• Title/Summary/Keyword: Crystal growth type

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The growth and characteristics $K_3$$Li_2$$Nb_5$$O_{15}$ of single crystals ($K_3$$Li_2$$Nb_5$$O_{15}$ 단결정의 성장과 특성에 관한 연구)

  • 김진수;김정남;김태훈;노지현;진병문
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.5
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    • pp.463-469
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    • 1999
  • The potassium lithium niobate $K_3$$Li_2$$Nb_5$$O_{15}$ single crystals were growing in $K_x$$Li_{1-x}$$NbO_3$ (x = 0.4~0.6) chemical formular by the Czorchralski method. Crystal growth is studied in two orientations with growth along a-axis and c-axis. We have subjected this crystal to x-ray diffraction studies and found that they are single-crystalline and belong to tetragonal system with the lattice parameters a = b = 12.577 $\AA$ and c = 3.997$\AA$. The temperature dependence of dielectric constant was measured in the region of the phase transition. Curie temperature and diffuseness of phase transition are influenced by composition concentration. The composition and cation distribution of ferroelectric TB-type niobate crystals has a strong influence on the ferroelectric properties. Growth condition, optical transmittance, etching pattern and dielectric properties are presented and discussed.

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Formation of Oriented Hydroxyapatite Rods by Hydrothermal Treatment of Calcite Single Crystal

  • Kim, Ill-Yong;Kikuta, Koichi;Ohtsuki, Chikara
    • Korean Journal of Materials Research
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    • v.22 no.8
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    • pp.397-402
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    • 2012
  • Morphological control on hydroxyapatite crystals has attractive prospects in research to clarify the effects of crystal planes on biological performance. Hydrothermal processing is known as a typical type of processing for fabricating well-grown crystals with unique morphology. The purpose of the present study is to examine the feasibility of well-crystallized crystals with oriented structures through hydrothermal treatment of calcite. A single crystal of calcite was applied to hydrothermal treatment in a phosphate solution at $160^{\circ}C$. Rod-shaped hydroxyapatite crystals with micrometer-size were formed on the {100} face of calcite after treatment, while nanometer-sized hydroxyapatite crystals were formed on the (111). The hydroxyapatite crystals formed on each plane were not morphologically changed with increasing treatment periods. An oriented structure of rod-shaped hydroxyapatite was constructed after hydrothermal treatment of {100} planes on the calcite single, while such orientation was not observed on the (111) plane after the treatment. The layer of hydroxyapatite formed on the {100} plane was thicker than that of the (111) plane. The {100} plane of calcite shows a higher reactivity than that of the (111) plane, which results in rapid crystal growth of hydroxyapatite. The difference in the morphology of the formed hydroxyapatite was governed by the reactivity of each crystal plane exposed to the surrounding solution.

Crystal growing of sodium type 13X zeolite by continuous crystallization method (연속결정화 방법에 의한 13X 제올라이트 결정성장)

  • 김익진;이해진;서동남
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.12 no.4
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    • pp.190-195
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    • 2002
  • NaX zeolite crystals of a uniform particle size of 50 $\mu$m were grown by continuous crystallization method from seed crystals (10~20 $\mu$m) added into a 0.5~2.0 g mother liquor having a composition $3.5Na_2O : Al_2O_3: 2.1SiO_2: 1000H_2O$. In order to investigate the crystal growing by continuous method, the mother solution was supplied after 7 days, 5 days, 3 days and 1 day, respectively. The seeding resulted in an increase in the fraction of large crystals compared with unseeded batches and successfully led to an uniform NaX zeolite crystal. It was postulated that the seeding in the synthesis mixture leaded out increase of surface area for physical contact reaction and directed growth of seed crystal without the nucleation in the synthesis gel.

The influence of mechanical damage on the formation of the structural defects on the silicon surface during oxidation (규소 결정 표면의 구조 결함의 형성에 미치는 기계적 손상의 영향)

  • Kim, Dae-Il;Kim, Jong-Bum;Kim, Young-Kwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.2
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    • pp.45-50
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    • 2005
  • During oxidation process, several type of defects are formed on the surface of the silicon crystal which was damaged mechanically before oxidation. As the size of abrasive particle increases multiple dislocation loops are produced favorably over oxidation-induced stacking faults, which are dominantly produced when ground with finer abrasive particle. These defects are not related with the crystal growth process like Czochralski or directional solidification. During directional solidification process, twins and stacking faults are the two major defects observed in the bulk of the silicon crystal. On the other hand, slip dislocations produced by the thermal stress are not observed. Thus, not only in single crystalline silicon crystal but also in multi-crystalline silicon, extrinsic gettering process with programmed production of surface defects might be highly applicable to silicon wafers for purification.

Characterization and crystal growth of InP by VGF method using quartz ampoule

  • Park, E.S.;C.H. Jung;J.J. Myung;J.Y. Hong;Kim, M.K.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.6
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    • pp.542-546
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    • 1999
  • InP single crystal, III-V binary compound semiconductor, was grown by VGF(vertical gradient freeze) method using quartz ampoule and its electrical optical properties were investigated. Phosphorous powders were put in the bottom of quartz ampoule and Indium metal charged in conical quartz crucible what was attached at the upper side position inside the quartz ampoule. It was vacuous under the pressure of $10^5$Torr and sealed up. Indium metal was melted at $1070^{\circ}C$ and InP composition was formed by diffusion of phosphorous sublimated at $450^{\circ}C$ into Indium melt. By cooling the InP composition melt ($2^{\circ}C$~$5^{\circ}C$/hr of cooling rate) in range of $1070^{\circ}C$~$900^{\circ}C$, InP crystal was grown. The grown InP single crystals were investigated by X-ray analysis and polarized optical microscopy. Electrical properties were measured by Van der Pauw method. At the cooling method. At the cooling rate of $2^{\circ}C$/hr, growth direction of ingot was [111] and the quality of ingot was better at the upper side of ingot than the lower side. It was found that the InP crystals were n-type semiconductor and the carrier concentration, electron mobility and relative resistivity were $10^{15}$~$10^{16}/\textrm{cm}^3$ , $2\times 10^3$~$3\times 10^4{\textrm}{cm}^2$/Vsec and$2\times 10^{-1}$~$2\times 10^{-3}$/ Wcm in the range of 150K~300K, respectively.

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SiC single crystal grown on a seed with an inserted epitaxial layer for the power device application

  • An, Jun-Ho;Kim, Jeong-Gon;Seo, Jeong-Du;Kim, Jeong-Gyu;Gyeon, Myeong-Ok;Lee, Won-Jae;Kim, Il-Su;Sin, Byeong-Cheol;Gu, Gap-Ryeol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.232-232
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    • 2006
  • SiC single crystal Ingots were prepared onto different seed material using sublimation PVT techniques and then their crystal quality was systematically compared. In this study, the conventional SiC seed material and the new SiC seed material with an inserted SiC epitaxial layer on a seed surface were used as a seed for SiC bulk growth. The inserted epitaxial layer was grown by a sublimation epitaxy method called the CST with a low growth rate of $2{\mu}m/h$ N-type 2"-SIC single crystals exhibiting the polytype of 6H-SiC were successfully fabricated and carrier concentration levels of below $10^{17}/cm^3$ were determined from the absorption spectrum and Hall measurements. The slightly higher growth rate and carrier concentration were obtained in SiC single crystal Ingot grown on new SiC Seed materials with the inserted epitaxial layer on the seed surface, maintaining the high quality.

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A study on the identification of type IIa natural diamonds treated by the HPHT method (HPHT(고온고압)에 의해 처리된 type IIa 천연 다이아몬드의 감별에 관한 연구)

  • 김영출;최현민
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.14 no.1
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    • pp.21-26
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    • 2004
  • Results from PL and Raman spectroscopic analyses of HPHT (high-pressure high-temperature) treated type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar color and type. We identify a number of significant changes by 325 nm He/Cd laser excitation. Several peaks are removed completely, including H4, H3 system in HPHT treated diamond. The N3 system, however, increased in emission. Also we can find the behaviour of the nitrogen-vacancy related center N-V centers at 575 and 637.1 nm, as observed with 514 nm Ar ion laser excitation. When these centers are present, the FWHM (full width at half maximum) of 637.1 nm luminescence intensities offers a potential means of separating HPHT-treated from untreated type IIa diamonds. The width of 637.1 nm $(N-V)^-$line measured at the position oi half the peak's height are determine to range from 19.8 to $32.1cm^{-1}$ for HPHT treated diamonds.

Investigations of Pd Based hybrid ohmic contacts to high-low doped n-type GaAs

  • Baik, Hong-Koo;Kwak, Joon-Seop
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1997.06a
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    • pp.231-236
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    • 1997
  • To improve electrical properties and uniformity of high-low doped n-type GaAs, new ohmic contacts with a low-resistance and the superior uniformity was developed using a concept of hybrid ohmic contact. The hybrid ohmic contact displayed good surface and interface morphology and had minimum contact resistivity of 3${\times}$10-6 $\Omega$$\textrm{cm}^2$ in a wide annealing temperature ranged from 340$^{\circ}C$ to 420$^{\circ}C$, which was much wider than that of conventional ohmic contacts. The microstructural analysis showed that the Pd/Ge ohmic contact at low annealing temperature (∼300$^{\circ}C$) and also annealing temperature (∼400$^{\circ}C$), resulting ij hybrid ohmic contacts.

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Deposition of Epitaxial Silicon by Hot-Wall Chemical Vapor Deposition (CVD) Technique and its Thermodynamic Analysis

  • Koh, Wookhyun;Yoon, Deoksun;Pa, ChinHo
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1998.06a
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    • pp.173-176
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    • 1998
  • Epitaxial Si layers were deposited on n- or p-type Si(100) substrates by hot-wall chemical vapor deposition (CVD) technique using the {{{{ {SiH }_{ 2} {Cl }_{2 } - {H }_{ 2} }}}}chemistry. Thermodynamic calculations if the Si-H-Cl system were carried out to predict the window of actual Si deposition procedd and to investigate the effects of process variables(i.e., the deposition temperature, the reactor pressure, and the source gas molar ratios) on the growth of epitaxial layers. The calculated optimum process conditions were applied to the actual growth runs, and the results were in good agreement with the calculation. The expermentally determined optimum process conditions were found to be the deposition temperature between 900 and 9$25^{\circ}C$, the reactor pressure between 2 and 5 Torr, and source gad molar ration({{{{ {H }_{2 }/ {SiH }_{ 2} {Cl }_{2 } }}}}) between 30 and 70, achieving high-quality epitaxial layers.

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$Cr^{6+}$ leaching property of cement using high performance lignin (고성능 혼화제를 이용한 시멘트의 $Cr^{6+}$ 용출특성)

  • Park, Hyun;Kim, Kyung-Nam
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.3
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    • pp.135-143
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    • 2009
  • To study possibility of $Cr^{6+}$ solid solution and efficiency of admixture, leaching property of Portland cement mortar was investigated by using KSLT (Korea Standard Leaching Test), TCLP (Toxicity Characteristic Leaching Procedure), Soacking procedure, as adding excess $Cr^{6+}$. As a result, admixture of lignin type showed high compressive strength of mortar but no changing leaching property.