• 한국결정성장학회지
• /
• 제2권1호
• /
• pp.43-50
• /
• 1992

인상속도를 변수로 Czochralski법을 이용하여 $ LiNbO_3$결정들을 성장시켰다. 성장된 단결정에 균열, 기포, 셀 구조 등의 결함들이 관찰되었다. 균열들은 인상속도와 냉각속도에 매우 민감하였는데 6~7mm/h의 인상속도와 20^{circ}C/h의 냉각속도가 직경 15mm정도의 결정성장에 적당한 조건임을 알 수 있었다. 소자응용에 필요한 유전적 성질 및 광학적 성질 등을 알아보기 위하여 a축, c축방향에 따라 절삭된 시편을 온도를 변화시켜가며 측정하였다.

• 한국결정성장학회:학술대회논문집
• /
• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
• /
• pp.113-116
• /
• 1998

A numerical study was performed on the fluid flow in the melt of the cold model for Czochralski growth system. The fluid flow in the melt of Woods metal with crucible diameter of 20cm was calculated using a three dimensional finite difference method. Since the crucible size is large, fully turbulent model as well as laminar model was used in the calculation. The effects of crucible rotation rate, crystal rotation rate and wall temperature difference on the velocity and temperature distribution were also investigated. For the purpose of verifying the results of calculation, a cold model experiment using Woods metal was also conducted and the velocity distribution in the melt of the model was measured.

• 한국세라믹학회지
• /
• 제26권1호
• /
• pp.37-42
• /
• 1989

Periodic layered domain structures in doped LiNbO3 crystals grown by Czochralski method were obtained by thermal fluctuation and crystal rotation with inhomogeneous radial temprature distribution. The stressinduced domain formation mechanism model was suggested and discussed.

• 한국결정성장학회지
• /
• 제9권4호
• /
• pp.381-383
• /
• 1999

First topic of this paper aims to clarify how oxygen and heat transfer in silicon melt under cusp-shaped magnetic fields. We obtained asymmetric temperature distribution by using time dependent and three-dimensional calculation. Second topic is study on molecular dynamics simulation, which was carried out to estimate diffusion constants of oxygen in silicon melt.

• 한국세라믹학회:학술대회논문집
• /
• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
• /
• pp.79.2-79
• /
• 2000

• 한국결정성장학회지
• /
• 제8권4호
• /
• pp.544-549
• /
• 1998

$KMgCl_3$ 단결정을 Ar 분위기에서 최초로 Czochralski 방법을 사용하여 육성하였다. 원료시약 KCl과 $KMgCl_2$를 화학량론적인 혼합으로는 KMgCl3를 육성할 수 없었고 비화학량론적인 방법을 사용하여 $KMgCl_3$를 육성할 수 있었다. KCl과 MgCl2를 1:1의 비율로 혼합하여 결정을 육성하였을 때에는 $K_2MgCl_4$단결정이 육성되었다. 육성되어진 $KMgCl_3$ 단결정의 연속적 상전이점들을 확인하기 위하여 DTA, DSC 등이 열적 실험을 수행하였다. 그리고 $KMgCl_3$ 단결정이 강탄성적 성질을 가짐을 확인하였으며 고온 편광현미경을 사용하여 온도에 따른 강탄성 domain의 변화를 조사하였다. 또한 stress-strain 이력곡선의 조사를 통하여 결정내 spontaneous strain의 온도에 따른 변화를 조사하였다.

• 센서학회지
• /
• 제17권3호
• /
• pp.217-222
• /
• 2008

$BaCl_2$ crystals were grown by using the Czochralski method, and their scintillation properties were measured. The emission spectrum was located in the range of $370{\sim}450$ nm, peaking at about 400 nm. The fluorescence decay time was approximately 75.9 ns for 662 keV ${\gamma}$-rays excitation. The energy resolution was about 24.4 % for $^{137}Cs$ 662 keV ${\gamma}$-rays, and the ${\alpha}/{\beta}$ ratio to $\alpha$ particles from a $^{210}Po$ 5.4 MeV was about 0.25.

• 한국재료학회지
• /
• 제20권12호
• /
• pp.645-648
• /
• 2010

The structure and morphology of epitaxial layer defects in epitaxial Si wafers produced by the Czochralski method were studied using focused ion beam (FIB) milling, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Epitaxial growth was carried out in a horizontal reactor at atmospheric pressure. The p-type Si wafers were loaded into the reactor at about $800^{\circ}C$ and heated to about $1150^{\circ}C$ in $H_2$. An epitaxial layer with a thickness of $4{\mu}m$ was grown at a temperature of 1080-$1100^{\circ}C$. Octahedral void defects, the inner walls of which were covered with a 2-4 nm-thick oxide, were surrounded mainly by $\{111\}$ planes. The formation of octahedral void defects was closely related to the agglomeration of vacancies during the growth process. Cross-sectional TEM observation suggests that the carbon impurities might possibly be related to the formation of oxide defects, considering that some kinds of carbon impurities remain on the Si surface during oxidation. In addition, carbon and oxygen impurities might play a crucial role in the formation of void defects during growth of the epitaxial layer.

• The Korean Journal of Ceramics
• /
• 제6권3호
• /
• pp.272-275
• /
• 2000

Starting from the stoichiometric composition of $K_2$CO$_3$: Li$_2$CO$_3$: Nb$_2$O$_5$=3 : 2 : 5 with the mole ratio, $K_3$LiNb$_6$O$_17$ 17/ single crystals were grown using the Czochralski method. Although the starting melt composition corresponds to the $K_3$Li$_2$Nb$_5$O$_15$ crystals, the chemical composition of the as grown crystals appears to be $K_2.95$Li$_1.33$Nb$_6.17$O$_17$ or $K_2.60$Li$_1.17$Nb$_{5.44}$ 5.44/O$_{15}$ which relatively contain fewer Li ions than $K_3$Li$_2$Nb$_5$O$_15$ crystals. We investigated the influence of the deficiency of the Li ions in the tetragonal tungsten bronze structure through the measurements of DE loop, temperature dependent dielectric constant, differential thermal analysis and temperature dependent X-ray diffraction pattern.

• Journal of Radiation Protection and Research
• /
• 제34권2호
• /
• pp.83-86
• /
• 2009

The single crystal scintillator of bismuth germinate ($Bi_4Ge_3O_{12}$:BGO) was successfully grown by the conventional Czochraski technique. The characteristics of the grown BGO were evaluated and presented on the excitation, emission responses and energy spectra of the $\gamma$-rays from $^{241}Am$, $^{133}Ba$, $^{57}Co$, $^{22}Na$, $^{137}Cs$ and $^{54}Mn$ radio-isotopes. The energy resolution of grown BGO, $\Delta$E/E, was estimated to be 12.1% at 662 keV of $\gamma$-ray for $^{137}Cs$ nuclide. Compared to the commercial BGO crystal, we confirmed that the grown BGO has a good performance and is comparable to reference one.