A5021873281- GaN-based semiconductor devices and materials
- ZnO doping and properties
- Ga2O3 and related materials
- Plasma Diagnostics and Applications
- Advanced Photocatalysis Techniques
- Metal and Thin Film Mechanics
- Advanced Chemical Sensor Technologies
- Nicotinic Acetylcholine Receptors Study
- Semiconductor materials and devices
- Silicon Carbide Semiconductor Technologies
- Olfactory and Sensory Function Studies
- Semiconductor Quantum Structures and Devices
- Acoustic Wave Resonator Technologies
Seoul National University
2023-2025
Tohoku University
2006-2009
The authors fabricated GaN-based light-emitting diodes (LEDs) on two different GaN templates with the same LED structure. One thin template (∼2μm) high dislocation density [low (109cm−2)] grown by metal-organic vapor-phase epitaxy (sample A) and other thick (∼20μm) comparatively low [high (108cm−2)] hydride B). In order to understand mechanism of leakage current in LEDs, correlation between current-voltage characteristics etch pit LEDs was studied.
Abstract GaN epitaxial films are grown on c‐plane sapphire substrates with CrN buffer. The layers show high crystalline quality and smooth surface morphology without being cracked. Selective etching of buffer is performed by wet using conventional Cr metal etchant, which results in success ful lift‐off thick layers. We confirm that the does not change through process. These indicate chemical process promising for production both freestanding vertical‐structure devices. (© 2008 WILEY‐VCH...
Our study presents photo-enhanced metal-assisted chemical etching of α-Ga 2 O 3 and its properties at various temperatures. The results show great potential for use in -based optoelectronic device fabrication.
A grazing incidence x-ray diffraction with a synchrotron radiation and cross-sectional high-resolution transmission electron microscopy were performed on the sapphire surface nitrided at 1080°C for 30min. The thickness of layer was about 2nm. It found out that wurtzite, zinc-blende, 30° rotated zinc-blende aluminum nitrides formed surface. zb-AlN incoherent interface has higher activation energy formation, while nonrotated coherent interface.
Abstract A one‐step approach to obtain high quality free‐standing GaN (FS‐GaN) substrates by hydride vapor phase epitaxy (HVPE) has been developed. FS‐GaN were fabricated the control of void density at GaN‐Al 2 O 3 interface using a novel evaporable buffer layer (EBL). The EBL consisted GaN‐crystallites imbedded in NH 4 Cl films, and was grown lowering growth temperature down 450 °C under HCl ambient HVPE system. evaporated during heating up for (HT‐GaN), resulting density, which plays key...
Abstract In order to understand the origin of leakage current, light emitting devices were grown on two different templates with apparently dislocation density: one thin GaN template (∼2 μm) higher density (low × 10 9 cm –2 ) prepared by metal‐organic vapor‐phase epitaxy (sample A), and other thick (∼20 comparatively low (high 8 hydride B). Especially, B showed very value for a screw component, 2.2 7 evaluated transmission electron microscope 2.3 approximated Williamson‐Hall plot which was...
Nerve agents are toxic organophosphorus chemicals and acetylcholinesterase inhibitors that have been used in terrorist acts. Because they exhibit fatal effects small amounts, technology is required to detect identify them early. Research for nerve agent detection using structural simulants of real may not function properly depending on the selectivity sensor. For practical sensor applications, experiments were conducted two agents, sarin VX, which terrorism attacks. Herein, human olfactory...
Abstract Thick GaN films were grown by HVPE (Hydride Vapor Phase Epitaxy) on c‐sapphire substrates with nano‐rod buffer layers. Lateral epitaxial growth mode was adapted to grow thick nano‐structure buffer. self‐separated during cooling down thermal stress caused the difference of expansion coefficient (TEC) between and sapphire. Since consists nano‐rods voids, it is mechanically weaker than planar layers contributes self‐separation films. 200 μm‐thick free‐standing show smooth surface...
Abstract Free‐standing GaN layers were successfully prepared by self lift‐off process. Single crystalline ZnO buffer layer and successively grown on sapphire substrate plasma assisted molecular beam epitaxy. Thick film was this template for the realization of stress‐free free‐standing hydride vapor phase The a ‐axis c lattice constants 3.189Å 5.185Å, respectively. Peak positions photoluminescence spectrum D 0 X 3.4715 eV FX A 3.4791 eV. These results suggest that (© 2007 WILEY‐VCH Verlag...
Abstract We investigate the effects of inserting defective stress absorbing layer (SAL) in between sapphire substrate and thick GaN layer. A two‐step growth technique, which layers grow at different rates each step, is adopted for growing high‐quality (NL) low rate SAL high by hydride vapor phase epitaxy (HVPE). SALs grown directly on c‐sapphire show hexagonal columnar shaped rough morphology with crystalline quality. Nevertheless, strain more relaxed compared quality NL. contains majority...