• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1772-1775
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• 2000

We have fabricated poly-Si TFTs by two-step crystallizaton. Poly-Si films have been prepared by furnace annealing(FA) and rapid thermal annealing(RTA) followed by subsequent the post-annealing, excimer laser annealing. The measured crystallinity of RTA and FA annealed poly-Si film is 77% and 68.5%, respectively. For two-step annealed poly-Si film, the crystallinity has been drastically to 87.7% and 86.3%. The RMS surface roughness from AFM results have been improved from 56.3${\AA}$ to 33.5${\AA}$ after post annealing. The measured transfer characteristics of the two-step annealed poly-Si TFTs have been improved significantly for the both FA-ELA and RTA-ELA. Leakage currents of two-step annealed poly-Si TFTs are lower than that of the devices by FA and RTA. From these results, we can describe the fact that the intra-grain defects has been cured drastically by the post-annealing.

• Journal of the Semiconductor & Display Technology
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• v.9 no.4
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• pp.1-5
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• 2010

The PVA (poly-vinyl alcohol) insulators were spun coated onto ITO coated glass substrates with the capacitors of Glass/ITO/PVA/Al structure. The effects of PVA concentrations (3.0, 4.0 and 5.0 wt%) on the morphology and electrical properties of the films were investigated. As the concentration of PVA increased from 3.0 to 5.0 wt%, the leakage current of device decreased from 17.1 to 0.23 pA. From the AFM measurement, the RMS value decreased with increasing PVA concentration, showing the improvement of insulator film roughness. The capacitances of the films with PVA concentrations of 4.0 and 5.0 wt% were about 28.1 and 24.2 nF, respectively. The lowest leakage current of 1.77 PA was obtained at the film thickness of 117.5 nm for the device with fixed PVA concentration of 5.0 wt%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.302-302
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• 2007

The $SrRuO_3$/Si thin film electrodes are grown with (00l) preferred orientations on SrO buffered-Si (001) substrates by pulsed laser deposition. The optimum conditions of SrO buffer layers for $SrRuO_3$ preferred orientations are the deposition temperature of $700^{\circ}C$, deposition pressure of $1\;{\times}\;10^{-6}\;Torr$, and the thickness of 6 nm. The 100nm thick-$SrRuO_3$ bottom electrodes deposited above $650^{\circ}C$ on SrO buffered-Si (001) substrates have a rms roughness of approximately $5.0\;{\AA}$ and a resistivity of 1700 -cm, exhibiting a (00l) relationship. The 100nm thick-$Pb(Zr_{0.2}Ti_{0.8})O_3$ thin films deposited at $575^{\circ}C$ have a (00l) preferred orientation and exhibit $2P_r$ of $40\;C/cm^2$, $E_c$ of 100 kV/cm, and leakage current of about $1\;{\times}\;10^{-7}\;A/cm^2$ at 1V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.40-43
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• 2018

Various Ni-doped carbon (C : Ni) thin films were fabricated using different Ni target power densities by unbalanced magnetron sputtering (UBM). The effects of target power density on the structural, physical, surface, and electrical properties of C : Ni films were investigated. The UBM C : Ni thin films exhibited uniformly smooth surfaces. The rms surface roughness and friction coefficient values of the C : Ni films decreased with the increase in target power density. The physical properties of the films such as hardness and elastic moduli increased while their electrical properties such as resistivity decreased with the increase in the target power density. These results show that an increase of the power density leads to an increase in the proportion of Ni and nanocrystallization of the amorphous carbon film; this contributes to the changes observed in the physical and electrical characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.155-156
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• 2006

Single crystalline ZnO fims were successfully grown on r-plane sapphire substrate by plasma-assisted molecular beam epitaxy. Epitaxial relationship between the ZnO film and the-r-plane sapphire was determined to be [-1101]$Al_2O_3\;{\parallel}$ [0001]ZnO, [11-20]$Al_2O_3\;{\parallel}$ [-1100]ZnO based on the in-situ RHEED analysis and confirmed again by HRXRD measurements. Grown (11-20) ZnO films showed faceted structure along the <0001> direction and the RMS roughness was about 4 nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.342-347
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• 2007

$Bi_6Mg_2Nb_4O_{21}(BMN)$ thin films were deposited at various substrates by sputtering system for embedded capacitor applications. BMN thin films deposited at room temperature are manufactured as MIM(Metal/Insulator/Metal) structures. Dielectric properties and leakage current density were investigated as a function of various substrates and thickness of BMN thin films. Leakage current density of BMN thin films deposited on CCL(Copper Clad Laminates) showed relatively high value ($1{\times}10^{-3}A/cm^2$) at an applied field of 300 kV/cm on substrates, possibly due to relatively high value of roughness(rms $50{\AA}$) of CCL substrates. 100 nm-thick BMN thin films deposited on Cu/Ti/Si substrates showed the capacitance density of $300 nF/cm^2$, a dielectric constant of 32, a dielectric loss of 2 % at 100 kHz and the leakage current density of $1{\times}10^{-6}A/cm^2$ at an applied field of 300 kV/cm. BMN capacitors are expected to be promising candidates as embedded capacitors for printed circuit board(PCB).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.137-141
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• 2009

AZO transparent conductive thin films were grown on $SiO_2$/Si and glass substrates using diethylzinc (DEZ) and trimethylaluminium (TMA) as the precursor and $H_2O$ as oxidant by atomic layer deposition. The structural, electrical, and optical properties of the AZO films were characterized as a function of film thickness at a deposition temperature of $150^{\circ}C$. The AZO films with various thicknesses show well-crystallized phases and smooth surface morphologies. The 190-nm-thick AZO films grown on Coming 1737 glass substrates exhibit rms(root mean square) roughness of 8.8 nm, electrical resistivity of $1.5{\times}10^{-3}\;{\Omega}-cm$, and an optical transmittance of 84% at 600nm wavelength. Atomic layer deposition technique for the transparent conductive oxide films is possible to apply for the deposition on flexible polymer substrates.

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.48-56
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• 2011

Black cobalt solar selective coatings were prepared by thermal oxidation of electroplated cobalt metal on copper and nickel substrates. The optical properties and structure of the black cobalt selective coating for solar energy utilizations were characterized by glow discharge spectrometry (GDS), ultraviolet-visible-near infrared (UV-VIS-NIR) spectrometer, atom force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). The optical properties of optimum black cobalt selective coating prepared on copper substrate were a solar absorptance of 0.82 and a thermal emittance of 0.01. From the GDS depth profile analysis of these coatings, the concentration of cobalt particles near the interface was higher than at the surface, but oxygen concentration at the surface was higher than at the interface. These results suggest that the selective absorption was dominated by this chemical composition variation in the coating. The surface of this film exhibited morphology with root-mean-square(rms) roughness of about 144.3nm. XPS measurements data showed that several phases of Co coexist($Co_3O_4$,CoO) in the film.

• Korean Journal of Metals and Materials
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• v.47 no.1
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• pp.38-43
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• 2009

To investigate the effect of RF power on the structural, optical and electrical properties of amorphous InGaZnO (a-IGZO), its thin films and TFTs were prepared by RF magnetron sputtering method with different RF power conditions of 40, 80 and 120 W at room temperature. In this study, as RF power during the deposition process increases, the RMS roughness of a-IGZO films increased from 0.26 nm to 1.09 nm, while the optical band-gap decreased from 3.28 eV to 3.04 eV. In the case of the electrical characteristics of a-IGZO TFTs, the saturation mobility increased from $7.3cm^2/Vs$ to $17.0cm^2/Vs$, but the threshold voltage decreased from 5.9 V to 3.9 V with increasing RF power. It is regarded that the increment of RF power increases the carrier concentration of the a-IGZO semiconductor layer due to the higher generation of oxygen vacancies.

• Progress in Superconductivity and Cryogenics
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• v.10 no.3
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• pp.5-8
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• 2008

On highly-textured IBAD-MgO templates, we have tried to find proper buffer layers among various candidate materials, including $LaMnO_3$ (LMO), $La_2Zr_2O_7$ (LAO), $LaAlO_3$ (LAO), $LaGaO_3$ (LGO), $NdGaO_3$ (NGO), and $BaZrO_3$ (BZO). All buffer layers were deposited on the IBAD-MgO templates by KrF pulsed laser deposition(PLD). LAO layer showed an armorphous phase. LZO, LGO, and NGO layers showed polycrystalline growth. Only LMO and BZO layers exhibited c-axis oriented biaxially textured films. Optimally processed LMO buffer layer at deposition temperature of $750^{\circ}C$ and $PO_2$ of 100mTorr exhibited ${\triangle}{\phi}$ value of ${\sim}-5.2^{\circ}$ and RMS roughness of 5.6nm. Interestingly, BZO buffer layers with ${\triangle}{\phi}$ values of ${\sim}-6^{\circ}$ could be routinely produced over a wide PLD processing condition.