• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.154-154
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• 2003

A stoichiometric mixture of evaporating materials for CuGaSe2 single crystal thin films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal CuGaSe2, it was found tetragonal structure whose lattice constant at and co were 5.615 ${\AA}$ and 11.025 ${\AA}$, respectively. To obtain the single crystal thin films, CuGaSe2 mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (MWE) system. The source and substrate temperatures were Slot and 450$^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (UXD). The carrier density and mobility of CuGaSe2 single crystal thin films measured with Hall effect by van der Pauw method are 5.0l${\times}$10$\^$17/ cm$\^$-3/ and 245 $\textrm{cm}^2$/V$.$s at 293K, respectively. The temperature dependence of the energy band gap of the CuGaSe2 obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 1.7998 eV - (8.7489${\times}$10$\^$-4/ eV/K)T$^2$/(T + 335 K. After the as-grown CuGaSe2 single crystal thin films was annealed in Cu-, Se-, and Ca-atmospheres, the origin of point defects of CuGaSe2 single crystal thin films has been investigated by the photoluminescence(PL) at 10 K The native defects of V$\_$CU/, V$\_$Se/, Cu$\_$int/, and Se$\_$int/ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted CuGaSe2 single crystal thin films to an optical n-type. Also, we confirmed that Ga in CuGaSe2/GaAs did not form the native defects because Ga in CuGaSe2 single crystal thin films existed in the form of stable bonds.

• 한국콘텐츠학회논문지
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• 제18권10호
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• pp.361-367
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• 2018

이 연구의 목적은 불화 수소산 에칭 처리가 안정화된 정방 정계 지르코니아 다결정 (Y-TZP)의 결합 강도에 미치는 영향을 평가하는 것이었다. 4 그룹의 지르코니아 - 수지 시멘트 시편을 준비 하였다. 1) ZGS 그룹 (zirconia, no treatment) 2) ZGSH 그룹 (zirconia, hydrofluoric acid etching treatment) 3) H-ZGS 그룹 (Hybrid zirconia, no treatment) 4) H-ZGSH 그룹 (Hybrid zirconia, hydrofluoric acid etching treatment). 지르코니아와 도재 사이의 전단 결합 강도는 Instron Universal Testing Machine (ModelBBP-500, Instron Corporation, Kyunggi, Korea)을 사용하여 측정 하였다. 독립표본 t-test와 two-way ANOVA (${\alpha}=0.05$)를 사용하여 데이터를 통계적으로 분석했다. 세라믹 - 수지 시멘트 결합강도는 불화 수소산 에칭 처리에 영향을 받았다 (p <0.05). 파단 표면의 디지털 현미경 검사는 불화 수소산 에칭 처리한 표면처리 된 지르코니아 및 하이브리드 지르코니아 그룹에서 접착성 및 응집성 파절이 동시에 발생하는 결함을 보였다.

• 한국결정학회지
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• 제11권4호
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• pp.212-223
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• 2000

A stochiometric mix of CuInTe₂ polycrystal was prepared in a honizonatal furnace. To obtain the single crystal thin films, CuInTe₂ mixed crystal was deposited on throughly etched GaAs(100) by the HWE system. The source and substrate temperatures were 610℃ and 450℃ respectively, and the thickness of the deposited single crystal thin film was 2.4㎛. CuInTe₂ single crystal thin film was proved to be the optimal growth condition when the excition emission spectrum was the strongest at 1085.3 nm(1.1424 eV) of photoluminescence spectrum at 10 K, and also FWHM of Double Crystal X-ray Rocking Curve (DCRC) was the smallest, 129 arcsec. The Hall effect on this sample was measured by the method of Van der Pauw, and the carrier density and mobility dependent on temperature were 9.57x10/sup 22/ electron/㎥, 1.31x10/sup -2/㎡/V·s at 293 K, respectively. The ΔCr(Crystal field splitting) and the ΔSo (spin orbit coupling splitting( measured at f10K from the photocurrent peaks in the short wavelength of the CuInTe₂ single crystal thin film were about 0.1200 eV, 0.2833 eV respectively. From the PL spectra of CuInTe₂ single crystal thin film at 10 K, the free exciton (E/sub x/) was determined to be 1064.5 nm(1.1647 eV) and the donor-bound exciton(D/sup 0/, X) and acceptor-bound exciton (A/sup 0/, X) were determined to be 1085.3 nm(1.1424 eV) and 1096.8 nm(1.1304 eV0 respectively. And also, the donor-acciptor pair (DAP)P/sub 0/, DAP-replica P₁, DAP-replica P₂ and self-activated (SA) were determined to be 1131 nm (1.0962 eV), 1164 nm(1.0651 eV), 1191.1 nm(1.0340 eV) and 1618.1 nm (0.7662 eV), respectively.

• 한국초전도ㆍ저온공학회논문지
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• 제15권3호
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• pp.5-8
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• 2013

We have studied Hall effect for potassium (K)-doped $BaFe_2As_2$ superconducting thin films by analyzing the relation between the longitudinal resistivity (${\rho}_{xx}$) and the Hall resistivity (${\rho}_{xy}$). The thin films used in this study were fabricated on $Al_2O_3$ (000l) substrates by using an ex-situ pulsed laser deposition (PLD) technique under a high-vacuum condition of ~$10^{-6}$ Torr. The samples showed the high superconducting transition temperatures ($T_c$) of ~ 40 K. The ${\rho}_{xx}$ and the ${\rho}_{xy}$ for K-doped $BaFe_2As_2$ thin films were measured by using a physical property measurement system (PPMS) with a temperature sweep (T-sweep) mode at an applied current density of $100A/cm^2$ and at magnetic fields from 0 up to 9 T. We report the T-sweep results of the ${\rho}_{xx}$and the ${\rho}_{xy}$ to investigate Hall scaling behavior on the basis of the relation of ${\rho}_{xy}={A{\rho}_{xx}}^{\beta}$. The ${\beta}$ values are $3.0{\pm}0.2$ in the c-axis-oriented K-doped $BaFe_2As_2$ thin films, whereas the thin films with various oriented-directions like a polycrystal showed slightly lower ${\beta}$ than that of c-axis-oriented thin films. Interestingly, the ${\beta}$ value is decreased with increasing magnetic fields.

• 대한치과보철학회지
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• 제46권3호
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• pp.227-237
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• 2008

STATEMENT OF PROBLEM: Zirconium oxide can be a substitute to titanium as implant materials to solve the esthetic problems of dark color in the gingival portion of implant restorations. PURPOSE: This study was performed to define attachment and growth behavior of osteoblast- like cells cultured on grooved surfaces of zirconium oxide and evaluate the genetic effect of zirconium oxide surfaces using the reverse transcriptase-polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: MC3T3-E1 cells were cultured on (1) commercially pure titanium discs with smooth surface (T group), (2) yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) with machined surface (ZS group), and (3) Y-TZP with $100{\mu}m$ grooves (ZG group). Cell proliferation activity was evaluated through MTT assay and cell morphology was examined by SEM. The mRNA expression of Runx2, alkaline phosphatase, osteocalcin, TGF-${\beta}1$, IGF-1, G3PDH in E1 cells were evaluated by RT-PCR. RESULTS: From the MTT assay, after 48 hours of adhesion of MC3T3-E1 cells, the mean optical density value of T group and ZG group significantly increased compared to the ZS group. SEM images of osteoblast-like cells showed that significantly more cells were observed to attach to the grooves and appeared to follow the direction of the grooves. After 24 hours of cell adhesion, more spreading and flattening of cells with active filopodia formation occurred. Results of RT-PCR suggest that T group, ZS group, and ZG group showed comparable osteoblast-specific gene expression after 24 hours of cell incubation. CONCLUSION: Surface topography and material of implants can play an important role in expression of osteoblast phenotype markers. Zirconia ceramic showed comparable biological responses of osteoblast-like cells with titanium during a short-time cell culture period. Also, grooves influence cell spreading and guide the cells to be aligned within surface grooves.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.273-280
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• 2002

The stochiometric mix of evaporating materials for the CuGaTe$_2$ single crystal thin films was prepared from horizontal furnance. For extrapolation method of X-ray diffraction patterns for the CuGaTe$_2$ polycrystal, it was found tetragonal structure whose lattice constant a$\_$0/ and c$\_$0/ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, CuGaTe$_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were 670 $^{\circ}C$ and 410 $^{\circ}C$ respective1y, and the thickness of the single crystal thin films is 2.1 $\mu\textrm{m}$. The crystalline structure of single crystalthin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. The carrier density and mobility of CuGaTe$_2$ single crystal thin films deduced from Hall data are 8.72${\times}$10$\^$23/㎥, 3.42${\times}$10$\^$-2/㎡/V$.$s at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the CuGaTe$_2$ single crystal thin film, we have found that the values of spin orbit coupling Δs.o and the crystal field splitting Δcr were 0.0791 eV and 0/2463eV at 10K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0470eV and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be 0.0490eV, 0.00558eV, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.230-233
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• 2004

The stochiometric mix of evaporating materials for the $CuInS_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuInS_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.524\;{\AA}$ and $11.142\;{\AA}$, respectively. To obtain the single crystal thin films, $CuInS_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperature were 640 t and 430 t, respectively and the thickness of the single crystal thin films was $2{\mu}m$. Hall effect on this sample was measured by the method of van dot Pauw and studied on carrier density and temperature dependence of mobility. The carrier density and mobility deduced from Hall data are $9.64{\times}10^{22}/m^3,\;2.95{\times}10^{-2}\;m^2/V{\cdot}s$ at 293 K, respectively The optical energy gaps were found to be 1.53 eV at room temperature. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the thin film, we have found that the values of spin orbit coupling splitting ${\Delta}So$ and the crystal field splitting ${\Delta}Cr$ were 0.0211 eV and 0.0045 eV at 10 K, respectively. From PL peaks measured at 10K, 807.7nm (1.5350ev) mean Ex peak of the free exciton emission, also 810.3nm (1.5301eV) expresses $I_2$ peak of donor-bound exciton emission and 815.6nm (1.5201eV) emerges $I_1$ peak of acceptor-bound exciton emission. In addition, the peak observed at 862.0nm (1.4383eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• 센서학회지
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• 제1권1호
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• pp.53-57
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• 1992

본 연구는 $CdS_{1-x}Se_{x}$의 박막을 제작하고 그 전기-광학적인 특성을 조사한 것이다. 전자선 가열증착법을 이용하여 $CdS_{1-x}Se_{x}$을 알루미나 기판위에 $1.5{\times}10^{-7}$ torr의 압력, 4kV의 전압, 2.5 mA의 전류 그리고 기판온도를 $300^{\circ}C$로 유지하여 증착하였다. 증착된 $CdS_{1-x}Se_{x}$ 박막은 X-ray 회절 실험을 통하여 볼 때, 육방정계의 결정구조를 가지며 성장되었다. $CdS_{1-x}Se_{x}$ 도전막은 특정분위기에서 $550^{\circ}C$, 30분간 열처리함으로써 높은 광전도성을 나타내게 되었다. 또한 Hall 효과, 광전류 스펙트럼, 감도, 최대 허용 전력과 응답시간 등을 조사하였다.

• The Journal of Advanced Prosthodontics
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• 제12권5호
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• pp.265-272
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• 2020

PURPOSE. The aims of this study were to investigate mechanical properties and hydrothermal degradation behaviour of the cubic-containing translucent yttrium oxide stabilized tetragonal zirconia polycrystal (Y-TZP). MATERIALS AND METHODS. Four groups of Y-TZP (T, ST, XT, and P), containing different amount of cubic crystal, were examined. Specimens were aged by autoclaving at 122℃ under 2 bar pressure for 8 h. Phase transformation was analyzed using X-ray diffraction (XRD) to measure phase transformation (t→m). Kruskal-Wallis test was used to determine the difference. Surface hardness, biaxial flexural strength, and fracture toughness in values among the experimental groups and verified with Wilcoxon matched pairs test for hardness values and Mann Whitney U for flexural strength and fracture toughness. RESULTS. XRD analysis showed no monoclinic phase in XT and P after aging. Only Group T showed statistically significant decreases in hardness after aging. Hydrothermal aging showed a significant decrease in flexural strength and fracture toughness in group T and ST, while group XT and P showed no effect of aging on fractural strength and fracture toughness with P<.05. CONCLUSION. Hydrothermal aging caused reduction in mechanical properties such as surface hardness, biaxial flexural strength, and fracture toughness of Y-TZP zirconia. However, cubic-containing zirconia (more than 30% by volume of cubic crystal) was assumed to have high resistance to hydrothermal degradation. Clinical significance: Cubic-containing zirconia could withstand the intraoral aging condition. It could be suggested to use as a material for fabrication of esthetic dental restoration.

• Restorative Dentistry and Endodontics
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• 제45권1호
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• pp.6.1-6.8
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• 2020

Objectives: This study investigated the effects of a hydrofluoric acid (HA; solution of hydrogen fluoride [HF] in water)-based smart etching (SE) solution at an elevated temperature on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics in terms of bond strength and morphological changes. Materials and Methods: Eighty sintered Y-TZP specimens were prepared for shear bond strength (SBS) testing. The bonding surface of the Y-TZP specimens was treated with 37% phosphoric acid etching at 20℃-25℃, 4% HA etching at 20℃-25℃, or HA-based SE at 70℃-80℃. In all groups, zirconia primers were applied to the bonding surface of Y-TZP. For each group, 2 types of resin cement (with or without methacryloyloxydecyl dihydrogen phosphate [MDP]) were used. SBS testing was performed. Topographic changes of the etched Y-TZP surface were analyzed using scanning electron microscopy and atomic force microscopy. The results were analyzed and compared using 2-way analysis of variance. Results: Regardless of the type of resin cement, the highest bond strength was measured in the SE group, with significant differences compared to the other groups (p < 0.05). In all groups, MDP-containing resin cement yielded significantly higher bond strength values than MDP-free resin cement (p < 0.05). It was also shown that the Y-TZP surface was etched by the SE solution, causing a large change in the surface topography. Conclusions: Bond strength significantly improved when a heated HA-based SE solution was applied to the Y-TZP surface, and the etched Y-TZP surface was more irregular and had higher surface roughness.