Nagoya University · Physics and Astronomy
Professor Jeong-Hwan Park's research lab specializes in advanced semiconductor materials and devices, with a primary focus on III-nitride and III–V compound semiconductors for next-generation optoelectronic applications. The lab investigates fundamental challenges in micro-light-emitting diodes (µLEDs), including sidewall surface passivation, defect engineering, and nonradiative recombination suppression to enhance device efficiency and stability. Key research directions include remote epitaxy using graphene, substrate decomposition dynamics under MOCVD conditions, and the development of high-performance blue and red µLEDs for next-generation displays. The lab also explores computational protein folding models, demonstrating interdisciplinary expertise in materials science and computational biophysics.
Figures are computed from collected data and may differ slightly.
Abstract The sidewall condition is a key factor determining the performance of micro‐light emitting diodes (µLEDs). In this study, equilateral triangular III‐nitride blue µLEDs are prepared with exclusively m ‐plane sidewall surfaces to confirm the impact of sidewall conditions. It is found that inductively coupled plasma‐reactive ion etching (ICP‐RIE) causes surface damages to the sidewall and results in rough surface morphology. As confirmed by time‐resolved photoluminescence (TRPL) and X‐ray
A challenging approach, but one providing a key solution to material growth, remote epitaxy (RE)-a novel concept related to van der Waals epitaxy (vdWE)-requires the stability of a two-dimensional (2-D) material. However, when graphene, a representative 2-D material, is present on substrates that have a nitrogen atom, graphene loss occurs. Although this phenomenon has remained a hurdle for over a decade, restricting the advantages of applying graphene in the growth of III-nitride materials, few
Abstract Graphene has been adopted in III−V material growth since it can reduce the threading dislocations and the III−V epilayer can easily be separated from the substrate due to the weak chemical bond. However, depending on the substrate supporting the graphene, some substrates decompose in the III−V material growth environment, which results in the problem that no graphene remains. In this study, the influence of temperature‐dependent substrate decomposition on graphene through an annealing p
Display technology has developed rapidly in recent years, with III–V system-based micro-light-emitting diodes (μLEDs) attracting attention as a means to overcome the physical limitations of current display systems related to their lifetime, brightness, contrast ratio, response time, and pixel size. However, for μLED displays to be successfully commercialized, their technical shortcomings need to be addressed. This review comprehensively discusses important issues associated with μLEDs, including
Abstract Nonradiative recombination rate that consists of dislocation‐related nonradiative recombination rate ( A 0 ) and surface recombination rate ( A s ) is one of the major parameters determining the performance of microlight‐emitting diodes (µLEDs). Recent demonstrations improving the efficiency of blue InGaN or red AlGaInP µLEDs using specific methods such as atomic layer deposition or chemical treatment confirm the suppression of A s . However, it is hardly found that those methods effect
The associative memory, water mediated, structure and energy model (AWSEM) is a coarse-grained protein force field. AWSEM contains physically motivated terms, such as hydrogen bonding, as well as a bioinformatically based local structure biasing term, which efficiently takes into account many-body effects that are modulated by the local sequence. When combined with appropriate local or global alignments to choose memories, AWSEM can be used to perform de novo protein structure prediction. Herein
As the size of micro light-emitting diodes (μLEDs) decreases, μLEDs encounter etching damage especially at the sidewalls that critically affects their properties. In this study, we investigated the influence of etching bias power (Pbias) on the performance of μLEDs and found that the current–voltage and light output–current characteristics of μLEDs were enhanced when Pbias was reduced. It was shown that at low Pbias, the chemical reaction between etching gas and gallium nitride, rather than ion
Herein, we investigate micro-light-emitting diodes (μLEDs) ranging in size from 160 × 160 to 10 × 10 μm2 and report that the differences in the behavior of InGaN-based blue (∼460 nm) and red (∼600 nm) μLEDs are related to carrier localization. The external quantum efficiency (EQE) of blue μLEDs decreases with size regardless of sidewall conditions, whereas that of red μLEDs is insignificant due to carrier localization. Atomic probe tomography examination of 30%, 15%, and 7.5% indium-concentrated
Abstract In this letter, we investigate the impact of periphery, width, length and area on the external quantum efficiency (EQE) of stripe-type InGaN-based red micro-light-emitting diodes ( µ LEDs). A longer periphery resulted in a higher light extraction efficiency ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>η</mml:mi> <mml:mrow> <mml:mtext>e</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) via the sidewall regardless
The purpose of this study is to investigate the overall spray behavior characteristics for various injection conditions in a gasoline direct injection(GDI) injector with multi-hole. The spray characteristics, such as the spray penetration, the spray angle, and the injection quantity, were studied through the change of the injection pressure, the ambient pressure, and the energizing duration in a high-pressure chamber with a constant volume. The n-heptane with 99.5% purity was used as the test fu
The present study investigated the feces production rate and fecal nitrogen production ratio of abalone, Haliotis discus hannai fed seaweed, Undaria pinnatifida. The abalone, with shell lengths of 3 cm, 5 cm, and 7 cm, were tested at temperatures of <TEX>$12^{\circ}C$</TEX>, <TEX>$16^{\circ}C$</TEX>, and <TEX>$20^{\circ}C$</TEX> in a semi-recirculating aquaculture system. Under the given experimental conditions, the weight specific feces production rate (FPw) of the abalone increased with the de
Abstract The sidewall condition is a key factor determining the performance of micro-light emitting diodes (μLEDs). In this study, we prepared equilateral triangular III-nitride blue μLEDs with exclusively m-plane sidewall surfaces to confirm the impact of sidewall conditions. It was found that inductively coupled plasma-reactive ion etching (ICP-RIE) caused surface damages to the sidewall and resulted in rough surface morphology. As confirmed by time-resolved photoluminescence (TRPL) and X-ray
We attempted to grow (10–13) semi-polar GaN on graphene to confirm the possibility of a remote epitaxy of semi-polar GaN. Single crystalline (10–13) GaN was obtained on an optimized template using optimized growth conditions. However, (10–13), (0002), and other GaN orientations were found under the same growth conditions on a graphene-coated template. Scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy revealed that multi-domain GaN and (0002) GaN occurred in areas
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