Research

Graphene

[ Multilayer graphene ]

In a Multilayer graphene (MLG) charge carriers are distributed different among the individual layers. Infrared Spectroscopy experiment reveals the layer-dependent carrier distribution precisely, which is vital information for super-capacitor device application.

[ Twisted bilayer graphene ]

Given with two pieces of graphene put together, you can tune the electronic band structure by twisting one against the other. (=twisted bilayer graphene; TBG) Optical transitions are surprisingly rich in this material.

[ Graphene FET ]

Infrared transmission of graphene field effect transistor tell us the scattering mechanisms of Dirac carrier

Related Article

Kwangnam Yu, Jiwon Jeon, Jiho Kim, Chang Won Oh, Yongseok Yoon, BeomJoon Kim, Jeong Ho Cho, and E. J. Choi

'Infrared study of carrier scattering mechanism in ion-gated graphene', Appl. Phys. Lett. 114, 083503, 2019 Article


Kwangnam Yu, Jiho Kim, Chul Lee, A-Rang Jang, Hyeon Suk Shin, Keun Soo Kim, Young-Jun Yu, and E. J. Choi

'Infrared study of large scale h-BN film and graphene/h-BN heterostructure', Appl. Phys. Lett. 108, 241910, 2016 Article

Kwangnam Yu, Jiho Kim, Joo Youn Kim, Wonki Lee, Jun Yeon Hwang, E. H. Hwang, and E. J. Choi

'Infrared spectroscopic study of carrier scattering in gated CVD graphene', Phys. Rev. B 94, 235404, 2016 Article


Chul Lee , N. Leconte , Jiho Kim , Doohee Cho , In-Whan Lyo and E.J. Choi

'Optical spectroscopy study on the effect of hydrogen adsorption on graphene', Carbon 103, 2016 Article


Chul Lee, Jiho Kim, SangJin Kim, Young Jun Chang, Keun Soo Kim, ByungHee Hong and E. J. Choi

'Strong hole-doping and robust resistance-decrease in protonirradiated graphene ', Scientific reports 6, 21311, 2016 Article

Topological Insulator


Topological insulator (TI) is a novel state of matter characterized by insulating bulk and metallic surface. We discover an optical peak that is associated with electron transition between the bulk and surface state.

Related Article

Jiwon Jeon, Kwangnam Yu, Jiho Kim, Jisoo Moon, Seongshik Oh, and E. J. Choi

'Observation of optical absorption correlated with surface state of topological insulator',Phys.Rev.B.100,195110, 2019 Article

Transparent Electrode




Oxide materials with high electrical conductivity and optical transparency constitute an important part of modern electro-optical technology, such as flat panel displays, light emitting diodes, and solar cells. We deposited transparent oxide electrodes by using PED, and measured their optical properties by using FTIR, ellipsometry. Although our oxide electrode have ordinary effective mass(m*) among other oxide electrodes, it has highest mobility.

Related Article

Dongmin Seo, Kwangnam Yu, Young Jun Chang, Egon Sohn, Kee Hoon Kim, and E. J. Choi

'Infrared optical spectroscopy of transparent conducting perovskite (La,Ba)SnO3 thin films', Appl. Phys. Lett. 104, 022102, 2014 Article


Dongmin Seo, Kwangnam Yu and E. J. Choi

'Infrared Conductivity of PED-grown (La,Ba)SnO3 Thin Films', Journal of Korea Physics Society 64, 764767, 2014 Article