• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.768-771
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• 2004

Pb0.5,Sr0.5TiO3(PST) thin films were deposited on Si with MgO (100) buffer layer by the alkoxide-based sol-gel method. Structural and dielectric properties of PST thin films for the tunable microwave device applications were investigated. For the MgO/Si buffer layer, the PST thin films exhibited highly (100) orientation. The MgO buffer layer affects the stress state of the (100)-oriented PST thin films. The dielectric constant, tunability, and FOM of the highly (100)-oriented PST thin film increased with increasing annealing temperature due to the decrease in lattice distortion. The differences in dielectric properties may be attributed to the change in the film stress. The dielectric constants, dielectric loss and tunability of the PST thin films deposited on the MgO/Si substrates measured at 10 kHz were 822, 0.025, and 80.1%, respectively.

• Journal of the Semiconductor & Display Technology
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• v.13 no.2
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• pp.13-16
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• 2014

We prepared the ITO/Ag multilayer thin films on soda-lime glass substrate by the Facing Target Sputtering System (FTS) at room temperature. To confirm the effect of Ag layer in ITO/Ag multilayer thin films, we have prepared various range of Ag layer in its thickness and investigated prior to the setting of ITO/Ag multilayer thin films. The thickness of Ag layer was controlled by the sputtering deposition time. Properties of as-prepared samples were investigated by using a four-point probe, UV-Visual spectrometer with a spectral visual range (400 - 800 nm) and X-ray diffractometer (XRD). As a result, the transmittance of as-prepared samples turned out to be very low in the visible range due to light-scattering on the surface of thin film as the thickness of Ag layer got increased. However, reduction of phenomenon of light-reflection in visual range was observed around 20nm of Ag thickness. We prepared the ITO/Ag multilayer thin film with a resistivity of about $8{\times}10^{-5}[{\Omega}-cm]$ and a transmittance of more than 80 % at 550 nm.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.49-51
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• 2002

In this thesis, Josephson junction using high-Tc superconducting multi-layer thin film has been fabricated by on-axis RF magnetron sputtering method. And, the characterizations were performed by X-ray diffraction, SEM and the measuring system of critical current density. The physical properties of multi-layer superconducting thin films were also analyzed with the measured results. To fabricate the multi-layer superconducting thin films, the optimum partial pressure of Argon and Oxgen and the temperature of substrate were measured. Also, YBaCuO thin film was grown on MgO and $SrTiO_3$ substrates by rf-sputtering and LGO thin film of 30 A was epitaxially grown on the YBaCuO thin film as a josephson junction with the same condition. The schottky barrier at the contact surface between YBaCuO/LGO and YBaCuO/Au and the energy gap of 0.5 ${\sim}$ 0.6 mV in Nb were observed from the dI/dV-V of YBaCuO/LGO/Au/Nb and YBaCuO/Au/Nb.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.203.1-203.1
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• 2013

Zinc oxide (ZnO) nanocrystalline thin films on various growth temperatures for active layer and different buffer layer thickness were grown by plasma-assisted molecular beam epitaxy (PA-MBE) on Si substrates. The ZnO active layer were grown with various growth temperature from 500 to $800^{\circ}C$ and the ZnO buffer layer were grown for different time from 5 to 40 minutes. To investigate the structural and optical properties of the ZnO thin films, scanning electron microscope (SEM), X-ray diffractometer (XRD), and photoluminescence (PL) spectroscopy were used, respectively. In the SEM images, the ZnO thin films have high densification of grains and good roughness and uniformity at $800^{\circ}C$ for active layer growth temperature and 20 minutes for buffer layer growth time, respectively. The PL spectra of ZnO buffer layers and active layers display sharp near band edge (NBE) emissions in UV range and broad deep level emissions (DLE) in visible range. The intensity of NBE peaks for the ZnO thin films significantly increase with increase in the active layer growth temperature. In addition, the NBE peak at 20 minutes for buffer layer growth time has the largest emission intensity and the intensity of DLE peaks decrease with increase in the growth time.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.147-147
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• 2015

The multilayer structure of the organic light emitting diode has merits of improving interfacial characteristics and helping carriers inject into emission layer and transport easier. There are many reports to control hole injection from anode electrode by using transition metal oxide as an anode buffer layer, such as V2O5, MoO3, NiO, and Fe3O4. In this study, we apply thin films of LiF which is usually inserted as a thin buffer layer between electron transport layer(ETL) and cathode, as an anode buffer layer to reduce the hole injection barrier height from ITO. The thickness of LiF as an anode buffer layer is tested from 0 nm to 1.0 nm. As shown in the figure 1 and 2, the luminous efficiency versus current density is improved by LiF anode buffer layer, and the threshold voltage is reduced when LiF buffer layer is increased up to 0.6 nm then the device does not work when LiF thickness is close to 1.0 nm As a result, we can confirm that the thin layer of LiF, about 0.6 nm, as an anode buffer reduces the hole injection barrier height from ITO, and this results the improved luminous efficiency. This study shows that LiF can be used as an anode buffer layer for improved hole injection as well as cathode buffer layer.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.943-946
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• 2011

The electronic absorption and surface morphology evolution of two types of molecular double layer thin films, copper phthalocyanine (CuPc) layer deposited on chloro[subphthalocyaninato]boron(III) (SubPc) layer, denoted as SubPc/CuPc, and vice versa, with various thicknesses were investigated using ultraviolet (UV)-visible spectroscopy and atomic force microscopy (AFM). Both types of double layer structures showed similar broadened absorption patterns in the UV-visible region that were consistent with the fitted spectra following simple linear combination of the single layer absorption spectra of the two materials. In contrast, the surface morphology of double layer structures was dependent on the order of deposition. For the CuPc/SubPc structures, surface morphology was characterized by elongated grains, which are characteristic of SubPc thin films, indicating that the morphological influence of the underlying CuPc layer on the subsequent SubPc layer was not large. For the SubPc/CuPc structures, however, the underlying SubPc layer acted as a morphological template for the subsequently deposited CuPc layer. It was also observed that the grain size of the CuPc layer varied according to the thickness of the underlying SubPc layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.354-357
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• 1999

This paper describes on the electrical and physical charateristics thin-film type Pt-RTD\\`s on Si wafers, in which MgO thin-films were used as medium layer in order to improve adhesion of Pt thin-films to SiO$_2$ layer. The MgO medium layer had the properties of improving Pt adhesion to SiO$_2$ and insulation without chemical reaction to Pt thin-films and the resistivity of Pt thin-films was improved. In the analysis of properties of Pt-RTD, TCR value had 3927 ppm/$^{\circ}C$ and liner in the temperature range of room temperature to 40$0^{\circ}C$

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1189-1192
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• 1993

Organic thin films were fabricated an using interelectrode capacitively coupled type plasma polymerizaion apparatus, and their optical properties were investigated. A deposition rate of styrene thin films is linearly increased, but one or vinyl-pyridine thin films is nonlinearly increased with increasing of polymerization time, pressure and monomer flow rate. The transmittance of single layer thin films is constant, but that of multi-layer appeared irregular peak with increasing of the number of layers. And then the refractive index of organic thin films is various from 1.55 to 1.65 with wavelength, the extinction coefficient indicated $10^{-3}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.627-630
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• 2002

Bi$_2$Sr$_2$CuOx(Bi-2201) thin films were fabricated by atomic layer-by-layer deposition using an ion bean sputtering method. 10 wt% and 90 wt% ozone mired with oxygen were used with ultraviolet light irradiation to assist oxidation. XRD and RHEED investigations revealed that a buffer layer is formed at the early stage of deposition (less than 10 unit cell), and then c-axis oriented Bi-2201 grows on top of it.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.215.2-215.2
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• 2015

We fabricated dual active layer (DAL) thin film transistors (TFTs) with indium tin zinc oxide (ITZO) and indium gallium zinc oxide (IGZO) thin film layers using solution process. The ITZO and IGZO layer were used as the front and back channel, respectively. In order to investigate the bias stress stability of ITZO SAL (single active layer) and ITZO/IGZO DAL TFT, a gate bias stress of 10 V was applied for 1500 s under the dark condition. The SAL TFT composed of ITZO layer shows a poor positive bias stability of ${\delta}VTH$ of 13.7 V, whereas ${\delta}VTH$ of ITZO/IGZO DAL TFT was very small as 2.6 V. In order to find out the evidence of improved bias stress stability, we calculated the total trap density NT near the channel/gate insulator interface. The calculated NT of DAL and SAL TFT were $4.59{\times}10^{11}$ and $2.03{\times}10^{11}cm^{-2}$, respectively. The reason for improved bias stress stability is due to the reduction of defect sites such as pin-hole and pores in the active layer.