSH, and has profound impact on spintronic technologies. However, an accurate measurement of θSH is not straightforward nor the identification of its origin. In this work, we apply

Sub-10 nm thick gadolinium-doped hafnia (Gd:HfO2) layers were grown in metal–insulator–metal (TiN/Gd:HfO2/TiN) stacks using a plasma-enhanced atomic layer deposition process. Thermally annealed Gd:HfO2 layers with a thickness of 8.8, 6.6, and 4.4 nm exhibited orthorhombic crystalline structure and showed ferroelectric properties. Indeed, polarization vs electric field hysteresis loops were recorded

The boom in high-power-density electronics and advanced pulsed power systems has led to a requirement for high-energy-density dielectric capacitors, for which the key enabler is the availability of dielectric materials with high energy densities and high efficiencies. Although antiferroelectric ceramics are promising dielectric materials with high energy densities, they have low efficiencies. In this

Using a relativistic symmetrized linear augmented cylindrical wave method, we investigated a formation of spin minigaps due to a torsion strain of the nonchiral hexagonal and gear-like armchair (n, n) and zigzag (n, 0) silicon nanotubes (SiNTs). In the absence of mechanical twisting, the hexagonal (n, n) SiNTs have an inversion symmetry and metallic band structures with the spin-degenerate states at

We fabricated superlattice films composed of Bi2 bilayers (BLs) and Bi2Te3 quintuple layers (QLs) by annealing pure Bi2Te3 films. It was found that Te desorbs from the QL to form the BL with an activation energy of 2.7 eV. Eventually, two distinct stoichiometric phases were formed, Bi1Te1 (QL–BL–QL) and Bi4Te3 (QL–BL), as evidenced by scanning transmission emission microscopy measurements. The surface-state

The discovery of another monoclinic polymorph in the niobium trisulfide system expands the structural possibilities for quasi-1D transition metal trichalcogenide materials. We describe here NbS3-VI prepared by chemical vapor transport (CVT) using ammonium chloride as the transport agent rather than the typical iodine or excess chalcogen. This example establishes precedent for transport agent control

Resistive switching properties based on molecular beam epitaxy-grown monolayer hexagonal boron nitride (h-BN) atomristors are studied by using metal insulator metal configurations with different electrode materials. Au/monolayer h-BN/Ni devices demonstrate a forming-free bipolar resistive switching (BRS) behavior, a good endurance with up to 97 cycles at a high compliance current of 100 mA, an average

The ultrathin metal film with excellent electrical conductivity and high visible-band transmittance has attracted considerable attention as a transparent electrode for the organic light-emitting devices (OLEDs). However, the deficient surface morphology and poor continuity of low thickness evaporated metal films and the surface plasmon-polaritons (SPPs) mode induced energy loss still seriously limit

This work reports an AlN/GaN/InGaN high electron mobility transistor (HEMT) with a steep subthreshold swing (SS) of sub-60 mV/dec utilizing a coupling-channel architecture. The fabricated transistors show a negligible hysteresis, a SS of 39 mV/dec, a large gate voltage swing of >4.2 V, and achieving an excellent quality factor Q = gm/SS of 6.3 μS-dec/μm-mV. The negative differential resistance effect

Smart materials offering tunable electrical properties in response to external stimuli are in high demand for their usage in reconfigurable electronics. This study reports the stability and reversibility of insulator-to-metal transition (IMT) in a vanadium dioxide (VO2) thin film grown on flexible glass substrates under the external strain. The systematic application of the external strain was used

Direct bandgap perovskite and indirect bandgap Si, which form the two active layers in a tandem solar cell configuration, have different optoelectronic properties and thicknesses. The charge-carrier dynamics of the two-terminal perovskite-on-Si tandem solar cell in response to a supercontinuum light pulse is studied using transient photocurrent (TPC) measurements. Spectral dependence of TPC lifetime

PbSe is a simple binary compound that has been studied extensively for use as a promising moderate-temperature thermoelectric material. In this Letter, we report the observation of the light-induced transverse thermoelectric (TTE) effect in c-axis inclined PbSe thin films that were grown epitaxially on c-axis miscut SrTiO3 single crystal substrates using the pulsed laser deposition technique. Because

Frequency comb in microelectromechanical systems has attracted many concerns, which is expected to realize great achievements analogous with the optical frequency comb. Previous frequency combs are generated by mode coupling in a single micro-resonator. To pursuit more excellent tunability and robustness, it is impending to create a frequency comb through another way, i.e., coupled but relatively independent

One widely employed method to study thermoelectric effects in nano- and mesoscopic systems is by utilizing on-chip metal strips. However, the standard technique loses sensitivity in the sub-Kelvin temperature regime because the resistance of metal strips saturates. Here, we report a possible solution that can extend the working point from the conventional window (10 to 300 K) down to temperatures below

This work presents the laterally vibrating Lamb wave resonators (LVRs) based on a 30% aluminum scandium nitride (Al0.7Sc0.3N) thin film with three interdigited transducer pairs operating in the S0 mode. In order to reduce the anchor loss, perfect matched layer-based finite element analysis simulations are utilized to design and optimize the device. Thanks to the high quality AlScN using magnetron sputtering

Exploring high-performance medium-temperature thermoelectric (TE) materials with nontoxicity and low price is of great significance for waste heat recovery. In spite of low price and nontoxicity, the poor intrinsic electrical properties of Cu3SbS4 restrict its potential commercial applications. Herein, intermediate-phase-free Cu3SbS4-based bulks were fabricated by incorporating a sulfurization process

The intrinsic p-to-n transition mechanism for Mg3Sb2-based thermoelectrics is revealed through pristine Mg3Sb2 by tunning extra Mg. By using TEM characterization combined with transport measurements, the Mg3Sb2 matrix is proposed to have three stages of evolution with the increase in extra Mg content: Mg vacancy-rich (Sb-rich phase) period, Mg vacancy-compensated (nearly no precipitates) period, and

Scalable quantum information processing requires that modular gate operations can be executed in parallel. The presence of crosstalk decreases the individual addressability, causing erroneous results during simultaneous operations. For superconducting qubits which operate in the microwave regime, electromagnetic isolation is often limited due to design constraints, leading to signal crosstalk that

Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) spectroscopy of bulk quantum materials have provided insight into phenomena, such as quantum phase criticality, magnetism, and superconductivity. With the emergence of nanoscale 2D materials with magnetic phenomena, inductively detected NMR and NQR spectroscopy are not sensitive enough to detect the smaller number of spins in nanomaterials

A minimally invasive transverse beam profile monitor based on supersonic gas curtain technology and beam-induced fluorescence has been developed and demonstrated. The concept presented can be used to measure both the profile of the proton beam in the Large Hadron Collider (LHC) and the concentricity of the electron and the proton beams in the LHC hollow electron lens. In this Letter, the performance

Molecular level interactions that take place at the interface of different materials determine their local electrical, chemical, and mechanical properties. In the case of solid interfaces, this information has traditionally been obtained with experimental techniques that require ultra-high vacuum conditions. However, these methods are not suitable for studying surface chemistry of aqueous interfaces

Spin currents are used to write information in magnetic random access memory (MRAM) devices by switching the magnetization direction of one of the ferromagnetic electrodes of a magnetic tunnel junction (MTJ) nanopillar. Different physical mechanisms of conversion of charge current to spin current can be used in two-terminal and three-terminal device geometries. In two-terminal devices, charge-to-spin

Phonon transport is a dominant mechanism of thermal conduction in solids that has been studied for decades. A good understanding of many transport regimes in micro- and nanostructures has been established, including ballistic and diffusive transport, mode softening, or band structure engineering in phononic crystals. However, the limit of quantized transport and the engineering of single transport

Controlling electrons with ever-greater precision is central to both classical and quantum electronics. Since the invention of the laser, virtually every property of coherent light has been tamed, making it one of the most precise tools available to science, technology, and medicine. Coherent control involves the transduction of an exquisitely defined property of light to an electronic system, imparting

Surface phonon polaritons (SPhPs) in van der Waals (vdW) materials are of great interest in fundamental and applied research fields. Probing the characteristics of vdW SPhPs at cryogenic temperatures is an essential task for their implementation in low-temperature physics. However, the most commonly used characterization technique of vdW SPhPs—scattering-type scanning near-field optical microscopy