Sungkyunkwan University · Materials Science
Professor Ki Kang Kim's research lab specializes in the synthesis, characterization, and application of two-dimensional materials, with a strong focus on hexagonal boron nitride (h-BN) and graphene-based nanomaterials. The lab investigates low-pressure and atmospheric pressure chemical vapor deposition (CVD) techniques to grow large-area, high-quality h-BN films with precise control over thickness and morphology, enabling their use in van der Waals heterostructures and 2D electronics. Additionally, the lab explores chemical doping strategies—particularly p-type doping using compounds like AuCl₃—to enhance the electrical properties of graphene and carbon nanotubes, significantly reducing sheet resistance and tuning work functions. The research integrates advanced spectroscopic and microscopic techniques to probe electronic and optical behaviors at the nanoscale.
Figures are computed from collected data and may differ slightly.
Hexagonal boron nitride (h-BN) is very attractive for many applications, particularly, as protective coating, dielectric layer/substrate, transparent membrane, or deep ultraviolet emitter. In this work, we carried out a detailed investigation of h-BN synthesis on Cu substrate using chemical vapor deposition (CVD) with two heating zones under low pressure (LP). Previous atmospheric pressure (AP) CVD syntheses were only able to obtain few layer h-BN without a good control on the number of layers.
Hexagonal boron nitride (h-BN) is a promising material as a dielectric layer or substrate for two-dimensional electronic devices. In this work, we report the synthesis of large-area h-BN film using atmospheric pressure chemical vapor deposition on a copper foil, followed by Cu etching and transfer to a target substrate. The growth rate of h-BN film at a constant temperature is strongly affected by the concentration of borazine as a precursor and the ambient gas condition such as the ratio of hyd
We report chemical doping (p-type) to reduce the sheet resistance of graphene films for the application of high-performance transparent conducting films. The graphene film synthesized by chemical vapor deposition was transferred to silicon oxide and quartz substrates using poly(methyl methacrylate). AuCl(3) in nitromethane was used to dope the graphene films and the sheet resistance was reduced by up to 77% depending on the doping concentration. The p-type doping behavior was confirmed by charac
We investigated the modulation of optical properties of single-walled carbon nanotubes (SWCNTs) by AuCl 3 doping. The van Hove singularity transitions (E 11 (S), E 22 (S), E 11 (M)) in absorption spectroscopy disappeared gradually with an increasing doping concentration and a new peak appeared at a high doping concentration. The work function was downshifted up to 0.42 eV by a strong charge transfer from the SWCNTs to AuCl 3 by a high level of p-doping. We propose that this large work function s
The construction of large surface area hexagonal boron nitride for van der Waals heterostructures and 2D-layered electronics is reviewed.
We report the peculiar behavior of the ${G}^{\ensuremath{'}}$ band Raman intensity, which is dependent on the metallicity of single-wall carbon nanotubes (SWCNTs). In the metallic SWCNTs, the ${G}^{\ensuremath{'}}$ band intensity was enhanced relative to the $G$ band intensity, while the ${G}^{\ensuremath{'}}$ band intensity was suppressed in the semiconducting SWCNTs. Resonance Raman spectroscopy (using laser energies of ${E}_{\mathit{\text{laser}}}=2.41$, 1.96, 1.58, and $1.165\phantom{\rule{0
The chemical doping of single-walled carbon nanotubes (SWCNTs) has been an important issue in tailoring the electronic structures of SWCNTs. This paper proposes a strategy for controlling the doping types and doping concentrations by choosing the reduction potential of a dopant relative to the redox potential of SWCNTs. For this purpose, the redox potential plot in terms of the chirality and diameter was generated based on theoretical calculations, which were in good agreement with the experimen
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