Hyung Gyu Park

Last Name

Park

First Name

Hyung Gyu

ORCID

0000-0001-8121-2344

Show all metadata

Search Results

Publications 1 - 10 of 22

Growth kinetics and uniform scaling-up of graphene synthesis
Celebi, Kemal; Cole, Matthew T.; Rupesinghe, Nalin; et al. (2013)
ECS Transactions ~ Graphene, Ge/III-V, and Emerging Materials for Post CMOS Applications 5
Understanding the interaction between energetic ions and freestanding graphene towards practical 2D perforation
Buchheim, Jakob; Wyss, Roman M.; Shorubalko, Ivan; et al. (2016)
arXiv
We report experimentally and theoretically the behavior of freestanding graphene subject to bombardment of energetic ions, investigating the ability of large-scale patterning of freestanding graphene with nanometer sized features by focused ion beam technology. A precise control over the He+ and Ga+ irradiation offered by focused ion beam techniques enables to investigate the interaction of the energetic particles and graphene suspended with no support and allows determining sputter yields of the 2D lattice. We find strong dependency of the 2D sputter yield on the species and kinetic energy of the incident ion beams. Freestanding graphene shows material semi-transparency to He+ at high energies (10-30 keV) allowing the passage of >97% He+ particles without creating destructive lattice vacancy. Large Ga+ ions (5-30 keV), in contrast, collide far more often with the graphene lattice to impart significantly higher sputter yield of ~50%. Binary collision theory applied to monolayer and few-layer graphene can successfully elucidate this collision mechanism, in great agreement with experiments. Raman spectroscopy analysis corroborates the passage of a large fraction of He+ ions across graphene without much damaging the lattice whereas several colliding ions create single vacancy defects. Physical understanding of the interaction between energetic particles and suspended graphene can practically lead to reproducible and efficient pattern generation of unprecedentedly small features on 2D materials by design, manifested by our perforation of sub-5-nm pore arrays. This capability of nanometer scale precision patterning of freestanding 2D lattices shows practical applicability of the focused ion beam technology to 2D material processing for device fabrication and integration.
A new approach to characterize charge transfer reaction for solid oxide fuel cell
Lee, Sanghoon; Park, Taehyun; Jeong, Wonyeop; et al. (2019)
Surface and Coatings Technology
Ion beam profiling from the interaction with a freestanding 2D layer
Shorubalko, Ivan; Choi, Kyoungjun; Stiefel, Michael; et al. (2017)
Beilstein Journal of Nanotechnology
Recent years have seen a great potential of the focused ion beam (FIB) technology for the nanometer-scale patterning of a freestanding two-dimensional (2D) layer. Experimentally determined sputtering yields of the perforation process can be quantitatively explained using the binary collision theory. The main peculiarity of the interaction between the ion beams and the suspended 2D material lies in the absence of collision cascades, featured by no interaction volume. Thus, the patterning resolution is directly set by the beam diameters. Here, we demonstrate pattern resolution beyond the beam size and precise profiling of the focused ion beams. We find out that FIB exposure time of individual pixels can influence the resultant pore diameter. In return, the pore dimension as a function of the exposure dose brings out the ion beam profiles. Using this method of determining an ion-beam point spread function, we verify a Gaussian profile of focused gallium ion beams. Graphene sputtering yield is extracted from the normalization of the measured Gaussian profiles, given a total beam current. Interestingly, profiling of unbeknown helium ion beams in this way results in asymmetry of the profile. Even triangular beam shapes are observed at certain helium FIB conditions, possibly attributable to the trimer nature of the beam source. Our method of profiling ion beams with 2D-layer perforation provides more information on ion beam profiles than the conventional sharp-edge scan method does.
Osmotic Transport across Surface Functionalized Carbon Nanotube Membrane
Lokesh, Mahesh; Youn, Seul Ki; Park, Hyung Gyu (2018)
Nano Letters
Pseudocapacitive Coating for Effective Capacitive Deionization
Li, Meng; Park, Hyung Gyu (2018)
ACS Applied Materials & Interfaces
Spacer-Assisted Amine-Coiled Carbon Nanotubes for CO2 Capture
Deng, Mengmeng; Park, Hyung Gyu (2019)
Langmuir
Modeling and optimization of atomic layer deposition processes on vertically aligned carbon nanotubes
Yazdani, Nuri; Chawla, Vipin; Edwards, Eve; et al. (2014)
Beilstein Journal of Nanotechnology
Many energy conversion and storage devices exploit structured ceramics with large interfacial surface areas. Vertically aligned carbon nanotube (VACNT) arrays have emerged as possible scaffolds to support large surface area ceramic layers. However, obtaining conformal and uniform coatings of ceramics on structures with high aspect ratio morphologies is non-trivial, even with atomic layer deposition (ALD). Here we implement a diffusion model to investigate the effect of the ALD parameters on coating kinetics and use it to develop a guideline for achieving conformal and uniform thickness coatings throughout the depth of ultra-high aspect ratio structures. We validate the model predictions with experimental data from ALD coatings of VACNT arrays. However, the approach can be applied to predict film conformality as a function of depth for any porous topology, including nanopores and nanowire arrays.
Repeated fast selective growth of prepatternable monolayer graphene of electronic quality
Choi, Kyoungjun; Jeong, Yong Jin; Ahn, Juhwan; et al. (2024)
Carbon
Pattern formation is becoming indispensable in many applications of high-quality synthetic graphene. Nevertheless, the use of multiple lithography and etching steps can often degrade the properties of graphene due to residual disorder. Here, we report a facile, selective, and recyclable method for graphene synthesis from acetylene (C2H2) via catalytic chemical vapor deposition on a bimetal catalyst (Cu–Ni alloy). The synergistic pairing of the Cu–Ni alloy and C2H2 facilitates a rapid (ca. 1 min) synthesis of high-quality graphene under an intermediate temperature condition, e.g., 800 °C, that is quite relaxed from the far-flung method based on a Cu–CH4 pair. Prepatterned Cu–Ni alloy not only produces monolayer graphene patterns without any postprocessing but is also detachable from the resultant graphene patterns electrochemically, hinting at catalyst recyclability. Our test device of an organic field-effect transistor based on the prepatterned monolayer graphene outperforms its top-down counterpart that has undergone lithography and etching. Our facile selective growth of prepatternable monolayer graphene at intermediate temperatures, along with catalyst recyclability, may altogether lend adaptability, productivity, and sustainability to graphene-incorporated applications.
Observation of the graphene surface structure at the early stages of graphene growth on copper
Celebi, Kemal; Altun, Ali O.; Teo, Ken B.; et al. (2011)
ECS Transactions ~ Dielectrics in Nanosystems -and- Graphene, Ge/III-V, Nanowires and Emerging Materials for Post-CMOS Applications 3

Publications 1 - 10 of 22

Hyung Gyu Park

Last Name

First Name

ORCID

Organisational unit

Filters

Search Results