• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.244-247
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• 1995

Physical, electrical and optical properties of Aluminum(Al) thin films were investigated in order to establish the optimum sputtering parameters in mirror reflection films. Al. thin films deposited on corning glass substrate by DC magnetron sputtering were grown as a variation of the input power, operation pressure and deposition time. The properties of the Al thin films have been discussed by deposition rate, SEM, XRD, sheet resistivity, resistivity and reflectance. Al thin films were obtained at the deposition conditions as follows: operating pressure, 3 mtorr; DC input power desnsitiy, 3W/$\textrm{cm}^2$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.378-382
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• 2003

Transparent conductive oxides (TCO) are necessary as front electrode for most thin film solar cell. In our paper, transparent conducting aluminum-doped Zinc oxide films (ZnO:Al) were prepared by rf magnetron sputtering on glass (Corning 1737) substrate as a variation of the deposition condition. After deposition, the smooth ZnO:Al films were etched in diluted HCI (0.5%) to examine the electrical and surface morphology properties as a variation of the time. The most important deposition condition of surface-textured ZnO films by chemical etching is the processing pressure md the substrate temperature. In low pressures (0.9mTorr) and high substrate temperatures ($\leq$$300^{\circ}C$), the surface morphology of films exhibits a more dense and compact film structure with effective light-trapping to apply the silicon thin film solar cells.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.314-319
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• 1998

TiN thin films were deposited on SKD 61 steel substrates by reactive sputtering under various deposition conditions, and subsequently their growth characteristics and properties were studied. Deposition rate was proportionally increased with total gas pressure as well as RF input power, while the increase of nitrogen in the reaction gas induced a significant suppression of deposition rate. The resulted films exhibited hillocks on the surface. The TiN film prepared using a typical deposition condition showed a (111) preferred orientation and maintained the stoichiometry of pure TiN.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.89-92
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• 2003

ITO thin films were deposited by RF-magnetron sputtering method and crystallization behavior of the films with and without external heating as a function of deposition time was examined. X-ray diffraction results indicated an amorphous state of the film when the deposition time is short about 10 min. When the deposition time was increased over 20 min development of crystallization of the films is observed. Because RF-sputtering transfers the high-energy to the growing film by energetic bombardment, it is believed that considerable activation energy for the crystallization of the film has transferred during deposition, which resulted in the crystallization of ITO thin films without external energy supply.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.97-100
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• 2000

Bi$_2$Sr$_2$CuO$\sub$x/(Bi(2201)) thin films are fabricated by atomic layer by layer deposition using ion beam sputtering(IBS) method. During the deposition, 10 %-ozone/oxygen mixture gas of typical 5.0 ${\times}$ 10$\^$-5/. Torr is applied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then c-axis oriented Bi(2201) is grown.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.676-680
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• 2008

TiN thin films were deposited on a $SiO_2(2000{\AA})/Si$ substrate by radio-frequency(rf) magnetron sputtering. TiN films were prepared under varying $N_2$ concentration in $N_2/Ar$ gas mix, rf power and gas pressure, and investigated in terms of deposition rate, resistivity and surface morphology. As $N_2$ concentration increased, the deposition rate and the surface roughness of the films decreased and the resistivity increased. With increasing rf power, the deposition rate increased but the resistivity was decreased. As gas pressure increased, little change in deposition rate was obtained but the resistivity rapidly increased. TiN film with resistivity of $2.46{\times}10^{-4}{\Omega}cm$ at 1 mTorr was formed. It was observed that there existed a correlation between the deposition rate and resistivity. In particular, the gas pressure has a strong influence on the resistivity of thin films.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.11
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• pp.36-43
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• 2008

In this parer aluminium-doped zinc oxide(ZnO:Al) conducting layer was deposited on polyethylene terephthalate(PET) substrate by r. f. magnetron sputtering method. The effects of gas pressure and r. f. sputtering power on the structural and electrical properties of ZnO:Al thin film were investigated experimentally. Especially the effect of position of PET substrate on the electrical properties of the film was studied and fixed to improve the electrical properties and also to increase the deposition rate. The results show that the structural and electrical properties of ZnO:Al thin film were strongly influenced by the gas pressure and sputtering power. The minimum resistivity of $1.1{\times}10^{-3}[{\Omega}-cm]$ was obtained at 5[mTorr] of gas pressure, and 18D[W] of sputtering power. The deposition rate of ZnO:Al film at 5[mTorr] of gas pressure was 248[nm/min]. and is higher by around 3 times compared to that at 25[mTorr].

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.3
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• pp.588-593
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• 2010

Sputter deposition on a Pt counter electrode was studied using radio frequency (RF) plasma as the improvement of incident photon to current conversion efficiency (IPCE) for dye-sensitized solar cells (DSCs). Effects of the sputtering thickness and the incident angle on a Pt counter electrode for DSCs were investigated. Experiments to get the optimal sputtering time for the performance of the DSCs were carried out. And it is found that the optimized sputtering time was 120 seconds, in addition, the incident angles of the substrate was adjusted from $0^{\circ}$ to $60^{\circ}$. The maximum efficiency of 5.37% was obtained at the incident angle of $40^{\circ}$ with an active cell area of $1cm^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.99-99
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• 2010

Recently, amorphous transparent oxide semiconductors (TOS) have been widely studied for many optoelectronic devices such as AM-OLED (active-matrix organic light emitting diodes). The TOS TFTs using a-IGZO channel layers exhibit a high electron mobility, a smooth surface, a uniform deposition at a large area, a high optical transparency, a low-temperature fabrication. In spite of many advantages of the sputtering process such as better step coverage, good uniformity over large area, small shadow effect and good adhesion, there are not enough researches about characteristics of a-IGZO thin films. In this study, therefore, we focused on the electrical properties of a-IGZO thin films as a channel layer of TFTs. TFTs with the a-IGZO channel layers and Y2O3 gate insulators were fabricated. Source and drain layers were deposited using ITO target. TFTs were deposited on unheated non-alkali glass substrates ($5cm{\times}5cm$) with a sintered ceramic IGZO disc (3 inch $\varnothing$, 5mm t), Y2O3 disc (3 inch $\varnothing$, 5mm t) and ITO disc (3 inch $\varnothing$, 5mm t) as a target by magnetron sputtering method. The O2 gas was used as the reactive gas. Deposition was carried out under various sputtering conditions to investigate the effect of sputtering process on the characteristics of a-IGZO thin films. Correlation between sputtering factors and electronic properties of the film will be discussed in detail.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.