• Journal of the Korean Vacuum Society
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• v.8 no.2
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• pp.141-147
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• 1999

The electrochromic characteristics of tungsten oxide films are largely affected by deposition conditions, such as substrate temperature and gas flow rate and also post-annealing. We have considered gas flow rate and temperature as important factors having an effect on an electrical, optical phenomenon and structural variation of $WO_3$ . The tungsten oxide films were deposited onto ITO(20$\Omega\box$, 1000$\AA$) using rf magnetron sputtering method. In particular, the films deposited at room temperature were annealed at various temperatures in air. All specimens had crystal structure except one being deposited at room temperature with nearly amorphous-like structure. The specimen deposited at $100^{\circ}C$ had a structure in which the increase in deposition temperature. The specimen deposited at $100^{\circ}C$ had a structure in which the cations$(Li^+)$ are easily movable because of void boundaries induced by regularly arrayed large grains. The specimen deposited at $300^{\circ}C$ had a dense structure with small grains but it exhibited the large mobility and charge density in $WO_3$ because of distinct grain boundaries.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.146-150
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• 1994

The simultaneous determination of Zn, Cd, Pb and Cu in 1.000%(w/v) tungsten matrix by differential pulse anodic stripping voltammetry at a hanging mercury drop electrode has been studied. Tartaric acid(pH=5.00) was used as a supporting electrolyte. Optimum analytical conditions were found that the deposition potential was -1.2 volt(vs. Ag/AgCl), the deposition time was 3 minutes. The linear concentration range of all trace metal ions in 1.000%(w/v) tungsten matrix were 10 to 50 ppb. And the detection limit(3${\sigma}$) of zinc, cadmium, lead and copper were 1.25, 1.02, 1.69, and 1.02 ppb respectively. This method was superior to the ICP-AES method which detection limits(3${\sigma}$) in 1.000%(w/v) tungsten matrix were 8.0, 5.0, 120 and 5 ppb respectively.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.147-153
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• 1998

Tungsten nitride is very attractive as absorber for X-ray lithographic mask and as a diffusion barrier for interconnecting metallization in Si VLSI technology. Microstructure of tungsten nitride films prepared by RF magnetron sputtering has been investigated as a function of deposition parameter. The crystal structure of sputtered films on silicon nitride membrane depends strongly on the NJAr gas flow ratio(0~18%1, gas pressure(l0~43mTorr). RF power (60~150W), target-substrate distance(4~8cm). Tungsten nitride films deposited at the $N_2/Ar$ gas flow ratio(- 10%). gas pressure(~10mmTorr), RF power(~150W) and target-substrate distance(6cm) are amorphous, but at other conditions are almost rough -surfaced polycrystalline. Amorphous films are very smooth($3.1\AA$ rms) and expected to be excellent absorber for X-ray mask.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.17-25
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• 1999

Tungsten nitride($WN_x$) films were deposited by PECVD method on silicon nitride($WSi_3N_4$) substrate. The characteristics of $WN_x$ film were investigated with changing various processing parameters ; substrate temperature, gas flow rate, rf power, and different nitrogen sources. The nitrogen composition in $WN_x$ film varied from 0 to 45% according to the $NH_3$ and $N_2$ flow rate. The highest deposition rate of 160 nm/min was obtained for the $NH_3$ gas and relatively low deposition rate of $WN_x$ films were formed by $N_2$ gas. $WN_x$ films deposited on $WSi_3N_4$ substrate had higher deposition rate than that of TiN and Si substrates. The purity of $WN_x$ film were analyzed by AES and higher purity $WN_x$ films were deposited using $NH_3$ gas. The XRD analysis indicates a phase transition from polycrystalline tungsten(W) to amorphous tungsten nitride($WN_x$), showing improved etching profile of $WN_x$ films Thick $WN_x$ films were deposited on various substrates such as Tin, NiCr and Al and maximum thickness of $1.6 {\mu}m$ was obtained on the Al adhesion layer.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.64-67
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• 2000

Tungsten silicide(WSi$_2$) is proposed for the alternate gate electrode of ULSI MOS devices. Good structural property and low resistivity of WSi$_2$ deposited by a low pressure chemical vapor deposition(LPCVD) method directly on SiO$_2$ is obtained after annealing. Especially, WSi$_2$-SiO2 interface remains flat after annealing tungsten silicide at high temperature. Electrical characteristics of annealed WSi$_2$-SiO$_2$-Si(MOS) capacitors were improved in view of charge trapping.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.354-355
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• 2009

In the fabrication of inverted top-emitting organic light emitting diodes (ITOLEDs), the sputtering process is needed for deposition of transparent conducting oxide (TCO) as top anode. Energetic particle bombardment, however, changes the physical properties of underlying layers. In this study, we examined plasma process effects on tungsten oxide ($WO_3$) hole injection layer (HIL). From our results, we suggest the theoretical mechanism to explain the correlation between the physical property changes caused by plasma process on $WO_3$ HIL and degradation of device performances.

• Journal of Powder Materials
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• v.25 no.1
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• pp.7-11
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• 2018

In this study, we synthesize tungsten oxide thin films by electrodeposition and characterize their electrochromic properties. Depending on the deposition modes, compact and porous tungsten oxide films are fabricated on a transparent indium tin oxide (ITO) substrate. The morphology and crystal structure of the electrodeposited tungsten oxide thin films are investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray photoelectron spectroscopy is employed to verify the chemical composition and the oxidation state of the films. Compared to the compact tungsten oxides, the porous films show superior electrochemical activities with higher reversibility during electrochemical reactions. Furthermore, they exhibit very high color contrast (97.0%) and switching speed (3.1 and 3.2 s). The outstanding electrochromic performances of the porous tungsten oxide thin films are mainly attributed to the porous structure, which facilitates ion intercalation/deintercalation during electrochemical reactions.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.268-272
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• 2003

The microstructures of tungsten films were controlled by changing the sputtering pressure and substrate temperatures during D.C. sputter deposition. As the sputtering pressures were decreased, the sputtered models of the tungsten films were changed from the zone I model to zone T model. The tungsten film having zone T model microstructure shows a resistivity of 10${\times}$10$\^$-6/ $\Omega$-cm and (110) preferred orientation. FBAR with Bragg reflector composed of $SiO_2$and tungsten films having zone T model microstructure shows quality factor, Q$\_$s/, of 494 and K$\_$eff/$\^$2/ of 5.5% due to the high acoustic impedance and the smooth surface.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.143-147
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• 2002

In this paper, we investigated the deposition condition of Bragg reflector formation that will be expected to play an important role in future FBAR device applications. The thin films were deposited using an RF/DC magnetron sputtering technique. The material characteristics such as deposition rates, grain structures and surface roughnesses of the deposited silicon dioxide (SiO$_2$) and tungsten (W) films were investigated for various deposition conditions. As a result, it was found that the deposition condition could significantly affect the material characteristics of the deposited films and also the optimization of the deposition process is essentially important to obtain the desirable Brags reflector structure consisted of high-quality in films.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2004.11a
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• pp.27-27
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• 2004