• 한국결정성장학회지
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• 제2권1호
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• pp.1-9
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• 1992

Czochralski법에 의한 단결정 성장 시스템에서 초기 결정 성장시 복사열 방출 관계를 계산하였다. 복사열 계산을 위해 표면 요소 사이의 형상계수를 계산하였으며 표면은 diffuse-gray 면으로 가정하였다. 같은 표면상에서도 표면 요소의 위치에 따라 형상계수의 값이 크게 다르게 나타났다. 초기 성장시 액상 표면에서 방출되는 총 열량이 결정 표면에 비해 3.6배 크게 나타났고 표면 요소를 고려하지 않았을 때는 표면 요소를 고려하였을 때에 비해 상대적으로 큰 열량이 방출되었다. 대기와 액상의 표면과 공통으로 접하고 있는 결정의 맨 아래 부분은 결정에 제일 가까운 액상 표면에 의해 크게 영향을 받았다. 따라서 초기 성장 모사를 위해서는 반드시 표면 요소 사이의 복사 열전달 관계가 고려되어야 한다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.526-526
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• 1996

The single crystal of LiTaO3 is well known eletro-optic material as well as the piezoelectric one applied to SAW filter. LiTaO3 has large electro-optic effects, so applied to optical switch, acosto-optic deflector, and optical memory device using photorefractive effects. The crystal growth of SAW-grade LiTaO3 has been studied many aspects, but there is no detail research about optic-grade crystal growth. The conditions of optic-grade LiTaO3 single crystal are as below. The optical transmittance must be over 75%, and axial and radial concentratiom uniformity below 1%. The variation of Curie temperature depending on Li/Ta ratio must be also below 2$^{\circ}C$ and no internal no internal cracks and defects. Because of the limitation of crystal quality, the growing of optic-grade LiTaO3 single crystal is very difficult compared with the growing of SAW-grade. In this research, upper conditions of optic-grade single crystal was investigated after growing of 1 inch diameter and 1.5 inch length LiTaO3 single crystal having no internal cracks and defects using Czochralski method. Curie temperature was determined with DSC and measuring capacitance and lattice parameter was calculated about the grown crystal and ceramic powder samples of various Li/Ta ratio. The result of Tc variation was below 1.2$^{\circ}C$ all over the grown crystal, so it is confirmed that LiTaO3 was grown under congruent melting composition having optical homogeniety. Also, the optical transmittance was about 78%, which was sufficient for optical device.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.449-461
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• 1996

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 14TH KACG TECHNICAL MEETING AND THE 5TH KOREA-JAPAN EMGS (ELECTRONIC MATERIALS GROWTH SYMPOSIUM)
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• pp.27-28
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• 1998

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.277-282
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• 2003

Computational calculations are now successfully introduced to design liquid crystal molecules for uses in modern active-matrix displays. These material technologies are practically applied to develop novel compounds, enabling formulation of advanced liquid crystal mixtures together with a newly developed mixture purification method. Typical examples of these liquid crystal mixtures are introduced for modern displays in various applications.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.266-272
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• 2002

The stochiometric mixture of evaporating materials for the ZnIn$_2$S$_4$ single crystal thin film was prepared from horizontal furnace. To obtain the ZnIn$_2$S$_4$ single crystal thin film, ZnIn$_2$S$_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100) in the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 610 $^{\circ}C$ and 450 $^{\circ}C$, respectively and the growth rate of the ZnIn$_2$S$_4$ single crystal thin film was about 0.5 $\mu\textrm{m}$/hr. The crystalline structure of ZnIn$_2$S$_4$ single crystal thin film was investigated by photo1uminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of ZnIn$_2$S$_4$ single crystal thin film measured from Hall effect by van der Pauw method are 8.51${\times}$10$\^$17/ cm$\^$-3/, 291 $\textrm{cm}^2$/V$.$s at 293 $^{\circ}$K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the ZnIn$_2$S$_4$ single crystal thin film, we have found that the values of spin orbit splitting ΔSo and the crystal field splitting ΔCr were 0.0148 eV and 0.1678 eV at 10 $^{\circ}$K, respectively. From the photoluminescence measurement of ZnIn$_2$S$_4$ single crystal thin film, we observed free excition (E$\_$X/) typically observed only in high quality crystal and neutral donor bound exciton (D$^{\circ}$,X) having very strong peak intensity. The full width at half maximum and binding energy of neutral donor bound excition were 9 meV and 26 meV, respectively. The activation energy of impurity measured by Haynes rule was 130 meV.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.171-174
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• 2004

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnace. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at $630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is $2.1{\mu}m$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $AgGaSe_2$ single crystal thin films measured from Hall effect by van der Pauw method are $4.89{\times}10^{17}\;cm^{-3},\;129cm^2/V{\cdot}s$ at 293K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $AgGaSe_2$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_o$ and the crystal field splitting ${\Delta}C_r$ were 0.1762 eV and 0.2494 eV at 10 K, respectively. From the photoluminescence measurement of $AgGaSe_2$ single crystal thin film, we observed free excition $(E_X)$ observable only in high quality crystal and neutral bound exciton $(D^o,X)$ having very strong peak intensity And, the full width at half maximum and binding energy of neutral donor bound excition were 8 meV and 14.1 meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.

• 한국결정성장학회지
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• 제14권1호
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• pp.12-16
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• 2004

본 실험은 대형의 고품질 DAST 결정을 위한 결정안정성과 재현성의 향상에 관하여 연구하였다. DAST 결정은 냉각법에 의한 메탄을 포화용액에서 성장시켰으며, 4-methyl-n-methyl pyridinum tosylate의 축합상태로 합성하였다. DAST 분말은 piperidine이 존재한 상태에서 r-picoline. methyl p-tolune sulfonate 그리고 P-dimethylaminobenzaldehyde로부터 제조하였다. 이때 DAST $H_2O$의 생성을 피하기 위하여 dry Argon분위기에서 합성하였다. 이것은 DAST분자가 습한 분위기에서 결정화될 경우 결정구조는 중심 대칭이 되고 그러한 경우에 DAST 미세결정이 습기를 함유하면 2차 비선형 광학특성은 사라지기 때문이다. 우리는 성장방향을 (001)면으로 고정시켰다. 성장조건은 $H_2O$/day로 서냉시켰으며 기간은 4일 동안이었다. seed 결정의 크기는 $2.5\times 3.6\times0.4\textrm{mm}^3$이며 $10\times 10.5\times3.0\textrm{mm}^3$의 DAST 결정을 제조했다. 육성된 DAST는 빨간색이며 메탈릭그린처림 보이는 표면특성을 나타내였다.

• 한국결정성장학회지
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• 제7권2호
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• pp.197-206
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• 1997

6H-SiC 위에 SiC 에피층이 화학 기상 증착(CVD)에 의하여 성장되었다. 성장된 SiC 에피층의 결정구조는 X-선 회절과 Raman 분광을 사용하여 조사되었으며, 이 에피층은 6H-SiC로서 성장되었음을 확인하였다. 수정된 Lely법으로 성장된 한 SiC 결정 분말의 결정구조를 확인하기 위하여 전형적인 SiC polytype들의 X-선 회절상을 계산하였으며, 측정된 X-선 회절상과 비교하여 이 SiC 결정에는 15R-SiC가 약간 혼재되어 있음을 확인하였다.

• 한국세라믹학회지
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• 제42권5호
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• pp.338-345
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• 2005

To prepare the complex gel of flux and pseudo-boehmite used in precursor of the flaky ${\alpha}-A1_2O_3$ crystal, aqueous solution of the mixture of sodium carbonate and sodium phosphate was added with stirring in aqueous solution of the mixture of sodium sulfate, potassium sulfate and titanium sulfate. The complex gel was dried at $110^{\circ}C$ and was crystallized above $1,050^{\circ}C$, and then the effect of the amount of titanium sulfate on size, morphology, thickness and crystal size distribution of the flaky ${\alpha}-A1_2O_3$ crystal was investigated. Addition of titanium sulfate was prevented the aggregation and generation of twin crystal, and had an effect on the crystal size and the thickness during crystal growth. When the amount of titanium sulfate was more than 6 g, particle size was decreased but was free from crystal twining and aggregation. On the other hand, when the amount of titanium sulfate was lower than 6 g, crystal size was increased but crystal twinning and aggregation were noticed.