Thermocrystals is a new type of artificial periodic structure that controls the transfer of heat. In this letter, a multiple lattice constants supercrystal structure is proposed, and a known narrow thermal spectral material is used to achieve a broad coverage between bandgap frequencies and thermal phonon frequencies. Simulation results show that the super-thermocrystals can reduce the thermal conductivity

The local structure and thermal expansion properties of balled-milled manganese nitride fine particles with median diameters on the sub-micrometer scale were investigated. Negative thermal expansion (NTE) properties of the manganese nitrides are noticeably altered even with particle sizes of several micrometers. The present study indicates that the alteration of NTE properties is attributable to the

Current-voltage-temperature characteristics (0 °C to 150 °C) of SBDs on highly compensated15 μ m and 30 μ m n-type GaN drift layer were measured for voltages up to −300 V and up to −800 V, respectively. When the temperature is between 75 °C and 100 °C, both SBDs exhibited a similar change in conduction mechanism from thermionic field emission (TFE) to thermionic emission (TE) due to the activation

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A buffer gas trap is applied successfully to accumulate more than 10 5 low energy positrons created with the electron linear accelerator at AIST, which can provide 40 MeV electron bunches at 40 Hz with the peak current of about 100 mA and create the average current of ∼1 pA, 40 Hz low energy positron pulses. Also, the accumulated positrons are extracted as a pulsed beam to be used for future experiments

Vertically ordered hexagonal boron nitride (h-BN) films were successfully sputtered on AlGaN/GaN heterostructure (HS) using high power impulse magnetron sputtering at room temperature. The h-BNs vertical ordering along the (0002) plane was confirmed using high-resolution transmission electron microscopy. After the h-BN deposition, degradation of two-dimensional electron gas (2DEG) properties was observed

Multilayer thin-film encapsulation plays an important role in Si-based organic micro-displays. In this letter, we demonstrate an efficient and low-process-temperature approach to fabricate high-performance barrier films by inserting in situ plasma oxidized Al layers between SiO x encapsulation layers. Calcium degradation tests show that the water vapor transmission rate of the SiO x /AlO x multilayer

We report a new technique to suppress beam-divergence fluctuations in a DC-biased KTa 1- x Nb x O 3 (KTN) optical beam deflector. In our new configuration, we introduced a temperature gradient in the direction of the electric field applied to the KTN crystal, to produce a permittivity gradient in the direction required to cancel out the effect of the asymmetry of the electron injection. We demonstrated

We report the generation of acoustic hook beams by a holographic lens. Compared with the conventional method, the intensity of the hook beam is greatly improved and the bending position is adjustable. We further rotate the hook beam into a two-dimensional axisymmetric structure with a cavity in the middle, forming a self-healing bottle beam. As an experiment, the generated bottle beam is used to trap

The impact of post-metallization annealing of N-polar AlSiO metal-oxide semiconductor (MOS) capacitors was investigated. Annealing in air at 320 °C and 370 °C reduced the density of near-interface traps from 5.6 × 10 11 to ~2.8 × 10 11 cm −2 and extended the region of flat-band voltage stability and low-leakage operation from 0–2.6 to 0–4 MV cm −1 in the forward bias accumulation region. Moreover,

ScAlN is a promising material for applications spanning wide-bandwidth filters, high-electron-mobility transistors, and ferroelectric memory. We investigate conditions influencing wurtzite phase purity for heteroepitaxial ScAlN, and present methods to rapidly identify phase purity degradation. Even for N-rich samples, phase purity is sensitive to the III/V ratio near the N-rich to metal-rich transition

We report on the modeling of polarization-induced two-dimensional electron gas (2DEG) formation at ε -AlGaO 3 / ε -Ga 2 O 3 heterointerface and the effect of spontaneous polarization ( P sp ) reversal on 2DEG density in ε -Ga 2 O 3 / ε -AlGaO 3 / ε -Ga 2 O 3 double heterostructures. Density-functional theory (DFT) is utilized to calculate the material properties of ε -Ga 2 O 3 and ε -AlGaO 3 alloys

According to the Stoner criterion, the density of states at the Fermi level is the crucial factor for the magnetic proximity effect (MPE), implying that the MPE can be controlled by applying a gate voltage. In this report, we examined the anomalous Hall effect (AHE) in a Pt layer with a small magnetic moment induced by the MPE, and the effect of the gate voltage. We observed a large AHE in CoFe 2 O

Nanodiamond composite (NDC) films deposited on silicon substrates by coaxial arc-plasma deposition at room temperature are easily peeled off with increasing film thickness. This research adapted additional NDC intermediate layers deposited at high temperatures, to induce atomic interdiffusion towards the Si substrates, which effectively enhances the adhesion of the intermediate layers with the substrates

Semipolar Al x Ga ##IMG## [http://ej.iop.org/images/1882-0786/13/6/061008/apexab9183ieqn1.gif] {${}_{1-x}$} N films (∼660 nm thick) are fabricated on (11̅02) ( r -plane) AlN substrates. X-ray diffraction measurements suggest that the structural quality is relatively good although lattice relaxation occurs. The experimentally evaluated relaxation degrees are 0.90 and 0.72 along the [11̅01̅] and [112̅0]

We demonstrate controlled chemical vapor deposition growth of lateral and vertical heterostructures of graphene and hexagonal boron nitride (h-BN) on Cu substrates by changing supply sequence of their precursors. When the graphene precursors are switched by the h-BN precursors, h-BN grows from the edges of the existing graphene islands, resulting in the lateral heterostrcutures. In the reversed supply

The behavior of Ga adatom on GaN non-planar facets during metalorganic vapor phase epitaxy (MOVPE) is investigated on the basis of ab initio calculations. For non-planar facet consisting of ##IMG## [http://ej.iop.org/images/1882-0786/13/6/065505/apexab9182ieqn1.gif] {$\left(1\overline{1}01\right)$} and ##IMG## [http://ej.iop.org/images/1882-0786/13/6/065505/apexab9182ieqn2.gif] {$\left(0001\right)$}

In-plane modification of hexagonal boron nitride (hBN) is demonstrated via plasma in solution without acid/base addition. Electron spin resonance spectroscopy clearly reveals an increase in nitrogen vacancies in the hBN plane. This could be a simple route to functionalizing the two-dimensional surface of hBN. Simultaneously, hydroxylation occurs, accompanied by an increase in the zeta potential.

To overcome the traditional problem of blocking low-frequency noise, this letter proposes a design of large-scale metamaterial panel with periodic tunable resonant cell arrays. Numerical calculations show that the tunable metamaterial panels exhibit multiple local resonance mechanisms, which result in sound transmission loss (STL) improvements over traditional mass law in low-frequency regions. The

The residence time effect of SiN x plasma atomic layer deposition processes was investigated. The reactive species (H x , NH y , SiH z ) were analysed by a mass spectrometer. In the NH 3 plasma step, a strong SiH 4 peak was observed and is attributed to the desorption of SiH 4 from the SiN x surface. A relatively low N/Si ratio of 1.16 was identified owing to the re-deposition of the desorbed SiH 4

We compare Bi 2 Te 3 powders prepared by conventional ball milling to powders milled in supercritical carbon dioxide (scCO 2 ). We demonstrate that scCO 2 milling overcomes size-reduction limitations reported for conventional milling. XRD and TEM reveal nanograins with smaller average sizes (< 10 nm) and narrower grain size distributions in the scCO 2 milled case. scCO 2 milling also preserves the

In this study, we theoretically investigated properties of magnetostatic spin waves in rare-earth and transition-metal ferrimagnets with various angular momentum. The resonant frequency of high- (low-) frequency mode has the lowest (highest) value at angular momentum compensation temperature ( T A ). It was found that both resonance modes show a maximum group velocity at T A . Furthermore, the low-frequency

We investigated the structural and electrical properties of superconducting NbN films epitaxially grown on AlN single-crystalline films using a sputtering technique. The NbN(111) films grown on AlN under optimized temperatures exhibited clear peaks with Pendellösung fringes attributed to the growth of the atomically flat surfaces in 2 θ / ω X-ray diffraction patterns. Scanning transmission electron

Halide vapor phase epitaxy of p-type GaN:Mg films was realized by using solid MgO as the Mg source. The Mg concentration was controlled by supplying HCl gas in a MgO source zone. Mg-related photoluminescence peaks were observed at around 3.3 and 2.9 eV. For a sample with a Mg concentration of 2.8 × 10 19 cm −3 , the Hall-effect measurement showed p-type conduction with a hole concentration and a hole

InN dots grown by metalorganic chemical vapor deposition were analyzed using atom probe tomography and transmission electron microscopy. A dot was found to be composed of pure InN at the core with a sharp interface with its underlying GaN layer and a more diffuse interface with its top GaN cap layer. Both techniques revealed the hexagonal truncated pyramid shape of the dots. APT has been used in the

The electronic structure of bilayer graphene under an external electric field is studied in terms of the interlayer stacking arrangements using the density functional theory combined with the effective screening medium method. The calculations showed that the accumulated carrier distribution strongly depended on the interlayer stacking arrangement. The carriers were highly concentrated on the topmost

Interfaces play a crucial role in determining the functional and mechanical properties of materials. However, predicting interface properties is not straightforward because the atomic arrangements at the interface are different from those in the bulk. Hence, in this study, we discovered a descriptor from the bulk that helps predict the interface properties without the need to determine the interface

The capacitance–voltage characteristics of MOS capacitors and ab initio theoretical calculations revealed that an amorphous film composed of WSi n clusters ( n = 6−12) had a low effective work function of 4.0 eV on SiO 2 with excellent thermal stability up to 600 °C. In Si Schottky diodes with WSi n insertion, the electron Schottky barrier height (SBH) was 0.58 eV for n = 6 and reduced to 0.45 eV when

Alignment of carbon nanotubes (CNTs) in CNT/polymer composite films is an attractive technique to obtain improved electrical, mechanical, and thermal properties. However, their alignment method is still confined to small laboratory scale sample preparation. In this letter, a novel method to prepare a continuous drawing of ribbon-like films of CNT/polymer composite is proposed using a robotic dispenser

A study of GaAs solar cells (SCs) with various quantum-sized objects has been carried out. In 0.2 Ga 0.8 As quantum wells, In 0.4 Ga 0.6 As quantum well-dots (QWDs), In 0.8 Ga 0.2 As and InAs quantum dots have been considered. The increment in photocurrent and the reduction of open-circuit voltage have been calculated using dark IV and spectral characteristics. An analytical model for estimating the

The presence of defects leads to a significant impact on the optical and electrical properties of transition metal chalcogenides (TMDCs). The photoelectric performance of TMDCs can be tailored through defect engineering. In this work, we study defect engineering by using controlled annealing in air as an approach to improve the performance of photodetector based on multilayer WSe 2 . The responsivity

The thermally induced deflection of bimaterial cantilevers was theoretically examined, and an optimal excitation configuration was determined. The optimal heat spot position, resulting in the maximal deflection, was observed at a central location at a 0.5-0.6 length for short cantilevers and it shifted backwards to the clamped position at 0.4 length for long cantilevers. The calculated values and recent

We propose a mechanism of broadband asymmetric acoustic transmission in a straight open duct, by breaking spatial symmetry using two geometrically-asymmetric components filled with natural material placed on two sides of duct. Thanks to low loss and dispersion of natural material, the resulting device enables high-efficiency and ultra-broadband transmission for plane waves coming from one port while

Fluctuations in superfluorescence were evaluated for a CuCl quantum dot assembly in a NaCl single crystal by measuring single superfluorescent spectra. The distributions of the spectral widths and peak intensities of the individual spectra were obtained as a function of the excitation density. The result showed that fluctuations decrease with an increase in excitation density due to the rapid establishment

Magnetic skyrmions are expected to offer novel functionalities in emerging magnetic devices. However, when the skyrmion moves along a nanotrack, its trajectory is generally curved by the skyrmion Hall effect, resulting in an annihilation of skyrmion at the edge. Here we propose a method to avoid this edge-induced skyrmion annihilation. We found that the annihilation of skyrmion is largely suppressed

Holes in germanium (Ge) exhibit strong spin–orbit interaction, which can be exploited for fast and all-electrical manipulation of spin states. Here, we report transport experiments in a tunable Ge hut wire hole double quantum dot. We observe the signatures of Pauli spin blockade (PSB) with a large singlet-triplet energy splitting of ∼1.1 meV and extract the g factor. By analyzing the PSB leakage current

Controlled carrier doping of single-wall carbon nanotubes (SWCNTs) is highly demanded for SWCNT electronic device applications. In this study, we propose a method for the controlled filling of n- and p-type dopant molecules in SWCNTs by co-encapsulating dopant and dummy molecules. The SWCNT dispersion was refluxed in 1,4-dioxane dissolving dopant and dummy molecules. The amount of encapsulated dopant

We report on comparative studies of the optical vortex-induced structures of both Si(100) and Si(111) by irradiation with a single optical vortex picosecond pulse. Furthermore, we address the effects of the total angular momentum (TAM) on the optical vortex-induced microneedle. Si(111) allows for the faster growth of the microneedle, although this impacts the monocrystallization of the needle. The

Charge transfer processes via deep levels (DLs) of a free-standing n-GaN grown by hydride vapor phase epitaxy is investigated using two types of excitations in time resolved photoluminescence (PL) analysis: above the bandgap energy ( E g ) (AEG) and sub- E g (SEG). Using SEG excitation allowing us the PL observation free from carrier dynamics around band-edges such as excitonic recombination varying

A dual-band absorption enhancement of monolayer molybdenum disulfide (MoS 2 ) by a tapered metamaterial waveguide slab (TMWS) is presented. Due to the gradient width of TMWS, double absorption bands of monolayer MoS 2 can be enhanced simultaneously via the fundamental waveguide mode resonance. The correlation between the selective absorption performances of the TMWS-based absorber and the resonant

An optical absorber with the advantages of flexibility, broadband, insensitivity to incident angle and high efficiency in double-sided incidence is studied, realized and characterized. The absorber is composed of the tapered concave nanostructure covered with thin Ni-SiN x film. Simulation results show that there exist two different mechanisms in the absorptive behavior. The absorption is measured

The light emission property of InGaN quantum wells is seriously deteriorated in the red wavelength with high indium concentration, which is accompanied by structural defects called trench defects. However, the formation mechanism of trench defects has not been fully understood. In this study, we reveal the origin of this defect by utilizing the simplest system, one consisting of a single InGaN quantum

A dual-comb-based asynchronous optical sampling (ASOPS) pump-probe measurement system is demonstrated for characterizing the relaxation dynamics in a photo-excited self-assembled InAs quantum dot (QD) semiconductor. Although the photo-excited QD material has multiple complex relaxation processes, the transient transmittance responses (from femtoseconds to nanoseconds) are successfully obtained within

In this study, crystalline cobalt ferrite thin films with large Faraday rotation (FR) coefficient were deposited on silicon by radiofrequency magnetron sputtering. An (100)-oriented MgO buffer layer was employed to solve the film/substrate discrepancy. A giant FR coefficient of 25 600 deg cm −1 was achieved for a cobalt ferrite film deposited at a substrate temperature (ST) of 600 °C. Moreover, the

(Bi 1/2 Na 1/2 )TiO 3 (BNT) is one of the candidates for lead-free piezoelectric ceramics. Recently, we found that the depolarization temperature T d of BNT could be increased by approximately 40 °C–80 °C with a quenching treatment after the sintering. To elucidate the mechanism, high-energy synchrotron X-ray powder diffraction data were collected in SPring-8 to analyze their crystal structures in

We demonstrate threshold voltage controllable short-channel transistors and organic inverter circuits with top-contact electrodes on flexible substrates. The source and drain electrodes were thermally evaporated on semiconductor material and patterned using photolithography and a wet etching process. The mobility of the fabricated transistors with channel lengths ( L CH ) of3 μ m was 0.495 ± 0.037

We report a Ni 2+ heavy metal sensor based on a graphene oxide (GO) functionalized micro-tapered long-period fiber grating (MTLPG) where light–matter interaction is enhanced. With high-quality GO coating on fiber with strong adhesion and controllable thickness, the GO-coated MTLPG demonstrated a resonant wavelength shift and intensity change, corresponding to a sensitivity of up to 5.12 × 10 −4 nm

We elucidated implicate ordering of amorphous Sn-doped In 2 O 3 films grown on glass substrates during the phase transition to polycrystalline by postannealing from room temperature to 300 °C for 55 min. X-ray diffraction with two-dimensional detector revealed the following. First, fine grains are developed. Second, crystallites are grown with (222) preferential orientation associated with growing

Metal-coated moth-eye films display broadband light-absorption (BLA) over the visible (380–780 nm) and near-infrared (780–1000 nm) spectral ranges when illuminated from the rear. The pillars on the moth-eye film function as a template of cone-shaped metallic cavities. The average absorptance is 91% over the visible wavelength range. Calculations based on the finite-difference time-domain method revealed

InAlGaN/AlN/GaN high electron mobility transistors (HEMTs) on a silicon substrate with high electron mobility is demonstrated for the first time. The InAlGaN/AlN/GaN heterostructures has a high electron mobility of 1540 cm 2 V −1 s −1 and low sheet resistance of 228.2 Ω sq −1 by inserting a thin GaN interlayer (IL) between InAlGaN and AlN layers. The experimental results demonstrate that an optimized

We investigated laser-pulse-induced terahertz (THz) emission in Ta/CoFeB/Ir/CoFeB/Ta layered synthetic magnets with different Ir spacer thicknesses. THz emissions were observed under no applied magnetic fields for samples exhibiting interlayer antiferromagnetic exchange couplings, and those THz emissions also showed oscillatory behavior against the Ir spacer thicknesses. These results are qualitatively

We fabricated two-dimensional assemblies of gold and silver nanoparticles on polycation coated substrates by a liquid–liquid interfacial precipitation method. The assembling of the metal nanoparticles on the substrate was evaluated by absorption spectroscopy and scanning electron microscopy. Raman scattering signals of Rhodamine 6G were detected on the metal nanoparticle-modified substrates. In particular

We propose and numerically analyze a unique optical waveguide crossing based on a silicon-on-insulator (SOI) slab waveguide structure. The optical waveguide crossing consisting of four curved mirrors made of silica walls and beam spot-size converters formed in a silicon core layer of the SOI slab waveguide. Based on our design with a device footprint of15 × 15 μ m 2 , we obtained excellent device performances

Using density functional calculations, we clarify the oxygen incorporation mechanism in vicinal m-GaN growth by metal-organic vapor-phase epitaxy. We first identify reconstructed structures of 5° off m-GaN toward the ± c directions. Next, we explore preferable sites for oxygen substitution near step edges. We find that oxygen prefers the lower nitrogen site of the step edge on the + c 5° off m-GaN

An asymmetric trimeric slit metasurface structure is proposed herein, which generated independently tunable double Fano resonances (DFRs), namely, Fano1 and Fano2. Rigorous simulations and experimental scanning near-field demonstrated that the non-radiative dark mode produces Fano1, while the magnetic toroidal mode generates peak Fano2. The mechanisms of the two Fano resonances infer that interference

In this work, we have systematically compared different factors of the bipolar incremental step pulse programming (ISPP) method in a one-transistor-one-resistor (1T1R) structure to lower the forming bias of RRAM, and also investigated the limitation of the forming voltage induced by the gate voltage of the transistor. Finally, we applied bipolar ISPP at high temperatures to further reduce the forming

p-type BaSi 2 /n-type crystalline Si (p-BaSi 2 /n-Si) heterojunction solar cells with various BaSi 2 thickness ( ##IMG## [http://ej.iop.org/images/1882-0786/13/5/051002/apexab8727ieqn1.gif] {${d}_{{{\rm{BaSi}}}_{2}}$} ) from 20 to 100 nm were fabricated using a simple preparation method, that is, post-annealing of undoped n-type BaSi 2 prepared by thermal evaporation. With decreasing ##IMG## [http://ej

This study reports the low-resistance state retention fail of InGaZnO resistive-switching random access memory (ReRAM) under constant DC bias stress conditions by Joule heating effect. There were the abrupt state changes of InGaZnO ReRAM devices with high voltage stress over 0.6 V because of thermal energy in conducting filament. In addition, SPICE simulation was conducted with verilog-A to verify

The unique optical properties of two-dimensional (2D) materials are largely dependent on the number of atomic layers. Hyperspectral imaging microscopy shows large potential for rapid and accurate thickness mapping. To process the acquired hyperspectral data set and to deal with pixel-level spectra remain a challenge for further application. In this work, two quantitative classification strategies including

We investigate the optical properties of the chiral smectic C phase of ferroelectric liquid crystals (FLCs) having a self-assembling helical structure that is regarded as a one-dimensional pseudo-photonic crystal. FLCs have several stop bands corresponding to full-pitch, half-pitch, and their high order bands under oblique incidence. It is expected that the center wavelength and bandwidth of the full-pitch