Published in Soft Matter
Complex fluids have a non-uniform local inner structure; this is enhanced under deformation, inducing a characteristic flow, such as an abrupt increase in extensional viscosity and drag reduction. However, it is challenging to derive and quantify the non-uniform local structure of a low-concentration solution. In this study, we attempted to charact...
Published in Journal of the Ceramic Society of Japan
Excellent quality amorphous aluminum oxide (AlOx) thin films have been obtained by atmospheric pressure solution-processed mist chemical vapor deposition (mist-CVD) technique at 400°C using water-free solvent. X-ray fluorescence investigations verified the formation of AlOx film by the mist-CVD. X-ray diffraction, X-ray photoelectron spectroscopy, ...
Published in Applied Surface Science
We conducted X-ray photoelectron spectroscopy (XPS) and first-principles calculations based on density functional theory (DFT) to confirm the presence of Ga2O sub-oxide in high-pressure water vapor annealed AlGaN surface. We note that the Ga 3d XPS peak broadens and shifts towards higher binding energies, which suggests surface oxide formation. Dec...
Published in Japanese Journal of Applied Physics
Aluminum titanium oxide (Al1–x Ti x O y , an alloy of Al2O3 and TiO2), an attractive high-κ dielectric material, was synthesized by mist chemical vapor deposition, utilizing Al2O3 and TiO2 precursors. X-ray diffraction investigations revealed that the Al1–x Ti x O y (0
Published in 2019 Compound Semiconductor Week (CSW)
With its wide-bandgap (~7 eV), high breakdown field (~10 MV/cm) and high dielectric constant (~9) amorphous aluminum oxide (Al 2 O 3 ) film is an attractive material for applications as gate insulator and/or surface passivation layers for electrical devices. Using several vacuum deposition techniques, such as sputtering, metal organic chemical vapo...
Published in 2019 Compound Semiconductor Week (CSW)
Tin oxide (SnO 2 ) is an n-type wide band-gap semiconductor with excellent properties such as optical, electrical and chemical properties. In this research, SnO 2 thin films were grown on m-plane sapphire substrates by mist chemical vapor deposition. However, it was difficult to deposit high quality SnO 2 films because of the large lattice mismatch...
Published in 2019 Compound Semiconductor Week (CSW)
High-k dielectric aluminum titanium oxide (AlTiO, an alloy of Al 2 O 3 and TiO 2 ) films were obtained by mist chemical vapor deposition (mist-CVD), utilizing Al 2 O 3 and TiO 2 precursors. By X-ray fluorescence (XRF) investigations, atomic composition ratios of Al and Ti ratios in the Al x Ti y O films were verified. X-ray diffraction (XRD) reveal...
Published in PISIKA - Journal of the Physics Society of the Philippines
With its wide bandgap of 3.4 eV, gallium nitride (GaN) is considered as a key semiconductor material for realizing ultra-low-loss power devices. However, GaN-based devices is still plagued by current collapse, which is the temporary reduction of current after application of electrical stress. In this work, we present the state-of-art Multi-Mesa-Cha...
Published in Japanese Journal of Applied Physics
ZnS is attractive as a material for low-cost light-emitting diodes. In this study, a non-polar ZnS layer was epitaxially grown on a sapphire substrate by inserting a ZnO buffer layer between ZnS and sapphire. The ZnS and ZnO layers were grown by a mist chemical vapor deposition system with a simple setup operated under atmospheric pressure. The sam...
Published in Materials Science in Semiconductor Processing
In this article, we review recent progress on AlGaN/GaN and InAlN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) using Al-based oxides, nitride dielectrics, SiO2 and high-k dielectrics. Although GaN MIS-HEMTs have been suffering from the instability of threshold voltage (VTH), recent interface technologies using in...
Published in Applied Physics Express
An analytical technique is proposed to reveal the relaxation time distribution of dynamic charge events using the current noise spectrum of a transistor, by applying an inverse integral transformation to the McWhorter model. In the proposed method, the continuous relaxation-time distribution function G(τ) can be analytically derived from the noise ...
Published in Extended Abstracts of the 2017 International Conference on Solid State Devices and Materials
Non-polar ZnS layers were epitaxially grown on mplane sapphire substrates by mist chemical vapor deposition at atmospheric pressure. For this growth, ZnO buffer layers were inserted between the ZnS and the sapphire because ZnO has an intermediate lattice constant.
Published in Semiconductor Science and Technology
The electrical properties of AlGaN/GaN MOSHFETs with HfO2 prepared by atomic layer deposition with and w/o oxygen-plasma treatment (further referred to as PHf-MOS and Hf-MOS) were investigated. The sub-threshold slope of the MOSHFETs (350 and 150 mV dec−1 for Hf-MOS and PHf-MOS, respectively) were lower than that for HFET (450 mV dec−1), which also...
Published in physica status solidi (a)
The crystal quality of ZnO films grown by mist chemical vapor deposition (mist‐CVD) was improved by introducing ZnO buffer layers on sapphire substrates. The ZnO films were grown by high‐speed rotation‐type mist‐CVD with a ZnCl2 aqueous solution, which provided uniform epitaxial layers over 2‐inch wafers. To grow the ZnO buffer layers, it is necess...
Published in Journal of Applied Physics
The energy spectrum of interface state density, Dit(E), was determined at oxide/III-N heterojunction interfaces in the entire band gap, using two complementary photo-electric methods: (i) photo-assisted capacitance-voltage technique for the states distributed near the midgap and the conduction band (CB) and (ii) light intensity dependent photo-capa...
Published in physica status solidi (c)
Tin dioxide (SnO2) thin films, as a candidate for realizing next‐generation electrical and optical devices, were grown on 2‐inch diameter m ‐plane sapphire substrates by mist chemical vapour deposition at atmospheric pressure. The SnO2 thin films were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), X‐ray diffract...
Published in Applied Physics Letters
Interface characterization was carried out on Al2O3/GaN structures using epitaxial n-GaN layers grown on free-standing GaN substrates with relatively low dislocation density (
Published in Journal of Physics D: Applied Physics
Recent years have witnessed GaN-based devices delivering their promise of unprecedented power and frequency levels and demonstrating their capability as an able replacement for Si-based devices. High-electron-mobility transistors (HEMTs), a key representative architecture of GaN-based devices, are well-suited for high-power and high frequency devic...
Published in Extended Abstracts of the 2016 International Conference on Solid State Devices and Materials
This paper presents the effects of the inductively coupled plasma (ICP) etching of AlGaN surface on the resulting threshold voltage (VTH) instability of Al2O3/AlGaN/GaN structures. It was found from the measured capacitance – voltage (C–V) characteristics that the ICP etching of the AlGaN surface showed larger VTH shifts than in the sample without ...
Tin dioxide (SnO 2 ) thin films, as a candidate for realizing next-generation power and optical devices, were grown on 2-inch diameter m-plane sapphire substrates by mist chemical vapor deposition at atmospheric pressure. The SnO 2 thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) in θ-2θ and ø scanning mo...
