Shin-Ik Kim
Korea Institute of Science and Technology
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Featured researches published by Shin-Ik Kim.
Scientific Reports | 2015
Seong Keun Kim; Shin-Ik Kim; Hyungkwang Lim; Doo Seok Jeong; Beomjin Kwon; Seung-Hyub Baek; Jin-Sang Kim
The two-dimensional electron gas (2DEG) at the interface between insulating LaAlO3 and SrTiO3 is intriguing both as a fundamental science topic and for possible applications in electronics or sensors. For example, because the electrical conductance of the 2DEG at the LaAlO3/SrTiO3 interface can be tuned by applying an electric field, new electronic devices utilizing the 2DEG at the LaAlO3/SrTiO3 interface could be possible. For the implementation of field-effect devices utilizing the 2DEG, determining the on/off switching voltage for the devices and ensuring their stability are essential. However, the factors influencing the threshold voltage have not been extensively investigated. Here, we report the voltage-induced shift of the threshold voltage of Pt/LaAlO3/SrTiO3 heterostructures. A large negative voltage induces an irreversible positive shift in the threshold voltage. In fact, after the application of such a large negative voltage, the original threshold voltage cannot be recovered even by application of a large positive electric field. This irreversibility is attributed to the generation of deep traps near the LaAlO3/SrTiO3 interface under the negative voltage. This finding could contribute to the implementation of nanoelectronic devices using the 2DEG at the LaAlO3/SrTiO3 interface.
Applied Physics Letters | 2013
Seong Keun Kim; Shin-Ik Kim; Jin-Ha Hwang; Jin-Sang Kim; Seung-Hyub Baek
We performed capacitance–voltage analysis of 5-nm-thick LaAlO3/SrTiO3 heterostructure containing two-dimensional-electron-gas (2DEG) at the interface. The complex impedance of the heterostructure was measured as a function of frequency for a wide range of gate biases. The impedance spectra showed a different behavior above and below an applied voltage of −1.8 V. The capacitance determined from the impedance was approximately 1.2 nF above −1.8 V and was drastically reduced to ∼0.01 nF below this voltage, owing to depletion of 2DEG and the insulating SrTiO3 underneath it. This suggests that devices utilizing LaAlO3/SrTiO3 can facilitate switching operations in a very small voltage range.
ACS Applied Materials & Interfaces | 2014
Haeri Kim; Seon Young Moon; Shin-Ik Kim; Seung-Hyub Baek; Ho Won Jang; Dong-Wook Kim
We investigated the influences of charge writing on the surface work function (W) and sheet resistance (R) of the LaAlO3/SrTiO3 (LAO/STO) heterointerface in several gas environments: H2(2%)/N2(98%), air, N2, and O2. The decrease in W and R due to charge writing was much larger in air (ΔW = -0.45 eV and ΔR = -40 kΩ/S) than in O2 (ΔW = -0.21 eV and ΔR = -19 kΩ/S). The reduced R could be maintained more than 100 h in H2/N2. Such distinct behaviors were quantitatively discussed, based on the proposed charge-writing mechanisms. Such analyses showed how several processes, such as carrier transfer via surface adsorbates, surface redox, electronic state modification, and electrochemical surface reactions, contributed to charge writing in each gas.
AIP Advances | 2017
Yun Li; Eui-Young Choi; Shin-Ik Kim; Seung-Hyub Baek; Seung-Young Park; Younghun Jo; Jiwon Seo
We investigate the origin of insulating weak-ferromagnetic phase in ultra-thin epitaxial La0.67Sr0.33MnO3 (LSMO) films on SrTiO3 substrate using density functional theory calculation together with X-ray linear dichroism (XLD). The calculations show that symmetry breaking of the crystal field at the LSMO surface largely lowers the energy level of Mn d3z2 orbital at the surface and leads to full occupancy of the d3z2 orbital in majority spin channel, and XLD spectra clearly show the preferential occupation of Mn d3z2 orbital at the surface. Such an orbital reconstruction and charge redistribution in the ultra-thin films largely suppresses double-exchange interaction and favors super-exchange interaction, resulting in G-type antiferromagnetic spin ordering and insulating state. The anisotropic exchange interaction due to spin-orbital interaction leads to spin canting, and thus the films show weak ferromagnetism.
Journal of The Magnetics Society of Japan | 1999
Jong-Ku Park; Shin-Ik Kim; J. Kim; K. Y. Kim; S.H. Han; Hyun-Jai Kim
Journal of Magnetism and Magnetic Materials | 2000
Shin-Ik Kim; K.H Kim; Y.I Jang; J. Kim; S.H. Han; Hyun-Jai Kim
Applied Surface Science | 2019
Mi-Jin Jin; Daeseong Choe; Seung Youb Lee; Jungmin Park; Junhyeon Jo; Inseon Oh; Shin-Ik Kim; Seung-Hyub Baek; Cheolho Jeon; Jung-Woo Yoo
Bulletin of the American Physical Society | 2017
Mi-Jin Jin; Seon Young Moon; Jungmin Park; Vijayakumar Modepalli; Junhyeon Jo; Shin-Ik Kim; Hyun Koo; Byoung-Chul Min; Hyun-Woo Lee; Seung-Hyub Baek; Jung-Woo Yoo
Journal of Physics and Chemistry of Solids | 2016
Chan-Rok Park; Seon Young Moon; Da-Hee Park; Shin-Ik Kim; Seong Keun Kim; Chong Yun Kang; Seung-Hyub Baek; Jung-Hae Choi; Jin-Sang Kim; Eunsoo Choi; Jin-Ha Hwang
한국진공학회 학술발표회초록집 | 2014
Chan-Rok Park; Myeong-Hee Ko; Shin-Ik Kim; Seong Keun Kim; Seung-Hyub Baek; Jin-Sang Kim; Jin-Ha Hwang