Kohei Ueno
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View article: Degenerate GaN source–drain AlN/Al<i>x</i>Ga1−<i>x</i>N/AlN high electron mobility transistors with a high breakdown electric field reaching 6.0 MV/cm
Degenerate GaN source–drain AlN/Al<i>x</i>Ga1−<i>x</i>N/AlN high electron mobility transistors with a high breakdown electric field reaching 6.0 MV/cm Open
This study presents a comprehensive analysis of the structural and electrical properties of degenerate GaN source–drain AlN/AlxGa1−xN/AlN high electron mobility transistors (HEMTs) fabricated using low-temperature pulsed sputtering epitaxi…
View article: Heavy Ge Doping in GaN via Pulsed Sputtering to Tailor the Optical Bandgap Energy
Heavy Ge Doping in GaN via Pulsed Sputtering to Tailor the Optical Bandgap Energy Open
The epitaxial growth of heavily Ge‐doped GaN films using pulsed sputtering deposition (PSD) on AlN (0001)/sapphire substrates is presented and the correlations among their structural, electrical, and optical properties are investigated. Hi…
View article: Temperature‐Dependent Characteristics of AlN/Al<sub>0.5</sub>Ga<sub>0.5</sub>N High Electron Mobility Transistors with Highly Degenerate n‐Type GaN Regrown Ohmic Contacts
Temperature‐Dependent Characteristics of AlN/Al<sub>0.5</sub>Ga<sub>0.5</sub>N High Electron Mobility Transistors with Highly Degenerate n‐Type GaN Regrown Ohmic Contacts Open
Herein, the temperature‐dependent characteristics of AlN/Al 0.5 Ga 0.5 N high electron mobility transistors (HEMTs) with highly degenerate n‐type GaN (d‐GaN) ohmic contacts fabricated via pulsed sputtering deposition (PSD) are investigated…
View article: Pulsed sputtering selective epitaxial formation of highly degenerate n-type GaN ohmic contacts for GaN HEMT applications
Pulsed sputtering selective epitaxial formation of highly degenerate n-type GaN ohmic contacts for GaN HEMT applications Open
This study describes the selective formation process of highly degenerate n-type GaN (d-GaN) ohmic contacts for the source and drain regions of GaN high electron mobility transistors (HEMTs) using pulsed sputtering deposition (PSD). The se…
View article: Structural characterization of epitaxial ScAlN films grown on GaN by low-temperature sputtering
Structural characterization of epitaxial ScAlN films grown on GaN by low-temperature sputtering Open
ScAlN has garnered substantial attention for its robust piezoelectric and ferroelectric properties, holding promise for diverse electronic device applications. However, the interplay between its structural attributes and physical propertie…
View article: Mid-infrared thermal radiation resonating with longitudinal-optical like phonon from n<sup>++</sup>-doped GaN–semi-insulating GaN grating structure
Mid-infrared thermal radiation resonating with longitudinal-optical like phonon from n<sup>++</sup>-doped GaN–semi-insulating GaN grating structure Open
The mid-infrared emission mechanism of line-and-space structures of metallic plates on dielectric materials is substantiated using high conductive n-doped (n ++ -) GaN–semi-insulating (SI-) GaN microstripe structures on an SI-GaN epitaxial…
View article: Dynamics of superattracting skew products on the attracting basins: Böttcher coordinates and plurisubharmonic functions
Dynamics of superattracting skew products on the attracting basins: Böttcher coordinates and plurisubharmonic functions Open
We study the dynamics of a superattracting skew product $f$ on the attracting basin. As the first strategy, we find out forward $f$-invariant wedge-shaped regions in the basin, on some of which $f$ is conjugate to monomial maps, and consid…
View article: Crystal‐Phase Controlled Epitaxial Growth of NbN<i><sub>x</sub></i> Superconductors on Wide‐Bandgap AlN Semiconductors (Adv. Mater. Interfaces 31/2022)
Crystal‐Phase Controlled Epitaxial Growth of NbN<i><sub>x</sub></i> Superconductors on Wide‐Bandgap AlN Semiconductors (Adv. Mater. Interfaces 31/2022) Open
Superconductor/Semiconductor Hybrid Devices In article number 2201244, Atsushi Kobayashi and colleagues report a high quality superconductor/semiconductor junction using hexagonal nitride crystals. They developed a technique to match the c…
View article: Pulsed Sputtering Preparation of InGaN Multi-Color Cascaded LED Stacks for Large-Area Monolithic Integration of RGB LED Pixels
Pulsed Sputtering Preparation of InGaN Multi-Color Cascaded LED Stacks for Large-Area Monolithic Integration of RGB LED Pixels Open
Micro-LEDs have been attracting attention as a potential candidate for the next generation of display technology. Here we demonstrate the feasibility of large-area monolithic integration of multi-color InGaN micro-LEDs via pulsed sputterin…
View article: AlN/Al<sub>0.5</sub>Ga<sub>0.5</sub>N HEMTs with heavily Si-doped degenerate GaN contacts prepared via pulsed sputtering
AlN/Al<sub>0.5</sub>Ga<sub>0.5</sub>N HEMTs with heavily Si-doped degenerate GaN contacts prepared via pulsed sputtering Open
This paper reports AlN barrier Al 0.5 Ga 0.5 N high electron mobility transistors (HEMTs) with heavily Si-doped degenerate GaN contacts prepared by pulsed sputtering deposition. Selectively regrown n-type GaN contacts exhibit typical degen…
View article: Photo-induced Tellurium segregation in $\mathrm{MoTe_2}$
Photo-induced Tellurium segregation in $\mathrm{MoTe_2}$ Open
We report on the coherent phonon spectroscopy of polymorphic $\mathrm{MoTe_2}$ single crystals using a femtosecond-pulsed laser to investigate the relationship between structural phase transitions and photo-thermal effects induced by high-…
View article: Identification of Lagopus muta japonica food plant resources in the Northern Japan Alps using DNA metabarcoding
Identification of Lagopus muta japonica food plant resources in the Northern Japan Alps using DNA metabarcoding Open
DNA metabarcoding was employed to identify plant-derived food resources for the Japanese rock ptarmigan (Lagopus muta japonica), which is registered as a natural living monument in Japan, in the Northern Japanese Alps in Toyama Prefecture,…
View article: Growth of InN ultrathin films on AlN for the application to field-effect transistors
Growth of InN ultrathin films on AlN for the application to field-effect transistors Open
Herein, we report the growth method of ultrathin indium nitride (InN) films on aluminum nitride (AlN) templates by sputtering and its application to field-effect transistors (FETs). Although island-like InN surfaces were formed at the init…
View article: Coherent epitaxial growth of superconducting NbN ultrathin films on AlN by sputtering
Coherent epitaxial growth of superconducting NbN ultrathin films on AlN by sputtering Open
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 cl…
View article: Improvement of Operability by Early Estimation of Operation Intention for Tele-operation Robot
Improvement of Operability by Early Estimation of Operation Intention for Tele-operation Robot Open
This research aims to construct a semi-automatic remote control system, which utilizes the autonomous function of a robot in a user’s remote control. One of the challenges in remote operation is the latency between the user’s operation and…
View article: Optical characteristics of highly conductive n-type GaN prepared by pulsed sputtering deposition
Optical characteristics of highly conductive n-type GaN prepared by pulsed sputtering deposition Open
View article: Characteristics of unintentionally doped and lightly Si-doped GaN prepared via pulsed sputtering
Characteristics of unintentionally doped and lightly Si-doped GaN prepared via pulsed sputtering Open
We have grown structurally high-quality GaN with a low residual shallow donor concentration (<5 × 1015 cm−3) through pulsed sputtering. Light Si doping to this film with a Si concentration of 2 × 1016 cm−3 leads to the formation of an n…
View article: AlN/InAlN thin-film transistors fabricated on glass substrates at room temperature
AlN/InAlN thin-film transistors fabricated on glass substrates at room temperature Open
In this study, InAlN was grown on glass substrates using pulsed sputtering deposition (PSD) at room temperature (RT) and was applied to thin-film transistors (TFTs). The surface flatness of the InAIN films was improved by reducing the grow…
View article: Experimental study on auditory impression of sounds produced by flutes in a concert hall
Experimental study on auditory impression of sounds produced by flutes in a concert hall Open
View article: Growth of Si-doped AlN on sapphire (0001) via pulsed sputtering
Growth of Si-doped AlN on sapphire (0001) via pulsed sputtering Open
The Si-doped AlN films were grown on sapphire (0001) by pulsed sputtering deposition (PSD), and their structural and electrical properties were investigated. A combination of PSD and high-temperature annealing process enabled the growth of…
View article: Electron transport properties of degenerate <i>n</i>-type GaN prepared by pulsed sputtering
Electron transport properties of degenerate <i>n</i>-type GaN prepared by pulsed sputtering Open
We report a systematic investigation of the transport properties of highly degenerate electrons in Ge-doped and Si-doped GaN epilayers prepared using the pulsed sputtering deposition (PSD) technique. Secondary-ion mass spectrometry and Hal…
View article: Fabrication of full-color GaN-based light-emitting diodes on nearly lattice-matched flexible metal foils
Fabrication of full-color GaN-based light-emitting diodes on nearly lattice-matched flexible metal foils Open
View article: N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering
N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering Open
High-quality N-polar GaN epitaxial films with an atomically flat surface were grown on sapphire (0001) via pulsed sputtering deposition, and their structural and electrical properties were investigated. The crystalline quality of N-polar G…
View article: Electrical properties of Si-doped GaN prepared using pulsed sputtering
Electrical properties of Si-doped GaN prepared using pulsed sputtering Open
In this study, we investigated the basic electrical properties of Si-doped wurtzite GaN films prepared using a low-temperature pulsed sputtering deposition (PSD) process. We found that the electron concentration can be controlled in the ra…
View article: GaN-Based Light-Emitting Diodes with Graphene Buffers for Their Application to Large-Area Flexible Devices
GaN-Based Light-Emitting Diodes with Graphene Buffers for Their Application to Large-Area Flexible Devices Open
Crystalline GaN films can be grown even on amorphous substrates with the use of graphene buffer layers by pulsed sputtering deposition (PSD). The graphene buffer layers allowed us to grow highly c-axis-oriented GaN films at low substrate t…
View article: Erratum: “Epitaxial growth of GaN films on nearly lattice-matched hafnium substrates using a low-temperature growth technique” [APL Mater. 4, 076104 (2016)]
Erratum: “Epitaxial growth of GaN films on nearly lattice-matched hafnium substrates using a low-temperature growth technique” [APL Mater. 4, 076104 (2016)] Open
First Page
View article: High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering
High hole mobility p-type GaN with low residual hydrogen concentration prepared by pulsed sputtering Open
We have grown Mg-doped GaN films with low residual hydrogen concentration using a low-temperature pulsed sputtering deposition (PSD) process. The growth system is inherently hydrogen-free, allowing us to obtain high-purity Mg-doped GaN fil…
View article: Fabrication of InGaN thin-film transistors using pulsed sputtering deposition
Fabrication of InGaN thin-film transistors using pulsed sputtering deposition Open
View article: Epitaxial growth of GaN films on nearly lattice-matched hafnium substrates using a low-temperature growth technique
Epitaxial growth of GaN films on nearly lattice-matched hafnium substrates using a low-temperature growth technique Open
We demonstrated epitaxial growth of GaN (0001) films on nearly lattice-matched Hf (0001) substrates by using a low-temperature (LT) epitaxial growth technique. High-temperature growth of GaN films results in the formation of polycrystallin…