A5019749275- GaN-based semiconductor devices and materials
- Ga2O3 and related materials
- Semiconductor materials and devices
- ZnO doping and properties
- Semiconductor Quantum Structures and Devices
- Metal and Thin Film Mechanics
- Semiconductor Lasers and Optical Devices
- Silicon Carbide Semiconductor Technologies
- Acoustic Wave Resonator Technologies
- Photocathodes and Microchannel Plates
- Nanowire Synthesis and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Optical Coatings and Gratings
- Copper Interconnects and Reliability
- Ferroelectric and Negative Capacitance Devices
- Integrated Circuits and Semiconductor Failure Analysis
- Photonic and Optical Devices
- Plasma Diagnostics and Applications
- Thin-Film Transistor Technologies
- Silicon Nanostructures and Photoluminescence
- Semiconductor materials and interfaces
- Characterization and Applications of Magnetic Nanoparticles
- Gas Sensing Nanomaterials and Sensors
- Advanced ceramic materials synthesis
- Electronic and Structural Properties of Oxides
Meijo University
2016-2025
Nagoya University
2009-2021
Sci-Tec (United States)
2021
Fracture Analysis Consultants (United States)
2016-2021
Science and Technology Interactive Center
2021
Asahi Kasei (Japan)
2017-2019
Niigata University
2017
Omron (Japan)
2014
Shanghai Institute of Ceramics
2011
Edge Technologies (United States)
2006-2010
We analyze the internal quantum efficiency (IQE) of whole-composition-range AlGaN multiquantum wells (MQWs) on with various dislocation densities (DDs) by excitation-density-dependent photoluminescence measurement. IQEs deep ultraviolet/ultraviolet (DUV/UV) MQWs are strongly dependent DD. IQE an excess carrier density 1×1018 cm-3 changes from 4 to 64% when DD 6×109 2×108 cm-2. This trend is almost same for DUV/UV emission wavelength ranging 230 350 nm. Thus, reduction very important...
We report on the fabrication and characterization of AlGaN-based deep ultraviolet light-emitting diodes (LEDs) with emission wavelength ranging from 255 to 280 nm depending Al composition active region. The LEDs were flip-chip bonded achieved external quantum efficiencies over 3% for all investigated wavelengths. Under cw operation, an output power more than 1 mW at 10 mA was demonstrated. A moth-eye structure fabricated back side sapphire substrate, on-wafer measurement indicated a 1.5-fold...
We demonstrated lateral Mg activation along p-GaN layers underneath n-GaN surface in nitride-based light emitting diodes (LEDs) with GaInN tunnel junctions. A high temperature thermal annealing was effective for the when were partly exposed to an oxygen ambient as etched sidewalls. The activated regions gradually extended from sidewalls centers increase of time, observed emission current injection. These results suggest that hydrogen diffuses not vertically thorough above but laterally...
An AlGaN ultraviolet-B laser diode at 298 nm was realized room temperature using pulse operation. The has a lattice-relaxed Al0.6Ga0.4N layer from the underlying AlN/sapphire template and composition-graded p-AlGaN cladding layer. multimodal spectrum with proper polarization properties obtained over threshold current 0.90 A corresponding to 67 kA cm–2. By broadening width of p-electrode 11.5 μm, density decreased 41
This study investigates the steepness of heterostructure interface between p-side optical-waveguide and electron blocking layer (EBL) in ultraviolet-B (UV-B) laser diodes (LDs), focusing on impact growth temperature. The results revealed that lowering temperature significantly reduced thickness “unintended compositionally graded layer” a diffusion formed at through solid-phase diffusion. However, bottleneck also existed LDs with extremely steep interfaces, where diode characteristics could...
We demonstrated a UV-laser diode grown on low-dislocation-density AlGaN. The combination of low-temperature-deposited AlN interlayer technology and heteroepitaxial lateral overgrowth yielded crack-free partially AlGaN grooved GaN substrate. A ridge waveguide was fabricated in the region. lasing wavelength under pulsed current injection at room temperature 350.9 nm, which is shortest ever reported.
Abstract We report on the fabrication and characterization of high efficiency ultraviolet (UV) light emitting diodes (LEDs) with emission wavelength ranging from 255 to 355 nm. Epi‐layers UV LEDs were grown AlGaN templates sapphire substrates. Flip‐chip configuration without removing is used for LEDs. External quantum efficiencies (EQEs) over 3% obtained all investigated wavelengths maximum value reaching 5.1% 280 nm LED. Under RT DC operation at a current 500 mA, output powers 38, 77, 64 mW...
High-performance GaInN-based solar cells with high open-circuit voltage, short-circuit current density, and good fill factor have been obtained using a combination of two different GaInN superlattice structures. The barrier thicknesses (3 0.6 nm) in both structures were optimized, resulting thick active layer low pit density the device. conversion efficiency is approximately 2.5% under simulator air mass 1.5G an irradiation intensity 155 mW/cm2.
Abstract The room-temperature continuous-wave operation of a 1.5λ-cavity GaN-based vertical-cavity surface-emitting laser with an n-type conducting AlInN/GaN distributed Bragg reflector (DBR) was achieved. A peak reflectivity over 99.9% obtained in the DBR so that current injected through for operation. threshold 2.6 mA, corresponding to density 5.2 kA/cm 2 , and operating voltage 4.7 V. lasing spectrum wavelength 405.1 nm full-width at half maximum 0.08 also observed.
Deep ultraviolet (DUV) light-emitting diodes (LEDs) on patterned sapphire substrates (PSSs) have been clearly demonstrated. AlN templates grown PSSs had average threading dislocation densities (TDDs) of as low 5×107 cm-2. Flip-chip DUV LEDs fabricated demonstrated a significantly high performance. The 266 nm LED exhibited an output power 5.3 mW and external quantum efficiency (EQE) 1.9% at 60 mA DC, the 278 8.4 EQE 3.4%. Moreover, 70% lifetime was more than 700 h 20 mA.
Abstract We demonstrate the effectiveness of a hybrid multiple-quantum-wells (MQWs) structure in InGaN-based orange light-emitting diodes (LEDs) grown by metalorganic vapor phase epitaxy. The MQWs-LED is composed InGaN double QWs and blue-green single QW. Using MQWs structure, LEDs exhibited electroluminescence spectra with narrow full widths at half maximum 51 nm 20 mA. light output power external quantum efficiency were 0.23 mW 0.6%, respectively,
To reduce the threshold current density (Jth) of ultraviolet (UV)-B AlGaN-based laser diodes, we investigated critical parameters aiming to increase injection efficiency ηi and optical confinement factor Γ. Optimization thickness waveguide layer, average Al content p-type AlGaN cladding film layer demonstrated that device characteristics can be improved. This optimization achieved a reduction in Jth 13.3 kA cm−2 at lasing wavelength 300 nm, thus offering lowest value yet for UV-B diode.
Abstract We report a 330 ppi monolithic RGB micro light-emitting diodes ( μ LED) array of blue, green and red GaInN-based LEDs stacked on the same wafer. Considering it is challenging to form ohmic electrodes plasma-etched p-type GaN surface, tunnel junctions were used connect each LED, anode for blue formed n-type AlGaN. The fabricated LED arrays tested at room temperature (approximately 26 °C) DC. Each emitted with peak wavelengths 486, 514 604 nm current density 50 A cm −2 .
High-quality AlN layers were grown on c -plane sapphire substrates by high-temperature metal-organic vapor phase epitaxy. of about 9 µm in thickness with an atomically flat surface obtained without cracks. Multiple modulation the V/III ratio during growth led to a reduction number dislocations transition period. The dislocation density was found be less than 3×10 8 cm -2 .
Zirconium diboride (ZrB 2 ) has a hexagonal crystal structure with an in-plane lattice constant of 3.168 Å, very close to that GaN (3.189 Å). It is metalloid compound and good electrical conductor, resistivity 4.6 µΩ·cm. We propose ZrB (0001) as electrically conductive lattice-matched substrate for GaN. Firstly, bulk growth using radio frequency (rf)-heated floating zone (FZ) method presented. Relatively large crystals (φ10 mm×60 mm) were obtained this method. The thermal expansion...
The growth temperature of AlN layers is one the most important factors in metal-organic vapor phase epitaxy (MOVPE) growth. were grown using our customized high-temperature MOVPE system. crystalline quality was discussed on basis X-ray diffraction, atomic force microscopy (AFM) and transmission electron (TEM) measurements. samples at a 1400 °C had much improved terms rocking curve full width half maximum values AFM root-mean-square roughness. In addition, according to TEM analysis, edge type...
Significant enhancement of photoluminescence in ALD Al<sub>2</sub>O<sub>3</sub> passivated porous 6H-SiC.
This paper describes the status and prospects of gallium nitride-based vertical-cavity surface-emitting lasers (VCSELs) with semiconductor-based distributed Bragg reflectors. These optoelectronic devices, which emit laser light from violet to green region, are expected be a superior source for next-generation displays illumination, such as retinal scanning adaptive headlights. The development discussed in comparison already commercialized arsenide-based infrared VCSELs.
Abstract A comprehensive study of surface passivation effect on porous fluorescent silicon carbide (SiC) was carried out to elucidate the luminescence properties by temperature dependent photoluminescence (PL) measurement. The structures were prepared using an anodic oxidation etching method and passivated atomic layer deposited (ALD) Al 2 O 3 films. An impressive enhancement PL intensity observed in SiC with ALD , especially at low temperatures. At temperatures below 150 K, two prominent...
Aluminum gallium nitride (AlGaN)-based ultraviolet-B band laser diodes (LDs) with a p-type AlGaN cladding layer using polarization doping were fabricated on lattice-relaxed Al0.6Ga0.4N/AlN/sapphire. The threshold current density Jth and lasing wavelength of this LD 25 kA cm−2 298 nm, respectively. internal loss (αi) was estimated by means variable stripe length method optical excitation. αi value relatively low (i.e. <10 cm−1), thus suggesting that the device is characterized both, proper...