Yonsei Institute of Convergence Technology

Incheon, South Korea

Yonsei Institute of Convergence Technology

Incheon, South Korea

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PubMed | Yonsei Institute of Convergence Technology and University of California at Davis
Type: Journal Article | Journal: Developmental psychology | Year: 2016

Four experiments examined how faces compete with physically salient stimuli for the control of attention in 4-, 6-, and 8-month-old infants (N = 117 total). Three computational models were used to quantify physical salience. We presented infants with visual search arrays containing a face and familiar object(s), such as shoes and flowers. Six- and 8-month-old infants looked first and longest at faces; their looking was not strongly influenced by physical salience. In contrast, 4-month-old infants showed a visual preference for the face only when the arrays contained 2 items and the competitor was relatively low in salience. When the arrays contained many items or the only competitor was relatively high in salience, 4-month-old infants looks were more often directed at the most salient item. Thus, over ages of 4 to 8 months, physical salience has a decreasing influence and faces have an increasing influence on where and how long infants look.


Baek J.,Yonsei University | Baek J.,Yonsei Institute of Convergence Technology | Ki B.,Yonsei University | Ki B.,Yonsei Institute of Convergence Technology | And 6 more authors.
Optical Materials Express | Year: 2016

We investigated the optical, electrical, and structural properties of epitaxially grown Ge-on-Si substrates after phosphorous implantation. Ion implantation increases n-type doping in Ge for an on-chip light source. However, its effects on Ge should be carefully studied as implantation may increase the recombination sites, and possibly reduce light-emitting efficiency. We studied the light-emitting efficiency of implanted Ge using various material characterizations. We found that phosphorous implantation increased the doping concentration of in situ doped Ge-on-Si, which boosted the photoluminescence by 12-30%. It is therefore critical to optimize the post-annealing and implantation doses to increase light-emitting efficiency of Ge. © 2016 Optical Society of America.


Yoon S.,Yonsei University | Yoon S.,Yonsei Institute of Convergence Technology | Bang J.,Yonsei University | Bang J.,Yonsei Institute of Convergence Technology | And 3 more authors.
Microelectronic Engineering | Year: 2016

We report on the electrical and microstructural analysis on Si/Ti/Al/Cu Ohmic contact for AlGaN/GaN high-electron-mobility transistors grown on Si (111) substrate. With optimized Si and Ti thickness in Si/Ti/Al/Cu Ohmic metallization, a minimum Ohmic contact resistance of 0.44 Ω mm and specific contact resistance of 3 × 10- 6 -cm2 with smooth surface morphology were achieved. Significant change in electrical performance and morphology showed high dependence of Ti and Si thickness on the multilayer metal scheme. Importantly, refractory behavior was shown in low annealing temperature, though uniform and continuous TiSix with low work function was formed on AlGaN. However, Ohmic behavior was shown in high annealing temperature, because thin AIN surrounding TiN promotes further N vacancies in GaN than the conventional Ti/Al-based Ohmic contact does. An outer Cu layer has low resistivity and the interfacial Si layer forms TiSix, which works as only a barrier to prevent Cu in-diffusion, not to transport current. As a result, we revealed that Ohmic contact mechanism in Si/Ti/Al/Cu is governed mainly by field emission near the Fermi level or themionic-field emission. Microstructural study on metal/semiconductor interface region was conducted by using transmission electron microscopy (TEM). © 2015 Published by Elsevier B.V.


Cho A.-J.,Yonsei University | Cho A.-J.,Yonsei Institute of Convergence Technology | Park K.C.,Konkuk University | Kwon J.-Y.,Yonsei University | Kwon J.-Y.,Yonsei Institute of Convergence Technology
Nanoscale Research Letters | Year: 2015

For several years, graphene has been the focus of much attention due to its peculiar characteristics, and it is now considered to be a representative 2-dimensional (2D) material. Even though many research groups have studied on the graphene, its intrinsic nature of a zero band-gap, limits its use in practical applications, particularly in logic circuits. Recently, transition metal dichalcogenides (TMDs), which are another type of 2D material, have drawn attention due to the advantage of having a sizable band-gap and a high mobility. Here, we report on the design of a complementary inverter, one of the most basic logic elements, which is based on a MoS2 n-type transistor and a WSe2 p-type transistor. The advantages provided by the complementary metal-oxide-semiconductor (CMOS) configuration and the high-performance TMD channels allow us to fabricate a TMD complementary inverter that has a high-gain of 13.7. This work demonstrates the operation of the MoS2 n-FET and WSe2 p-FET on the same substrate, and the electrical performance of the CMOS inverter, which is based on a different driving current, is also measured. © 2015, Cho et al.; licensee Springer.


Cho A.-J.,Yonsei University | Cho A.-J.,Yonsei Institute of Convergence Technology | Yang S.,Yonsei University | Yang S.,Yonsei Institute of Convergence Technology | And 7 more authors.
ECS Solid State Letters | Year: 2014

Two-dimensionalmaterials like graphene have great potential to excess the mobility limit of conventional silicon devices. Particularly, MoS2 FETs have high mobility and low off-current simultaneously due to their sizable band-gap. However, large hysteresis in its transfer curve is an obstacle for implementation to logic circuits and switching devices. Here, we report on a multi-layer MoS2 FET using atomic layer deposition Al 2O3 as a gate insulator, showing small hysteresis of 0.86 V. It is thought that, such improvement in the hysteresis attributes to the small trap at the MoS2/Al2O3 interface, and it is confirmed through a constant current stress test. © 2014 The Electrochemical Society.


Yoon S.,Yonsei Institute of Convergence Technology | Bang J.,Yonsei Institute of Convergence Technology | Song Y.,Yonsei Institute of Convergence Technology | Oh J.,Yonsei University
Thin Solid Films | Year: 2015

A complementary metal-oxide semiconductor (CMOS)-compatible Au-free Si/Ti/Al/Cu ohmic metallization scheme has been developed for AlGaN/GaN power transistors epitaxially grown on Si substrates. The Si/Ti/Al/Cu metallization exhibited a low specific contact resistance of 3.5 × 10- 6 ω cm2 after optimizing the Si interface layer. The ohmic metal surface was smooth with a root-mean-square roughness of 24 nm. Physical characterization confirmed that Cu diffusion into the semiconductor was suppressed because locally segregated TiSix alloys acted as a barrier. Shallow interfacial reactions of localized TiN alloys occurred in the AlGaN/GaN heterostructure. Without a designated diffusion barrier as in conventional Au-based metallization, the contact resistivity and surface morphology in Si/Ti/Al/Cu improved significantly, which helps address critical challenges associated with the fabrication of AlGaN/GaN power transistors on a Si CMOS platform. © 2015 Elsevier B.V.


Jung S.-M.,Yonsei University | Won Y.-Y.,Yonsei Institute of Convergence Technology | Han S.-K.,Yonsei University
International Conference on ICT Convergence | Year: 2013

We propose a technique to reduce the OBI noise in OFDMA-PON link. A self-homodyne balanced detection can improve the SNR of DMT signal as well as reduce OBI noise with the help of local laser. © 2013 IEEE.


Lee S.,Yonsei University | Ju D.Y.,Yonsei Institute of Convergence Technology
IEEE ISI 2013 - 2013 IEEE International Conference on Intelligence and Security Informatics: Big Data, Emergent Threats, and Decision-Making in Security Informatics | Year: 2013

Smartphone OS, such as Android, enables us to install third party applications. However, security threats of malicious applications are rapidly increasing due to the nature of the third party applications where only developers can assign required permissions. For this reason, attackers can inject exploits into a normal application with inappropriately acquired permissions. In this paper, we propose a method to distinguish an application by analyzing permissions set and enhanced user interfaces to improve the chance of making right decisions. The proposed methods are intended for users to make better decisions with more information provided by the system. © 2013 IEEE.


Namgung S.D.,Yonsei University | Namgung S.D.,Yonsei Institute of Convergence Technology | Yang S.,Yonsei University | Yang S.,Yonsei Institute of Convergence Technology | And 7 more authors.
Nanoscale Research Letters | Year: 2015

Two-dimensional materials have recently been spotlighted, due to their unique properties in comparison with conventional bulk and thin-film materials. Among those materials, MoS2 is one of the promising candidates for the active layer of electronic devices because it shows high electron mobility and pristine band gap. In this paper, we focus on the evolution of the electrical property of the MoS2 field-effect transistor (FET) as a function of post-annealing temperature. The results indicate that the off current drastically decreased at 200°C and increased at 400°C while other factors, such as the mobility and threshold voltage, show little variation. We consider that the decreasing off current comes from the rearrangement of the MoS2 film and the elimination of the surface residue. Then, the increasing off current was caused by the change of the material's composition and adsorption of H2O and O2. © 2015, Namgung et al.; licensee Springer.


PubMed | Yonsei University and Yonsei Institute of Convergence Technology
Type: | Journal: Nanoscale research letters | Year: 2015

Two-dimensional materials have recently been spotlighted, due to their unique properties in comparison with conventional bulk and thin-film materials. Among those materials, MoS2 is one of the promising candidates for the active layer of electronic devices because it shows high electron mobility and pristine band gap. In this paper, we focus on the evolution of the electrical property of the MoS2 field-effect transistor (FET) as a function of post-annealing temperature. The results indicate that the off current drastically decreased at 200C and increased at 400C while other factors, such as the mobility and threshold voltage, show little variation. We consider that the decreasing off current comes from the rearrangement of the MoS2 film and the elimination of the surface residue. Then, the increasing off current was caused by the change of the materials composition and adsorption of H2O and O2.

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