• 한국전기전자재료학회논문지
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• 제34권5호
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• pp.283-295
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• 2021

For the last decades, a research hotspot for the halide perovskites (HPs) is now showing great progress in terms of improving efficiency for numerous photovoltaic devices (PVDs). However, it still faces challenges in the case of long-term stability in the air atmosphere. Defect-free high-quality HP single crystals show their promising properties for the remarkable development of highly efficient and stable PVDs. Here, we summarize the growth processing routes for the stable HP single crystals as well as briefly discuss the pros and cons of those well-established synthesis routes. Furthermore, we briefly include the comparison note between the HP single crystals and polycrystalline perovskite films regarding their device applications. Based on the future progress, the review concludes subjective perspectives and current challenges for the development of HPs high-quality PVDs.

• 한국전기전자재료학회논문지
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• 제32권2호
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• pp.100-103
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• 2019

The change in vanadium amount according to the growth direction of vanadium-doped semi-insulated (SI) SiC single crystals using high-purity SiC powder was investigated. High-purity SiC powder and a porous graphite (PG) inner crucible were placed on opposite sides of SiC seed crystals. SI SiC crystals were grown on 2 inch 6H-SiC Si-face seeds at a temperature of $2,300^{\circ}C$ and growth pressure of 10~30 mbar of argon atmosphere, using the physical vapor transport (PVT) method. The sliced SiC single crystals were polished using diamond slurry. We analyzed the polytype and quality of the SiC crystals using high-resolution X-ray diffraction (XRD) and Raman spectroscopy. The resistivity of the SI SiC crystals was analyzed using contactless resistivity mapping (COREMA) measurements.

• 한국자기공명학회논문지
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• 제20권1호
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• pp.1-6
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• 2016

The proton NMR line widths and spin-lattice relaxation rates, $T_1^{-1}$, of ferroelectric $LiH_3(SeO_3)_2$, $Li_2SO_4{\cdot}H_2O$, and $LiN_2H_5SO_4$ single crystals were measured as a function of temperature. The line width measurements reveal rigid lattice behavior of all the crystals at low temperatures and line narrowing due to molecular motion at higher temperatures. The temperature dependences of the proton $T_1^{-1}$ for these crystals exhibit maxima, which are attributed to the effects of molecular motion by the Bloembergen - Purcell - Pound theory. The activation energies for the molecular motions of $^1H$ in these crystals were obtained. From these analysis, $^1H$ in $LiH_3(SeO_3)_2$ undergoes molecular motion more easily than $^1H$ in $LiN_2H_5SO_4$ and $Li_2SO_4{\cdot}H_2O$ crystals.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.481-484
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• 1999

The undoped-InSe and Sn-doped InSe single crystals were grown by vertical Bridgman method and their properties were invesigated. These crystals were obtained by lowering the quartz ampoule for growth in the furnace and growth rate at optimum condition is 0.4mm/hr. The orientations and the crystallinites of these crystals were identified by X-ray diffraction(XRD), double crystal rocking curve(DCRC) and etch-pit density(EPD) measurements. From the Raman spectrum at room temperature, TO, LO modes together with their overtones and combinations were observed. Optical properties were investigated by photoluminescence at 12K and direct band gap of these crystals obtained from optical absorption spectrum. Compared with undoped-lnSe, electrical properties of Sn-doped InSe were increased and the electrical conductivity type were n-type. But electrical properties along growth direction of crystals and radial direction of wafer showed nearly uniform distribution.

• 한국결정성장학회지
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• 제4권1호
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• pp.100-104
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• 1994

KTP 종자결정의 육성을 수열법에 의해 행하였으며, 육성결정의 물성은 적외분광 광도계를 이용하여 조사하였다.종자결정의 육성에 있어 큰 성장속도를 나타내는 수열 조건은 다음과 같다. 즉, 온도범위,$430~450^{\circ}C $ ; 수열용매, 4몰 KF용액 ; 온도차, $30<{\triangle}T<65^{\circ}C$ ; 충진율%, 65% ; 육성방법, 수직온도 구배법. 이와 같은조건하에서 얻어진 KTP단 결정의 형태는(100), (011), (201)면이 잘 발달하는 경향이 있었으며 그리고 육성결정 중에는hydroxyl group이 존재하였다.

• 한국세라믹학회지
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• 제27권2호
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• pp.155-160
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• 1990

Al-rich Mg-Al spinel single crystals were grown by Verneuil process using oxygen and hydrogen flame. Spinel single crystals were grown in chemical compositions from MgO : Al2O3 mole ratio 1 : 1 to 1 : 3. Mole ratio 1 : 1 was hard to be grown and mole ratio 1 : 2.5 and 1 : 3 were grown well. Selecting well-grown mole ratio 1 : 3, seeds were prepared having [100], [110] and [111] orientation respectively. Growth rate were highest in [100] orientation and lowest in [111] orientation.

• 한국세라믹학회지
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• 제24권5호
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• pp.461-469
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• 1987

Single crystals of Mn-Zn Ferrite were grown by slow cooling method using Na2B4O7 as flux agent. The effects of flux content and cooling rate on the types of crystals, and the relation between supersaturation and growth mechanism were studied. As a result, the types of grown crystals occurred as plate, hopper and octahedral crystals. The occurrence of these crystal types was dependent on flux content. The habit was found to correlate with the growth rate and supersaturation. The lateral growth of a dendritic crystal is related to the twin layer. The growth of crystals from borax melts mainly occurred by the layer-spreading growth following corner and edge nucleation caused by high supersaturation in the melt. Especially, the plate crystals were produced on top of the melts. The hopper and octahedral crystals occurred at lower supersaturation than the plate crystals.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권7호
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• pp.382-387
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• 2000

The $CdAl_2S_4 and CdAl_2S_4 : Co^{2+}$ single crystals were grown by the chemical transport reaction method using iodine as a transport agent. The $CdAl_2S_4 and CdAl_2S_4 : Co^{2+}$single crystals were crystallized into a defect chalcopyrite structure. The optical energy gap of the $CdAl_2S_4 and CdAl_2S_4 : Co^{2+}$ single crystals was found to be 3.377 eV and 2.924 eV, respectively, at 300 K. Blue emission with peaks in 456nm~466nm at 280K was observed in the $CdAl_2S_4$ single crystal. Optical absorption and emission peaks due to impurities in the $CdAl_2S_4 Co^{2+}$ single crystal were observed and described as originating from the electron transition between energy levels of the $Co^{2+} ion sited at the Td symmetry point.

• 한국결정학회지
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• 제12권1호
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• pp.5-9
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• 2001

Nd/sub 0.05/Y/sub 0.95/Ca₄O(BO₃)₃(Nd:YCOB) single crystals were grown by the Czochralski method using a iridium crucible under N₂ atmosphere. Optimum growth parameters to get high quality of single crystals were 1.5∼2 mm/hr of growth rate and 10∼20 rpm of rotation rate. The grown crystals were transparent with light purple color and well-developed in cleavage planes. The crystal structure of Nd;YCOB were identified to monoclinic by XRD method. Crystal defects acting as light scattering centers, such as micro-pores, secondary phases, inclusions and cracks were not observed under the He-Ne laser illuminations. Three red, green, blue laser devices for the RGB laser oscillations were designed and then fabricated from the grown Nd:YCOB crystals according to the phase-matching angles of negative type-I which were φ=16.40°, 33.95° and θ=22.59° with the flatness of λ/6 at least, respectively.

• 한국결정성장학회지
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• 제18권2호
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• pp.68-71
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• 2008

승화법에 의하여 AlN 결정을 성장하였다. 성장된 결정의 상은 미세한 단결정상이 응집된 다결정상이었으며, 약 2${\sim}$3mm의 길이와 직경 1인치의 크기로 증착되어진 성상을 얻었다. 성장된 결정의 표면에 탄소의 흡착이 관찰되었으며, 광학현미경과 SEM을 통하여 AlN 결정의 성장 거동에 대하여 고찰하여 보았다.