We report GaN-based vertical-cavity surface-emitting lasers (VCSELs) with buried GaInN tunnel junctions (TJs). Under room-temperature continuous-wave operation, the VCSEL with an 8 μ m aperture exhibited a low operating voltage of 5.3 V at 10 kA cm −2 and a differential resistance of 110 Ω. In addition, the VCSEL with a 10 μ m aperture showed a threshold current of 14.4 mA and a peak output power of

The change in surface morphology of an amorphous TiO 2 protective film coated on a Mo/Si multilayer of an extreme ultraviolet (EUV) light collector mirror has been investigated. After long-time operation of an EUV light source, many pinholes of about 10 nm diameter were observed on the protective TiO 2 film surface. Accelerated aging tests with thin film samples that simulated surface conditions on

In this letter, a temperature compensated differential (TCD) photoacoustic (PA) method is proposed to simultaneously suppress the side-effect of multiple interferences, significantly improving the accuracy and sensitivity of liquid PA detection. We firstly established a theoretical model to prove the validity of this method. Then a differential PA detection system was set up to detect glucose concentration

Resistive pulse sensing is a particle analyzing technique using small pores. When particles pass through a pore, interruptions in ion current flow are recorded as passing particles. One problem that arises is that measurements can be prevented by clogging from impurity adsorption on the pore surface. This problem is strongly dependent on non-specific adsorption forces, such as hydrophobic interactions;

Supercritical CO 2 fluid is reported as an effective media in optimizing the SiO 2 /SiC interface in 4H-SiC(0001) MOS structures at a temperature as low as 150 °C. After SCCO 2 treatment, the breakdown electric field is improved to 10.7 MV cm −1 . The near-interfacial oxide traps is decreased from 1.62 × 10 11 to 1.84 × 10 10 cm −2 . The interface state density at 0.2 eV below E C is reduced from 6 × 10

We investigate the impact of the spatial beam oscillations in a graded-index multimode fiber (MMF) upon the trapping and blue-shifting of dispersive pulses by a multimode soliton. We find that the dispersive pulses trapped by solitons can be controlled through adjusting the degree of compression of the spatial beam. This can provide an explanation for the enhanced blue spectral extension observed in

We report on a new member of the III-nitride family, wurtzite AlP y N 1− y , tensile strained, or lattice matching (at ≈10.6% P) on (0001) GaN. Unlike lattice-matched AlInN, AlP y N 1− y can be grown between 1050 °C to 1250 °C under hydrogen atmosphere in metal-organic vapor phase epitaxy. The transition from GaN to AlP y N 1− y is sharp, there is no Ga carry over. Due to the small P content, physical

A microwave (MW)-cavity antenna was designed to manipulate the spin state in diamond. It consists of an Ω antenna and a MW cavity with a thickness of 0.35 mm and a Q -value of 65. The MW intensity increased 12 times compared to that of the Ω antenna. The size of the homogeneity area is ##IMG## [http://ej.iop.org/images/1882-0786/13/11/112002/apexabbb3bieqn1.gif] {$25\pi {{\rm{mm}}}^{2}$} and the heterogeneity

Thermocrystal is a new type of artificial periodic crystal structure, which reduces the thermal conductivity of materials. The main factor affecting the thermal conductivity of thermocrystals is the coverage area between the bandgap frequency range and the thermal spectrum. In this letter, we found that, compared with the circular air hole, the elliptical air hole can significantly improve the thermal

In this work, we demonstrate a single-mode 1.0 THz quantum-cascade laser source with difference-frequency generation. The room temperature electrically pumped monolithic source is based on a long-wavelength dual-upper-state active region, in which high MIR to THz conversion efficiency is obtained. A two-section buried distributed feedback grating configuration with two different lengths is used to

Three-dimensional distribution of grain boundaries (GBs) and generation sources of dislocation clusters is examined in a cast-grown high-performance multicrystalline silicon ingot for commercial solar cells. A significant number of dislocations are generated nearby some triple junctions of random angle GBs, although it is believed that such non-coherent GBs would not induce large strain during the

The highest extraction efficiency (9.4%) of a free electron laser (FEL) oscillator has been achieved at the midinfrared FEL facility of Kyoto University. Because of the interaction between the electron beam and FEL electromagnetic field, a maximum electron energy decrease of 16% was observed. The measured energy decrease was consistent with the measured FEL spectrum. An FEL micropulse energy of ∼100 μ

An all-optical modulator based on graphene-photonic crystal fiber (G-PCF) is demonstrated, where the G-PCF is fabricated by directly growing graphene onto inner hole walls of the PCF with atmospheric pressure chemical vapor deposition. A 1550 nm pump laser is used to induce all-optical intensity modulation of probe light. A G-PCF with a length of 2 cm achieves a significant modulation depth of 2.58 dB

This study aims to expand the antibacterial activity of the cross-linked film derived from oligoglucosamine by processing sharp protrusion nanostructures on the film surface in ultraviolet nanoimprint lithography using a solvent-permeable template. The solvent-permeable template was able to remove the dilution solvent contained in the flowable liquid derived from oligoglucosamine for life science and

The nanoscale tribological characteristics of atomic-layered niobium diselenide (NbSe 2 ) were investigated using atomic force microscopy (AFM). Two-dimensional NbSe 2 atomic layers were produced on a weakly-adherent silicon wafer using two different methods: (1) mechanical exfoliation and (2) controlled synthesis via chemical vapor deposition. Using an AFM cantilever tip, a normal force was applied

Solid-phase crystallization is rapidly developing as a method for obtaining high-quality polycrystalline Ge layers. We propose a four-step heating process, focusing on post-deposition annealing (PDA), which is performed between the film deposition and crystallization. PDA at an appropriate temperature (500 °C) reduces the grain size while improving the crystallinity of Ge (150 nm thickness), which

Self-Q-switched lasing was demonstrated for the first time around 2 μ m in Thulium (Tm) doped CaF 2 single-crystal fiber (SCF) using a compact linear cavity. Maximum average output power of 1.17 W was obtained under 2.38 W absorbed pump power, corresponding to the slope efficiency of up to 56.01%. Self-Q-switched laser with a1.736 μ s shortest pulse width at 48.80 kHz repetition rate was successfully

Internal quantum efficiency of radiation (IQE) for the near-band-edge (NBE) emission of freestanding-GaN crystals was observed by omnidirectional photoluminescence spectroscopy at various temperatures between 12 K and 300 K. A photoluminescence quenching ratio ( R q ), defined by a spectrally integrated NBE emission obtained at 300 K to that obtained at 12 K, showed a lower value (2%) comparing with

Photoluminescence (PL) spectroscopy under ideal pulsed selective and non-selective excitation conditions is used to study 265 nm AlGaN-based light-emitting diodes grown on AlN substrates. Excitation-power-density-dependent PL measurements under selective excitation conditions show that the internal quantum efficiency of the quantum-well layers is unity at cryogenic temperatures under weak excitation

Quasicrystal hole arrays are expected to be adopted as new focusing optical elements, owing to the characteristic self-imaging effect and the possibility of overcoming the diffraction limit. Using one such element, we achieved soft X-ray focusing. We designed a fivefold symmetric quasicrystal based on a Penrose tiling pattern consisting of 301 1.5 μ m diameter holes. The light source was 10 nm synchrotron

In this work, we develop a finite differential hot-wire method to uncover the localized heat dissipation physics along microwires. The localized convection effect can be decoupled at the finite differential element with a spatial resolution of 10 microns. The heat convection coefficient is characterized from 314 W m −2 K to 1116 W m −2 K along different positions of microwires with different diameters

Depth profiling of the dry-etching damage in n-type GaN induced by inductively coupled plasma reactive ion etching was carried out by cyclical electrochemical impedance spectroscopy (EIS) measurements and damage-free photo-electrochemical (PEC) etching. The GaN samples were dry-etched under different etching bias power ( P bias ) conditions, and PEC etchings were conducted in increments of 10 nm after

The effects of excess hydrogen-doping on rutile TiO 2 thin film have been investigated by low-temperature hydrogen ion beam irradiation with in situ transport measurements. The hydrogen irradiation at 300 K dramatically decreases the resistivity of TiO 2 film. Further irradiation at 50 K for excess H-doping and subsequent heating to room temperature result in reversible change in resistance between

Ultrananocrystalline diamond/hydrogenated amorphous carbon films were synthesized by coaxial arc plasma deposition. The morphological and structural evolutions of the films driven by laser irradiation (ArF, 193 nm, 20 ns) are examined at different laser energies (0.4–1 J cm −2 ). Up on laser irradiation, the films revealed hydrogen effusions accompanied by the transformation of sp 3 into sp 2 -hybridization

The effects of precleaning processes by O 3 and SC-1 in depositing high- κ gate dielectric are closely investigated in experimental comparison study. The study is made in the p-type MOSFET on the 28 nm technology node in product. O 3 cleaning demonstrated significant effects of increasing the effective oxide thickness in the inversion operation mode, reducing the gate leakage, and suppressing the standby

We succeeded in bridging unzipped graphene nanoribbons (GNRs) and separating them from unwanted single-walled carbon nanotubes (SWNTs) using a frequency-dependent dielectrophoresis (DEP) method by varying the frequency and applied voltage used for future assembly. Atomic force micrographs and Raman spectra proved that unzipped GNRs were successfully bridged by the DEP method at frequencies higher than

We have investigated the dynamical motion of a single Ce atom encapsulated in a C 82 fullerene cage (Ce@C 82 ) by using terahertz (THz) spectroscopy. A Ce@C 82 molecule is placed in a sub-nm gap of metal electrodes and excited by THz radiation. Two broad peaks are observed in the THz photocurrent spectra around 5 meV and 15 meV and are attributed to the lateral and longitudinal vibrational modes of

Multiple-quantum-well diodes (MQW diodes) naturally have key functionalities of light emission, transmission, modulation and detection all at the same time, enabling new forms of information and energy conversion between photons and electrons. When approximately biased and illuminated at the same time, a multifunctional MQW diode allows simultaneous light emission and detection within a single diode

We introduce a miniaturized magnetic shield integrated into the physics package of a chip-scale atomic clock. The primary shield, which is formed by a stack of precision-machined high-permeability plates, compactly sits inside the package as it is designed to be the internal supporting frame. Further improved by a Kovar lid, the best frequency sensitivity to a longitudinal external field is 1.1(3) × 10

Plasma-activated medium (PAM) is defined as a medium irradiated with non-thermal plasma; multiple in vitro and animal experiments have demonstrated that PAM exhibits anti-tumor effects against various cancers. PAM contains various reactive species that contribute to these anti-tumor effects. To increase the abundance of such reactive species, we used laser-generated plasma (LGP). We used a LGP consisting

Complementary split-ring resonator (CSRR) metasurfaces present interesting applications in terahertz biosensing. Indium tin oxide (ITO) is an essential optoelectronic material because of its optical transparency, high conductivity, and good stability. In this letter, we innovatively suggest that ITO-based CSRR metasurfaces can excite multi-peaks resonance in 0.1–2 THz by numerical simulation and experimental

The formation of multiple parallel twin boundaries at grain boundary grooves during Si solidification was investigated using an in situ observation system. Twin boundaries were repeatedly generated at a crystal/melt interface from a step-like grain boundary during solidification. The growth velocity of the micro-facet at the grain boundary groove accelerated and decelerated, which resulted in the nucleation

In this report, we present a vertical memristor based on a layered FePS 3 two-dimensional material with the structure Ag/FePS 3 /Au, where FePS 3 is a single-crystalline layer with a thickness of ∼151 nm. By operating a device with a pulse voltage of 0.1 V dual modes of resistive switching with both analog and digital features are implemented in a single device. One mode lies between the OFF and ON

We report the experimental realization of acoustic bi-anisotropy by asymmetric acoustic metamaterials (AAMs). Asymmetric phases of reflection coefficients are achieved in different-bilayer AAM with different resonant properties on either side, and asymmetric amplitudes of reflection coefficients are achieved by introducing material loss. The existence of acoustic bi-anisotropy means that the effective

Mica, a cleavable layered material, is a single-crystalline phyllosilicate having unique electronic and mechanical properties such as a wide bandgap and tolerance to strong electric fields and high temperatures, and is applicable to flexible electronics. This paper describes the nanometer-level layer etching of mica nanosheets exfoliated from artificially synthesized phlogopite and affixed on substrates

We demonstrated microfluidic electrogenerated chemiluminescence cells incorporated with titanium dioxide nanoparticles (TiO 2 NPs). SU-8-based microchannels were fabricated on a fluorine doped tin oxide cathodes-patterned glass substrate. TiO 2 NPs were coated on the cathodes as an electron injection layer. The enclosed microchannels were achieved by a direct bonding of the SU-8 surface to an indium

In the present study, we have investigated the effect of Eu 2+ doping on the stability and electronic properties of MAPbI 3 based on first-principles calculations. Our calculated results indicate that Eu doping is a good strategy to improve the structural stability of MAPbI 3 . The predicted band gaps for the Eu-doped MAPbI 3 are in the range of 1.5–2.8 eV. A direct-to-indirect band gap transition

A specially-designed optically transparent medium (OTM) is employed to map a pulse spectrum to a temporal waveform and utilize a single-pixel photodiode for detection at the MHz scale. We propose and demonstrate a feasible experimental arrangement for photonic time-stretch imaging (PTSI), composed of a compact OTM with a 200 × 180 × 10 mm volume, which results in 37 inner reflections and an 8.04 m

Commercialized bulk constantan with a low dimensionless figure of merit and its film fabricated by electroplating were prepared to demonstrate the feasibility of impedance spectroscopy for estimating thermoelectric parameters. From the frequency dependence of the impedance, the resistivity and dimensionless figure of merit were directly estimated as 5.3 × 10 −7 Ωm and 0.026 for the bulk and 3.8 × 10

Magnon propagation length in a ferrimagnetic insulator yttrium iron garnet (YIG) has been investigated by measuring and analyzing the YIG-thickness t YIG dependence of the spin Peltier effect (SPE) in a Pt/YIG junction system. By means of the lock-in thermography technique, we measured the spatial distribution of the SPE-induced temperature modulation in the Pt/YIG system with the t YIG gradation,

An acoustic jet generated by a mesoscale particle has been proved to be able to achieve sub-wavelength focusing. In this work, we propose two kinds of mask structures to accurately modulate the characteristics of the acoustic jet, such as the focal distance, FWHM and decay length by adjusting the position of incident sound waves. Our simulations show that an ultra-narrow beam waist width ( λ /3) in

Conditions for the direct nitridation of the 4H-SiC(0001) surface by H 2 /N 2 treatment and resulting surface structure were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED). The FTIR analysis probed both Si–H stretching vibration with back-bond containing N atoms and Si–N stretching vibration on the nitrided

AlInN/GaN power diodes consisting of a p-type GaN and a 300 nm thick n-type AlInN drift layer are demonstrated. The p–n junction is grown using metalorganic chemical vapor deposition, and the Al x In 1− x N drift layer is lattice-matched to GaN ( x ∼ 0.82) with an electron concentration of ∼8 × 10 16 cm −3 after correcting for the 2-dimensional electron gas. The diodes exhibit ∼−60 V blocking capability

Photoreflectance measurements were performed for GaAs 1− x − y N x Bi y layers in the temperature range of 20–300 K. For each sample a transition related to the band-gap was observed, which red-shifts with increasing nitrogen and bismuth content. The temperature dependencies of the band-gap were fitted by the Varshni and Bose–Einstein formulas and simulated within the band anticrossing model of the

Layered perovskite oxyhalides Bi 4 MO 8 X (M = Nb, Ta; X = Cl, Br) are promising visible-light photocatalysts for water splitting, where the polar structure may enhance the conductivity of photocarriers. In this study, the domain structure of Bi 4 NbO 8 Br single crystal was investigated using piezoresponse force microscopy and transmission electron microscope. We observed a rare domain structure with

In this study, the terahertz (THz) emission in a Co 2 MnSi/Pt structure was investigated. The THz emission intensity increased after annealing, and the optimized temperature was above 400 °C owing to the increase in B 2 ordering. The THz emission intensity of Co 2 MnSi/Pt was 1.4–2.0 times larger than that of CoFe/Pt. The THz conductivity for Co 2 MnSi/Pt was smaller than that for CoFe/Pt. The ultrafast

Weak signal detection plays an important role in industrial production. We propose the space-coiling gradient acoustic grating to control the sound wave transmission and realize acoustic enhancement. The numerical results show that the acoustic pressure amplitude can be amplified more than 240 times, and the corresponding frequency can be reduced to 500 Hz. Besides, we optimize properties of the space-coiling

We propose the design of an ultrathin planar acoustic metasurface with wavelength-dependent manipulation of a reflected wave. The metasurface comprises meta-atoms composed of multiple resonant elements working collectively to produce desired phase responses at different frequencies. We numerically demonstrate the performance of the proposed device via distinctive examples of achromatic acoustic convergence

We report an Ultrawide Bandgap Al 0.4 Ga 0.6 N channel metal-oxide-semiconductor heterostructure field effect transistor with drain currents exceeding 1.33 A mm −1 (pulse) and 1.17 A mm −1 (DC), around a 2-fold increase over past reports. This increase was achieved by incorporating a hybrid barrier layer consisting of an AlN spacer, n -doped Al 0.6 Ga 0.4 N barrier and a thin reverse graded Al x Ga

A self-reference plasmonic sensor is numerically demonstrated on surface plasmon polaritons (SPP) and cavity resonances. The sensitivity of the SPP mode is up to 1220 nm RIU −1 for detecting refractive index variations. The cavity mode is insensitive to refractive index variations, which is used to monitor the environment variations. Owing to the low radiative loss of the SPP mode propagating on a

The oxide vapor phase epitaxy (OVPE) method enables the fabrication of low-resistivity GaN crystals. However, polycrystal formation is detrimental to the growth of thick GaN crystals at the high growth rate by the OVPE method. In this study, we focused on H 2 O additive under the high-rate and high-temperature growth condition to suppress generation of Ga droplet, the origin of polycrystalline GaN

In this letter, an anode configuration with multi-aperture structure and fully recessed AlGaN barrier layer is proposed in the AlGaN/GaN Schottky barrier diode. With the Schottky junction formed between the Ni anode metal and the channel of two-dimensional electron gas, as well as the evidently enlarged contact profile by the introduction of multiple apertures, the device’s forward turning-on performances

By using synchrotron radiation photoemission, this study investigates the room-temperature surface electronic structure of Si 1− x Ge x (001)-2 × 1 grown by molecular-beam epitaxy on an epi Ge(001) substrate. The electronic structure of the Ge content, which ranges from 10% to 90%, shows similar surface behaviors. The Ge 3d core-level spectra of Si 1− x Ge x (001)-2 × 1 are essentially the same as

This study concludes the possibility of controlling the period of the laser-induced periodic surface structures (LIPSSs) by deposition of a layer of different kinds of material on the processing sample. When the Pt-Pd or ZnO layers were deposited on the sapphire substrate, the period of the LIPSS formed at the sapphire surface was significantly shortened. For deposition layers thicker than 40 nm, LIPSS

Most of terahertz lattice-induced transparency behaviors are investigated under the lattice modes matching the plasmonic modes. Alternatively, we propose terahertz polarization-insensitive array-induced transparency effect due to diffractive coupling in between two collective eigenmodes of meta-atoms on sublattice-sites in the metasurface of embedded square lattice. Aforementioned two collective eigenmodes

Delineating sub-cellular mechanical properties influenced by various cellular components is a challenge in biology in health and disease. We proposed a method to statistically analyze stiffness distribution in indentation depth direction from multiple force curves measured by AFM. The stiffness distributions revealed clear depth-dependent mechanical features of cancer cells and human liver organoids

By introducing a lattice translation of the unit cell of a phononic crystal, a general recipe to invert the acoustic Zak phase—i.e. the one-dimensional geometric phase at each phononic band—is provided and verified by surface impedance measurement. Multiband acoustic interface states are thus generated and may help the design of future acoustic waveguides. The propagation properties of these topological

Composite wavelength tuning is proposed and demonstrated in a soliton self-frequency shift (SSFS)-based coherent anti-Stokes Raman scattering (CARS) system in order to realize a fast and precision measurement of the Raman spectrum. The Stokes wavelength can be continuously tuned over 300 nm, corresponding to a molecular vibrational range of approximately 3600 cm −1 . The CARS three-dimensional spectrogram

Dinaphthothienothiophene (DNTT) has attracted considerable attention as a next-generation material for organic thin-film transistors, replacing the conventional basic material of pentacene. Although the performance of DNTT devices is higher than that of pentacene, and has been reported numerously, a comprehensive understanding of thin-film growth is lacking. In fact, thin-film structures have long

This paper demonstrates nanoscale infrared thermal imaging in electrically biased bilayer graphene (BLG) by using a scattering-type scanning near-field optical microscope (s-SNOM). s-SNOM provides a noncontact technique to detect the thermally excited electromagnetic evanescent fields (∼21 THz) generated on the surface of a Joule-heated BLG. With increasing bias current, a strong near-field signal