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Postdoctoral researcher: Strongly correlated oxides, Photovoltaic and Organic Field Effect Transistor under Prof. Vitaly Podzorov's supervision
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Ph.D: Functional (magnetic, electric) transport properties, Multiferroicity, Photovolataic and
Non volatile RAM effect in transition metal oxides under Prof. Sang-Wook Cheong's supervision in the R-CEM.
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M.S: Development of Optical MEMS device and
Design optical router using MOEMS and enhanced anisotropy wet eching technique with UV LED
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Quantum well disordering for integrated optical devices in InGaAs/InGaAsP multi-quantum well system using by SiNx & SiO2 dielectric materials
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Research Skills:
Low
& room temperature measurement
MPMS
(Magnetic Property Mesurement System): temp. & magnetic field dependence of susceptibility
PPMS(Physical Property Mesurement System): resistance,ac susceptibility and thermal conductivity
I-V and
C-V measurements, Photovoltaic
and Field effect transistor measurement
Growth
of single & poly crystals (~400 samples)
Flux method: e.g.Ca3Co2-xMnxO6, BiFeO3, Floating zone method: e.g. Ba2CoGe2O7, PLD (Pulsed Laser Deposition) method: e.g. MnV2O4
Clean room fabrication
Scanning Electron
Microscope (SEM), E-beam and thermal evaporator, Sputtering, Photo lithography, Plasma-enhanced chemicalvapor deposition (PECVD), Photoluminescence, Ellipsometry, Rapid
Thermal Annealing (RTA) etc
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2011
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1. H.
T. Yi, Y. Chen, K.
Czelen and
V. Podzorov “Vacuum
lamination approach to fabrication of high-performance
single-crystal organic field-effect transistors”, Adv. Mater. (Accepted in
October 2011)
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2. M. Ramazanoglu, W. Ratcliff II, H. T. Yi, A. A. Sirenko, S.-W. Cheong, and V.Kiryukhin,
“Giant effect of uniaxial pressure on magnetic domain
populations in multiferroic bismuth ferrite”, Phys. Rev. Lett. 107,
067203 (2011)
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3. H.
T. Yi, T. Choi, S. G. Choi, Y. S. Oh and
S.-W. Cheong, “Mechanism of the
switchable photovoltaic effect in ferroelectric BiFeO3”, Adv. Mater. 23,
3403-3407 (2011)
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4. S. G. Choi, H. T. Yi, S. -W. Cheong, J. N. Hilfiker, R. France,
A. G. Norman, “Optical anisotropy and
charge-transfer transition energies in BiFeO3 from 1.0 to 5.5 eV”, Phy. Rev.
B. 83, 100101
(2011)
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5. D. Talbayev, S. A. Trugman, Seongsu Lee, Hee Taek Yi, S-W Cheong, A. J. Taylor,
“Long-wavelength magnetic and magnetoelectric excitations in the ferroelectric
antiferromagnet BiFeO3”, Phy.
Rev. B. 83, 094403 (2011)
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2010
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6.T. Choi, Y. Horibe, H. T. Yi, Y. J. Choi, W. Wu, & S-W.
Cheong, "Insulating Interlocked Ferroelectric and Structural Antiphase Domain
Walls in Multiferroic YMnO3", Nature Materials 9, 253 (2010) [link]
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7. R. Flint, H. T. Yi, P. Chandra, S.-W.Cheong & V. Kiryukhin, "Spin-state crossover in multiferroic Ca3Co2-xMnxO6
”, Phys. Rev. B 81, 092402 (2010) [link]
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2009
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8. H. T. Yi, T. Choi
& Sang-Wook Cheong, "Reversible colossal resistance switching in
(La,Pr,Ca)MnO3: Cryogenic nonvolatile memories" Appl. Phys. Lett. 95,
063509 (2009) [link]
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9. T. Lancaster, S. J. Blundell, P. J. Baker, H. J. Lewtas, W. Hayes, F. L.
Pratt, H. T. Yi, & S.-W.Cheong, "Spin freezing and dynamics in Ca3Co2-xMnxO6
(x~0.95) investigated with implanted muons: Disorder in the anisotropic
next-nearest-neighbor Ising model", Phys. Rev. B 80, 020409(R) (2009) [link]
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10. V. Kiryukhin, Seongsu Lee, W. Ratcliff II, Q. Huang, H. T. Yi, Y. J. Choi, & S-W. Cheong "Order by Static Disorder in the Ising
Chain Magnet Ca3Co2-xMnxO6" Phys. Rev. Lett. 102, 187202 (2009) [link]
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11. Y. J. Jo, S. Lee, E. S. Choi, H. T. Yi, W. Ratcliff II, Y. J. Choi,
V. Kiryukhin, S. W. Cheong, & L. Balicas, "3:1 magnetization plateau
and suppression of ferroelectric polarization in an Ising chain multiferroic" Phys. Rev. B 79, 012407(2009) [link]
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< 2009
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12. WeidaWu, V. Kiryukhin, H.-J. Noh, K.-T. Ko, J.-H. Park, W. Ratcliff II,
P. A. Sharma, N. Harrison, Y. J. Choi, Y. Horibe, S. Lee, S. Park, H. T. Yi,
C. L. Zhang, & S.-W. Cheong, "Formation of pancakelike ising domains and
giant magnetic coercivity in ferrimagnetic LuFe2O4" Phys. Rev. Lett. 101, 137203 (2008) [link]
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13.H.
T. Yi, Y. J. Choi, S. Lee & Sang-Wook Cheong "Multiferroicity in the square-lattice
antiferromagnet of Ba2CoGe2O7"Appl. Phys. Lett. 92, 212904 (2008)
[link]
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14. Y. J. Choi, H. T. Yi, S. Lee, Q. Huang, V. Kiryukhin, & S.-W. Cheong,
"Ferroelectricity in an Ising chain magnet" Phys. Rev. Lett. 100, 047601 (2008) [link]
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15. H. T. Yi, M.
Thakurdesai, &
M. A. Parker “Control of Sidewall Angles Using UV
LEDs During Wet Etching of GaAs”, Electrochemical
and Solid-State Letters, 7,C137 (2004)
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16. W. J. Choi, H.
T. Yi, J. I. Lee, & D. W. Woo "“Dependence of the intermixing in InGaAs/InGaAsP Quantum Well on Capping Layer" J. Korean Phys. Soc. 45,
773 (2004)
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17. H. T. Yi, J. Cho, W. J. Choi, D. H.
Woo, S. H. Kim, &
K. N. Kang, "Dielectric cap quantum well disordering
for band gap tuning of InGaAs/InGaAsP quantum well structure using various
combinations of semiconductor-dielectric capping layers" J.
Mat. Sci. Lett., 21, 1739 (2002)
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18. H. T. Yi, J. Cho, W. J. Cho,
D. H. Woo, S. H. Kim, & K. N. Kang, "Dependence of quantum well
disordering of InGaAs/InGaAsP quantum well structure on the various combination
of semiconductor-dielectric capping layers" J. Mat. Sci. Lett., 19,
835 (2000)
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19. W. J. Choi, H. T. Yi, D. H. Woo, S. H. Kim, & J. Y. Cho, "Dependence of the Intermixing of
an InGaAs/InGaAsP Quantum Well in Impurity Free Vacancy Disordering on the NH3
Flow Rate During the Growth of a SiNx Capping Layer" Sae-Mulli, 40, 349 (2000)
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20. H. T. Yi, W. J. Choi, D. H. Woo, S. H. Kim, & J.
Cho, "Effect
of Dielectric and Semiconductor Cap Layer Combinations in Impurity Free Vacancy
Disordering of an InGaAs/InGaAsP Single Quantum Well Structure" Sae-Mulli,
41,
193 (2000)
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