• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.447-450
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• 2003

This paper presents a process optimization of antireflection (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a double-layer AR (DLAR) coating of MgF$_2$/CeO$_2$. We investigated CeO$_2$ films as an AR layer because they have a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ deposited at 40$0^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04% in the wavelengths ranged from 0.4${\mu}{\textrm}{m}$ to 1.1${\mu}{\textrm}{m}$. We achieved the efficiencies of solar cells greater than 15% with 3.12% improvement with DLAR coatings. Further details on MgF$_2$, CeO$_2$ films, and cell fabrication parameters are presented in this paper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.593-596
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• 1999

This paper presents a process optimization of antireflectiun (AR) coating on crystalline Si solar cells. Theoretical and experimental investigations were performed on a doble-layer AR(DLAR) coating of MgF$_2$/CeO$_2$, We investigated CeO$_2$ films as an All layer because they hale a proper refractive index of 2.46 and demonstrate the same lattice constant as Si substrate. RF sputter grown CeO$_2$ film showed strong dependence on a deposition temperature. The CeO$_2$ film deposited at 400 $^{\circ}C$ exhibited a strong (111) preferred orientation and the lowest surface roughness of 6.87 $\AA$. Refractive index of MgF$_2$ film was measured as 1.386 for the most of growth temperature. An optimized DLAR coating showed a reflectance as low as 2.04 % in the wavelengths ranged from 0.4 7m to 1.1 7m. We achieved the efficiencies of solar cells greater than 15% with 3.12 % improvement with DLAR coatings . Further details on MgF$_2$, CeO$_2$ films, and cell fabrication Parameters are presented in this paper.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.67.1-67.1
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• 2008

• Journal of the Korean Vacuum Society
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• v.1 no.3
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• pp.389-394
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• 1992

용액분무법으로 (100) MgO 단결정 기판위에 YBa2Cu3O7-x 초전도박막을 제조하 였다. YBa2Cu3O7-x 초전도 박막의 Y, Ba, Cu 원자의 상대적인 비는 EDX의 검출 한계내에 서 1 : 2 : 3이었고, 이는 분무 용액속의 금속이온의 비와 같았다. YBa2Cu3O7-x 초전도 박 막의 결정구조는 단일 상의 사방구조였으며, 기판에 수직인 c축의 방향으로 grain이 성장되 었고, 격자상수 c0는 11.678$\AA$였다. 95$0^{\circ}C$의 공기중에서 10분간 열처리한 박막의 Tc-on=100K, Tc-zero=80K, Jc=2.5 $\times$ 104A/cm2였고, 95$0^{\circ}C$의 흐르는 산소분위기에서 10분간 열처리한 박막의 Tc-on=103K, Tc-zero=80K, Jc=1.0 $\times$ 105A/cm2였다. 초전도 박막의 미세구 조, grain 크기와 grain 경계폭은 제조후 열처리(post-annealing) 시간과 가스 분위기에 강 한 영향을 받았다.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.188-193
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• 1997

The lanthanum-modified lead titanate (PLT) thin films on (100) cleaved MgO single crystal substrate have been prepared by RF magnetron sputtering method using PbO-rich target with varing La contents. The substrate temperature, working pressure, $Ar/O_{2}$, and RF power density of PLT thin films were $580^{\circ}C$ 10mTorr, 10/1, and $1.7W/cm^{2}$, respectively. In these conditions, the c-axis growth and tetragonality of the PLT thin films decreased for addition of La content and the PLT thin films showed diffuse phase transition from high temperature XRD patterns. The infrared sensor was fabricated. The remanent polarization was above $1.71{\mu}C/cm^{2}$ and the pyroelectric voltage was above 500mV with 10:1 signal to noise ratio.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.3
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• pp.120-123
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• 2005

The 5 mol% ZnO doped $LiNbO_3$ film and the 2 mol% MgO doped $LiNbO_3$ film were grown on the $LiNbO_3$ (001) substrate by liquid phase epitaxy (LPE) method with $Li_2CO_3-V_2O_5$ flux system. The crytsallinity and the lattice mismatch between $Zn:LiNbO_3$, film and $Mg:LiNbO_3$, film were analyzed by x-ray rocking curve (XRC). In addition, the ZnO and MgO distribution in the cross-section of the multilayer thin films was observed using electron probe micro analyzer (EPMA).

• Electrical & Electronic Materials
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• v.9 no.4
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• pp.357-363
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• 1996

The superconducting properties of YBa$_{2}$Cu$_{3}$$O_{7-x}$(YBaCuO) thin films prepared by laser ablation have been investigated. The x-ray diffraction patterns of the films were substantially different from one another. The Y and Ba oxides are formed by the collisions with oxygen molecules. On the other hand, the Cu oxide is mainly formed at initial stage of the laser irradiation. The YBaCuO films manufactured on MgO(100) substrate were indicated T$_{c}$(zero)=90 K, T$_{c}$(onset)=92 K, and J$_{c}$=3.5*10$^{5}$ A/cm$^{2}$(at 77.3K). The optimum conditions were found to be a substrate temperature of 710.deg. C, an energy density of 2 J/cm$^{2}$, and a target-substrate distance of 60mm in an oxygen partial pressure of 200 mTorr.0 mTorr.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.83-86
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• 2003

YBa$_2$Cu$_3$$O_{7-x}$ thin films for coated conductor application were deposited on a MgO single crystalline substrate by a metal organic chemical vapor deposition (MOCVD) system of a vertical type using a single liquid source. The film uniformity was enhanced by controlling the gas shower head structure, the distance between the shower head and substrate, and the rotation of the substrate. The source mole ratio of Y(thd)$_3$: Ba(thd)$_2$: Cu(thd)$_2$ was changed for obtaining stoichiometric film. The phase formation, crystal orientation, surface morphology and film composition were investigated with different source mole ratios, and the critical temperature (T$_{c}$) was measured.red.

• Journal of the Korean Magnetics Society
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• v.16 no.2
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• pp.140-143
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• 2006

Single crystalline $CoFe_2O_4$ thin films on (100) MgO substrates were fabricated using a rf magnetron sputtering method. The deposited films were investigated for their crystallization by X-ray diffraction, Rutherford back-scattering spectroscopy and field emission scanning electron microscopy. When a cobalt ferrite film was deposited at the substrate temperature of $600^{\circ}C$, squared grains of about 200 nm were uniformly distributed in the film. However, the grains became irregular and their sizes also varied from 30 to 150 nm when the substrate temperature was $700^{\circ}C$. Hysteresis loops of a film deposited at $600^{\circ}C$ showed that the magnetically easy axis of the film was perpendicular to the substrate surface. Except for the squareness ratio, magnetic properties of the cobalt ferrite films grown by the present rf sputtering method were as good as those of the films prepared by a laser ablation method: The in-plane and perpendicular coercivities were 283 and 6800 Oe, respectively. As the thickness of the deposited film increased twice, the saturation magnetization became double but the coercivity remained unchanged. However, deposition of the Co ferrite films with a higher rf powder decreased the squareness ratio and the perpendicular coercivity of the films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.7
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• pp.472-476
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• 2014

We report the characteristics of thin-film transistor (TFT) to make the bi-channel structure with stacked $Mg_{0.1}Zn_{0.9}O$ (Mg= 10 at.%) and ZnO. The ZnO and $Mg_{0.1}ZnO_{0.9}O$ thin films were deposited by radio frequency (RF) co-sputter system onto the thermally oxidized silicon substrate. A total thickness of active layer was 50 nm. Firstly, the ZnO thin films were deposited to control the thickness from 5 nm to 30 nm. Sequentially, the $Mg_{0.1}ZnO_{0.9}O$ thin films were deposited to change from 45 nm to 20 nm. The bi-layer TFT shows more improved properties than the single layer TFT. The field effect mobility and subthreshold slope for $Mg_{0.1}ZnO_{0.9}O$/ZnO-TFT are $7.40cm^2V^{-1}s^{-1}$ and 0.24 V/decade at the ZnO thickness of 10 nm, respectively.