To produce high-quality GaN (0001) substrates with a low threading dislocation density (TDD) and a small off-angle variation, we have developed a technique named the “maskless-3D method.” This method, which is applied during GaN boule growth by hydride vapor phase epitaxy (HVPE), induces three-dimensional (3D) growth on a normal GaN (0001) seed substrate. We showed that by an appropriate choice of

One of the issues in semiconductor device manufacturing is particle contamination on wafers. To improve the production yield of devices, it is necessary to reduce the number of particles. One approach to avoiding particle contamination caused by scattering in semiconductor processing apparatuses is by improving the adhesion forces between particles and surfaces of apparatus components. Such forces

Digital holography with two wavelengths that are close to each other is applied to the height measurement of solder bumps having a spherical specular surface and a height of several tens of micrometers. To meet industrial requirements, the error should be less than about1 μ m, and therefore the two wavelengths should have a difference of just a few nanometers for digital holographic measurement. In

Amorphous vanadium oxide (V x O y ) thin films were grown on SiO 2 glass substrates by pulsed laser deposition at RT in high vacuum of 1.0 × 10 −5 Pa. The electric conductivity of the film was increased from 0.34 S cm −1 at 323 K to 4.2 S cm −1 at 473 K, and the film showed positive Seebeck coefficient of15 μ V K −1 at 323 K and positive Hall voltage of10 μ V at RT, indicating p-type semiconductor

High performance and uniform thin-film transistors were fabricated on a grain-boundary (GB) free single crystal Si strip for the first time. Here sputter-SiO 2 gate insulator was used. Electron mobility μ was 548 cm 2 V −1 s −1 , subthreshold swing ss was 0.279 V dec −1 , and on/off ratio was 2.4 × 10 7 . Variability of ss was only 9.4% but that of μ was 34.2%. Carrier scattering was known to be dominated

We examined by transmission electron microscopy the structure and crystallization behavior of hydrogenerated and non-hydrogenerated amorphous germanium films (a-Ge:H and a-Ge) prepared by sputtering to figure out the effects of hydrogen on them. In pair-distribution function, first and second peaks at the interatomic distance of 0.26 and 0.40 nm, respectively, were found to be higher and sharper in

Boundary lubrication is one of the most interesting topics in the field of tribology, and many studies have been conducted in the past to gain deeper understanding of the behaviour of boundary lubrication layers formed by additives mixed in lubricants because the layer largely affects the tribological property of the target surface. With a strong demand to clarify the behaviour of boundary lubrication

A planar-type uni-leg thermoelectric generator (TEG) using a SiGe membrane is proposed and analyzed theoretically. First, we built a model for a unit cell of the TEG, which can be fabricated by photolithography which is suitable for mass production. Then, the output power density was simulated by the finite element method to find the optimal dimension of the TEG. The estimated maximum power density

The atomic structure of Zn for the Zn-doped β -Ga 2 O 3 film formed through mist chemical vapor deposition was investigated via X-ray absorption spectroscopy using a high-sensitivity detector and spectra simulations. The measured and simulated spectra agree, revealing that Zn atoms are located at substitutional Ga sites and at both tetrahedral and octahedral sites, not one of the two.

Junctionless p-type polycrystalline silicon (poly-Si) nanowire (NW) transistor with ideal subthreshold slope (SS) is successfully demonstrated by a gate-all-around channel structure and improved fabrication processes with highly suppressed grain boundary defects in the poly-Si. The fabricated devices, whose NW width is 9.6 nm, exhibit nearly ideal SS of 60 mV dec −1 at room temperature. Furthermore

We have realized a new optical system to form multiple aerial images by use of thin optical components. The proposed optical system is based on aerial imaging by retro-reflection (AIRR). The aerial image formed by AIRR is visible over a wide viewing angle without using 3D glasses. In addition to AIRR, we have introduced a technique called infinity mirror in which a mirror and a half mirror are arranged

We performed an open-air-type plasma treatment of polytetrafluoroethylene (PTFE) at atmospheric pressure to increase the adhesion strength between PTFE and an Ag metal film obtained from Ag ink. When PTFE was Ar plasma-treated without H 2 O addition for 600 s, the coloration of the PTFE surface occurred, and the Ag/PTFE adhesion strength was 0.06 N mm −1 . This adhesion strength was the same as that

Nowadays advanced magnetic tunnel junction applications demand very high tunnel magnetoresistance at room temperature, thus it is quite important to explore high Curie temperature T c half-metallic Heusler alloys. In this article first-principles calculation unveiled that NiCrMnSi has a T c of 1200 K comparable to that of traditional Co 2 MnSi Heusler alloys, even though it does not contain a Co element

We propose a thermo-optic phase shifter utilizing multimode interference in a silicon waveguide. The electrodes were attached to the section where the multimode interference had the minimum optical electric field around the sidewalls. We designed the multimode waveguide width to reduce optical propagation loss in the C–L wavelength band(1.53–1.625 μ m). We succeeded in developing a low optical loss

To obtain high device fabrication uniformity and reproducibility for vertically curved silicon waveguide optical coupler, we developed the high accuracy ion implantation bending (IIB) method by incorporating a tungsten mask that can partially shield the ion implantation. The developed IIB method improved the positional accuracy of the origin of vertically curved Si wire bending from a wet etching-level

Graphene oxide (GO) is widely used as a graphene conversion material for transparent electrodes and conductive films via reduction treatment. However, GOs are typically provided as mixtures that include various chemical structures and oxidation degrees, including strongly damaged ones. Since the contamination of these defective GOs decreases the conductivity of the resulting reduced GOs (rGOs), purification

The influences of both high-voltage stress and hygrothermal stress were studied for homojunction and heterojunction crystalline Si photovoltaic (PV) modules. In order to separately access the influence of these stresses, these PV modules were subjected to sequential tests with hygrothermal stress and high-voltage stress for various stress durations of each test. It was found that for p-type homojunction

This paper describes the frequency characteristics of a highly sensitive barometric pressure change sensor. Here, we propose a method to measure pressure changes based on microelectromechanical systems piezoresistive cantilevers and an air chamber. The proposed sensor structure realizes a mechanical high pass filter to eliminate the influence of the barometric pressure change due to meteorological

Wavefront coding is a hybrid optical–digital technique proposed to increase the effective depth of focus of optical systems. The key to wavefront coding lies in the design of a suitable phase mask placed at the system’s aperture to achieve invariant imaging properties over a range of defocus. In systems limited by temporally or spatially varying aberrations the use of wavefront coding has not yet been

A high-power, narrow-linewidth Yb fiber laser with a fiber Bragg grating (FBG) pumped difference frequency generation (DFG) in a periodically poled lithium niobate (PPLN) crystal was investigated in detail. A mid-IR power of approximately 2.3 microW at 3.3 micrometers with a slope efficiency of 0.85 mW/W2 was achieved. A Doppler-broadened absorption spectrum of CH4 at 3038.497 cm-1 (3.2911 micrometers)

A Yb fiber laser pumped cw narrow-linewidth tunable mid-IR source based on a difference frequency generation (DFG) in a periodically poled LiNbO3 (PPLN) crystal for trace gas detection was demonstrated. A high power Yb fiber laser and a distributed feedback (DFB) laser diode were used as DFG pump sources. This source generated mid-IR at 3 microns with a powers of ~2.5 microW and a spectral linewidth

The real-time measurement of radiation environment was made with an improved real-time radiation monitoring device (RRMD)-II onboard Space Shuttle STS-79 (S/MM#4: 4th Shuttle MIR Mission, at an inclination angle of 51.6 degrees and an altitude of 250-400km) for 199 h during 17-25 September, 1996. The observation of the detector covered the linear energy transfer (LET) range of 3.5-6000 keV/micrometer

A new telescope consisting of three two-dimensional position-sensitive silicon detectors which can measure the linear energy transfer (LET) distribution over the range from 0.2 to 400keV/micrometers has been developed as a real-time radiation monitor in manned spacecraft. First, the principle of LET measurement and its design method are described. Second, suitable electronic parameters for the LET