Publications by authors named "Hyo-Sok Ahn"

Atomic layer-deposited (ALD) dielectric films on graphene usually show noncontinuous and rough morphology owing to the inert surface of graphene. Here, we demonstrate the deposition of thin and uniform ALD ZrO films with no seed layer on chemical vapor-deposited graphene functionalized by atmospheric oxygen plasma treatment. Transmission electron microscopy showed that the ALD ZrO films were highly crystalline, despite a low ALD temperature of 150 °C.

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We propose a method of producing a tungsten probe with high stiffness for atomic force microscopy (AFM) in order to acquire enhanced phase contrast images and efficiently perform lithography. A tungsten probe with a tip radius between 20nm and 50nm was fabricated using electrochemical etching optimized by applying pulse waves at different voltages. The spring constant of the tungsten probe was determined by finite element analysis (FEA), and its applicability as an AFM probe was evaluated by obtaining topography and phase contrast images of a Si wafer sample partly coated with Au.

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Article Synopsis
  • A new type of elastic film made from graphene oxide and a polymer (GO-PDDA) has been created using a special layering technique.
  • This film is applied on silver nanowires and a flexible material, showcasing its adaptability.
  • The research highlights that the film maintains high mechanical stability and flexibility, particularly due to its thickness and the elastic properties of its layers.
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Polymer surface layers comprised of mixed chains grafted to a functionalized silicon surface with a total layer thickness of only 1-3 nm are shown to exhibit reversible switching of their structure. Carboxylic acid-terminated polystyrene (PS) and poly (butyl acrylate) (PBA) were chemically attached to a silicon surface that was modified with an epoxysilane self-assembled monolayer by a "grafting to" routine. While one-step grafting resulted in large, submicron microstructures, a refined, two-step sequential grafting procedure allowed for extremely small spatial dimensions of PS and PBA domains.

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