Dae Kyu Kim
Korea University
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Featured researches published by Dae Kyu Kim.
Journal of Applied Physics | 2014
Dae Kyu Kim; Jeong Do Oh; Eun Sol Shin; Hoon Seok Seo; Jong Ho Choi
The neutral cluster beam deposition (NCBD) method has been applied to the production and characterization of ambipolar, heterojunction-based organic light-emitting field-effect transistors (OLEFETs) with a top-contact, multi-digitated, long-channel geometry. Organic thin films of n-type N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide and p-type copper phthalocyanine were successively deposited on the hydroxyl-free polymethyl-methacrylate (PMMA)-coated SiO2 dielectrics using the NCBD method. Characterization of the morphological and structural properties of the organic active layers was performed using atomic force microscopy and X-ray diffraction. Various device parameters such as hole- and electron-carrier mobilities, threshold voltages, and electroluminescence (EL) were derived from the fits of the observed current-voltage and current-voltage-light emission characteristics of OLEFETs. The OLEFETs demonstrated good field-effect characteristics, well-balanced ambipolarity, and substantial EL unde...
Journal of Materials Chemistry C | 2016
Jeong Do Oh; Dae Kyu Kim; Jang Woon Kim; Young Geun Ha; Jong Ho Choi
High-performance pentacene thin-film transistors operating at low voltages were fabricated using hafnium (Hf)-based blend gate dielectrics. Crosslinked HfOx/1,6-bis(trimethoxysilyl)hexane blend (CLHB) dielectric films were prepared by varying the ratio of HfOx and 1,6-bis(trimethoxysilyl)hexane (BTMH), and the resulting films were deposited by solution-processed sol–gel chemistry. p-Type pentacene was deposited on the dielectric films using the neutral cluster beam deposition method. The dielectric properties and morphologies of the films were systematically investigated with respect to the relationship between the compositions of blend dielectrics and device performance. In comparison to the pristine HfOx-based OFETs, as the BTMH molar ratio increased, the leakage current, capacitance, dielectric constant and trap density of the interface states decreased, leading to an increase in the CLHB-based transistor performance such as increased hole-carrier mobility and current on/off ratio and a decrease in subthreshold swing. The OFETs demonstrated similar device performance at high HfCl4 : BTMH molar ratios of 1 : 0.5 and 1 : 0.8. At the molar ratio of 1 : 0.5, the OFETs operating under −4 V had μh,avgeff = 1.6 cm2 V−1 s−1 and Ion/Ioff = 2 × 105 with the corresponding leakage current and capacitance of ∼2 × 10−7 A cm−2 at 2 MV cm−1 and ∼137 nF cm−2. The performance enhancement was found to be closely correlated with the blend dielectrics.
Applied Physics Letters | 2013
Jeong Do Oh; Hoon Seok Seo; Eun Sol Shin; Dae Kyu Kim; Young Geun Ha; Jong Ho Choi
In this paper, the authors first report ZrO2-dielectric based low-voltage organic thin-film complementary metal-oxide semiconductor inverters. Two active layers of p-type pentacene and n-type N,N′-dioctyl-3,4,9,10-perylenedicarboximide were successively deposited on the thermally stable, transparent ZrO2 using the neutral cluster beam deposition method. Based on the good balance between p- and n-type transistors, the complementary inverters exhibited ideal characteristics including sharp inversions, complete switching, high gains, and large voltage swings at low operating voltage levels.
Journal of Materials Chemistry C | 2016
Jang Woon Kim; Jeong Do Oh; Dae Kyu Kim; Han Young Lee; Young Geun Ha; Jong Ho Choi
Low-voltage organic field-effect transistors (OFETs) and complementary metal oxide semiconductor (CMOS) inverters based on pentacene and N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13) were fabricated on HfTiOx gate dielectrics. Both pristine dielectrics and substrates passivated with self-assembled monolayers (SAMs) of n-dodecylphosphonic acid (PA-C12) were employed. The high capacitance and low leakage current of the HfTiOx-based dielectrics enabled the devices to operate at |V| < 3 V. Passivation with PA-C12 was highly effective in improving the device characteristics. In particular, an electron mobility of 0.72 cm2 V−1 s−1 was measured for the device fabricated with the passivated HfTiOx dielectric, which represents the best performance reported to date for perylene-based OFETs prepared with thin, high-k gate dielectrics. The CMOS inverters exhibited fast switching and high gain characteristics, which were attributed to good coupling between the optimized p- and n-type OFETs.
Journal of Physical Chemistry C | 2013
Hoon Seok Seo; Dae Kyu Kim; Jeong Do Oh; Eun Sol Shin; Jong Ho Choi
Organic Electronics | 2012
Jeong Do Oh; Hoon Seok Seo; Dae Kyu Kim; Eun Sol Shin; Jong Ho Choi
Organic Electronics | 2016
Jeong Do Oh; Jang Woon Kim; Dae Kyu Kim; Jong Ho Choi
Journal of Physics D | 2015
Eun Sol Shin; Jeong Do Oh; Dae Kyu Kim; Young Geun Ha; Jong Ho Choi
Journal of Physical Chemistry C | 2016
Dae Kyu Kim; Jeong Do Oh; Jang Woon Kim; Han Young Lee; Jong Ho Choi
Journal of Physics D | 2012
Hoon Seok Seo; Jeong Do Oh; Dae Kyu Kim; Eun Sol Shin; Jong Ho Choi