Youl-Moon Sung

Surface-discharge characteristics of MgO-thin films prepared by reactive RF unbalanced magnetron sputtering

Abstract The performance of a.c. plasma display panels (PDP) is influenced strongly by the surface glow-discharge characteristics on the MgO-thin films. This paper deals with the surface glow-discharge characteristics and some physical properties of MgO-thin films prepared by reactive RF planar unbalanced magnetron sputtering in connection with a.c. PDP. The samples prepared with the d.c. bias voltage of −10 V showed lower discharge voltage, lower erosion rate by ion bombardment, higher optical transparency and higher crack resistance in the annealing process than those samples prepared by conventional magnetron sputtering or E -beam evaporation.

Fabrication of Titanium-Doped Indium Oxide Films for Dye-Sensitized Solar Cell Application Using Reactive RF Magnetron Sputter Method

To develop high-efficiency transparent conductive oxide glass in a longer wavelength zone for dye-sensitized solar cell (DSC) application, we fabricate titanium-doped indium oxide (ITiO) films on a soda-lime glass substrate by an RF magnetron sputtering. The ITiO films showed a minimum resistivity of 1.25 times 10-3 Omega ldr cm. The transmittance increases from 80% at 450 nm to 90% at 700 nm in the visible spectrum. From the atomic force microscopy result, the surface roughness of the sample showed a change from 10 to 50 nm with annealing temperature. From the XPS result, the concentration ratio (%) for In, Ti, and O was 27 : 2 : 42. The annealing treatment on the ITiO films improves the photovoltaic characteristics of the ITiO-based DSCs, and energy conversion efficiency (eta) is 5.79% (FF: 0.62, Voc: 0.71 V, Jsc: 13.23 mA/cm2) at 100-mW/cm2 light intensity.

Comparison of transparent conductive indium tin oxide, titanium-doped indium oxide, and fluorine-doped tin oxide films for dye-sensitized solar cell application

In this study, we investigate the photovoltaic performance of transparent conductive indium tin oxide (ITO), titanium-doped indium oxide (ITiO), and fluorine-doped tin oxide (FTO) films. ITO and ITiO films are prepared by radio frequency magnetron sputtering on soda-lime glass substrate at 300 °C, and the FTO film used is a commercial product. We measure the X-ray diffraction patterns, AFM micrographs, transmittance, sheet resistances after heat treatment, and transparent conductive characteristics of each film. The value of electrical resistivity and optical transmittance of the ITiO films was 4.15×10 -4 Ω-cm. The near-infrared ray transmittance of ITiO is the highest for wavelengths over 1,000 nm, which can increase dye sensitization compared to ITO and FTO. The photoconversion efficiency (η) of the dye-sensitized solar cell (DSC) sample using ITiO was 5.64%, whereas it was 2.73% and 6.47% for DSC samples with ITO and FTO, respectively, both at 100 mW/cm 2 light intensity.

Studies on the optimum condition for the formation of a neutral loop discharge plasma

In order to obtain guidelines for the design and operation of a new plasma source by a magnetic neutral loop discharge, electron behavior was studied experimentally and numerically. Experimentally, the magnetic field gradient was changed over a wide range, and it was found that there existed an optimum value for efficient plasma production. Analyses of the electron behavior were performed using a model that included effects of a three-dimensional electromagnetic field with spatial decay of the rf electric field, and the limitation of the spatial extent of the electron motion (the existence of walls and the electron loss at wall surfaces). These factors were found to explain the existence of the optimum magnetic field gradient.

Texture, Morphology and Photovoltaic Characteristics of Nanoporous F:SnO₂ Films

The nanoporous F:SnO₂ materials have been prepared through the controlled hydrolysis of fluoro(2-methylbutan-2-oxy)di(pentan-2,4-dionato)tin followed by thermal treatment at 400-550℃. The main IR features include resonances at 660, 620 and 540 ㎝-1. From the TG-DTG result, three main mass losses of 6.5, 13.3 and 3.8 at 81, 289 and 490℃ are observed between 50 and 650℃ yielding a final residue of 76.0%. The size of Sn O2 nanoparticles rose from 5 ㎚ to 10-12 ㎚ as the temperature of thermal treatment is increased from 400 to 550℃.

Surface Treatment of

Surface processing was studied using a dc atmospheric nonthermal plasma jet with nitrogen gas as a method for preparing the glass plate with a fluorine-dope-tin-oxide membrane, coated with titanium oxide (TiO2) and sintered at 450degC for dye-sensitized solar cells. The results showed that characteristics of the TiO2 surface were enhanced by the dc atmospheric nonthermal plasma jet and, hence, the energy conversion efficiency increased by 1.3% as compared to samples without surface treatment. From the results of X-ray photoemission spectroscopy and spectroscopic analyses, it was found that the nitrogen radicals (condition from C3Piu toB3Pig) generated by the dc atmospheric nonthermal plasma jet were closely related with the enhancement of the energy conversion efficiency.

\hbox{TiO}_{2}

Abstract A new type sputter ion plating system with facing target sputtering source and RF discharge has been developed for hard coating of metals and various compound materials. In this system, the plasma density of 1010–1012 cm is obtained in the discharge space, and the electron temperature is in the range of 3–6 eV. Moreover, the incident ion energy on the substrate can be controlled by the sheath potential of the de bias applied to the substrate. The adhesive force of the TiN thin film prepared by this system on the stainless steel substrate is in the range of 20–50 N at the scratch test. The adhesive force, Vickers hardness, preferred oriemation and resistivity of the TiN thin film are influenced significantly by the dc substrate bias voltage. Moreover, by controlling the RF power the concentration ratio for Ti and N can be controlled.

Films by Pulse Plasma for Dye-Sensitized Solar Cells Application

A new type of dye-sensitized solar cell (DSC) based on a porous type Ti electrode without using a transparent conductive oxide (TCO) layer is fabricated for low-cost high-efficient solar cell application. The TCO-free DSC is composed of a glass substrate/dye-sensitized TiO₂ nanoparticle/porous Ti layer/electrolyte/Pt sputtered counter electrode. The porous Ti electrode (∼350 ㎚ thickness) with high conductivity can collect electrons from the TiO₂ layer and allows the ionic diffusion of I?/I₃?through the hole. The vacuum annealing treatment is important with respect to the interfacial necking between the metal Ti and porous TiO₂ layer. The efficiency of the prepared TCO-free DSC sample is about 3.5% (ff: 0.48, V oc : 0.64V, J sc : 11.14 ㎃/㎠).

TiN hard coating prepared by sputter ion plating system with facing target sputtering source and RF discharge

In order to study the plasma structure and its application to processing, experimental and numerical analyses of the distribution of the electron temperature (Te) and electron density (ne) in a neutral loop discharge (NLD) plasma were performed. From the experiments, NLD plasma possesses Te and ne peaks. In the cases of NL radii of RNL=80, 100, and 120 mm, the maximum values measured for Te were around the NL. However, the ne peaks of the cases mentioned were located about 30–40 mm radially inward of the NL. We calculated the electron behavior in three dimensions to analyze these measured results, taking into consideration the actual experimental conditions such as the magnetic field, antenna position, and chamber walls. We found electrons are trapped in a region that is more inward of the NL due to a mirror field that causes the peak of ne. Also it is shown that good plasma uniformity could be obtained by dynamically controlling these Te and ne peaks.

Synthesis of TCO-free Dye-sensitized Solar Cells with Nanoporous Ti Electrodes Using RF Magnetron Sputtering Technology

Abstract The plasma parameters and ion bombardment energy were quantitatively investigated to find the optimum condition and the correlation between the plasma conditions and film properties. The electron density ( n e ) of approximately 10 17 /m 3 was obtained in the substrate region under the condition where gas pressure was 1 mTorr and both power of the microwave and RF source were 500 W, and the electron temperature ( T e ) and ion saturation current ( I 0 ) were in the range of 3–5 eV and 1–1.5 mA/cm 2 , respectively. High resistivity of TiN films above −50 V bias was attributed to the amorphization of TiN films by ion bombardment effect, which was confirmed by X-ray diffraction analysis. It was found that there was an optimum bias voltage for best-quality TiN film formation, which showed a strong correlation with the ion bombardment energy.