Kyu Hyo Han

Korea Advanced Institute of Science and Technology

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Sang Ouk Kim

Korea Advanced Institute of Science and Technology

Jang Hwan Kim

Ajou University

Geon Gug Yang

Korea Advanced Institute of Science and Technology

Hyeong Min Jin

Chungnam National University

Hee Jae Choi

Korea Advanced Institute of Science and Technology

Seung Keun

Korea Advanced Institute of Science and Technology

Taeyeong Yun

Korea Electronics Technology Institute

Gil Yong Lee

Sejong University

Dong‐Ha Kim

Massachusetts Institute of Technology

In Ho Kim

Korea Advanced Institute of Science and Technology

Cooperative Institutions

Korea Advanced Institute of Science and Technology

Government of the Republic of Korea

Daejeon University

Kootenay Association for Science & Technology

Institute for Basic Science

Samsung (South Korea)

Hanyang University

Seoul National University

Korea Institute of Science and Technology

Ulsan National Institute of Science and Technology

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Highly Aligned Carbon Nanowire Array by E-Field Directed Assembly of PAN-Containing Block Copolymers

ACS Applied Materials & Interfaces (2020)

Kyu Hyo Han Hohyung Kang Gil Yong Lee Ho Jin Lee Hyeong Min Jin

Nanoscale engineering of carbon materials is immensely demanded in various scientific areas. We present highly ordered nitrogen-doped carbon nanowire arrays via block copolymer (BCP) self-assembly under an electric field. Large dielectric constant difference between distinct polymer blocks offers rapid alignment of PMMA-b-PAN self-assembled nanodomains under an electric field. Lithographic patterning of the graphene electrode as well as straightforward thermal carbonization of the PAN block creates well-aligned carbon nanowire device structures. Diverse carbon nanopatterns including radial and curved arrays can be readily assembled by the modification of electrode shapes. Our carbon nanopatterns bear a nitrogen content over 26%, highly desirable for NO2 sensing, as the nitrogen element acts as adsorption sites for NO2 molecules. Aligned carbon nanowire arrays exhibits a 6-fold enhancement of NO2 sensitivity from a randomly aligned counterpart. Taking advantage of well-established benefits from device-oriented BCP nanopatterning, our approach proposes a viable route to highly ordered carbon nanostructures compatible to next-generation device architectures.

Carbon fibers

10.1021/acsami.0c15491

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Citations (9)

Synthesis of carboxylic acid-functionalized polymethacrylate-b-polystyrene as an Ag ion-loadable block copolymer thin film template

Polymer (2021)

I. D. Shin Kyu Hyo Han Seung Keun Sang Ouk Kim Myungeun Seo

Polystyrene

10.1016/j.polymer.2021.123462

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Citations (4)

Large‐Area Uniform 1‐nm‐Level Amorphous Carbon Layers from 3D Conformal Polymer Brushes. A “Next‐Generation” Cu Diffusion Barrier? (Adv. Mater. 15/2022)

Advanced Materials (2022)

Yun‐Ho Kang Sang‐Bong Lee Young-Woo Choi Won Kyung Seong Kyu Hyo Han

Conformal Amorphous Carbon Ultrathin Cu diffusion barriers with high conformality have gained great attention for next-generation ultrahigh-density semiconductor device miniaturization. In article number 2110454, Sun Hwa Lee, Rodney S. Ruoff, Ki-Bum Kim, Sang Ouk Kim, and co-workers introduce a handy and reliable method for the preparation of conformal amorphous carbon (a-C) barrier layers with nanometer-level thickness. A polystyrene brush layer is grafted onto a 3D copper structure with self-limiting chemistry, and subsequent carbonization yields large-area uniform 1 nm-level a-C layers with excellent Cu blocking performance.

Polystyrene

Carbon fibers

Diffusion barrier

Conformal coating

Nanometre

10.1002/adma.202270113

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Multilevel Self-Assembly of Block Copolymers and Polymer Colloids for a Transparent and Sensitive Gas Sensor Platform

ACS Nano (2022)

Geon Gug Yang Jaehyun Ko Hee Jae Choi Dong‐Ha Kim Kyu Hyo Han

The recent emerging significance of the Internet of Things (IoT) demands sensor devices to be integrated with many different functional structures and devices while conserving their original functionalities. To this end, optical transparency and mechanical flexibility of sensor devices are critical requirements for optimal integration as well as high sensitivity. In this work, a transparent, flexible, and sensitive gas sensor building platform is introduced by using multilevel self-assembly of block copolymers (BCPs) and polystyrene (PS) colloids. For the demonstration of an H2 gas sensor, a hierarchically porous Pd metal mesh structure is obtained by overlaying the two different patterned template structures with synergistic, distinctive characteristic length scales. The hierarchical Pd mesh shows not only high transparency over 90% but also superior sensing performance in terms of response and recovery time owing to enhanced Pd-to-hydride ratio and short H2 diffusion lengths from the enlarged active surface areas. The hierarchical morphology also endows high mechanical flexibility while securing reliable sensing performance even under severe mechanical deformation cycles. Our scalable self-assembly based multiscale nanopatterning offers an intriguing generalized platform for many different multifunctional devices requiring hidden in situ monitoring of environmental signals.

Template

10.1021/acsnano.2c07499

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Atomically Flat, 2D Edge‐Directed Self‐Assembly of Block Copolymers (Adv. Mater. 3/2023)

Advanced Materials (2023)

Jang Hwan Kim Hyeon U Jeong Hye‐In Yeom Kyu Hyo Han Geon Gug Yang

Self-Assembled Nanodomains In article number 2207338, Jang Hwan Kim, Hyeong Min Jin, Jaeup U. Kim, Sang Ouk Kim, and co-workers demonstrate the realization of sub-10-nm scale nanopatterns that are remarkably well aligned along the atomic edge of 2D flakes. Self-assembled nanodomains are elucidated based on alternation of the wetting layer of the BCP film in the presence of intermediate 2D flakes. This novel approach highlights the synergistic integration of bottom-up nanofabrication.

Molecular self-assembly

10.1002/adma.202370014

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Citations (0)

Large‐Area Uniform 1‐nm‐Level Amorphous Carbon Layers from 3D Conformal Polymer Brushes. A “Next‐Generation” Cu Diffusion Barrier?

Advanced Materials (2022)

Yun‐Ho Kang Sang‐Bong Lee Youngwoo Choi Won Kyung Seong Kyu Hyo Han

A reliable method for preparing a conformal amorphous carbon (a-C) layer with a thickness of 1-nm-level, is tested as a possible Cu diffusion barrier layer for next-generation ultrahigh-density semiconductor device miniaturization. A polystyrene brush of uniform thickness is grafted onto 4-inch SiO2 /Si wafer substrates with "self-limiting" chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transforms this polymer film into an ultrathin a-C layer without pinholes or hillocks. The uniform coating of nonplanar regions or surfaces is also possible. The Cu diffusion "blocking ability" is evaluated by time-dependent dielectric breakdown (TDDB) tests using a metal-oxide-semiconductor (MOS) capacitor structure. A 0.82 nm-thick a-C barrier gives TDDB lifetimes 3.3× longer than that obtained using the conventional 1.0 nm-thick TaNx diffusion barrier. In addition, this exceptionally uniform ultrathin polymer and a-C film layers hold promise for selective ion permeable membranes, electrically and thermally insulating films in electronics, slits of angstrom-scale thickness, and, when appropriately functionalized, as a robust ultrathin coating with many other potential applications.

Conformal coating

Diffusion barrier

Barrier layer

Polystyrene

10.1002/adma.202110454

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Citations (13)

Large‐Area Alignment of Supramolecular Columns by Photothermal Laser Writing

Advanced Materials (2020)

Kangho Park Hyeong Min Jin Kiok Kwon Jang Hwan Kim Haeju Yun

Abstract Controlling the orientation of highly periodic supramolecular structures of small feature size (<5 nm) is the first step for potential applications in optoelectronics, membranes, and template synthesis. A new method, namely, laser photothermal writing, is introduced to direct the orientation of supramolecular columns over a large area. Supramolecular columns consisting of taper‐shaped molecules with long aliphatic tail groups are aligned by a thermal gradient, which is induced by exposing a near‐infrared laser beam to a graphene photothermal conversion layer. Intriguingly, the orientation of the supramolecular columns can be controlled in a facile manner by varying the laser scanning velocity and power. In contrast to previous methodologies for aligning supramolecular structures, this laser photothermal mechanism allows the directional and continuous alignment of supramolecular structures over an arbitrary large area with the easy control of laser irradiation. Besides, the laser process also enables area‐selective orientation of the supramolecular structures for device‐oriented nanopatterning.

Photothermal effect

10.1002/adma.202002620

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Citations (9)

A 2D Ultrathin Nanopatterned Interlayer to Suppress Lithium Dendrite Growth in High‐Energy Lithium‐Metal Anodes (Adv. Mater. 34/2022)

Advanced Materials (2022)

Kyu Hyo Han Jae Young Seok In Ho Kim Kyoohee Woo Jang Hwan Kim

Lithium-Metal Anodes In article number 2203992, Jae Young Seok, Sang Ouk Kim, and co-workers introduce an ultrathin multilayered protective layer under 1 μm, composed of lithiophilic Ag nanoparticle seeds, a 2D Li-suppressing reduced graphene oxide (rGO) layer, and vertically porous block copolymer self-assembled nanochannels for lithium-metal anodes. The synergetic integration of each component enhances the mechanical robustness by stress relaxation, and homogenizes the Li-ion flux at the same time. As a result, stabilized Li growth with a smooth interface and outstanding cycling stability can be achieved.

Lithium metal

Dendrite (mathematics)

10.1002/adma.202270247

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Citations (1)

Ultralarge Area Sub-10 nm Plasmonic Nanogap Array by Block Copolymer Self-Assembly for Reliable High-Sensitivity SERS

ACS Applied Materials & Interfaces (2018)

Hyeong Min Jin Ju Young Kim Minsung Heo Seong‐Jun Jeong Bong Hoon Kim

Effective surface enhancement of Raman scattering (SERS) requires strong near-field enhancement as well as effective light collection of plasmonic structures. To this end, plasmonic nanoparticle (NP) arrays with narrow gaps or sharp tips have been suggested as desirable structures. We present a highly dense and uniform Au nanoscale gap array enabled by the customized design of NP shape and arrangement employing block copolymer self-assembly. Block copolymer self-assembly in thin films offers uniform hexagonally packed nanopost template arrays over the entire surface of a 2 in. wafer. Conventional evaporative metal deposition over the nanotemplate surface allows precise geometric control and positional arrangement of metal NPs, constituting tunable, strong plasmonic near-field enhancement particularly at the "hot spots" near interparticular nanoscale gaps. Underlying field distribution has been investigated by a finite-difference time-domain simulation. In the detection of thiophenol, our Au nanogap array shows a remarkable enhancement of Raman intensity greater than ∼104, a standard deviation as small as 12.3% compared to that of the planar Au thin film. In addition, adenine biomolecules can be detected with a detection limit as low as 100 nM. Our approach proposes highly sensitive and reliable SERS on the basis of a scalable, low-cost bottom-up strategy.

10.1021/acsami.8b17325

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Citations (70)

Block Copolymer Nanopatterning for Nonsemiconductor Device Applications

ACS Applied Materials & Interfaces (2022)

Geon Gug Yang Hee Jae Choi Kyu Hyo Han Jang Hwan Kim Chan Woo Lee

Block copolymer (BCP) nanopatterning has emerged as a versatile nanoscale fabrication tool for semiconductor devices and other applications, because of its ability to organize well-defined, periodic nanostructures with a critical dimension of 5-100 nm. While the most promising application field of BCP nanopatterning has been semiconductor devices, the versatility of BCPs has also led to enormous interest from a broad spectrum of other application areas. In particular, the intrinsically low cost and straightforward processing of BCP nanopatterning have been widely recognized for their large-area parallel formation of dense nanoscale features, which clearly contrasts that of sophisticated processing steps of the typical photolithographic process, including EUV lithography. In this Review, we highlight the recent progress in the field of BCP nanopatterning for various nonsemiconductor applications. Notable examples relying on BCP nanopatterning, including nanocatalysts, sensors, optics, energy devices, membranes, surface modifications and other emerging applications, are summarized. We further discuss the current limitations of BCP nanopatterning and suggest future research directions to open up new potential application fields.

10.1021/acsami.1c22836

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Citations (56)