Research
Terahertz Biosensor
Metamaterial and plasmonic devices operating in the terahertz (THz) frequency range turned out to be one of the ideal candidates for highly sensitive and selective microbial sensing. The target substance includes fungi, bacteria, viruses, proteins, and DNAs.
Related Article:
Terahertz thermal curve analysis for label-free identification of pathogens
Nature Communications 13, 3470 (2022); DOI: 10.1038/s41467-022-31137-2
S. W. Jun, Y. H. Ahn*
Identifying different types of microorganisms with terahertz spectroscopy
Biomedical Optics Express 11, 406 (2020); DOI: 10.1364/BOE.376584
S. A. Yoon, S. H. Cha, S. W. Jun, S. J. Park, J.-Y. Park, S. Lee, H. S. Kim, Y. H. Ahn*
Detection of microorganisms using terahertz metamaterials
Scientific Reports 4, 4988 (2014); DOI: 10.1038/srep04988
S. J. Park, J. T. Hong, S. J. Choi, H. S. Kim, W. K. Park, S. T. Han, J. Y. Park, S. Lee, D. S. Kim, Y. H. Ahn
Sensing viruses using terahertz nano-gap metamaterials
Biomedical Optics Express 8, 3551 (2017); DOI: 10.1364/BOE.8.003551
S. J. Park, S. H. Cha, G. A. Shin, Y. H. Ahn
Dielectric constant measurements of thin films and liquids using terahertz metamaterials
RSC Adv. 6, 69381 (2016); DOI: 10.1039/c6ra11777e
S. J. Park, S. A. N. Yoon, Y. H. Ahn
Terahertz metamaterial sensing on polystyrene microbeads: shape dependence
Opt. Mater. Express 5, 2150 (2015); DOI: 10.1364/OME.5.002150
S. J. Park, S. W. Jun, A. R. Kim, Y. H. Ahn
Sensitive detection of yeast using terahertz slot antennas
Opt. Express 22, 30467 (2014); DOI: 10.1364/OE.22.030467
S. J. Park, B. H. Son, S. J. Choi, H. S. Kim, Y. H. Ahn
Suspended single-walled carbon nanotube fluidic sensors
Nanoscale 7, 15421 (2015); DOI: 10.1039/C5NR03215F
B. H. Son, J. Y. Park, S. Lee, Y. H. Ahn
Terahertz Metamaterials and Plasmonics with Novel Functional Materials
We are developing hybrid devices with tunable quantum states by incorporating lead halide perovskites into metamaterials.
Related Article:
Phonon-Polaritons in Lead Halide Perovskite Film Hybridized with THz Metamaterials
Nano Letters 20, 6690 (2020); DOI: 10.1021/acs.nanolett.0c02572
H. S. Kim, N. Y. Ha, J.-Y. Park, S. Lee, D.-S. Kim, Y. H. Ahn*
Mechanical Control of Polaritonic States in Lead Halide Perovskite Phonons Strongly Coupled in THz Microcavity
J. Phys. Chem. Lett. 14, 10318 (2023); DOI: 10.1021/acs.jpclett.3c02717
H. S. Kim, A. A. Khan, J.-Y. Park, S. Lee, Y. H. Ahn*
Crystallization Kinetics of Lead Halide Perovskite Film Monitored by In Situ Terahertz Spectroscopy
J. Phys. Chem. Lett. 8, 401 (2017); DOI: 10.1021/acs.jpclett.6b02691
S. J. Park, A. R. Kim, J. T. Hong, J. Y. Park, S. Lee, Y. H. Ahn*
We also use the highly conductive nanomaterial films (such as carbon nanotube, graphene, silver nanowire) as a novel platform for THz optical devices such as polarizers, metamaterials, and plasmonic devices.
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Graphene Oxides as Epsilon-Near-Zero Platforms Operating in Terahertz Frequency Range
Laser & Photonics Reviews, 2300726 (2023); DOI: 10.1002/lpor.202300726
S. W. Jun, J. H. Yim, J.-Y. Park, S. Lee, Y. H. Ahn*
Terahertz slot antenna devices fabricated on silver nanowire network films
Opt. Mater. Express 7, 1679 (2017); DOI: 10.1364/OME.7.001679
J. T. Hong, S. J. Park, J-. Y. Park, S. Lee, Y. H. Ahn
UV-induced terahertz wave modulation in freestanding ZnO nanowire films
Opt. Mater. Express 6, 3751 (2016); DOI: 10.1364/OME.6.003751
J. T. Hong, J. Y. Park, S. Lee, Y. H. Ahn
Dielectric Constant Engineering of Single-Walled Carbon Nanotube Films for Metamaterials and Plasmonic Devices
J. Phys. Chem. Lett. 4, 3950 (2013); DOI: 10.1021/jz4020053
J. T. Hong, D. J. Park, J. H. Yim, J. K. Park, J. Y. Park, S. Lee, Y. H. Ahn
Terahertz conductivity of reduced graphene oxide films
Opt. Express 21, 7633 (2013); DOI: 10.1364/OE.21.007633
J. T. Hong, K. M. Lee, B. H. Son, S. J. Park, D. J. Park, J. Y. Park, S. Lee, and Y. H. Ahn
Terahertz Wave Applications of Single-Walled Carbon Nanotube Films with High Shielding Effectiveness
Appl. Phys. Express 5, 015102 (2012)
J. T. Hong, D. J. Park, J. Y. Moon, S. B. Choi, J. K. Park, F. Rotermund, J. Y. Park, S. Lee, Y. H. Ahn
Scanning Photocurrent Microscopy on Nanoscale Devices
Scanning photocurrent microscopy (SPCM) uses a focused light beam as a local excitation source to generate a photocurrent and maps the measured current signal as a function of position in a non-contact and non-destructive manner. Since the SPCM signals originate from local electric fields, their position, intensity, and polarity provide the localized electronic information originating from metal contacts, defects, inhomogeneities, junctions, and interfaces.
Related articles:
In-plane mixed-dimensional 2D/2D/1D MoS2 /MoTe2 /Mo6Te6 heterostructures for low contact resistance optoelectronics
Chemical Engineering Journal 468, 143678 (2023); DOI: 10.1016/j.cej.2023.143678
H. Kim, Y. C. Kim, Y. H. Ahn*, Y. Yoo*
Electronic Band Alignment at Complex Oxide Interfaces Measured by Scanning Photocurrent Microscopy
Scientific Reports 7, 3824 (2017); DOI: 10.1038/s41598-017-04265-9
J. H. Yoon, H. J. Jung, J. T. Hong, J. Y. Park, S. Lee, S. W. Lee, Y. H. Ahn
Imaging surface charge distribution near carbon nanotube device in aqueous environments
Appl. Phys. Lett. 105, 223101 (2014); DOI: 10.1063/1.4902401; featured (cover) article
J. K. Park, B. H. Son, J. Y. Park, S. Lee, Y. H. Ahn
High-speed scanning photocurrent imaging techniques on nanoscale devices
Curr. Appl. Phys.13 2076 (2013); DOI: 10.1016/j.cap.2013.08.019
J. K. Park, B. H. Son, J. Y. Park, S. Lee, Y. H. Ahn
Imaging of Photocurrent Generation and Collection in Single-Layer Graphene
Nano Lett. 9, 1742 (2009)
J. Park, Y. H. Ahn, C. Ruiz-Vargas
Photocurrent Imaging of p-n Junctions in Ambipolar Carbon Nanotube Transistors
Nano Lett. 7, 3320 (2007)
Y. H. Ahn, A. W. Tsen, B. Kim, Y. W. Park, J. Park
Ultrafast Scanning Photocurrent Microscopy
Ultrafast Scanning Photocurrent Microscopy, which is combined scanning photocurrent microscopy and femtosecond (10-15 second) pump-probe optical techniques, can be used for visualization of the charge carrier movement inside the working semiconductor devices. This information will provide an important guideline to fabricate high-speed electronic and optoelectronic devices.
Related article:
Imaging Ultrafast Carrier Transport in Nanoscale Field-Effect Transistors
ACS Nano 8, 11361 (2014); DOI: 10.1021/nn5042619; SPIE newsroom
B. H. Son, J. K. Park, J. T. Hong, J. Y. Park, S. Lee, Y. H. Ahn
Evaluation of Transport Parameters in MoS2/Graphene Junction Devices Fabricated by Chemical Vapor Deposition
ACS Appl. Mater. Interfaces 10, 5771 (2018); DOI: 10.1021/acsami.7b16177
Y. C. Kim, V. T. Ngyuen, S. Lee, J.-Y Park*, Y. H. Ahn*
Solar Cell Characterization
The carrier diffusion lengths in semiconductor electrode layers of solar cells can be determined by using scanning photocurrent microscopy. We found a strong correlation between the carrier diffusion length and the cell efficiency, which proved that improvement in the diffusion length is the crucial factors for optimizing device performance. Our work will provide an important guideline for optimizing various contemporary and future photovoltaic devices based on the nanoscale materials and structures.
Related articles:
Crystallization Kinetics of Lead Halide Perovskite Film Monitored by In Situ Terahertz Spectroscopy
J. Phys. Chem. Lett. 8, 401 (2017); DOI: 10.1021/acs.jpclett.6b02691
S. J. Park, A. R. Kim, J. T. Hong, J. Y. Park, S. Lee, Y. H. Ahn
Diffusion Length in Nanoporous Photoelectrodes of Dye-Sensitized Solar Cells under Operating Conditions Measured by Photocurrent Microscopy
J. Phys. Chem. Lett. 3, 3632 (2012); DOI: 10.1021/jz301751j
J.-K. Park, J.-C. Kang, S. Y. Kim, B. H. Son, J.-Y. Park, S. Lee, Y. H. Ahn
Diffusion Length in Nanoporous TiO2 Films under Above-Band-Gap Illumination
AIP. Adv. 4, 067106 (2014); DOI: 10.1063/1.4881875
J. D. Park, B. H. Son, J. K. Park, S. Y. Kim, J. Y. Park, S. Lee, Y. H. Ahn