• Applied Science and Convergence Technology
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• v.26 no.2
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• pp.26-29
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• 2017

Thin films of europium-doped yttrium oxide ($Y_2O_3$:Eu) were prepared on Si (100) substrates by using a radio frequency (RF) magnetron sputtering. After the deposition, the films were annealed at $1000^{\circ}C$ in an air ambient for 1 hour. X-ray diffraction analysis revealed that the $Y_2O_3$:Eu films had a polycrystalline cubic ${\alpha}-Y_2O_3$ structure. The as-deposited films showed no photoluminescence (PL), which was due to poor crystalline quality of the films. The crystallinity of the $Y_2O_3$:Eu films was significantly improved by annealing. The strong red PL emission was observed from the annealed $Y_2O_3$:Eu films and the highest intensity peak was centered at around 613 nm. This emission peak originated from the $^5D_0{\rightarrow}^7F_2$ transition of the trivalent Eu ions occupying the $C_2$ sites in the cubic ${\alpha}-Y_2O_3$ lattice. The broad PL excitation band was observed at wavelengths below 280 nm, which was attributed to the charge transfer transition of the trivalent Eu ion.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1055-1061
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• 1999

Indium Tin Oxide (ITO) films were fabricated by vacuum deposition technique and their microwave shielding properties were investigated for the application to the transparent shield material. The vacuum coating was conducted in a RF co-sputtering machine. The film composition and structure associated with the sputtering conditions (argon and oxygen pressure. substrate temperature. RF input power) were investigated for the attainment of high electrical conductivity and good transparency. The electrical conductivity of IT0 films fabricated under the optimum deposition conditions (substrate temperature : $300^{\circ}C$. Ar flow rate : 20 sccm, Oxygen flow rate : 10 sccm, In/Sn input power : 50/30 W) showed 5.6$\times10^4$mho/m. The optical transparency is also considerably good. The microwave shielding properties including the dominant shielding mechanism are investigated from the electrical conductivity, thickness and skin depth of the ITO films. The total shielding effectiveness is then estimated to be 26 dB, which provides a suggestion that the IT0 films can be effectively used as the transparent shield material.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.4 s.346
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• pp.1-7
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• 2006

AlN thin films have been fabricated by using RF magnetron sputtering method and their crystal orientations, microstructures and piezoelectric properties have been investigated with variation of the $Ar/N_2$ gas ratio and the substrate temperature. Particularly, when the $Ar/N_2$ gas ratio and the substrate temperature are 10/10 (sccm) and $400^{\circ}C$, respectively, the AlN thin film exhibits the highest (002) orientation. The result of the surface roughness measurement by using AFM shows that the surface roughness becomes better as the partial pressure of $N_2$ increases at the substrate temperature of $400^{\circ}C$ and it becomes the smallest value of 2.1 nm when $Ar/N_2$ is 0/20 (sccm). The AFM measurement also shows that when $Ar/N_2$ is 10/10 (sccm) shows that surface roughness becomes better as the substrate temperature increases from room temperature up to $300^{\circ}C$ and then it becomes worse as the substrate temperature goes up from $300^{\circ}C$. At the substrate temperature of $300^{\circ}C$ and $Ar/N_2$=10/10 (sccm), the surface roughness is 3.036 nm. The piezoelectric constant ($d_{33}$) of AlN thin film is measured by Pneumatic probe method. The measurement shows that the AlN thin film with the highest (002) orientation, fabricated at $Ar/N_2$=10/10 (sccm) and the substrate temperature of $400^{\circ}C$, has the best Piezoelectric constant ($d_{33}$) of 6.01 pC/N.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.414-420
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• 2001

A 30-kV plasma immersion ion implantation setup (P $I^3$) has been equipped with a self-developed 6'-magnetron to perform hard coatings with enhanced adhesion by P $I^3$D(P $I^3$ assisted deposition) process. Using ICP source with immersed Ti antenna and reactive magnetron sputtering of Ti target in $N_2$/Ar ambient gas mixture, the TiN films were prepared on Si substrates at different pulse bias and ion-to-atom arrival ratio ( $J_{i}$ $J_{Me}$ ). Prior to TiN film formation the nitrogen implantation was performed followed by deposition of Ti buffer layer under A $r^{+}$ irradiation. Films grown at $J_{i}$ $J_{Me}$ =0.003 and $V_{pulse}$=-20kV showed columnar grain morphology and (200) preferred orientation while those prepared at $J_{i}$ $J_{Me}$ =0.08 and $V_{pulse}$=-5 kV had dense and eqiaxed structure with (111) and (220) main peaks. X-ray diffraction patterns revealed some amount of $Ti_{x}$ $N_{y}$ in the films. The maximum microhardness of $H_{v}$ =35 GN/ $M^2$ was at the pulse bias of -5 kV. The P $I^3$D technique was applied to enhance wear properties of commercial tools of HSS (SKH51) and WC-Co alloy (P30). The specimens were 25-kV PII nitrogen implanted to the dose 4.10$^{17}$ c $m^{-2}$ and then coated with 4-$\mu\textrm{m}$ TiN film on $Ti_{x}$ $N_{y}$ buffer layer. Wear resistance was compared by measuring weight loss under sliding test (6-mm $Al_2$ $O_3$ counter ball, 500-gf applied load). After 30000 cycles at 500 rpm the untreated P30 specimen lost 3.10$^{-4}$ g, and HSS specimens lost 9.10$^{-4}$ g after 40000 cycles while quite zero losses were demonstrated by TiN coated specimens.s.

• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.128-132
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• 2009

Transparent conducting thin films of indium tin oxide(ITO) co-sputtered with aluminum-doped zinc oxide(AZO) were deposited on glass substrate by dual magnetron sputtering. It was found that the electrical properties and structural characteristics of the films are significantly changed according to the sputtering power of the AZO target. The IAZTO film prepared with D.C power of ITO at 100 W and R.F power of AZO at 50 W shows an electrical resistivity of $4.6{\times}10^{-4}{\Omega}{\cdot}cm$ and a sheet resistance of $30{\Omega}/{\square}$ (for 150 nm thick). Besides of the improvement of the electrical properties, compared to the ITO films deposited at the same process conditions, the IAZTO films have very smooth surface, which is due to the amorphous nature of the films. However, the electrical conductivity of the IAZTO films was found to be deteriorated along with the crystallization in case of the high temperature deposition (above $310^{\circ}C$). In this work, high quality amorphous transparent conductive oxide layers could be obtained by mixing AZO with ITO, indicating possible use of IAZTO films as the transparent electrodes in OLED and flexible display devices.

• Progress in Superconductivity
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• v.3 no.2
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• pp.178-182
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• 2002

Superconducting four-element patch array antenna was designed and fabricated using $high-T_{c}$ superconducting (HTS) thin film. The array antenna has single-feed circularly polarization and a resonance frequency of 11.85 GHz fur satellite communication system. To fabricate this antenna $YBa_2$$Cu_3$$O_{7-x}$(YBCO) superconducting thin films were deposited using rf-magnetron sputtering technique. Sequential rotation technique based on radiation elements($0^{\circ}$ , $90^{\circ}$, 1$80^{\circ}$, $270^{\circ}$ phase delay) was utilized to achieve circularly polarization. Simulated and measured results, the analysis on resonant frequency(fr), return loss, and bandwidth are presented. The results show that 10 dB return loss bandwidth of the array antenna is 11.04 GHz~12.59 GHz (13.15%) and 3dB axial ratio bandwidth is 11.42~12.52 GHz (9.2%).).).

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.32-39
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• 1995

SnO2/AI/Ag/AI/SnO2층 구조로 이루어진 열처리 가능한 열선반사막을 직류 스퍼터링법에 의해 soda-lime silicate 유리위에 형성시켰다. 이 코팅유리를 $650^{\circ}C$에서 열처리하면 가시광선 투과율 85%이상, plasma wavelength 970nm 이하를 얻을 수 있었다. 따라서 이 구조의 막은 유리 곡가공에 견디는 열적 안정성을 나타내었으며, 코팅유리의 열처리에 따른 전기적 특성 및 열적 안정성은 각각 Ag와 AI층의 두께에 의존하였다.

• Solar Energy
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• v.16 no.2
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• pp.87-96
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• 1996

Electochromic tungsten oxide thin films were prepared on the ITO coated glass by rf magnetron sputtering from a compressed powder tungsten oxide target in an argonoxygen atmosphere. The influence of the preparation conditions, especially the substrate temperature, on the chemical stability of film was investigated. These films were cycled in 0.6M $LiClO_4$ and 0.6M $H_2SO_4$ electrolyte respecitively, and exhibited electrochromic behavior upon the electrochemical insertion and extraction of ion. Among these tungsten oxide thin films, films prepared at a substrate temperature of $150^{\circ}C$ were found to be most stable in terms of cyclic durability.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.7
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• pp.282-287
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• 2003

″H″ type resonator has the advantage for the miniaturization of high-T7 superconducting (HTS) microstrip antenna in comparison with the conventional microstrip antenna such as rectangular type or circular type. In this paper we designed miniaturized HTS antennas using this "H"-type resonator and reported the characteristics of our antennas including return loss, bandwidth, radiation patterns, efficiency and so on. To fabricate the "H" type antenna, HTS YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) thin films were deposited on MgO substrates using rf-magnetron sputtering. For comparison between normal conducting antennas and superconducting antennas, the gold antennas with the same dimension were also fabricated. An aperture coupling was used for impedance matching between 50 $\Omega$ feed line and HTS radiating patch. The ″H" type superconducting antenna showed the performance of 1.38 in SWR, 26 % in efficiency, and 13.8 dB in the return loss superior to the normal conducting counterpart.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.13-16
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• 2009

In this study, AlN thin films were deposited on a polycrystalline (poly) 3C-SiC buffer layer for surface acoustic wave (SAW) applications using a pulsed reactive magnetron sputtering system. AFM, XRD and FT-IR were used to analyze structural properties and preferred orientation of the AlN/3C-SiC thin film. Suitability of the film in SAW applications was investigated by comparing the SAW characteristics of an interdigital transducer (IDT)/AlN/3C-SiC structure with the IDT/AIN/Si structure at 160 MHz in the temperature range $30-150^{\circ}C$. These experimental results showed that AlN films on the poly 3C-SiC layer were highly (002) oriented. Furthermore, the film showed improved temperature stability for the SAW device, $TCF\;=\;-18\;ppm//^{\circ}C$. The change in resonance frequency according to temperature was nearly linear. The insertion loss decrease was about $0.033dB/^{\circ}C$. However, some defects existed in the film, which caused a slight reduction in SAW velocity.