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.

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Nature Communications 13, 3470 (2022); DOI: 10.1038/s41467-022-31137-2

S. W. Jun, Y. H. Ahn*

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*

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

Biomedical Optics Express 8, 3551 (2017); DOI: 10.1364/BOE.8.003551

S. J. Park, S. H. Cha, G. A. Shin, Y. H. Ahn

RSC Adv. 6, 69381 (2016); DOI: 10.1039/c6ra11777e

S. J. Park, S. A. N. Yoon, Y. H. Ahn

Opt. Mater. Express 5, 2150 (2015); DOI: 10.1364/OME.5.002150

S. J. Park, S. W. Jun, A. R. Kim, Y. H. Ahn

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

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.

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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*

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*

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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Laser & Photonics Reviews, 2300726 (2023); DOI: 10.1002/lpor.202300726

S. W. Jun, J. H. Yim, J.-Y. Park, S. Lee, Y. H. Ahn* 

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

Opt. Mater. Express 6, 3751 (2016); DOI: 10.1364/OME.6.003751

J. T. Hong, J. Y. Park, S. Lee, Y. H. Ahn

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

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

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.

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Chemical Engineering Journal 468, 143678 (2023); DOI: 10.1016/j.cej.2023.143678

H. Kim, Y. C. Kim, Y. H. Ahn*, Y. Yoo*

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

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

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

Nano Lett. 9, 1742 (2009)

J. Park, Y. H. Ahn, C. Ruiz-Vargas

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.

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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

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:

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

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

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