The interest in the use of borate crystals in ultraviolet(UV) nonlinear optics(NLO) has increased because all solid-stste UV lasers obtained with NLO are in highly demand. Much effort has been spent on developing borates series, such as{{{{ { beta -BaB }_{2 } {O }_{4 }(BBO), {LiB }_{ 3}{O }_{5 }(LBO)}}}} and{{{{{ CsKiB}_{6 }{O }_{10 }(CLBO)}}}} in this decade. Recently another new borate crystals, {{{{{ YCa}_{4 }O({BO }_{3 })_{3}}}}} and{{{{{Gd }_{x }{Y }_{1-x }{Ca }_{4 }O({BO }_{ 3})({Gd }_{x }{Y }_{1-x }COB)}}}} have been developed by the present authors. Here, the growth and NLO properties of YCOB and {{{{ {Gd }_{ x} {Y }_{ 1-x} }}}}CO B crystal are reported and their properties discussed in relation to those of other nonlinear optical crystals, such as LBO.

L-Histidine tetrafluoroborate single crystals have been grown from the aqueous solution. The profitable pH value to grow large crystals, the relative flow rate to get clear crystals, crystals habit and the orientation of the obtained crystal have been clarified. We have also demonstrated that the LHBF crystal has very high damage threshold which is potentially good for generation of the phase conjugated waves.

In this work, nonlinear crystals are investigated as investigated ad future diode pumped host laser materials in the green. Optical properties( absorption, emission, secind harmonic generation, and continuous wave lader oscillation in the green) of the most relevant neodymium activeated oxide lader crystals{{{{ ({LiNbO }_{ 3}:MgO, YAI({BO }_{3})_{4} and {LaBGeO }_{ 5})}}}} are investigated and compared under similar experimental conditions

The domain formation phenomena of {{{{ { LiLbO}_{ 3} }}}} crystals was investigated and the method for the periodic domain formation in {{{{ { LiLbO}_{ 3} }}}} single crystals during growth was proposed in this study. The strees-induced domain formation mechanism was proposed and explained. The strong piezoelectric effect of{{{{ { LiLbO}_{ 3} }}}} at elevated temperature would be the direct driving force for the inversion of the tensile component of the internal stresses can inverse the original direction of the spontaneous polarization.

Transport phenomena paly an inmportant role in bulk crystal growth processes. During crystal growth, the control of the growth front and the dopant concentration is crucial to crystal quality. The growth feasibility in thus determined by the heat transfer controlling the interface convexity and by the mass transfer controlling the constitutional supercooling. Through numerical modeling, a thorough understanding of the growth processes is possible, which in turn is a key to process improvenment. In this paper, we will summarize some work dine in my laboratory, both numerical and experimental, to illustrate the importance of understanding the transport phenomena during crystal growth processes.

The momentum, heat and mass transport in the melt of several sizes of crucibles are calculated using a three dimensional numerical simulation technique with and without the k-$\varepsilon$ turbulent model. When turbulent model is not used, non-axisymmetric profiles of velocity, temperature and oxygen concentration appear in the melt of all sizes of crucibles. Axisymmetric profiles are obtained when the k-$\varepsilon$ model is adopted.

Single crystals of{{{{ { Zn}_{ 1-x} {Mn }_{x }{Te} }}}} with x=0.3-0.6 were prepared by the standard Bridgeman method. Diffuse neutron diffraction intensities due to the short range magnetic ordering is found in the vicinities of 1 1/2 0 reciprocal point and its equivalent point, indicating that the magnetic correlation of the clusters is the type III antiferromangetic one do the F-type Bravais class crystals, being identical with that of {{{{{ Cd}_{ 1-x} {Mn }_{x }Te }}}}. Neutron inelastic scattering measure-ment has been performed for {{{{{ Zn}_{ 0.6} { Mn}_{ 0.4}Te }}}} sample using the cold neutron spectrometer. AGNES. High resolution measurement with the energy resolution of {{{{ TRIANGLE E= +- .01meV}}}} was carried out in the temperature range from 10K to the ambient. Critical scattering, closely related with the spin glass transition, has been observed for the first time in this semimagnetic semi-conductor. The critical scattering is observed at temperatures in the vicinity of the spin glass transition temperature, 17K. The scattering is observed as a kind of quasielastic scattering in the reciprocal range where the elastic magnetic diffuse scattering has been observed, e.g., 11/20 reciprocal point, indicating the spin fluctuation has dynamic components in this material. Photoconductivity has been discovered below 150K in {{{{{ Zn}_{ 0.4} {Mn }_{0.6 } Te}}}}. The electric AC conductivity has been increased dramatically under the laser light with the wave lengths of {{{{ lambda =6328,5145 and4880 }}}}$\AA$ ,respectively. After the light was darkened, the conductivity was reduced to the original level after about 2000 seconds at 50K, being above the spin glass transition temperature. This phenomenon is the typical persistent photoconductivity; PPC which was similarly found in {{{{ { Zn}_{ 1-x} { Mn}_{x} Te}}}}.

For the single crystal growth of silicon, a global analysis of heat transfer in a CZ furnace was carried out using the finite element method, where the radiative heat transfer between the surfaces that possess both specular and/or diffuse reflectance components was taken into account, and then the effect of the specular reflection of the crystal and/or melt on the CZ crystal growth was numerically investigated.

The growth of diamond films in plasma enhanced chemical vapor deposition(PECVD) processes requires high substrate temperatures and gas pressures, as well as high-power excitation of the gas source. Thus determining the substrate temperature in this severe environment is a challenge. The issue is a critical one since substrate temperature is a key parameter for understanding and optimizing diamond film growth. The precise Si substrate temperature calibration based on rapid-scanning spectroscopic ellipsometry have been developed and utilized. Using the true temperature of the top 200 ${\AA}$ of the Si substrate under diamond growth conditions, real time spectroellipsometry (RTSE) has been performed during the nucleation and growth of nanocrystallind thin films prepared by PECVD. RTSE shows that a significant volume fraction of nondiamond(or{{{{ {sp }^{2 } -bonded}}}}) carbon forms during thin film coalescence and is trapped near the substrate interface between ∼300 ${\AA}$ diamond nuclei.

Lean zirconate titanate (PZT) is an attractive material for the memory device applications. We have investigated Pt and{{{{ { RuO}_{2 } }}}} as a botton electrode for a device application of PZT thin film. The bottom electrodes were prepared by using an RF magnetron sputtering method. The substrate temperature influenced the resistivity of Pt and {{{{ { RuO}_{2 } }}}} a s well as the film crystal structure. XRD examination shows that a preferred(111) orientations for the substrate temperature of 30$0^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of 30$0^{\circ}C$ for the bottom electrode growth. We investigated and anneal temperature effect because Perovskite PZT structure is recommended for the memory device applications and the structural transformation is occurred only after and elevated heat treatment. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Rt and {{{{ { RuO}_{2 } }}}} w as decreased. Surface morphology was observed by AFM as a function of post anneal temperature.

PZT ceramics were rapidly sintered in a 2.45GHz microwave oven without no addition of lead to the atmosphere and afterwards the piezoelectric properties were investigated. The specimens were sintered between 1050 and 1130$^{\circ}C$ with the sintering time totaling less then 20 minutes, reducing processing times and costs from those of established methods. The relative dielectric constant, mechanical quality factor and electro-mechanical coupling factor of the PZT specimens at 1090$^{\circ}C$ were 1990, 80,0.53 respectively, which is comparable to conventionally sintered values.

The Spray-ICP technique uses the ICP(Inductively Coupled Plasma) of ultra-high temperature which is produced by r.f power. The ICP is well-kwown as a clean heat source for the preparation of pure ceramic particles because the ICP is a electrodeless-thermal plasma without contamination. In this study,{{{{ { SnO}_{2 } }}}} particles were sythesized from metal salt solution by Spray-ICP technique. The effects of concentration of solution, collecting location of powders were investicated. The prepared {{{{ { SnO}_{2 } }}}} particles from each concentration of solution had same crystalline phase(tetragonal {{{{ { SnO}_{2 } }}}}) a nd the mean size decreased in proportion to the increase of solution concentration. Each {{{{ { SnO}_{2 } }}}} p owders collector in reactor and electrostatic collector had same crystalline phase and morphologies. The mean size of {{{{ { SnO}_{2 } }}}} p articles prepared by Spray-ICP technique was below 30nm.

$Er^{3+}$ doped $NdF_{3}$ single crystalline thin films with smooth, microcrack-free, and high-crystalline quality were grown on $CaF_{2}(111)$ substrate at $500^{\circ}C$by molecular beem epitaxy(MBE). The relation-ship between subcell and supercell showing the reconstructed $3^{1/2} \times 3^{1/2}$ structure was studied by reflection high-energy electron diffraction(RHEED) investigation. The film surface and the growth mode were examined in studied by RHEED patterns and atomic force microscope(AFM) images ex situ. The crystallinity of film and the lattice mismatch between $NdF_{3}Er}^{3+}(0002)$ film and $CaF_{2}(111)$ substrate depending in the $Er^{3+}$ concentration were investigated by X-ray rocking curve analysis.

Fly ash 70wt% contained green bodies were sintered by using a 2.45 Ghz microwave oven and their properties were investigated. Samples were sintered at 1,150$^{\circ}C$ and kept at that temperature up 50 minutes by 10 minutes intervals. Numerical analysis on the microwave heated system was carried out in order to figure out the heat transfer phenomena in the cavity.

Metallic chromium was diffused in the{0001},{1120} white sapphires which were grown by the Verneuil method to enhance the physical properties of the sapphires. Chromium metal vapour pressure and {{{{ { N}_{2 } }}}} pressure were kept by {{{{ { 1$\times$10}^{-4 } }}}} torr at 21 50 $^{\circ}C$ and 6 atm in the quartz-tube, respectively. The color do the Cr-doped sapphires was changed to light red. Chromium was diffused faster in the {1120} than 수 the {0001} plane. It was speculated that the planar density was one the factors determining diffusion coeffcient

The light aggregates were fabricated by sintering green bodies made form the fly ash-clay alip. The content of fly ashes in the slip could be increased up to 70wt.% due to controlled rheological behavior of the slip, and the green body of uniform microstructure could be obtained by DCC(Direct Coagulation Casting)method. The apparent density, microstructure and compressive strength for sintered bodies fired at 1100∼1200$^{\circ}C$ were evaluated. The properties of light aggregates fabricated depend on slip density, particle behavior in the slip and sintering conditions. The sintered body prepared by firing a green body made from slip of density 1.60 at 1150$^{\circ}C$/2hr satisfied conditions of a light aggregate as apparent density of 1.49${\pm}$0.02 and compressive strength of 584${\pm}$62kg/$\textrm{cm}^2$.

ABSTRACT- we have analyzed the effect of microstructure and interface conditions on the anisotropic exchange filelds of NiO/NiFe bilayers. The NiO films were deposited by R.F. magentron sputtering. By using different atgon pressure NiO Films, Grain Size And Surface Roughness Of NiO can be manipulated. The exchange field is enhanced in the small granined NiO And This Increment Is Based On The Formation Of Small Domains In NiO

Exchange anisotropy between IrMn antiferromagnetic layer and NiFe ferromagnetic layer has been studied in IrxMn(100-x)/NiFe/Buffr/Si(100) films deposited by D. C. magnetron sputtering method. Among Zr, Ta, and Cu used as buffer layer, Zr and Ta enhanced the fcc(111) texture of NiFe and IeMn layer, but Cu did not affect microstructure of those layer. Strong fcc(111) texture of IrMn layer was confirmed to be the origin of exchange anisotropy of IrMn. Ir composition control in IrMn layer showed that {{{{ gamma -phase}}}} IrMn is stabilized between 10 and 30 at % Ir, an 21 at. % Ir in IrMn layer was optimum composition that showed maximum exchange anisotropy field. above 200 ${\AA}$ thickness of IrMn, antiferromagnetic property is stabilzed to show saturated exchange anisotropy field. Based pressure was confirmed to be critical requisite in IrMn-based spin-valve GMR system.

Langasite({{{{ { La}_{ 3} {Ga }_{5 } {SiO }_{14 } , LGS}}}}) powder was prepared by a polymerized complex method based on the Pechini-type reaction. A mixed solution of ethylene glycol(EG), cotric acid(CA), lanthanum, gallium and silicon ions, with a molar ratio of EG:CA:La:Ga:Si=100:25:3:5:1, was polymerzed to from a transparent resin, which was used as a precursor for the synthesis of LGS. X-ray diffraction(XRD) patterns indicated that the LGS phase could be formed by the heat-treatment in air at 1000$^{\circ}C$ for 3hrs

Lithium Niobate {{{{ { LiNbO}_{ 3} }}}} single crystals grown by Czichralski method at the congruent composition, have ferroelectric microdomains. These microdomins were investigated by chemical etching with hydrofluoric acid (HF) AND NITRIC ACID ({{{{ { HNO}_{3 } }}}}), and by us ing optical microscopy, scanning electron microscopy and atomic force microscopy

Possibilities of substitution was investigated in the Langadite({{{{ {La }_{3 } {Ga }_{ 5}{SiO }_{14 }}}}}) system.{{{{{TiO}_{2 }}}}} was substitutes for{{{{{SiO}_{2 }}}}} followed by the substitution of{{{{{Nd}_{2 }{O}_{3}}}}}fo{{{{{La}_{2 }{O}_{3}}}}}. An effort to replace GeO2, which is reported to have been substitution for{{{{{SiO}_{2 }}}}} in the Langasit e system, for{{{{{TiO}_{2 }}}}} i n{{{{{ Nd}_{ 3} {Ga }_{5 } {TiO }_{14 } }}}} was also undertaken. In another experiment,{{{{{ Y}_{ 2}{ O}_{3 } }}}} was substituted for{{{{{ La}_{2 } {O }_{ 3} }}}}. All of substitution possibilities were investigated through solid state reactions and analyzed with XRD. Further analysis was carried out with an SEM. Lastly, the dielectric constants of the sintered body were measured.

Langasite is a new piezoelectric material which is similar to quartz in its acoustic behaviours. In this study, pure Langasite and Langasite family grouo powders were synthesized by the solid state reaction in air. And then diffusion of synthesized powders were controlled by B and C ions in the{{{{ { A}_{ 3} { B}_{5} { CD}_{ 14 }}}}} structure. Dielectric constant and lattice anisotripy of Langasite and family group were measured to be 17, 22~27 in the range of 1 kHz to 13 MHz and about 1.6. respectively.

Undoped and 5mol%MgO DOPED {{{{ { LiNbO}_{ 3} }}}} were grown by floating zone method. The grown crystals were poled to c-azis in different electric conditions. Ferroelectric domain patterns related to the poling conditions were investigated by chemical etching and the poling effects on the piezoelectric in the undoped and MgO doped Crystals were studied.

Fluoride({{{{ { CaF}_{2 } }}}}) films exhibited a cubic structure with similar lattice constant to that of Si and have sufficient breakdown electric field as gate dielectric material. Therefore, {{{{ { CaF}_{2 } }}}} are expected to replace conventional insulator such {{{{ { SiO}_{ 2},{Ta}_{2}{O}_{ 2} and{Al}_{2}{O}_{5}. However, {CaF}_{2}}}}} films showed hystereisis properties due to mobile charges in the film. To solve this problem we performed thermal treatment and achieves field. C-v results indicate a reduced hystereisis window of {{{{ }}}}ΔV =0.2v, LOW INTERFACE STATE {{{{{D}_{it}=2.0 TIMES {10}^{11}{cm}^{-1}{eV}^{-1}}}}} in midgap, and good WIS diode properties. We observed a preferential crystallization of(200) plane from XRD analysis. RTA treatment effects on various material properties of {{{{{CaF}_{2}}}}} are presented in this paper.

In this work, aiming at improvement of growth processes for the bulk GaAs single crystals, efforts have been made first in investigate thermodynamic properties of the Ga and As system and second to suggest that bulk GaAs crystals could be grown in principle with the single temperature zone only by determining the excess arsenic charge as a function of growth conditions. During crystal growth, this will be evaporized inside the growth chamber to induce the required inner pressure, instead of aesenic vapor pressure in the double temperature zone method, so as to be in equilibrium with the method, growth experiments have been prepared and carried out for dopes and undoped GaAs crystals with the newly built Bridgman system which was designed according to this principle. To compare the results to those of the double temperature zone method, the same numbers of GaAs crystals have been grown with both processes and all of them were characterized in single crystallinity, lattice defects and electrical properties. Especially, the relationship between growth conditions and crystal quality was discussed from the viewpoint of growth peculiarities with this method.

Sapphire crystals were grown by Horizontal Bridgman method. The effects of sliding rate (growth rate) of Molybdenum container, growth atmosphere, temperature gradient and orientation of see on crystal qualities were investigated. The size of the crystals grown was up to 150-200 mm in length, 90 mm in width and 25-35 mm in thickness. Crystals grown under the optimum conditions were colorless, transparent and could not be observed and macroscopic defects, such as bubbles, cracks, twins and mosaic structure. With the grown crystals, prototypes of sapphire substrate for blue wafers were characterized. As a result, we can get hight quality of sapphire wafers with c-axis, 1.5 inches in diameters and 0.33 mm in thickess.

Erbium doped garnet crystals were grown by Czochralski method. Relationshipes between crystal quality and crystal growth factors such as pulling rate, rotation rate and concentration of active ions and sensitizers were investigated. Optimum pulling and rotation rate for high quality Er:YAG crystal were 1 mm/hr and 20 rpm and for Er,Cr:YSGG crystal 2-4 mm/hr and 10 rpm respectively. The size of the crystals grown was up to 20-30 mm in diameters and 95-135 mm in length. Er:YAG crystal grown under the nitrogen atmosphere was pink and transparent and Er,Cr:YSGG under the 98% {{{{ { N}_{ 2} }}}} and 2% {{{{ { O}_{2 } }}}} was dark green and transparent. Under the polarizing microscopic observations with crossed polar, striations and {211} core facets were detected. Spectroscopic properties for Er,Cr:YSGG laser rods with <111> axis, 80 mm in length and 6.3 mm in diameter for medical laser applications of 2.79 ${\mu}$m wavelength were manufactured and then laser oscillation was achieved.

Nd:YAG crystals were grown by Horizontal Bridgman method. The effects of sliding rate (growth rate) of Molydbenum container, growth atmosphere and concentration of Neodymium ions on crystal qualities were investigated. The size of the crystals grown was up to 150-200 mm in length, 70 mm in width and 25-35 mm in thickness. Crystals grown under the optimum conditions were violet, transparent and could not be observed any macroscopic defects. Under the polarizing microscopoc observations with crossed polar, striations, {211} facets and inclusions were detected. With the grown crystals, prototypes of laser rods for 1.06$\mu$m laser application were manufactured and then characterized. As a result, we can get high quality of Nd:YAG laser rods with <111> and <110> axis, 63 mm in length and6.3 mm in diameter.

A phyaical model of the Czochralski method for silicon single crystals is designed to measure the change of velocities and temperature profilles in the melt. Wood's metal(Bi 50%, Pb 26.7%, Sn 13.3%, Cd 10%, m.p. 70℃) is used to simulate the silicon melt in the crucible. To measure the local velocity change, electromagnetic probe is adopted as a velocity sensor. The output voltage of the sensor shows linear relationship to the velocity of the melt.

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.