We report on the growth and characterization of metalorganic vapor-phase epitaxy-grown β -(Al x Ga 1− x ) 2 O 3 / β -Ga 2 O 3 modulation-doped heterostructures. Electron channel is realized in the heterostructure by utilizing a delta-doped β -(Al x Ga 1– x ) 2 O 3 barrier. The electron channel characteristics are studied using transfer length method, capacitance–voltage and Hall measurements. A Hall

N-type conduction of sputter-deposited polycrystalline Al 0.78 Sc 0.22 N films was verified by Si ion implantation followed by activation annealing. The activation of dopants was found above an annealing temperature of 800 °C. Under a dose of 2 × 10 15 cm −2 with an activation annealing at 900 °C, n-type conduction was obtained with Hall mobility and a carrier concentration of 8.6 cm 2 V −1 s −1 and

In situ phosphorus-doped silicon (ISPD) has been actively investigated as a source/drain material. However, defect formation during the epitaxial growth of ISPD layers in 3D structures deteriorate the device performance. In this study, we investigate the elimination of inherent defects in ISPD layers using nanosecond laser annealing (NLA). High-density twin- and stacking-fault defects in the ISPD layers

Dihydroxybenzoic acid (DHB) crystal layers were formed via mist deposition. Crystal layers exhibiting whiskers measuring a few hundred micrometers were formed at a nozzle temperature of 200 °C. DHB crystal layers exhibited strong absorbance in the ultra-violet wavelength regions, and Raman spectroscopy confirmed their vibrational property. The lipid component was analyzed by matrix-assisted laser

The three-dimensional (3D) distribution of nanosized silicon (Si) crystallites within a hydrogenated nanocrystalline Si (nc-Si:H) material is examined by laser-assisted atom probe tomography (APT). The amorphous and crystalline phases in nc-Si:H are distinguished by obtaining the 3D density distribution of H atoms, because the former contains a high H density. The H content in the amorphous phase is

The optical cavity with high quality factor ( Q ) has been successfully employed to improve the sensitivity of magnetometer. However, complex system design and tedious data processing hinder the progress of application, since synchronized with other equipments and undergo additional post-processing. To overcome the limitation, we propose a single-loop frequency-locking (SLFL) optomagnetic (OM) signal

A near-field vector sensing (VS) strategy is developed for three-dimensional (3D) large-scale hybrid sound absorption based on a lightweight structure. By simultaneously detecting sound pressures and normal particle velocities at discrete positions on the absorbing surface, the reflected sound power is minimized to obtain the optimal secondary excitation. For the one-dimensional case, low-frequency

Main-chain-scission-type resists have been widely used for the fabrication of nanodevices. A copolymer consisting of methyl α -chloroacrylate and α -methylstyrene, known as the ZEP series of ZEON, is a popular main-chain-scission-type positive-tone resist. In this study, the dissolution kinetics were investigated using the ZEP series to clarify the effects of the molecular weight distribution and developer

We determined the entire spectral shape of a broad band around 0.8 eV, previously termed the C08-band, which was observed commonly in Si by room-temperature photoluminescence after electron irradiation. The band has a peak at 0.77 ± 0.01 eV with long tails on both sides. We identified that the C08-band has the same origin as the C-line and occurs as a result of the recombination between a free electron

Atomic layer deposited Al 2 O 3 /GaN metal-oxide-semiconductor (MOS) diodes with and without post-metallization annealing (PMA) were irradiated with gamma-rays. Capacitance–voltage measurements were made before and after irradiation to investigate trap formation in Al 2 O 3 films and interface states between Al 2 O 3 and GaN. Negative flat-band voltage shifts were observed. The flat-band voltage shift

Optical coherence elastography based on the measurements of elastic wave speeds can quantify elastic moduli in the wave propagation directions and provide high-resolution elasticity maps for tissue. Here, we simultaneously visualized a longitudinal shear wave propagating along the depth and a Rayleigh wave propagating in the lateral direction, and analyzed the propagation characteristics of the elastic

We evaluate the enhancement of two-photon excited fluorescence from fluorescent dye by ultrafast intensity fluctuations of light generated by a nanosecond optical parametric generator (OPG). By modifying the well-established techniques for measuring the second-order coherence on ultrashort timescale, we observed the enhancement of the fluorescence from Rhodamine B dye by a factor of two due to the

We introduce wFLFM, an approach that enhances the resolution of Fourier light-field microscopy (FLFM) through a hybrid wide-field image. The system exploits the intrinsic compatibility of image formation between the on-axis FLFM elemental image and the wide-field image, allowing for minimal instrumental and computational complexity. The numerical and experimental results of wFLFM present a two- to

We report a high-efficiency geometric-phase metasurface composed of hybrid all-dielectric nanofins, of which the conversion efficiency 93% is obtained in visible frequency. Such high efficiency originates from the stimulation of the anti-ferromagnetic resonance modes of polarization-dependent parity, i.e. even and odd number of anti-parallel magnetic dipoles would introduce π phase delay among two

We report a recessed-gate enhancement-mode Al 2 O 3 -ZrO 2 /Al 0.6 Ga 0.4 N/Al 0.4 Ga 0.6 N metal-oxide-semiconductor heterostructure field-effect transistor (MOSHFET) with drain current as high as 0.48 A mm −1 at a gate-source voltage of +12 V. This was enabled by a pseudomorphic HFET structure with graded back barrier for strain management and to screen the growth interface from the channel. The

We demonstrate an all fiber high-repetition-rate erbium-doped ultrashort laser based on the Ti 3 C 2 T x -Mxene saturable absorber (SA), and the 56th harmonic mode-locking with a repetition rate of 622.2 MHz, a central wavelength of 1590.7 nm, and a pulse duration of 1.31 ps is achieved. Meanwhile, dual-wavelength mode-locking pulses are also realized, with the central wavelengths of 1575.6, 1587.5 nm

Spin–orbit torque (SOT) magnetoresistance (MR) devices have attracted attention for use in next-generation MR devices. The SOT devices are known to exhibit different write properties based on the relative angle between the magnetization direction of the free layer and the write-current direction. However, few studies that compare the write properties of each type have been reported. In this study,

Cu or Cu/Au (80 nm thick Cu, 50 nm thick Au) sputtered on Si were kept at 25 °C for a week or annealed at a temperature from 80 to 300 °C, then tested for THz emission under femtosecond laser irradiation (35 fs-800 nm). THz radiation was detected from samples annealed from 80 to 170 °C, which had a Cu 2 O/Cu interface as the THz source. Cu/Au/Si annealed at 80 °C emitted the highest THz radiation because

This paper demonstrates highly efficient GaN high-electron-mobility transistors (HEMTs) on GaN substrates with reduced interface contamination. By applying a hydrofluoric acid-based pre-growth treatment to a GaN substrate, the Si impurity concentration at the interface between the GaN substrate and the epitaxial layer can successfully be reduced. RF performance was enhanced by pre-growth treatment

A compact design for realizing narrowband optical absorbers at deep subwavelength is proposed, the physical regime of which is based on the excitation of quasi-surface plasmon polariton (quasi-SPP) mode at metal–substrate interface. Due to its small intrinsic loss balanced with the radiation loss, peak absorbance exceeding 99.9% with full width at half-maximum (FWHM) 2.6 nm is achieved at normal incidence

Defect time-evolution was investigated in Mg ion-implanted GaN after annealing at 1573 K for an unprecedentedly long duration. Transmission electron microscopy directly revealed that annealing for over 30 min reduced defects inhibiting Mg activation, just like annealing at 1753 K for a short duration. The cathodoluminescence intensity of donor–acceptor pair originating from Mg acceptors increased as

Generally speaking, the self-sweeping effect relies on the dynamical grating formed in active fiber. Here, the normal self-sweeping was generated in a ytterbium-doped fiber which serves as a fiber saturable absorber and is introduced to the laser cavity by a circulator in this experiment. The sweeping rate and the sweeping range alter as usual, both of which can be controlled by the pump power. Further

The buckling deformation of a serpentine interconnect on a flexible electronic composite film is analyzed by a scanning electron microscope miniature tensile stage in situ observation workstation. The buckle formed at the junction of the interconnect pattern under a tensile load is observed. Combined with the buckle size and a theoretical model, the interface adhesion energy and shear stress are derived

In this study, we proposed a method to measure the escape time of DNA molecules trapped in front of a nanogap by concentrating DNA molecules in front of a nanogap and observing the escape process upon their entry. We measured the escape time for λ DNA molecules entering a 25 nm deep nanogap in the semi-dilute unentangled regime to verify the validity of our method. Our obtained escape time was the

The gel column chromatographic separation technique is one of the most rapid and reliable methods to prepare high-purity semiconducting single-wall carbon nanotubes (SWCNTs). However, the use of the expensive dextran-based gels limits the utility and scalability of this technique. Herein, we report the cross-linking gelation of a cost-efficient polysaccharide isomaltodextrin (IMD) for the high-purity

We present a study of the light output power and the thermal impedance of 281 nm emission AlGaN based micropixel LEDs. A modular interconnected micropixel array design is presented which enables dense packing with area and power scalability. We study5–15 μ m diameter stand-alone devices and parallel-connected micropixel arrays with5 μ m interpixel gaps. A standalone5 μ m pixel emits 291 W cm −2 at

We have investigated the 1:1 internal mode coupling strength in a GaAs doubly-clamped MEMS beam resonator by thermally tuning the frequencies of two neighbored resonant modes. The anti-crossing of the resonant frequencies indicates that the two modes couple with each other, and the mode coupling strength was estimated by the splitting of the anti-crossed frequencies of the two modes. When the oscillation

Ultra-small red micro-LEDs(<10 μ m) with measurable output power have proved difficult to demonstrate. The smallest state-of-the-art red micro-LEDs (AlInGaP) to have exhibited a decent output power of ∼1.75 mW mm −2 are20 μm × 20 μ m in dimension. InGaN-based red micro-LED development has primarily been impeded due to the large lattice mismatch between the substrate and the quantum wells along with

The impacts of high-temperature UV nanosecond pulsed laser annealing (LA) on a chemically grown SiO 2 /Si system are systematically investigated as a function of the number of irradiated pulses. A progressive transition is observed for both the tetrahedral SiO 4 network and the SiO 2 /Si interface, being assumed to play an essential role in controlling bulk SiO 2 traps and interface states. The presented

Non-coherent Σ3{111} grain boundaries (GBs) with a positive deviation in the tilt angle ( θ 〈110〉 > 70.5°) exhibit a high recombination activity in high-performance multicrystalline silicon ingots. Most of the GB segments are composed of edge-type dislocations with the Burgers vector b of a /3〈111〉, unlike Lomer dislocations with b = a /2〈110〉 observed for negative deviations, arranged on coherent

We demonstrate a laser-based displacement measurement using an intensity modulator as a simple and wide-band intensity correlator. The proposed method applies intensity modulation not only to the output probe beam but also to the reflected beam from a target, where the fundamental frequency of modulation signal is the same for both, but the phase of modulation signal for the reflected beam is also

We demonstrated GaN-based vertical-cavity surface emitting lasers (VCSELs) with 5–30 μ m wide nano-height cylindrical waveguide formed by BCl 3 etching. A 5 nm-depth etching with BCl 3 showed the most efficient current blocking at the interface of the etched p ++ -GaN and an ITO electrode among the cases with BCl 3 , Ar, or O 2 , which could be due to not only etching damages but also diffused B atoms

By using synchrotron X-ray diffraction, we investigated the in-plane distribution of preferential glide planes in a metamorphic InGaAs solar cell with a relatively low open-circuit voltage ( V oc ) compared to other cells fabricated on the same wafer. The reciprocal-space maps revealed that the low- V oc cell contains several domains with different preferential glide planes of β dislocations. Since

This paper reveals a relation between the cut-off frequency and the simplified equivalent circuit of a spoof surface plasmon polariton (SSPP). An SSPP transmission line (TL) with low upper cut-off frequency is proposed based on the relation. In this SSPP-TL, a double-layer interdigital strip is constructed to increase the capacitance in the simplified equivalent circuit model, and in turn the cut-off

We present a high-power, high-efficiency, laser-diode-pumped 2.8 μ m Er:Lu 2 O 3 ceramic laser generating record power at room temperature. Careful thermal management and pump-radius enlargement resulted in a continuous-wave output power of 6.7 W at 2845 nm, with a 30.2% slope efficiency. To our knowledge, this is the highest output power and slope efficiency ever achieved from a laser-diode-pumped

A spinning optical resonator is an excellent platform for realizing nonreciprocity. Here, we demonstrate the distinctive isolation features in spinning indirectly coupled resonators, where the nonreciprocal light propagation and probing mechanism via mechanical rotation have been achieved. Interplay with nanoparticles induces a tunable one- or two-way transmission through differential rotation, which

Voltage control of current-induced spin–orbit torque (SOT) in an in-plane-magnetized Pd/Co/Pd system with a low-temperature-deposited HfO x and a gate electrode on top is studied. An application of the gate electric field to the HfO x layer is to induce a non-volatile electrochemical effect from the Pd/HfO x interface. By means of low-frequency harmonic Hall measurements, the voltage modulation of

The electrical properties of vertical GaN trench MOSFETs without drift layers were evaluated to investigate the effect of nitrogen plasma treatment on the trench sidewalls. It is demonstrated that nitrogen plasma treatment improves the channel property of the vertical GaN trench MOSFET. The possible mechanism of this improvement is the supply of nitrogen atoms from nitrogen plasma treatment to the

To investigate the effect of irradiation-induced defects on the superconducting characteristics of industrially produced superconductor—GdBa 2 Cu 3 O 7− δ (GdBCO)—coated conductors (CCs), we irradiated the GdBCO CCs with Au ions at 2 or 10 MeV and probed them using a slow positron beam. Vacancy clusters were detected in both unirradiated and irradiated GdBCO CCs. However, the effect of ion irradiation

One-dimensional tellurides Ta 4 SiTe 4 and Nb 4 SiTe 4 were found to show high thermoelectric performance below room temperature. This study reported the synthesis and thermoelectric properties of Ta 4 SiTe 4 -Nb 4 SiTe 4 solid solutions and Mo- or Ti-doped (Ta 0.5 Nb 0.5 ) 4 SiTe 4 . Thermoelectric power of the solid solutions systematically increased with increasing Ta content, while their electrical

The internal quantum efficiency (IQE) and photoluminescence lifetime ##IMG## [http://ej.iop.org/images/1882-0786/13/12/121005/apexabcd73ieqn1.gif] {$\left({\tau }_{{\rm{PL}}}\right)$} of the near-band-edge emission in a ZnO single crystal grown by the hydrothermal method were measured by the omnidirectional photoluminescence and time-resolved photoluminescence spectroscopy, respectively. The IQE showed

Laser-assisted atom probe tomography was used to identify the impurity distribution in Si heterojunction (SHJ) solar cells composed of thin doped/intrinsic amorphous Si layers on the textured surface of a crystalline Si wafer. A site-specific lift-out technique involving a focused ion beam enabled the selection of a∼2 × 2 μ m 2 area on an arbitrary pyramidal surface. The distributions of B, P and C

A new type of high-performance and polarization-sensitive bolometer to detect millimeter waves is proposed, fabricated, and characterized using a Mn-Co-Ni-O film. The proposed bolometer successfully avoids the complicated micro-bridge structure and experimentally achieves sensitive polarization detection by planar dipole antennas. Besides, we introduce periodic metal grating structures on the active

Single-photon amplification can be used to overcome the photon loss in long-distance quantum communication. However, the trade-off of success probability and amplification gain should be further improved. We propose a single-photon polarization qubit amplification using weak measurement. The polarization qubit can be amplified by the pre- and post-selection of the single-photon meter state weakly coupling

To clarify the behavior of the AlGaN in 20 nm wide Ga-rich current pathways in an n-AlGaN layer, which assists carrier localization in AlGaN-based light-emitting diodes, we performed a detailed analysis using an n-Al 0.7 Ga 0.3 N layer on AlN with dense macrosteps on a 1.0° miscut sapphire substrate. Energy-dispersive X-ray spectra, obtained using cross-sectional scanning transmission electron microscopy

While fluorescence protein immobilized at the metal–solution interface has been known to exhibit voltage-dependent fluorescence, the underlying mechanism has remained unresolved. Here, we addressed the cathodic mechanism employing the characteristic properties of three different fluorescence proteins showing conventional pH-sensitivity, inverse pH-sensitivity, and green-to-red photo-convertibility

We obtained a high-quality 40-pair AlInN/GaN distributed Bragg reflector with a high growth rate of the AlInN layers (500 nm h −1 ), showing almost no threading dislocations and a peak reflectivity of 99.9% at 413 nm, by using a 0.3 nm GaN cap layer grown on the AlInN layer at low growth temperature. We also found that the threading dislocations generated at the interfaces between the bottom AlInN

Major features of silicon carbide (SiC) power devices include high blocking voltage, low on-state loss, and fast switching, compared with those of the Si counterparts. Through recent progress in the material and device technologies of SiC, production of 600–3300 V class SiC unipolar devices such as power metal-oxide-semiconductor field-effect transistors (MOSFETs) and Schottky barrier diodes has started

Low-energy cross-sectional cathodoluminescence (CL) with a beam energy of 1 keV was applied to Si-ion-implanted β -Ga 2 O 3 (−201) wafers to investigate implantation damage and recovery. The semi-quantitative CL-intensity depth profiles were obtained by considering nonradiative recombination at the surface. We found that the CL intensity did not fully recover, even after annealing at 1273 K. Such insufficient

Tube shape-controlled Ce-doped Y 3 Al 5 O 12 (tube-Ce:YAG) single-crystal scintillators were directly grown from a melt via the micro-pulling-down method using a specially-designed iridium crucible. Back-scattering Laue images and X-ray diffraction measurements revealed the tube-Ce:YAG was a single crystal with the YAG phase. Ce distribution in the tangential direction of the tube-Ce:YAG specimen showed

We have investigated the electron spin relaxation time of a (110)-oriented GaAs/AlGaAs superlattice (SL) with tunnel-coupled quantum wells at room temperature. As the tunnel coupling between quantum wells increased, the spin relaxation time decreased. Even when the strength of tunnel coupling was as large as 25 meV, the spin relaxation time was 0.7 ns, about seven times longer than that of bulk GaAs

We report the detection of a single tunneling event of electrons in a physically defined silicon quantum dot system. In the measurement, we observed single-shot tunneling events in a quantum dot using a charge sensor; however, the tunneling statistics are difficult to acquire because of their weak signals. Hence, two numerical treatments using a digital filter and a change point detection technique

The metal–insulator–metal (MIM) nanostructures on polystyrene sphere (PS) were fabricated by the sputtering method. Asymmetric PS-MIM nanocrescent (AMNC) was separated and dispersed into the solution employing the sonication method. The absorption properties of AMNC colloidal solution were measured and calculated with the use of spectroscopy and discrete dipole approximation methods. The results indicated

Rapid interwell carrier transport is a key process for a uniform carrier distribution and reduced Auger recombination in multiple quantum well (MQW) light emitting devices. In this work, the interwell transport has been studied by time-resolved photoluminescence in In 0.12 Ga 0.88 N MQWs with In x Ga 1− x N ( x = 0 ÷ 0.06) and Al 0.065 Ga 0.935 N barriers. Only for the InGaN barriers the transport

The photon flux-dependent transient absorption spectroscopy is employed to investigate the carrier dynamics of Cs 2 AgBiBr 6 nanocrystals (NCs), exhibiting that the hot carrier cooling, the self-trapping process, the surface defect capture and the carrier recombination together participate in the carrier relaxation process after photoexcitation. The evolution of their lifetimes as a function of 〈N〉

We explore phonon-mediated quantum transport through electronic noise characterization of a commercial CMOS transistor. The device behaves as a single electron transistor thanks to a single impurity atom in the channel. A low noise cryogenic CMOS transimpedance amplifier is exploited to perform low-frequency noise characterization down to the single electron, single donor and single phonon regime simultaneously

We formed SiC/SiO 2 structures by various procedures that excluded an oxidation process. We found that a SiC/SiO 2 interface with a low interface state density near the conduction band edge of SiC ( D it ∼ 4 × 10 10 cm −2 eV −1 at E c −0.2 eV) is obtained for a fabrication process consisting of H 2 etching of the SiC surface, SiO 2 deposition, and high-temperature N 2 annealing. D it is rather high

We developed a machine learning model to predict interstitial oxygen (Oi) concentration in a Czochralski-grown silicon crystal. A highly accurate prediction can be ensured by selecting the appropriate experimental parameters that represent the change in the furnace conditions. A neural network was trained using the dataset of 450 ingots, and its prediction error for the testing dataset was 4.2 × 10

RT spin injection and optical polarization in nitride-based spin-LEDs are investigated. By employing CoFeB/MgO as the spin injector, the spin relaxation time and diffusion length in n-type GaN film are revealed to be 54.9 ps and 214.4 nm, respectively, through the three-terminal Hanle measurement. As the spin injector structure is applied to blue spin-LED, a maximal circular polarization of 3.3% is

Recent studies on magnetization dynamics induced by spin–orbit torque have revealed a weak dependence of the critical current for magnetization switching on the damping constant of a ferromagnetic free layer. This study, however, reveals that the damping constant nevertheless plays a key role in magnetization switching induced by spin–orbit torque. An undesirable switching, returning to an initial