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• We would like to demonstrate the successful production of a Cu single crystals by the Czochralski method using a conical die (CD-CZ). • Successfully grown single crystals with a diameter of 2-inches. • The CD-CZ method enables stable growth of copper single crystals by narrowing the distance between the crystal and the die wall, and also suppresses film formation and solidification on the melt surface. Copper (Cu) and other metal single crystals are useful as substrates for the deposition of atomic layer materials for many electronic applications, but the growth of large-sized single crystals is difficult to achieve. Characteristics of the metal material, namely seed elongation and intense cooling radiation at high temperatures during crystal growth, are the main challenges encountered when growing ingots with large diameters. These problems can be resolved by optimizing the crystal growth parameters. By adjusting the shoulder formation angle of the ingot shape to approximately 20° to 40°, we are able to grow a large (1-inch diameter, 30 mm length) single crystal of metal Cu using the Czochralski (CZ) method. However, the generation of suspended solids and film impurities such as reactants and precipitates and their nucleation, growth, and solidification, limited the further increase in size of the Cu crystal. Using the cone-shape die CZ (CD-CZ) method solves this problem and a 2-inch diameter Cu single crystal is successfully grown. This is the world's largest single crystal metal grown using this method and it paves the way for the growth of other metal crystals. [ABSTRACT FROM AUTHOR]

C s 3 C u 2 I 5 : T l is a novel scintillator boasting high density, a substantial light yield, and excellent energy resolution, making it promising for applications in gamma-ray spectroscopy. In this paper, we developed a multi-functional melt growth furnace capable of convenient configuration for the Czochralski (Cz), Edge-defined Film-fed (EFG), and Bridgman methods. We successfully grew C s 3 C u 2 I 5 : T l crystals using the Cz, EFG, and Bridgman methods, yielding crystal sizes of Φ 15 mm, Φ 12 mm, and Φ 30 mm, respectively. The obtained crystals exhibit satisfactory crystalline quality, although they are susceptible to cracks during the cooling, cutting, and polishing processes. Samples are taken from the crystals to undergo analysis to investigate their optical and scintillation properties. Findings indicate that our C s 3 C u 2 I 5 : T l possess a large Stokes shift of 175 nm with nearly no spectral overlap between the PLE and PL spectra. The radioluminescence emission peaked at 505 nm, accompanied by a scintillation decay time of 828 ns. The samples exhibited a commendable energy resolution of 4.8% at 662 KeV and a high light yield of 83000 ph/MeV when coupled with a PMT. This study validates the viability of employing CZ and EFG methods for the growth of C s 3 C u 2 I 5 : T l crystal, in addition to showcasing the Bridgman method for the growth of centimeter-scale C s 3 C u 2 I 5 : T l crystals. • Development of a multi-functional for the melt growth of metal halide crystals. • Growth of centimeter-sized C s 3 C u 2 I 5 : T l crystals by Cz, EFG, and Bridgman methods. • The as-grown C s 3 C u 2 I 5 : T l has 83000 ph/MeV light yield and 4.8% energy resolution. • C s 3 C u 2 I 5 : T l crystals grown by Cz, EFG, and Bridgman show similar performances. [ABSTRACT FROM AUTHOR]

We grow MnAl films on different underlayers by molecular beam epitaxy (MBE), and investigate their structural and magnetic properties. L 1 0 -ordered MnAl films were successfully grown both on an MgO(0 0 1) single-crystalline substrate and on an Mn 4 N(0 0 1) buffer layer formed on MgO(0 0 1) and SrTiO 3 (0 0 1) substrates. For the MgO substrate, post rapid thermal annealing (RTA) drastically improved the crystalline quality and the degree of L 1 0 -ordering, whereas no improvement in the crystallinity was achieved by altering the substrate temperature ( T S ) during MBE growth. However, high-quality L 1 0 -MnAl films were formed on the Mn 4 N buffer layer by simply varying T S . Structural analysis using X-ray diffraction showed MnAl on an MgO substrate had a cubic structure whereas MnAl on the Mn 4 N buffer had a tetragonal structure. This difference in crystal structure affected the magnetic properties of the MnAl films. The uniaxial magnetic anisotropy constant ( K u ) was drastically improved by inserting an Mn 4 N buffer layer. We achieved a perpendicular magnetic anisotropy of K u  = 5.0 ± 0.7 Merg/cm 3 for MnAl/Mn 4 N film on MgO and 6.0 ± 0.2 Merg/cm 3 on STO. These results suggest that Mn 4 N has potential as an underlayer for L 1 0 -MnAl. [ABSTRACT FROM AUTHOR]

Abnormal grain growth (AGG) has been a common phenomenon during the ceramic or metallurgy processing since prehistoric times. However, usually it had been very difficult to grow big single crystal (centimeter scale over) by using the AGG method due to its so-called occasionality. Based on the AGG, a solid-state crystal growth (SSCG) method was developed. The greatest advantages of the SSCG technology are the simplicity and cost-effectiveness of the technique. But the traditional SSCG technology is still uncontrollable. This article first summarizes the history and current status of AGG, and then reports recent technical developments from AGG to SSCG, and further introduces a new seed-free, solid-state crystal growth (SFSSCG) technology. This SFSSCG method allows us to repeatedly and controllably fabricate large-scale single crystals with appreciable high quality and relatively stable chemical composition at a relatively low temperature, at least in (K 0.5 Na 0.5 )NbO 3 (KNN) and Cu-Al-Mn systems. In this sense, the exaggerated grain growth is no longer 'Abnormal' but 'Normal' since it is able to be artificially controllable and repeated now. This article also provides a crystal growth model to qualitatively explain the mechanism of SFSSCG for KNN system. Compared with the traditional melt and high temperature solution growth methods, the SFSSCG method has the advantages of low energy consumption, low investment, simple technique, composition homogeneity overcoming the issues with incongruent melting and high volatility. This SFSSCG could be helpful for improving the mechanical and physical properties of single crystals, which should be promising for industrial applications. [ABSTRACT FROM AUTHOR]

Droplet Epitaxy of AlGaN nanostructures was investigated in this work. Growth was carried out by Plasma Assisted Molecular Beam Epitaxy (PA-MBE) under extreme group III rich conditions, where the excess metal remained on the growth surface and formed nanoscale metallic droplets due to the interplay of surface energy, surface diffusion and desorption, all of which are strongly dependent on the relative arrival rates of gallium and aluminum and the substrate temperature. Intermittent exposure of this metallic film to active nitrogen forms various types of nanostructures, whose morphology, composition and luminescence properties were evaluated. Our results indicate that for AlN, the droplet epitaxy process forms random arrays of uniform well oriented [0 0 0 1] nanorods with a height of ∼1 µm and a diameter of 250 nm. For AlGaN grown under excess gallium, and intermittent exposure to the active plasma, structures with diameters of 200 µm to 600 µm and a height of 80 nm were observed. We report the spontaneous formation of lateral concentric heterostructures under these conditions. A single photoluminescence (PL) peak was observed at about 260 nm with a room temperature to 4 K intensity ratio of ∼25%. [ABSTRACT FROM AUTHOR]

The homoepitaxial growth of N-polar GaN was investigated by ammonia molecular beam epitaxy. Systematic growth studies varying the V/III flux ratio and the growth temperature indicated that the strongest factor in realizing morphologically smooth films was the growth temperature; N-face films needed to be grown approximately 100 °C or greater than Ga-face films provided the same metal flux. Smooth N-face films could also be grown at temperatures only 50 °C greater than Ga-face films, albeit under reduced metal flux. Too high a growth temperature and too low a metal flux resulted in dislocation mediated pitting of the surface. The unintentional impurity incorporation of such films was also studied by secondary mass ion spectroscopy and most importantly revealed an oxygen content in the mid 10 17 to the mid 10 18  cm −3 range. Hall measurements confirmed that this oxygen impurity resulted in n-type films, with carrier concentrations and mobilities comparable to those of intentionally silicon doped GaN. [ABSTRACT FROM AUTHOR]

The method of growing of ZnS and ZnSe single crystals doped with chromium and iron using a combination of the solid phase recrystallization and diffusion doping during the high-temperature gas-static pressing has been implemented. The isostatic pressing up to 110 MPa has made it possible to increase the process temperature up to 1300 °C, increase the rate of grain growth and diffusion of Fe 2+ and Cr 2+ ions in zinc chalcogenides crystalline samples, reduce processing time to 25–150 h. ZnS:Cr (Fe) and ZnSe:Cr (Fe) single crystals from several to tens mm in size with dopant concentrations of (1–5)×10 19 cm −3 for Cr 2+ and (5–20)×10 18 cm −3 for Fe 2+ and at the total impurity's content no more than 5×10 −4 wt% have been obtained. The lasers made from the crystals demonstrated 55% differential lasing efficiency for the absorbed power. [ABSTRACT FROM AUTHOR]

Dislocation clusters are the main crystal defects in multicrystalline silicon and are detrimental for solar cell efficiency. They were formed during the silicon ingot casting due to the relaxation of strain energy. The evolution of the dislocation clusters was studied by means of automated analysing tools of the standard wafer and cell production giving information about the cluster development as a function of the ingot height. Due to the observation of the whole wafer surface the point of view is of macroscopic nature. It was found that the dislocations tend to build clusters of high density which usually expand in diameter as a function of ingot height. According to their structure the dislocation clusters can be divided into light and dense clusters. The appearance of both types shows a clear dependence on the orientation of the grain growth direction. Additionally, a process of annihilation of dislocation clusters during the crystallization has been observed. To complement the macroscopic description, the dislocation clusters were also investigates by TEM. It is shown that the dislocations within the subgrain boundaries are closely arranged. Distances of 40–30 nm were found. These results lead to the conclusion that the dislocation density within the cluster structure is impossible to quantify by means of etch pit counting. [ABSTRACT FROM AUTHOR]

Mm-sized LiMn 1− x Fe x PO 4 single crystals with 0 ⩽ x ⩽ 1 were grown by means of the traveling floating-zone technique at elevated Argon pressure of 30 bar. For the various doping levels, the growth process was optimized with respect to the composition-dependant effective light absorption and transparency of the materials. A convex crystal/melt interface, determined by the angle of incident light, was identified to be particularly crucial for a successful growth. The resulting large single crystalline grains are stoichiometric. Structure refinement shows that lattice parameters as well as the atomic positions and bond lengths linearly depend on the Mn:Fe-ratio. Oriented cuboidal samples with several mm 3 of volume were used for magnetic studies which imply an antiferromagnetic ground state for all compositions. The Néel-temperature changes from T N = 32.5(5) K in LiMnPO 4 to 49.5(5) K in LiFePO 4 while the easy magnetic axis in the ordered phase flips from the crystallographic a - to the b -axis upon Fe-doping of x < 0.2 . [ABSTRACT FROM AUTHOR]

In vitro biomimetic synthesis of calcium carbonate (CaCO 3 ) in the presence of shell proteins is a heavily researched topic in biomineralization. However, little is known regarding the function of bivalve ligament proteins in the growth of CaCO 3 crystals. In this study, using fibrous protein K58 from Siliqua radiata ligaments or coverslips as substrates, we report the results of our study of CaCO 3 precipitation in the presence or absence of acid-soluble proteins (ASP) from inner ligament layers. ASP can disturb the controlling function of K58 or a coverslip on the crystalline phase, resulting in the formation of aragonite, calcite, and vaterite. In addition, we identified the following four primary components from ASP by mass spectroscopy: alkaline phosphatase (ALP), ABC transporter, keratin type II cytoskeletal 1 (KRT 1), and phosphate ABC transporter, phosphate-binding protein (PstS). Further analysis revealed that the first three proteins and especially ALP, which is important in bone mineralisation, could affect the polymorphism and morphology of CaCO 3 crystals by trapping calcium ions in their domains. Our results indicate that ALP may play an important role in the formation of aragonite in S. radiata ligaments. This paper may facilitate our understanding of the biomineralization process. [ABSTRACT FROM AUTHOR]

Large single crystals of La 8 Cu 7 O 19 have been grown using the travelling-solvent floating zone method. A rather high oxygen pressure of 9 bar in the growth chamber and a slow growth speed of 0.5 mm/h were among the most important parameters in stabilizing the growth of this incongruently melting compound. Interestingly, a novel growth scenario has been witnessed. The crystal structure of the grown La 8 Cu 7 O 19 crystal has been analyzed using single crystal diffractometry to extract important structural parameters of this compound. We find that La 8 Cu 7 O 19 crystallizes in a monoclinic structure with space group C 2 / c and has the lattice parameters a ≈ 13.83 Å , b ≈ 3.75 Å , c ≈ 34.59 Å , and β ≈ 99.33 ° , in good agreement with the data obtained on polycrystalline samples in the literature. The magnetization shows a highly anisotropic behavior, and an anomaly at T ≈103 K. [ABSTRACT FROM AUTHOR]

A red LiInSe 2 crystal with 20 mm in diameter and a yellow LiInSe 2 crystal with 30 mm in diameter were obtained by the vertical gradient freezing method in a two-zone furnace. The thermal annealing technologies in different atmospheres were investigated. The thermal and optical properties were characterized by simultaneous differential scanning calorimetric/thermo-gravimetric (DSC-TG) analysis and an infrared (IR) spectrophotometer. Four as-grown and annealed wafers whose colors changed from red to yellow were discussed in detail on the basis of IR spectra. The results demonstrate that the transparent range of all LiInSe 2 samples is from 0.6 μm to 13.5 μm. The thermal annealing processes both in vacuum and in LiInSe 2 polycrystalline can obviously reduce the optical losses of red crystals. The optical losses of the deep red annealed crystal is at the level of 0.1 cm −1 in the range 2.0–8.5 μm. The yellow as-grown crystals exhibit a better transmittance especially in near IR range by comparison with red crystals. [ABSTRACT FROM AUTHOR]

Selections of growing crystals during directional solidification of a polycrystalline binary alloy were numerically investigated using two-dimensional phase-field simulations. To accelerate the simulations, parallel graphics processing unit (GPU) simulations were performed using the GPU-rich supercomputer TSUBAME2.5 at the Tokyo Institute of Technology. Twenty simulations with a combination of five sets of different seed orientation distributions and four different temperature gradients covering dendritic and cellular growth regions were performed. The unusual grain selection phenomenon, in which the unfavorably oriented grains preferentially grow instead of the favorably oriented grains, was observed frequently. The unusual selection was more remarkable in the cellular structure than in the dendritic structure. [ABSTRACT FROM AUTHOR]

Tb 3+ doped Na 3 La 9 O 3 (BO 3 ) 8 (Tb:NLBO) crystals have been grown by the top-seeded solution growth (TSSG) method. X-ray powder diffraction results show that the introduction of Tb 3+ does not change the structure of NLBO crystal. Tb 3+ concentration was determined by inductively coupled plasma optical emission spectrometry to be 1.089×10 21 ions/cm 3 . The absorption and emission spectra were measured at room temperature by using a (1 0 0) oriented crystal wafer. According to the Judd–Ofelt theory, the spontaneous transition probabilities, fluorescence branch ratio, and the radiation lifetime of 5 D 4 state were calculated. The unpolarized and polarized emission properties under the 367 nm excitation were evaluated. The decay time of the 543 nm emission assigned to the 5 D 4 – 7 F 5 transition was also measured. All the results show that Tb:NLBO crystal would be a promising green laser material. [ABSTRACT FROM AUTHOR]

A detailed analysis of the crystal morphology of triclinic n-docosane (C 22 H 46 ) is presented together with a preliminary assessment of the supersaturation-dependence of the growth rates for the predicted ( h k l ) faces. A methodology to index the experimentally observed crystal faces, based on a combined BFDH and zone axis methodology is defined. Analysis using this methodology yields the morphological indexation of n-docosane to be (001), (112), (102), (010), and (1−33) or (130) based on the expected triclinic crystal structure. Crystals of n-docosane growing from supersaturated n-dodecane (C 12 H 26 ) solutions, as studied using in-situ optical microscopy, at three different supersaturation ( σ ) levels 0.01, 0.02 and 0.05, reveal that the crystal morphology changes with increasing in supersaturation, evolving from a habit consistent with a triclinic crystal system to a habit that is perhaps more representative of an orthorhombic structure. Growth rates determined for the (112) and (102) faces as well as for those less dominant faces range between 0.51 and 9.85 µm/s, in good agreement with previously reported data for other organic molecules including n-alkanes. [ABSTRACT FROM AUTHOR]

In nanowire catalytic growth, the catalyst particles usually remain at the tip of as-grown nanowires, which can be utilized to prepare matchstick-like heterostructures at the nanoscale. Based on this feature and a solution-phase catalytic growth route, we herein report the synthesis of Ag 2 Se–ZnSe matchstick-like hetero-nanorods, consisting of Ag 2 Se head and ZnSe rod-like stem. Three different kinds of silver sources, including Ag(0), Ag 2 S, and Ag 2 Se, are selected as initial seeds for growing ZnSe crystalline nanowire/rods. By comparison with the case of Ag(0) or Ag 2 Se, the use of Ag 2 S nanoparticles, which alter the chemical composition of catalytic particles and convert to Ag 2 Se catalyst after adding Se precursor (SeO 2 ), is highly effective for the formation of uniform Ag 2 Se–ZnSe hetero-nanorods. The reason for this result may be attributed to a synergistic effect between the size of catalyst particles and the chemical conversion of Ag 2 S to Ag 2 Se. [ABSTRACT FROM AUTHOR]

In this paper, a novel, vertical Bridgman-type technique for growing multicrystalline silicon (mc-Si) ingots in an induction furnace is described. In contrast to conventional growth, a modified setup with a cone-shaped crucible and susceptor is used for the first time. The temperature field and melt flow in the modified setup are calculated numerically and compared with the situation in a cylindrical standard setup. A cone-shaped mc-Si ingot is presented and analyzed with focus on the microstructure (inclusions, dislocations, grains) and the minority carrier lifetime, which are compared with the properties of a cylindrical ingot grown under similar conditions. Results of numerical simulations and growth experiments are discussed with respect to the influence of the cone-shaped setup on the temperature and flow fields in the melt, as well as on the microstructure and the minority carrier lifetime in the crystal. They indicate the potential of the novel technology to produce mc-Si ingots with a globular grain structure, low dislocation density, and high carrier lifetime. [ABSTRACT FROM AUTHOR]

Flux growth involves dissolving the components of the target compound in an appropriate flux at high temperatures and then crystallizing under supersaturation controlled by cooling or evaporating the flux. A refractory crucible is generally used to contain the high temperature melt. The reaction between the melt and crucible materials can modify the composition of the melt, which typically results in growth failure, or contaminates the crystals. Thus one principle in designing a flux growth is to select suitable flux and crucible materials thus to avoid any reaction between them. In this paper, we review two cases of flux growth in which the reaction between flux and Al 2 O 3 crucible tunes the oxygen content in the melt and helps the crystallization of desired compositions. For the case of La 5 Pb 3 O, the Al 2 O 3 crucible oxidizes La to form a passivating La 2 O 3 layer which not only prevents further oxidization of La in the melt but also provides [O] to the melt. For the case of La 0.4 Na 0.6 Fe 2 As 2 , it is believed that the Al 2 O 3 crucible reacts with NaAsO 2 and the reaction consumes oxygen in the melt thus maintaining an oxygen-free environment. [ABSTRACT FROM AUTHOR]

A technique to locally grow germanium-on-insulator (GOI) structure on silicon (Si) platform is studied. On (001) Si wafer, silicon dioxide (SiO 2 ) is thermally grown and patterned to define growth window for germanium (Ge). Crystalline Ge is grown via selective hetero-epitaxy, using SiO 2 as growth mask. Lateral overgrowth of Ge crystal covers SiO 2 surface and neighboring Ge crystals coalesce with each other. Therefore, single crystalline Ge sitting on insulator for GOI applications is achieved. Chemical mechanical polishing (CMP) is performed to planarize the GOI surface. Transmission electron microscopy (TEM) analysis, Raman spectroscopy, and time-resolved photoluminescence (TRPL) show high quality crystalline Ge sitting on SiO 2 . Optical response from metal–semiconductor–metal (MSM) photodetector shows good optical absorption at 850 nm and 1550 nm wavelength. [ABSTRACT FROM AUTHOR]

The arrangement of a polar twin structure in Czochralski grown α-SrB 4 O 7 crystals has been investigated. The transversal twin boundaries are stretched along [ 1 0 1 ] and [ 1 0 0 ] directions. The lateral twin boundaries are parallel to ( 0 1 0 ) plane. The twin structures have an extension up to centimeter size in all directions. Supposedly, they originate from polysynthetic polar microtwins revealed to form in ( 1 0 1 ¯ ) and ( 1 ¯ 0 1 ¯ ) growth pyramids. The dimensions, planarity and thickness stability of each individual twin are favorable for organizing quasi-phase matching conditions for nonlinear optical doubling of high-aperture beams. [ABSTRACT FROM AUTHOR]

The influence of order degree of amorphous germanium (a-Ge) on metal induced crystallization (MIC) of a-Ge was explored. Prior to the MIC process, a pre-annealing step was employed to slightly increase the order degree of a-Ge. The pre-annealing process did indeed contribute to the crystalline ratio but tended to result in multi-preferential orientations, as evidenced by XRD curves showing both broad (111) and (220) peaks. By contrast, applying just the MIC process led to the observation of a single (111) orientation. This conflict prevented mutual diffusion between Ge and Al, reducing the effect of MIC. Due to this behavior, Al was left on the surface and formed interesting patterns. [ABSTRACT FROM AUTHOR]

We report how the crystallinity and orientation of hydroxyapatite (HAp) films deposited on sapphire substrates depend on the crystallographic planes. Both solid-phase crystallization of amorphous HAp films and crystallization during sputter deposition at elevated temperatures were examined. The low-temperature epitaxial phase on C -plane sapphire substrates has c -axis orientated HAp crystals regardless of the crystallization route, whereas the preferred orientation switches to the (310) direction at higher temperatures. Only the symmetric stretching mode ( ν 1 ) of PO 4 3 − units appears in the Raman scattering spectra, confirming well-ordered crystalline domains. In contrast, HAp crystals grown on A -plane sapphire substrates are always oriented toward random orientations. Exhibiting all vibrational modes ( ν 1 , ν 3 , and ν 4 ) of PO 4 3 − units in the Raman scattering spectra reflects random orientation, violating the Raman selection rule. If we assume that Raman intensities of PO 4 3 − units represent the crystallinity of HAp films, crystallization terminating the surface with the C -plane is hindered by the presence of excess H 2 O and OH species in the film, whereas crystallization at random orientations on the A -plane sapphire is rather promoted by these species. Such contrasting behaviors between C -plane and A -plane substrates will reflect surface-plane dependent creation of crystalline seeds and eventually determine the orientation of resulting HAp films. [ABSTRACT FROM AUTHOR]

A crucible cover is designed in a furnace for growing sapphire crystals by heat exchanger method. Global simulations of heat transfer are carried out to investigate its effects on the thermal field and melt flow in the crucible during the growth of sapphire crystal. It is found that the crucible cover has significant effect on the thermal field in the melt. When the crucible cover is installed, the radial temperature gradient in the melt at the melt–crystal interface decreases while the axial temperature gradient increases. The melt flow is weakened accordingly. The melt–crystal interface becomes flatter and the thermal stress in the crystal is reduced with the installed crucible cover. It can be therefore concluded that use of a crucible cover is favorable for crystal growth. [ABSTRACT FROM AUTHOR]

We report a fluxing technique for ZrMo 2 O 8 single crystal growth. The volatility of MoO 3 coupled with the limited temperature range of its stability with the liquid phase makes the single crystal growth of ZrMo 2 O 8 a formidable challenge. Single crystal growth of ZrMo 2 O 8 was carried out in a horizontal tubular furnace using a platinum boat and utilizing Li 2 MoO 4 as a fluxing agent. The synthesized faceted crystals were up to 3 mm along the maximum dimension. Laue and single crystal X-ray diffraction confirmed the monoclinic crystal structure having a space group C 1 2/c 1 (S.G#15), and a single crystallographic domain within the crystals. Reduced elastic modulus and hardness were determined to be 108±4 GPa and 6.4±0.2 GPa respectively using nanoindentation. Appearance of additional peaks in Raman spectra of the indented region when compared with the fresh crystal indicated a possible pressure induced phase transformation during indentation. [ABSTRACT FROM AUTHOR]

The epitaxial growth of the photoconductive MnAl 2 S 4 with a layered-type rhombohedral structure was first achieved by means of the hot-wall epitaxy method. From the Hall effect measurement, two dominant scattering mechanisms on the mobility were extracted. One was an acoustic phonon scattering caused by lattice vibrations at the high-temperature range of T >100 K and the other one was an impurity ion scattering at the low-temperature range of T <100 K. Also, from the relation between the reciprocal temperature and the carrier concentration, two activation energies were evaluated to be the deep level of 83.1 and a shallow level of 14.1 meV at high-temperature and middle-temperature ranges, respectively. From the photocurrent ( PC ) measurement, the A , B , and C peaks were observed at whole temperature range. The electronic origin of these three peaks were caused by the band-to-band transitions from the valence band states of Γ 4 (z), Γ 5 (x), and Γ 5 (y) to the conduction band state of Γ 1 (s), respectively. Thus, the parameters of the crystal-field and the spin–orbit splitting were directly extracted by means of PC spectroscopy, and those values were 3.5 and 39.9 meV, respectively. The band gap energies estimated from PC and absorption measurements were well expressed by E g ( T )= E g ( 0 )−2.80×10 −4 T 2 /( T +287), where E g ( 0 ) were found to be 3.7920, 3.7955, and 3.8354 eV at the valence band states of Γ 4 (z), Γ 5 (x), and Γ 5 (y), respectively. [ABSTRACT FROM AUTHOR]

The grain control in multi-crystalline silicon growth by directional solidification is crucial to the ingot quality. In order to study the nucleation and grain growth behavior, we carried out ingot growth using porous silica coatings, with different Si/SiO 2 ratios, and the traditional nitride coating for comparison, at the bottom of a small crucible. It was observed that with more silica in the coating, smaller and uniform grains, as well as columnar growth, could be obtained. As a result, more non- Σ grain boundaries were found as well. On the contrary, as silicon became a continuous phase in the coating, the grain refinement was less effective and their grain development in the porous coating was examined. The possible grain nucleation and growth mechanisms in the porous coatings were further proposed. [ABSTRACT FROM AUTHOR]

Nonlinear optical (NLO) crystal K 3 B 6 O 10 Br with the size of 27×29 ×14 mm 3 was successfully grown by top seeded solution growth (TSSG) technique. Its second harmonic generation (SHG) coefficients were determined by Maker fringe method as: d 22 =1.23±0.01 pm/V and d 33 =0.43±0.01 pm/V. Its linear electro-optical (EO) coefficient γ 22 =0.81±0.06 pm/V, which is usually employed in transverse modulation, was measured with polarimetric method. [ABSTRACT FROM AUTHOR]

Cr,Nd:CaYAlO 4 single crystals were grown by the floating zone method and their spectroscopic properties were investigated. Many voids were observed in the crystals grown with a stoichiometric feed rod even at a relatively low growth rate of 2.5 mm/h, while a void-free crystal was grown at the same growth rate using a feed rod the composition of which was Y-rich to Ca. These results indicate that voids were attributable to constitutional supercooling due to the segregation of main constituents caused by the difference in congruent and stoichiometric compositions. The as-grown crystals were deep red and showed strong absorption in the wavelength region of 320–600 nm. The absorption cross section for σ-polarization at 430 nm, where Cr,Nd:YAG has the maximum absorption, is about 1160×10 −20 cm 2 , which is 165 times as large as that of Cr,Nd:YAG. By pumping at 400 nm, which is a part of the absorption band of Cr 3+ , Cr,Nd:CaYAlO 4 showed fluorescence bands around 900 nm and 1080 nm by Nd 3+ indicating energy transfer from Cr 3+ to Nd 3+ in the crystal. Cr,Nd:CaYAlO 4 single crystals are therefore one of the promising gain media for solar-pumped solid state laser systems. [ABSTRACT FROM AUTHOR]

It is well known that non-centrosymmetric tetragonal antiferromagnets can host a number of interesting properties, including multiferroicity as well as magnetic skyrmions and Ba 2 CuGe 2 O 7 is one notable example. The study of all these complex phenomena requires the availability of good crystals. We have carried out the single crystal growth of the helimagnet Ba 2 CuGe 2 O 7 by the floating zone technique, using different gas atmospheres and pressures and report the optimal growth conditions allowing the synthesis of large crystals. X-ray Laue back reflection has been used to determine the orientations of the as-grown crystals. The morphology and chemical composition of the crystals have been investigated by scanning electron microscopy (SEM) with wavelength dispersive spectrometry (WDS). By using powder X-ray diffraction and energy dispersive spectroscopy (EDS) maps, the composition of the starting polycrystalline rods was checked. Powder X-ray diffraction has been also used to check the composition of the grown single crystals. Furthermore, the excellent quality of the Ba 2 CuGe 2 O 7 crystals was confirmed by rocking curve measurements, giving a FWHM of ~0.012°. The crystal growth parameters reported in this work allow the synthesis of high quality single crystals suitable for detailed investigations of the complex magnetic phase diagram of this non-centrosymmetric compound. [ABSTRACT FROM AUTHOR]

The growth of bulkx β-Ga 2 O 3 single crystals by the Czochralski method is reported and discussed in terms of crucial growth conditions and correlated with basic electrical and optical properties of the obtained crystals. β-Ga 2 O 3 crystals have a tendency to a spiral formation due to free carrier absorption in the near infrared (NIR) wavelength range, which hampers radiative heat transfer through the growing crystal. Moderate or low free electron concentrations (<5×10 17 cm −3 ) lead to cylindrical crystals with a high crystallized fraction ( g ≥0.5). The use of a CO 2 -containing growth atmosphere provides oxygen partial pressures between 0.8 and 4.4×10 −2 bar that is sufficient to obtain cylindrical and semiconducting crystals. Doping with Sn increases the free electron concentration in the crystals to high values (~10 19 cm −3 ) that lead to an immediate spiral formation, while doping with Mg (>6 wt ppm) provides insulating crystals with reduced probability of the spiral formation. The estimated Mg equilibrium segregation coefficient across the liquid–solid interface is 0.10–0.12. Annealing of undoped crystals in an oxidizing atmosphere at temperatures ≥1200 °C for 20 h decreases the bulk free electron concentration by about one order of magnitude, while the crystal surface becomes insulating. However, Mg:β-Ga 2 O 3 crystals are insensitive to annealing in both oxygen- and hydrogen-containing atmospheres. The transmittance spectra showed a steep absorption edge at 260 nm and virtually full transparency in the visible and NIR wavelength range for low and moderate free electron concentrations. We also demonstrated the possibility of growing 2 in. diameter β-Ga 2 O 3 single crystals by the Czochralski method. The good crystal quality is evidenced by rocking curve FWHM values of below 50". We noted that most dislocations propagate parallel to (100) plane. Further, we also provide thermal properties of the crystals as a function of temperature. [ABSTRACT FROM AUTHOR]

We performed ammonothermal synthesis of a self-nucleated GaN seed and grew crystalline GaN on the seed in the presence of an NH 4 F-based mineralizer. Our results suggest that spontaneously nucleated, high-quality GaN crystals can be obtained by recrystallization of polycrystalline hydride vapor phase epitaxy (HVPE) GaN under acidic ammonothermal conditions. We achieved average growth speeds of up to 410 and 465 μm/day on the c - and m -directions, respectively, after four consecutive crystal growths of GaN on a self-nucleated seed. GaN crystals grown on an HVPE seed and on a self-nucleated seed had comparable crystal quality, judged from room-temperature photoluminescence measurements. [ABSTRACT FROM AUTHOR]

Sm3+-doped La2CaB10O19(Sm:LCB) crystal with size of 40×25×15mm3 has been grown by the top-seeded solution growth (TSSG) method. The absorption and fluorescence spectra of Sm:LCB were measured at room temperature, and the fundamental spectral parameters, including transition probability A, fluorescence branch ratio β c , radioactive lifetime τ r , emission cross-sections σ em and intensity parameters Ω t(2,4,6), have been calculated by applying the Judd–Ofelt theory. In Sm:LCB crystal, a strong 599nm orange fluorescence emitting peak was observed under 410nm excitation, which may be applied in the medicine and biological detection. Sm:LCB crystal may be a promising orange laser material. [ABSTRACT FROM AUTHOR]

GaAsO4 crystals were grown by a hydrothermal epitaxial process. Microcrystalline GaAsO4 powder was first synthesized by hydrothermal methods by using GaAs as a starting material in a sulfuric acid solvent under oxidizing conditions. Experimental conditions were optimized and the yield of the nutrient synthesis reached 88%. GaAsO4 powder was then used as the nutrient for growing GaAsO4 single crystals by epitaxy on (21P0) oriented GaPO4, AlPO4 and GaAsO4 plates. Crystal growth was performed in a horizontal PTFE-lined autoclave divided into two parts using sulfuric acid as the solvent under a slow heating gradient. Hydrothermal conditions were optimized in order to improve the crystal quality. The influence of the nature and orientation of the seeds on the growth rate was studied. From the solubility curve, the solute supply ΔS as a function of temperature during the growth process was calculated. Transparent crystals were obtained with ΔS between 0.002 and 0.009mol/L. Large crystals (3.9×1.8×1.4cm3) of gallium arsenate were obtained. These crystals were cut into (21P0), (010) and (001) plates. Mapping using Raman spectroscopy was performed in order to study the growth recovery on the seed. GaAsO4 crystals were characterized by infrared spectroscopy in order to quantify the amount of OH groups in the crystal structure. A low value of the absorption coefficient α at 3300cm−1 was measured 0.067cm−1 indicating a good crystal quality. Optical measurements were performed on GaAsO4 crystals by UV–vis–NIR spectrophotometry. Gallium arsenate exhibits the highest value of birefringence in the α-quartz group with Δn=0.033. The transmission in the spectral region above 250nm yields a bandgap of 5.85eV. Piezoelectric properties were measured on resonators. An electromechanical coupling coefficient of 20% was measured which is the highest in the α-quartz group. A quality factor QF of 3.2×1010 was obtained on a Y-cut plate. The C66 elastic constant was found to be 20GPa. [ABSTRACT FROM AUTHOR]

Abstract: Tb2Sn2O7 (TSO) single crystals have been grown by the top-seeded solution growth (TSSG) method using a Na2B4O7–NaF mixture as the flux. In this paper, the morphology of as-grown TSO crystals is briefly described and the valences of terbium and tin in crystal were analyzed by X-ray photoelectron spectroscopy. The transmission spectrum was measured in the wavelength range of 400–1600nm at room temperature and the Faraday rotation of a TSO crystal was investigated at 532, 633 and 1064nm wavelengths by the extinction method. Results show that TSO crystals exhibit typical paramagnetism when the temperature is above 2K and have a larger Verdet constant than that reported for TGG. [Copyright &y& Elsevier]

Abstract: 4-aminopyridinium p-aminobenzoate dihydrate (4APAB) compound was synthesized successfully and single crystals were grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study was conducted to evaluate the cell parameters of grown crystal. The crystalline perfection of 4APAB crystal was assessed by HRXRD studies. Thermal studies revealed the thermal stability of grown crystal up to 126°C. The optical transmittance window and lower cut-off wavelength of 4APAB crystal were estimated by using UV–vis–NIR studies. The second harmonic efficiency of 4APAB was measured by powder test using Nd:YAG laser radiation. The dielectric tensor studies revealed that 4APAB crystal shows normal dielectric behavior. The single and multiple shots laser damage threshold values of grown crystal were measured. [Copyright &y& Elsevier]

Abstract: The thermo-physical properties of quaternary compound Cu2ZnSnS4 (CZTS) have been evaluated from high-quality single crystals grown by the solution method. The Debye temperature, one of the important properties, was determined from the measured heat capacity value below 7K using the Debye function. The experimental Debye temperature is 302K, which is a reference value for the thermo-physical understanding of CZTS. The present result can be used to stimulate future experimental and theoretical work. [Copyright &y& Elsevier]

Abstract: We have investigated the optical properties of 1mol% Nd-doped SrBr2 crystal grown by the Bridgman technique for an X-ray scintillator application. We succeeded in obtaining a transparent crystal, whose X-ray diffraction was measured under dry condition because of its hygroscopic nature. Roughly, we estimated that 90% of this crystal dissolved within 300min. under 25°C and 65–70% humidity. Under excitation by 270 and 400nm photons several emission peaks originating from 4F3/2 or 4G i1→4I i2 (i1=5/2 and 7/2 and i2=13/2, 11/2, and 9/2) transitions of Nd3+ were observed. 1mol% Nd:SrBr2 had a maximum quantum yield of approximately 45%. Additional emission peaks were observed under X-ray excitation. [Copyright &y& Elsevier]

Abstract: Results of the material purification, crystal growth, and optical characterization of Tm-doped KPb2Cl5 (KPC) and KPb2Br5 (KPB) for ~2μm photonic applications are presented. Undoped KPC and KPB were synthesized from ultra dry starting materials and purified through multi-pass translation in a zone-refinement system. 1wt% of ultra-dry Tm-halides (TmCl3 or TmBr3) were added to the purified host materials and molten under bubbling of HCl or HBr gas, respectively. Tm: KPC and Tm: KPB crystals were subsequently grown using the Bridgman technique. The good optical quality of the resulting crystals was indicated by infrared transmissions as high as ~70–75%. Under optical pumping, both crystals exhibited broad infrared emission bands centered at ~1.82µm with nearly exponential decay times ranging from ~2–3ms. Judd–Ofelt intensity parameters were calculated to determine the radiative lifetimes of the 3F4→3H6 Tm3+ transition. The optical absorption and emission cross-sections of Tm: KPC and Tm: KPB were determined using the McCumber theory. The investigated crystals were also evaluated as potential solid-state materials for optical cooling applications. [Copyright &y& Elsevier]

Abstract: Nd and Yb doped CaYAlO4 crystals have been grown by the micro-pulling down method. The segregation coefficient along the growth direction and the radial dopant distribution were measured by using electron probe micro-analysis (EPMA). The X-ray induced luminescence spectra in the spectral range from 300 to 1500nm were measured: Nd and Yb doped CaYAlO4 showed intense peaks at 990 and 1045nm, respectively. These crystals would be promising materials for near infrared emission scintillators. [Copyright &y& Elsevier]

Abstract: Ce:Gd3(Al x Ga1−x )5O12 (x=2.5/5 and 3/5, Ce:GAGG-2.5 and Ce:GAGG-3) crystals were grown by the Czochralski process in order to reduce cost of the starting materials as compared with conventional Ce:Gd3Al2Ga3O12 (Ce:GAGG-2) crystal which have high light output. Although perovskite phase was detected in Ce:GAGG-3, Ce:GAGG-2.5 had single-phase garnet structure. Solidification fraction for the Ce:GAGG-2.5 growth was 0.52. Optical properties including transmittance, emission, and excitation spectra of 30 samples cut from the Ce:GAGG-2.5 bulk ingot did not depend on their original position along the growth axis. These samples had light outputs of approximately 58,000±3000 photons/MeV. However, scintillation decay times varied from 140 to 200ns and depended on the position clearly. [Copyright &y& Elsevier]

Abstract: We developed high-temperature autoclaves which are capable of growing GaN crystals at temperature <850°C and pressure <150MPa. A high-temperature acidic ammonothermal method with acidic mineralizer revealed retrograde solubility of GaN, and yielded GaN crystals with XRC-FWHM values of around 30″. [Copyright &y& Elsevier]

Abstract: The metamorphic growth of lattice-mismatched materials has allowed optimizing the bandgap combination in multijunction solar cells for the solar spectrum under consideration. Buffer structures are used to accommodate the lattice-mismatch by introducing dislocations and relaxing the material in a controlled way. However, the metamorphic buffers typically involve significant growth time and material usage, which increases the cost of these solar cells. In this work, the thinning of buffer structures with continuously, linearly graded misfit is addressed with the goal of increasing the cost-effectiveness of metamorphic multijunction solar cells. The relaxation dynamics and quality of the buffer layers analyzed were assessed by in-situ stress measurements and ex-situ measurements of residual strain, threading dislocation density and surface roughness. Their ultimate quality has been tested using these buffers as templates for the growth of 1eV Ga0.73In0.27As solar cells. The deleterious effect of thinning the grade layer of these buffer structures from 2 to 1μm was investigated. It is shown that prompting the relaxation of the buffer by using a stepwise misfit jump at the beginning of the grade layer improves the quality of the thinned buffer structure. The residual threading dislocation density of the optimized thin buffers, grown at a high growth rate of 7μm/h, is 3×106 cm−2, and solar cells on these buffers exhibit near-ideal carrier collection efficiency and a V oc of 0.62V at 1-sun direct terrestrial spectrum. [Copyright &y& Elsevier]

Abstract: High-purity germanium (HP-Ge) crystals were grown in hydrogen atmosphere by Czochralski method. The control of dislocation density in high-purity germanium crystal growth was studied. It could be shown that by control of the temperature gradient during crystal growth the dislocation density distribution in the crystal can be controlled to a degree which allows for the growth of crystal fulfilling detector requirements. Crystals with diameters of 3.5 and 9cm were grown according to the relationship between axial temperature gradient and dislocation density to be able to meet the requirements of detector fabrication by having dislocation density in the range 2000–7000cm−2. [Copyright &y& Elsevier]

Abstract: A computationally efficient model to quantify the distribution of microdefect population at any given location in Czochralski grown silicon crystals is proposed and numerically solved. For this purpose, all microdefects are approximated as spherical clusters and the concentration fields of intrinsic point defects and other intermediate species are evolved using a lumped model which eliminates the requirement to store formation and path histories of the clusters. The formation of all clusters is modeled by the classical nucleation theory, while they grow by diffusion-limited kinetics. The model is validated by comparing its predictions against that of a rigorous model, where actual cluster population distribution is captured on the basis of formation and path histories of the clusters. [Copyright &y& Elsevier]

Heavily indium (In)-doped Si crystals were grown by the Czochralski method under a consideration of the effects of co-doping of electrically neutral group-IV elements (C, Ge or Sn). The In concentration in In-doped Si increased with the amount of In charged into the crucible and reached 3.5×1017 cm−3. The carrier concentration was at most 6×1016 cm−3, limited by the low ionization ratio of ~20% of In. Co-doping of C and Ge effectively enhanced the In concentration while Sn did not, which was examined in terms of the atomistic size, lattice parameter change, mutual bonding energy and solubility of group-IV elements in Si. However, no sufficient increase in carrier concentrations was detected in Si by the co-doping, and formation of some clusters or complexes was suggested. [ABSTRACT FROM AUTHOR]

Abstract: A 0.25at% Nd doped La0.05Lu0.95VO4 mixed crystal was grown by the Czochralski method. The thermal properties including thermal expansion, specific heat, thermal diffusion, and thermal conductivity were systematically studied. Meanwhile the reasons for cracking of this mixed crystal were also discussed. The refractive index at wavelengths of 633nm and 1539nm were obtained with the prism coupling method. The polarized absorption and fluorescence spectra of the crystal were also measured at room temperature. It was found that the fluorescence lifetime of 4 F 3/2 manifold for Nd3+ in Nd:La0.05Lu0.95VO4 is about 90μs. Diode-pumped continuous-wave (CW) laser operations at 1.06μm with a- and c-cut crystals were demonstrated. For the a-cut crystal a maximum output power of 5.41W was obtained at an incident pump power of 12.9W. Different from the a-cut crystal, the laser spectrum of the c-cut crystal was found to be dual-wavelength. [Copyright &y& Elsevier]

Abstract: Bismuth silicate (Bi4Si3O12, BSO) crystals including and excluding segregation layers have been grown by the Bridgman method. The morphology and composition of segregation layers existing in the defective crystal were investigated, and the crystallization habit of BSO crystal was discussed. In order to grow large size BSO crystals, several growth techniques were suggested to restrain the segregation layers. The optical properties including transmittance, photoluminescence, X-ray excited luminescence spectra and light yield of BSO crystal were also measured and discussed in this paper. [Copyright &y& Elsevier]

Abstract: This investigation presents the growth of (100), (110) and preferential (111)-oriented Pb0.6Sr0.4TiO3 thin films prepared on different orientations LaNiO3 buffered silicon substrates via radio-frequency magnetron sputtering method. The effects of the orientation on microstructure and dielectric response were systematically investigated. The capacitance–voltage property versus the crystallographic orientation analysis revealed that preferential (111)-orientation film possesses the largest relative permittivity and tunability of 1180 and 84% (at 400kV/cm) respectively, which are much higher than those of (100)- and (110)-oriented thin films. These results suggest preferential (111)-orientation films as promising candidates for microwave tunable devices. [Copyright &y& Elsevier]

Abstract: Droplet elimination by radical-beam irradiation (DERI), which is suitable for the growth of InN and periodic InN/InGaN structures, was developed for the growth of thick InGaN films by radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). In this method, Ga-to-nitrogen radical (N ) beam flux ratio was fixed in the entire growth process, and In beam supply was modulated under the condition in which excess In of more than 2–3 monolayer wetting layers always existed on the surface, that is, no precise control of In beam flux during growth was needed. Thick and uniform InGaN films were successfully grown by the developed method. In addition, InGaN films with an entire alloy composition could be simply grown by controlling Ga-to-N beam flux ratio. [Copyright &y& Elsevier]

Abstract: Morphology and growth of hydrate crystals with cyclic structure inhibitors at a hydrate–liquid interface were directly observed through a microscopic manipulating apparatus. Tetrahydrofuran (THF) hydrate was employed as an objective. The effects of four kind of cyclic structure inhibitors, polyvinylpyrrolidone (PVP), poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine) (PVPP), poly(2-vinyl pyridine-co-N-vinylcaprolactam) (PVPC) and poly(N-vinylcaprolactam) (PVCap), were investigated. Morphological patterns between each hydrate crystal growth from hydrate–liquid interface into droplet were found differ significantly. Lamellar structure growth of hydrate crystal was observed without inhibitor, while with PVP was featheriness-like, PVPP was like long dendritic crystal, PVPC was Mimosa pudica leaf-like and PVCap was like weeds. The growth rate of hydrate crystal without inhibitor was 0.00498mm3/s, while with PVPP, PVPC and PVCap, were 0.00339mm3/s, 0.00350mm3/s, 0.00386mm3/s and 0.00426mm3/s, respectively. Cyclic structure inhibitors can decrease the growth rate, degree of reduction in growth rate of hydrate crystals decrease with the increase of cylinder number. [Copyright &y& Elsevier]