Yong‐Hoon Cho

We have systematically studied both the spontaneous and stimulated emission properties in blue-light-emitting ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}/\mathrm{G}\mathrm{a}\mathrm{N}$ multiple quantum well structures using various linear and nonlinear optical techniques. Our experimental observations are consistently understandable in the context of localization of carriers associated with large potential fluctuations in the ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\m

Graphene-based quantum dots (QDs) have received a tremendous amount of attention as a new type of light-emitting materials. However, their luminescence origins remain controversial due to extrinsic states of the impurities and disorder structures. Especially, the function of oxygen-contents should be understood and controlled as a crucial element for tuning the optical properties of graphene-based QDs. Herein, a series of graphene oxide QDs (GOQDs) with different amounts of oxygen-contents are f

The hybridised resonances between Mie-scatterers and lattice resonances, i.e. quasi-guided mode resonances, are investigated. The scattering of the Mie-resonators is improved by the first order of transmitted diffracted light which is coupled to the lattice formed by the Mie-resonators. The conditions of coupling are dependent on the refractive index of the substrate and the effective refractive index of the unit cell of the resonators. Based on the momentum matching conditions, the cut-off wave

carbon subdomains emitting intrinsic PL. To the best of our knowledge, this is the first investigation of the role of epoxide functional groups on the luminescence mechanism in GOQDs.

= 81). From our findings, we believe that WLEDs based on dodecagonal ring structures become a platform enabling a high-efficiency warm white light-emitting source without the use of phosphors.

We present the first monolithic fabrication of a-IGZO TFTs on a GaN-based micro-LED array at a low temperature to overcome the weak thermal endurance constraint of the organic planarization layer for high resolution and stable low-cost LED displays.

Group III-nitride semiconductor-based ultraviolet (UV) light emitting diodes have been suggested as a substitute for conventional arc-lamps such as mercury, xenon and deuterium arc-lamps, since they are compact, efficient and have a long lifetime. However, in previously reported studies, group III-nitride UV light emitting diodes did not show a broad UV spectrum range as conventional arc-lamps, which restricts their application in fields such as medical therapy and UV spectrophotometry. Here, we

The degree of oxygen-functional groups in graphene-based quantum dots (QDs) is controlled by chemical oxidation and reduction processes. On page 3773, T. S. Seo, Y.-H. Cho, and co-workers exhibit the luminescence mechanisms of a series of graphene-based QDs and observe an irreversible photoluminescence emission between those changing from pristine to oxidized graphene QDs via oxidation processes and those from oxidized to reduced graphene QDs via reduction processes. This is attributed to the di

Control of the growth front in three-dimensional (3D) hexagonal GaN core structures is crucial for increased performance of light-emitting diodes (LEDs), and other photonic devices. This is due to the fact that InGaN layers formed on different growth facets in 3D structures exhibit various band gaps which originate from differences in the indium-incorporation efficiency, internal polarization, and growth rate. Here, a-plane {[Formula: see text] } facets, which are rarely formed in hexagonal pyra

Abstract We investigated the structural, optical, and electrical properties of Ni‐based Schottky type Al x Ga 1–x N ultraviolet (UV) photodetectors. Three different types of Al x Ga 1–x N/GaN heterostructures were epitaxially grown on (0001) sapphire substrates by metal‐organic chemical vapor deposition. We found that the thin Al x Ga 1–x N layer directly grown on the optimized GaN buffer layer showed the most excellent crystal quality and opto‐electrical properties of Ni‐based Schottky type UV