• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.143-146
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• 2009

One of the most important issues of crystalline silicon solar cell is minimizing reflectance at the surface. Laser texturing is an isotropic process that will sculpt the surface of a silicon wafer, regardless of its crystallographic orientation. We investigated surface texturing process using Nd-YAG laser ($\lambda$=1064 nm) on multi-crystalline silicon wafer. Removal of slag formed after the laser process was performed using acid solution (HF : $HNO_3$ : $CH_3COOH$ : DI water). The reflectance and carrier lifetime of the samples were measured and analyzed using UV-Vis spectrophotometer and carrier lifetime tester. It was found that the minimum reflectance of the samples was 16.39% and maximum carrier life time was $21.8\;{\mu}s$.

• Journal of the Mineralogical Society of Korea
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• v.9 no.1
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• pp.7-16
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• 1996

Partially sericitized tourmaline from a pegmatite, Black Hills, South Dakota, U.S.A., was investigated using high-resolution transmission electron microscopy (HRTEM). Muscovite occurs as the only alteration product of tourmaline, and it is developed extensively as narrow veinlets along the {110} and {100} cleavage directions of tourmaline, indicating that a cleavage-controlled alteration mechanism was dominant. Muscovite was characterized mainly as two-layer polytypes with minor stacking disorder, but tourmaline is almost free of structural defects. HRTEM images of tourmaline-muscovite interfaces revealed that the interfaces between two minerals are composed of well-defined {110} and {100} boundaries of tourmaline. The (001) of muscovite is in general parallel to the c-axis of tourmaline, but tourmaline and replacing muscovite do not show specific crystallographic orientation relationship; muscovite consists of numerous 100-1000$\AA$ thick subparallel packets, and the angles between the (001) of muscovite and (110) of tourmaline is highly variable. Al/Si ratios of both minerals suggest that tourmaline to muscovite alteration by late magnetic fluids has been facilitated by their similar Al/Si ratio in the incipient alteration stage, in that the hydration reaction with preservation of Al and Si would require only addition of K+ and H2O. Aluminous minerals other than muscovite were not characterized as the alteration products of tourmaline, indicating that tourmaline reacted directly to muscovite; the tourmaline alteration apparently occurred by the presence of residual fluids in which K+ is available and silica was not undersaturated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.3
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• pp.96-101
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• 2001

In this study, diluted magnetic $Zn_{1-x}Mn_{x}Te$ epilayers were grown on GaAs(100) substrates by hot-wall epitaxy, and their characteristics were systematically examined. The maximum Mn composition of the $Zn_{1-x}Mn_{x}Te$ epilayers was 0.97. The crystallographic orientation was toward <100> and the structure of the $Zn_{1-x}Mn_{x}Te$ epilayers was the zincblende structure, identical to those of the GaAs substrate. With increasing the substrate temperature (350~$400^{\circ}C$), Mn composition increased (0.02~0.23) and he quality of the epilayer became worse. The lattice constants increased linearly with increasing Mn composition, but the band gap energy increased nonlinearly with increasing x.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2214-2218
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• 2007

The effects of bath temperature on electrochemical behavior, alloy composition, crystallographic structure, morphology and the magnetic properties of electrodeposited Co-Pt-W(P) films were investigated. Electrochemical studies show that alloy electrodeposition has been shifted to more positive potentials and the critical time for nucleation decreased as electrolyte temperature increased. As the temperature increased from 40 oC to 80 oC, tungsten content in the deposit increased, while phosphorus content decreased. The films deposited at T = 40 oC exhibited soft magnetic properties. However, electrodeposited at T = 70 oC, the films exhibited hard magnetic properties. It is also demonstrated that higher temperature more than 70 oC could weaken hard magnetic properties. XRD results indicated that the deposits obtained at 50 oC-70 oC showed enhancement of [00.1] P.O. (preferred orientation) with the bath temperature, which resulted in the stronger perpendicular magnetic anisotropy.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.531-534
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• 2015

In this work, we undertake a comparative study of the crystallographic microstructures and photo-catalytic properties of rutile $TiO_2$ nanorods grown on FTO facing up and down by a hydrothermal method. An analysis of the fine structures showed that $TiO_2$ nanorods grown on FTO facing up were mixed with sea urchin and microsphere. These structures induced a vertical orientation of the nanorods on FTO. The saturated photocurrent densities of the $TiO_2$ nanorods grown both up and down were $1.5mA/cm^2$ in the former case, the IPCE was increased to 10% at 300~350 nm. The onset potential (${\fallingdotseq}$ flat band potential) of the nanorods grown on FTO facing up is negatively shifted to a value of -0.31 V. This is caused by an increase in the surface state, in this case the number of oxygen vacancies, and by the formation of $Ti^{3+}$. Therefore, the FTO facing direction is considered as a critical factor during the hydrothermal reaction for $TiO_2$ growth so as to develop an efficient photo-catalytic system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.305-309
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• 2002

We have successfully fabricated a Metal-Ferroelectric-Insulator-Semiconductor (MFIS) structure using Bi$\sub$4-x/La$\sub$x/Ti$_3$O$\sub$12/ (BLT) ferroelectric thin film and SiO$_2$/Nitride/SiO$_2$ (ONO) stacked buffer layers for single transistor type ferroelectric nonvolatile memory applications. BLT films were deposited on 15 nm-thick ONO buffer layer by sol-gel spin-coating. The dielectric constant and the leakage current density of prepared ONO film were measured to be 5.6 and 1.0 x 10$\^$-8/ A/$\textrm{cm}^2$ at 2MV/cm, respectively, It was interesting to note that the crystallographic orientations of BLT thin films were strongly effected by pre-bake temperatures. X-ray diffraction patterns showed that (117) crystallites were mainly detected in the BLT film if pre-baked below 400$^{\circ}C$. Whereas, for the films pre-baked above 500$^{\circ}C$, the crystallites with preferred c-axis orientation were mainly detected. From the C-V measurement of the MFIS capacitor with c-axis oriented BLT films, the memory window of 0.6 V was obtained at a voltage sweep of ${\pm}$8 V, which evidently reflects the ferroelectric memory effect of a BLT/ONO/Si structure.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1279-1281
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• 1998

The Co-Cr thin films are one of the most suitable candidates for perpendicular magnetic recording media. The facing targets sputtering(FTS) method has a advantage of preparing films over a wide range of working gas pressure on plasma-free substrates. In this study, we investigated the possibility of employing FTS system for depositing Co-Cr films, Co-Cr thin films were deposited with continuously sputter gas pressure ($P_{Ar}$ = 0.1 mTorr) by FTS method at temperature of $40^{\circ}C$. We find that the change of thickness and deposition rate of sputtered Co-Cr thin films affect crystal orientation and magnetic properties. Crystallographic and magnetic properties were evaluated by x-ray diffractometry(XRD) and vibrating sample magnetometer(VSM) respectively. It has been confirmed that the FTS method is very useful for preparing Co-Cr thin film recording media.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.222-227
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• 2010

ZnO nanorods array have been grown on the seed crystal coated Si(100) substrate by hydrothermal method. The growth, structural and optical properties of ZnO nanorods array were investigated with a variation of precursor concentration from 0.01 M to 0.04 M. The array density of grown ZnO nanorods per same area was increased with increasing the concentration of precursor solution. Vertically aligned ZnO nanorods with hexagonal wurtzite structure have highly preferred c-axis orientation along (002) lattice plane. Especially, ZnO nanorods array developed from 0.04 M precursor solution showed a diameter of about 85 nm and length of 1.2 {\mu}m$ without any crystallographic defects. The photoluminescence spectra of ZnO nanorods from heavier precursor concentration exhibited stronger UV emission around 380 nm corresponding with near-band-edge emission.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.150-156
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• 2001

Nea-inositol is triclinic P???, with a =4.799(1), b=6.520(1), c=6.505(1) Å, α=70.61(1), β=69.41(1), γ=73.66(1)°, Z=1, molecular symmetry ???. Scyllo-inositol, from A, is monoclinic, P2₂/c, with a=5.089(1), c=11.948(2)Å, β=116.98(2)°, Z=2, molecular symmetry ???. Form B is triclinic, P???, with a=6.725(1), b=6.797(1), c=8.635(2)° Å, α=95.45(2), β=99.49(2), γ=99.19(2)°, Z=2, molecular symmetry ???. This crystal structure is pseudo-monoclinic, having two centrosymmetrical molecules with the almost identical conformation and orientation in the crystal lattice. The molecules have the expected chair conformations with puckering parameters of Q=0.609(2)Å for n대, 0.581(2)Å for Scyllo-A, and 0.566(2) Å for Scyllo-B. The bond lengths and angles are normal, C-C, 1.505 to 1.531 8A, C-O, 1.415 to 1.440 Å, C-C-C, 108.2 to 112.9°. The molecules are linked by systems of finite and infinite chains of hydrogen bonds.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.171-176
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• 2001

HgCdTe films were grown on the (100). (111), (211) CdZnTe, and (100) GaAs substrates by metal organic chemical vapor epitaxy. We have investigated the surface morphology, electrical properties, crystalline qualities, and composition of HgCdTe with substrates orientation. Three dimensional facet growth was occurred on (111) CdZnTe substrate. The crystalline quality of HgCdTe on (100) CdZnTe was superior to that of HgCdTe on (100) GaAs. FWHM values of double crystal x-ray diffraction of HgCdTe on (100) CdZnTe and (100) GaAs were 55 and 125arcsec, respectively. HgCdTe on GaAs substrate showed n-type conductivity with high mobility, however, HgCdTe on CdZnTe showed p-type conductivity with carrier concentration of higher than 10/sup 16/㎤.