Selectivity of GaAs on GaAs(100)substrates pattemed with a Si0_2 mask was studied by Periodic Supply Epitaxy(PSE)/MBE. Smooth GaAs epitaxial layers were successfully grown in the window areawhile no material was found to be formed onto the Si0_2 mask after the growth.

View full abstract

In epitaxial lateral overgrowth(ELO), steps are found supplied from either misoriented substrate or screw dislocations. An atomically flat and step free ELO layer has been obtained when no screw dislocation exists. In most cases the vertical growth is concducted by the spiral steps. The sources of spiral steps have been found frequently located at corners of the ELO layers, where a high supersaturation is expected.

View full abstract

The plasma CVD process of silicon carbide is investigated by OES(Optical Emission Spectroscopy). OES can determine activated and ionized atoms and molecules in gas phase without disturbing the plasma.The process of the film growth is explained from the bond energies of MTS and the determination of existing species in the plasma.

View full abstract

The growth process of SiC-CVD was investigated by thermogravimeter, using MTS. The temperature dcpendence and MTS partial pressure dependence of SiC growth rate were examined. SiC growth mechanism was explained on the basis of a stagnant gas layer model.

View full abstract

Distribution of p-type dopants was characterized in 6H-SiC{0001}wafer grown by the sublimation method. A colored ring pattern was observed in the central part of the wafer grown on(0001)Si-face. Secondary ion mass spectroscopy(SIMS)analysis found that A1-and B-concentration increased in the dark gray areas.

View full abstract

Sic and Si_3N_4 whiskers were grown from silica Black ores at 1350〜1450℃ in an argon and nitrogen atmosphere, respeotively.' Whi Skeres of siC and si3N4 were in a size of I x severa] tens um and several tens x several hundreds μm respectively. Their growth was explained on the basis of VLS mechanism.

View full abstract

Atomic force microscopy(AFM)reveals{111}thin layer of the charge halide salt or the transport agent nas Cover ne surface of CVD Cu whiskers. In the AFM images the hights are often enhanced many times. The caliculation shows introducing Coulomb's potential the enhanced hights of images can be interprited. The contamination of probe tip can cause a localized electric charge such as a Cu ion on the tip. Cu whiskers show only surfaces without any low-misfit interfaces with{111}halide surface. These surfaces are{100}for whiskers grown from CuCl or CuBr, and{110} for ones grown from CuI.

View full abstract

The effect of media flow on the shape of DLA-like electrodeposition is simulaed on the basis of a DLA model in a complex field where a massflow and an electric field are considered. The presence of flow changes the shape of aggregation markedly. Both the flactal dimension of the aggregation and the number of branches are decreased when a centriftigal flow is present. Also, they are increased when a centripetal flow is added.

View full abstract

TiO_2 particles were produced by introducing oxygen gas into a flow of Ti particles. It was found that the particle of a rutile structure can be produced at a temperature higher than that of an anatase structure. The particle shape of the anatase structure is spherical, while that of the rutile structure is complicated polyhedral.

View full abstract

ZnTe particles produced by gas evaporation method have been heated at 300℃ in air. The particle surface was covered with ZnO thin layer at the initial stage of the reaction. With the growth of ZnO layer, central part of ZnTe become Te crystal. As the heating time increase, the Te crystal region change to Te0_2 particles which covered with ZnO layer with thickness about 10nm.

View full abstract

A-B composite nanoparticles were prepared by the condensation of vapor B onto flying nanoparticles A which were produced in advance by a gas-evaporation technique. The growth process of the particles of Al-In, Cu-Zn and Cu-C_<60>Systems is discussd.

View full abstract

The characteristics of snow crystal growth by vapor diffusion at water saturation and in free fall were quantitatively investigated in a vertical supercooled cloud tunnel for periods up to 30 min at temperatures from -3 to -23℃.

View full abstract

Molecular dynamics simulations of ice(OOO1)and ice(1010) faccs at temperature conditions below the mclting point were carried out. As a result, anisotropic surface phase transitions were indicated on a molecular scale.

View full abstract

So far, the shape of ice crystal has been recognized to be disklike. Ice crystals had been grown from water in which air was dissolved. Now ice crystals were grown from exhausted water and the shape of angular plate was observed. Also, disk crystals grew in O_2, N_2 and Ar environment.

View full abstract

Growth behavior of ice crystals in water under pressure is studied with a high pressure optical cell. Instability is caused more rapidly on hexagonal crystals, whose melting temperature T_m is low, than on disk crystals, whose T_m is high. Dendrite tip of hexagonal crystals grow stablely.

View full abstract

In-situ observations of formation and growth processes of C0_2 hydrate crystal were carried out in a liquid C0_2 and water system by using a Mach-Zehnder interferometer. Since the hydrate crystal is transparent, the interferometric method is useful to measure the growth process and physical properties of the hydrate crystal. The shift of interference fringes between C0_2 dissolved water and C0_2 hydrate crystal provided the difference of refractive indices of these phases.

View full abstract

Gas hydrates are going to bc looked at with a keen interest in industrial applications as well as energy and environmentai problems. Various growth behaviors of gas hydrates were observed by using a pressure vessel, even though growth conditions were almost same. A new thermobalance was developed to study the growth process at low temperatures and high pressures.

View full abstract

In-situ study on growth forms of clathrate hydrate in aqueous solutions has been performed. It was observed that the growth forms was depend on the temperature and pressure. The Raman spectra of crystal have bcen measured in order to examine the relation bctween the orientation of the crystal growth and the rotation of the gas molecules. We discuss the influence of the anisotropic rotation of the gas molecules in the hydrogen bonded network on the anisotropy of the crystal growth.

View full abstract

Molecular dynamics simulations of clathrate hydrate have been performed to investigate the dynamic behavior of C0_2 and CH_4 molecules in the cage. Taking advantage of the KKY potential model used in the present simulations, we obtained the intramolecular vibrational spectra from the Fourier transform of the velocity autocorrelation function. We found the spectral difference between intramolecular vibrations for C0_2 and CH_4 molecules in the large cage and those in the small cage. We discuss these spectral difference compared with the experimental results.

View full abstract

GaAs self-organized quantum nano-structures were fabricated by metalorganic chemical vapor deposition on vicinal and patterned GaAs substrates. Using step bunching phenomena during GaAs growth on vicinal GaAs substrate, high density quantumwire array was formed. GaAs quantum dots were also fabricated on GaAs pyramidal structures grown SiNx masked(001)GaAs with square opening.

View full abstract

In spite of the large lattice mismatch between nitrides and sapphire, highquality nitride films have been successfully grown by using the low-temperature deposited AlN buffer layer. It is also found that nitride alloys are coherently grown even though the thickness exceeds critical layer thicknesses calculated from theories of Matthews and Blakeslee and Fischer et al.

View full abstract

We give an historical perspective of efforts to model the growth of an ice disk from pure supercooled water. A disk shape occurs essentially because growth along the c axis is strongly limited by interfacialkinetics but growth in the basal plane is relatively isotropic and limited by heat flow. Thus, although the growth is predominantly two-dimensional, the heat flow problem is three dimensional and practically that of heat liberated by a hot expanding ring whose thickness increases very slowly. Quantitative modeling of this heat flow by Fujioka in his doctoral work of 1978 will be presented. Morphological stability analysis of the ice disk also turns out to be an interesting three dimensional problem, even though early attempts to model it by Williamson and Chalmers were strictly two dimensional. Indeed, the mean curvature, K=1/R1 + 1/R2 where R1 and R2 are principal radii of curvature, is known to provide the stabilizing effect that offsets the destabilizing effect of heat flow into supercooled water. One of these radii, R1, is the order of the disk radius, R, while the other, R2, is of the order of the disk thickness, h Since h << R, the stabilizing effect is mostly related to the disk thickness, not its radius, even though both increase together This is in agreement with two experimental observations: First, discs of the same radius R can be either thick or thin depending on initial conditions; the thin ones are stable and the thick ones are unstable. Second, the len<gth scale of an instability, when it occurs, is comparable to h, not R In order to quantify these phenomena, some simultaneous measurements of disk thickness and radius by optical techniques were made by El Zayyat, but the work was never completed. Now, years later, beautiful work under by Professor Furukawa and his collaborators is yieldinga detailed experimental knowledge of the complex surface morphology of lce disks and dendrites as well as theoretical understanding of the origin of growth anisotropies and instabilities. Yet some mysteries remain to be explored.

View full abstract

We have successfully grown new Gd-Yb-Ga-garnet(GYGG)single crystals for optical isolator applications. GLGG single crystals showed promising properties as the substrate for the growth of high quality magneto-optical garnet films, such as large lattice parameter and high transparency.

View full abstract

We have successfully grown undoped and RE^<3+>doped GdVO_4 single crystals by a modified Czochralski technique in which a steep temperature gradient was maintained at the interface during growth. We have investigated distribution coefficients of RE^<3+>ions in GdV0_4 single crystals. The value of the equilibrium distribution coefficient (k_0) of Yb3^<3+> in GdV0_4 single crystals have been determined to be 0.58.

View full abstract

Aμ-PD and double-die μ-PD (dd-μ-PD) processes of various crucible-crystal arrangement have been designed for growth of doped Mn:LiNb0_3 fiber and ribbon-like microcrystals. The dopant profile was found to be affected by the cruciblecrystal arrangement, faceting and electric field phenomena on the solid-liquid interface. Some useful examples of dd-μPD crucible design are given; clad doped Mn:LiNb0_3 fibers of improved optical performance were grown successfully

View full abstract

Shaped rod-kike crystals of Nd-doped Gdv04 were grown by Edge-defined Film-fed Growth method. The axiai dopant distribution was found to be uniform, but the radial one depends on the development of faceted areas at growth interface and on the geometry of the die top and feeding capillary channels. The optimal die top design and growth conditions for high-quality homogeneously doped crystals are discussed.

View full abstract

Microcrystals of KNb0_3 have been grown by the micro-pulling-down (μ-PD) method from the melts corresponding to vicinity of stoichiometric composition of KNb0_3. In the main the size of crystals was more than 1 mm in cross-section and more than 10 mm in length with constant diameter.

View full abstract

We have grown LiTaO_3 single crystals with different compositions by the conventional CZ method and Double-Crucible method Investigations of photorefractive properties of LiTa0_3 in the ultraviolet and visible wavelength region demonstrate that LiTaO_3 has great potential as an optimum photorefractive material for short wavelength laser applications.

View full abstract

The influence of an interface electric field on the solute partitioning during LiNb0_3 single crystal fiber by μ-PD method has been studied. Mn was rich in the core of the crystal fiber which was two-dimensionally analyzed to predict the redistribution of the ionic solute by an electric field.

View full abstract

We have grown crack-free Ce-doped stoichiometric LiNb0_3 single crystals by the TSSG method from a melt with the Li/Nb ratio of 1.0, to with 6wt% K_2O has been added as a flux. Ce-doped crystals show appropriate absorption in ultraviolet wavelength region, suggesting a good potential of this material for short wavelength PR applications.

View full abstract

Stoichiometric LiNbO_3 containing nonstoichiometric detfects much less than congruent LiNb0_3 exhibits some advantageous properties for the holographic data storage application.The merit and demerit of stoichiometric LiNbO_3 in properties and growth will be disccussed.

View full abstract

We have grown Rare-Earth(Re) Calcium Oxyborate(ReCa_4B_3O_<10>single crystals by the Czochralski method. YCOB has a larger temperature acceptance bandwidth and birefringence than that of GdCOB, and third harmonic generation is possiblc in this crystal.

View full abstract

LuAG single crystal, which has been expected as a new host of quasi-3 lebel solid state laser,was grown with Yb activator.The outline of the growth technics, an effective distribution coefficient of Yb for LuAG and optical nbsorption properties are reported.

View full abstract

The existence of non-stoichiometry jn GdV0_4 and LuV0_4 crystals was evaluated by the compositional varlations in lattice parameters and photo[urninescence intensities under the UV light irradiation. The peak intensity of photoluminescence decreases writh decrease in vanadium concentration.

View full abstract

sr_3Al_20_6 SrAl_20_4 srAl_40_7 and SrAl_<l2>0_<19> crystals doped with Eu and Dy have been grown by a floating zone technique for the long persistent phosphor applications . The extremely long persistent phosphorescence with peak wavelengths of λ=520 um, 480 nm and 400 nm were seen in srAl_20_4, srAl_40_7 and srAl_<l2>0_<19>crystals, respectively.

View full abstract

Lithium Tetraborate is a promising new nonlinear crystal in the ultraviolet region. Large crystals with high quality were grown along the phase matching directions for the fourth and fifth harrnonics generation of a Nd:YAG laser. Polycrystallization associated with the rapid growth was resolved under the condition of the high temperature gradient.

View full abstract

In the study to delermine the effects of atmospheric moisture on CLBO crystal. we found the formation of Cs_2 B_<10>O_<16>8H_20 on the surface of CLBO crystal exposed to atmospheric moisture. This hydrate on the surface of CLBO crystal caused refractive index change and cracking CLBO crystdls were free from these problems by keeping CLBO crystals in dry atmosphere and/or annealing over 130℃.

View full abstract

The solute-feeding Czochralski method was developed to a new technique of suppressing the influence of temperature fluctuation on a growing alloy composition. A homogeneous Ca0.37In0.63Sb alloy was successfully pulled from Ga-In-Sb solution by establishing a certain growth condition.

View full abstract

Various ceramic micro-coils, such as carbon,TiC, TiN, SiC, TaC, TaN, NbC, etc,have been vaporphase prepared, and preparation conditions, morphology, growth mechanism, and mechanical and electromagnetical properties were examined.

View full abstract

Fine single crystais of BaFe_<12>O_<19>with a submicron size were grown by the slow cooling technique from aBaF_2-BaCl_2flux. Optimumgrowth conditions were nutrient BaFe_<12>O_<19>・80 wt9%, flux BaCl_2;・20wt% soaking temp.; 1100℃, cooling rate; 4℃/h. Chracterlzauon of grown crystals was examined by the XRD,SEM and VSM.

View full abstract

Kigh purity and good quality ZnSe single crystals have been grown on ZnSe(111)B seed crystals by the sublimation mcthod using the vertical growth equipment. The growth rate of the crystals was controlled by both of the tempcrature difference between at the seed and at the source and the Ar pressure in the growth ampoule. The grown crystals were cbaracterized by X-ray diffraction and photoluminescence at 4.2K.

View full abstract

In situ measurements were made of the etch pit density of InP/Si at the growth temperature using a PH3-HCI vapor phase etching method. It was found that the high dislocation density in InP/Si is caused by thermal stress.

View full abstract

Cleaning method of silicon substrate surfaoe is studied in hydrogen ambient at atmospheric pressure using HF gas at room temperature for removing native oxide film and HCl gas at 973K tor removing organic hydrocarbon film on the substrate surface. Epitaxial silicon film can be grown on the surface after the cleaning method in this study.

View full abstract

A chemical equilibrium model is applied to the MBE growih of InN, GaN and ALN semiconductors using atomic nitrogen source. The equilibrium partial pressure and the growih rate are calculated. The phase diagram of the deposition indicating etching, droplet and growih regions is computed for the growth. In addition, the interactive phase diagram system, which provides thermodynamic information on the growth conditions for every crystal-growers,is shown.

View full abstract

Chemisorption of hydrogen atoms on the GaAs(OO1) Ga surface is reported. The dependence of the surface photoabsorption(SPA)signal on the hydrogen partial pressure is investigated on the GaAs(OO1)Ga surface. Moreover, the present ad initio method, density functional theory(DFT), predicts that molecular hydrogen dissociatively chemisorbs as atomic hydrogen on the reconstructed Ga-Ga dimer to form monohydride on the Ga surface.

View full abstract

permeation mechanism of Ga Into an InSb substrate was Investlgated. The direct observation of the Ga incorporation on an InSb substrate clearly showed that the{111}planes appeared at the front of the layer and the InGaSb crystal was grown after the movement of liquid belt.

View full abstract

The In_x Ga_<1-x>As(x=0.06)layers were grown on siN_x-masked GaAs(111)B substrates with trenches of 1 mmo in diameter and 20-50μm in depth by liquid Phase epitaxial method. In the case of trench of more than 40μm in depth, the InGaAS layer made a bridge over a trench as well as laterally grew on the SiN_x film. As the grown layer did not contact the substrate except the trench periphery, high quality layers were grown.

View full abstract

A technique to produce atomically flat surface of magnetic materials has been studied. We report an observation of flat surfaces on a spherical single crystal at the end of Ni wire melted by electron bombardment.

View full abstract

BP films were grown on silicon(100)by thermal decomposition of a BCl_3-PCl_3 mixture in a hydrogen atmosphere. The layer grown on silicon(100)surfaces was found to be a single crystal boron mono phosphide with zinc blende structure by measuring X ray diffraction. This paper describes the growth conditions and the evaluation of BP films obtained.

View full abstract

GalnP alloy with desired compositions were grown on GaP substraies using the compositional ceonvesion technique, A relatively good Galnp layer was obtained. Furthermore, to have better understanding this mechanism using solid-liquid-diffusion model, numerical simulation was. carricd. Numcrical solutions agreewith experimental results and explain well the conversion phenomenon.

View full abstract