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32 results on '"Lee, Byoung Taek"'

2. Depletion layer thickness and Schottky type carrier injection at the interface between Pt electrodes and (Ba,Sr)TiO3 thin films

Author

Hwang, Cheol Seong, Lee, Byoung Taek, Kang, Chang Seok, Lee, Ki Hoon, Cho, Hag-Ju, Hideki, Horii, Kim, Wan Don, Lee, Sang In, and Lee, Moon Yong

Subjects
Electrodes -- Research, Platinum -- Research, Thin films -- Research, Sputtering (Physics) -- Research, Physics
Abstract

A study was conducted to analyze the electrical conduction characteristics of rf sputter-deposited films on platinum and IrO2 electrodes and metalorganic chemical vapor deposited films on a platinum electrode. Experimental results indicated Schottky emission behavior at measurement temperatures higher than 120 degrees C. In addition, tunneling related behavior was observed below 120 degrees C for films supporting a thickness of 40 nm.

Published
1999

3. A comparative study of the electrical conduction mechanisms of (Ba0.5Sr0.5)TiO3 thin films on Pt and IrO2 electrodes

Author

Hwang, Cheol Seong, Lee, Byoung Taek, Kang, Chang Seok, Kim, Jin Won, Lee, Ki Hoon, Cho, Hag-Ju, Horii, Hideki, Kim, Wan Don, Lee, Sang In, Roh, Young Bum, and Lee, Moon Yong

Subjects
Capacitors -- Research, Thin films -- Electric properties, Physics
Abstract

A Schottky emission behaviour with interface potential barrier heights of around 1.5 eV to 1.6 eV has been observed in a Pt/BST/IrO2 capacitor. The surface electron trap states of the (Ba,Sr)TiO3 (BST) are the main determining factor for barrier height. It is therefore vital to pin the Fermi level of the Pt/BST interface to a place as deep as possible in the band gap in order to obtain a large potential barrier height and low leakage current. The Pt/BST/IrO2 capacitor shows a very distinctive electronical conduction behaviour.

Published
1998

26. Electrical properties of sputtered (Ba, Sr)TiO3thin films prepared by two-step deposition method

Author

Lee, Byoung Taek, Kim, Wan Don, Lee, Ki Hoon, Lim, Han Jin, Kang, Chang Seok, Hideki, Horii, Joo, Suk Ho, Park, Hong Bae, Yoo, Cha Young, Lee, Sang In, and Lee, Moon Yong

Abstract

The influence of two-step deposition on the electrical properties of sputtered (Ba,Sr)TiO3thin films was investigated. BST thin films with thickness 40 nm were deposited by a simple two-step radio frequency-magnetron sputtering technique, where the BST thin film consisted of a seed layer and a main layer. The dielectric constant was strongly dependent on the thickness of seed layer, but there was no dependence on deposition temperature of the seed layer. For a 2 nm seed layer, the dielectric constants were higher by about 29% than those of single-step BST thin films due to higher crystallinity and the leakage current was nearly the same as that of a single-step sample in bias voltage from −2 to 2.5 V. However, an improvement of the dielectric constant was not observed for samples having above 4 nm thick seed layers. A 40 nm thick BST film with 2 nm thick seed layer deposited by a two-step method exhibited a SiO2equivalent thickness of 0.385 nm and a leakage current density of 2.74 × 10−8A/cm2at+1.5V after post-annealing under an atmosphere of flowing N2for 30 min at 750°C.

Published
1999
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27. Influences of interfacial intrinsic low-dielectric layers on the dielectric properties of sputtered (Ba,Sr)TiO[sub 3] thin films.

Author

Lee, Byoung Taek and Hwang, Cheol Seong

Subjects
*THIN films, *DIELECTRICS, *ANNEALING of metals
Abstract

The influences of low-dielectric interfacial layers on the dielectric properties of Pt/(Ba,Sr)TiO[sub 3]/Pt capacitors were investigated before and after postannealing. The interfacial layer is believed to be the intrinsic dead layer (low-dielectric layer) due to the termination of chemical bonds of the (Ba,Sr)TiO[sub 3] (BST) material at the interfaces. The dielectric constant of the capacitor decreases with decreasing BST film thickness owing to the low dielectric constant of the dead layer. The dead-layer capacitance varies with processes such as film deposition temperature, and postannealing. Higher deposition temperatures result in a larger dead-layer capacitance and a higher bulk dielectric constant. Although annealing under a N[sub 2] atmosphere is less effective in reducing the dead-layer effect than under an O[sub 2] atmosphere, it is more effective in increasing the bulk dielectric constant. Therefore, a N[sub 2], rather than an O[sub 2] atmosphere, results in a larger increase in the overall dielectric constant. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000
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29. Deposition Characteristics of (Ba, Sr)TiO3Thin Films by Liquid Source Metal-Organic Chemical Vapor Deposition at Low Substrate Temperatures

Author

Kang, Chang Seok, Cho, Hag-Ju, Hwang, Cheol Seong, Lee, Byoung Taek, Lee, Ki-Hun, Horii, Hideki, Kim, Wan Don, Sang In Lee, Sang In Lee, and Moon Yong Lee, Moon Yong Lee

Abstract

The deposition characteristics of (Ba, Sr)TiO3(BST) thin films using a liquid source metal-organic chemical vapor deposition on a 6-inch-diameter Pt/SiO2/Si wafer were investigated. Ba(DPM)2tetraglyme, Sr(DPM)2tetraglyme and Ti(DPM)2(O-i-Pr)2, dissolved in n-butyl acetate, were used as the sources of Ba, Sr and Ti, respectively. Step coverage, within-wafer uniformities in composition and thickness of the BST films were investigated as a function of substrate temperatures ranging from 420° C to 570° C. As the substrate temperature decreased, the step coverage improved, whereas the within-wafer uniformities degraded. From BST films deposited in a temperature range from 450° C to 480° C, good step coverage (>80%), as well as good within-wafer uniformity were obtained. However, in that temperature range, hazy deposition was observed due to many humps on the surface. The humps are an agglomeration of crystalline grains and are a few hundred Å in diameter, which have a Ti-rich composition compared to flat film region.

Published
1997
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30. Structural and Electrical Properties of Ba0.5Sr0.5TiO3Films on Ir and IrO2Electrodes

Author

Cho, Hag-Ju, Kang, Chang Seok, Hwang, Cheol Seong, Kim, Jin-Won, Horii, Hideki, Lee, Byoung Taek, Sang In Lee, Sang In Lee, and Moon Yong Lee, Moon Yong Lee

Abstract

High-dielectric Ba0.5Sr0.5TiO3(BST) thin films are grown on Ir and IrO2electrodes by a rf sputtering method. The structural and electrical properties of BST films are investigated. After postannealing at 750° C for 30 min in N2atmosphere, the interface between BST and IrO2remains flat and the IrO2does not show any structural change. On the other hand, a thin IrO2layer is formed at the interface between the BST and Ir after the same post-annealing. A larger grain size of BST film is obtained on the Ir electrode compared to that of BST film on the IrO2electrode. Dielectric constants of 36-nm-thick BST films on Ir and IrO2are 338 and 290, respectively. The leakage current densities of both the Pt/BST/Ir and Pt/BST/IrO2capacitors are about 20 nA/cm2at ±1.5 V, which is sufficiently small for application to dynamic random access memory devices.

Published
1997
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31. Preparation and Electrical Properties of SrTiO3Thin Films Deposited by Liquid Source Metal-Organic Chemical Vapor Deposition (MOCVD)

Author

Kang, Chang Seok, Hwang, Cheol Seong, Cho, Hag-Ju, Lee, Byoung Taek, Park, Soon Oh, Kim, Jin Won, Horii, Hideki, Lee, Sang In, Young Bum Koh, Young Bum Koh, and Moon Yong Lee, Moon Yong Lee

Abstract

SrTiO3thin films with thicknesses ranging from 30 nm to 60 nm were grown on 6-inch-diameter, platinized Si wafers by liquid source metal-organic chemical vapor deposition (MOCVD). The crystalline quality and cation concentrations of the films are strongly dependent on the deposition temperature with optimum temperatures ranging from 500° C to 550° C. Semi-conformal deposition on submicron-sized storage node patterns is obtained but further improvements in conformality and reproducibility are required. The dielectric constant is about 210 irrespective of the film thickness and leakage current densities are sufficiently small for the dynamic random access memory (DRAM) applications. SiO2equivalent thickness (Tox) of the 30-nm-thick STO film is 0.51 nm. The finding that the leakage current density and dielectric constant are independent of the film thickness can be explained by a fully depleted model of the STO film.

Published
1996
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32. Annealing effect on magnetic and electronic properties of polycrystalline Ge1-xMnx semiconductors grown by MBE

Author

Cho, Young Mi, Yu, Sang Soo, Ihm, Young Eon, Kim, Dojin, Kim, Hyojin, Baek, Jong Sung, Kim, Chang Soo, and Lee, Byoung Taek

Subjects
*POLYCRYSTALS, *NANOTECHNOLOGY, *ELECTRIC conductivity, *SEMICONDUCTORS
Abstract

MBE-grown poly Ge1-xMnx/SiO2/(1 0 0)Si semiconductor thin films were annealed, and magnetic properties of the annealed semiconductors have been studied. As-grown poly Ge1-xMnx semiconductor has p-type carriers and electrical resistivity is in the range of 4.0×10-3–0.5×10-3 Ω cm at room temperature. The carrier type is not changed during annealing, but the electrical resistivity increases with annealing temperature and time. During annealing Ge3Mn5 ferromagnetic phase transforms into Ge8Mn11 anti-ferromagnetic phase and then the Ge8Mn11 phase is decomposed into Ge, β-Mn and some unidentified phases. [Copyright &y& Elsevier]

Published
2004
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