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Showing 1–11 of 11 results
Advanced filters: Author: Hongseok Oh Clear advanced filters
  • Refining microstructure is an important goal in many material systems. Here, the authors report an approach for microstructure refinement based on nanoparticle self-assembling on a growing phase, which is shown to be effective for both metallic and organic systems.

    • Lian-Yi Chen
    • Jia-Quan Xu
    • Xiao-Chun Li
    ResearchOpen Access
    Nature Communications
    Volume: 5, P: 1-9
  • The in-situ growth of epitaxial GaN with a short-range ordered (SRO) BN interlayer is proposed to demonstrate a high manufacturing scalability of the epitaxial lateral overgrowth (ELOG) process. During the GaN growth, the mask formation of the SRO BN occurred in the on-site chamber within a few minutes. The BN interlayer efficiently reduced microstructural defects, such as screw-type and edge-type threading dislocations, to achieve high structural and optical characteristics of the GaN overlayer, whose results are comparable to those of the previously reported ex-situ ELOG approaches. These improvements were also demonstrated in the device performances of the GaN light-emitting diodes.

    • Heesoo Kim
    • Anh Thi Dieu Nguyen
    • Kunook Chung
    ResearchOpen Access
    NPG Asia Materials
    Volume: 17, P: 1-10
  • Here, we utilize large-size scalable single-crystal 2D films to grow single crystalline inorganic semiconductors. Centimeter-scale hexagonal boron nitride (h-BN) films were synthesized on a single-crystal Ni(111) using chemical vapor deposition (CVD). Single-crystal GaN layers were directly grown on h-BN using metal–organic vapor phase epitaxy. The CVD-grown h-BN exhibited many atomic cliffs that enabled us to grow high-density GaN islands to be merged as homogeneous and flat GaN films. We also investigated the crystallinity and growth mechanism of the GaN films grown on CVD-grown h-BN using transmission electron microscopy and X-ray diffraction.

    • Kunook Chung
    • Hongseok Oh
    • Gyu-Chul Yi
    ResearchOpen Access
    NPG Asia Materials
    Volume: 9, P: e410
  • A novel technique is demonstrated for the fabrication of flexible and highly sensitive 1D piezoelectric pressure sensors containing ZnO nanotube arrays grown on 2D graphene layers. Due to the morphology-controlled tunable sensitivity, ultra-small size, and capability of detecting extremely low pressures, the sensors are able to efficiently detect human breath and pulse.

    • Jun Beom Park
    • Minho S. Song
    • Gyu-Chul Yi
    ResearchOpen Access
    NPG Asia Materials
    Volume: 13, P: 1-9
  • Architectured ZnO nanostructures were grown by van der Waals (vdW) heteroepitaxy on hexagonal BN (hBN) layers with artificially patterned atomic ledges. Electron microscopic and theoretical computational analyses presented non-covalent epitaxial features of domain-aligned incommensurate ZnO/hBN heterostructure. The vdW epitaxial ZnO/hBN heterostructures exhibited excellent electrical insulation of hBN, and were applied to fabricate the ultraviolet photodetector devices, as an example of functional optoelectronic device applications.

    • Hongseok Oh
    • Young Joon Hong
    • Gyu-Chul Yi
    ResearchOpen Access
    NPG Asia Materials
    Volume: 6, P: e145
  • Centimeter-sized, epitaxial hexagonal boron nitride (h-BN) few-layer films were heteroepitaxially grown on Ni(111) single-crystal substrates using atmospheric pressure chemical vapor deposition with ammonia-borane single precursor. The grown films were transferred to arbitrary substrates via an electrochemical delamination technique, and the remaining Ni(111) substrates were repeatedly re-used. Over repeated growth and transfer after the initial annealing, no significant degradation of Ni(111) substrates was observed and the crystallinity of h-BN layers was reproduced reliably. The grown h-BN films showed typical physical characteristics of h-BN, with a high uniformity over a wide area. The large-area synthesis and transfer of atomically thin uniform epitaxial h-BN layers can be applied in various fields where high quality two-dimensional insulating layers are required.

    • Hongseok Oh
    • Janghyun Jo
    • Gyu-Chul Yi
    ResearchOpen Access
    NPG Asia Materials
    Volume: 8, P: e330