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We have studied the microstructure of the growth surface of the 4H-SiC grown by the m-face solution growth. Atomic Force Microscopy (AFM) revealed the micro-striped morphology with the asperity of several nm in the band-like morphology region. The cross-sectional Transmission Electron Microscopy (XTEM) showed that the growth surface consisted of a bunch of nanofacets and vicinal surface. This peculiar morphology is totally different from that of conventional spiral growth on c-face, which can be closely related with the growth mechanism of the m-face solution growth.

As graphene grows on a metal substrate, step bunching and terrace formation occur due to thermodynamic instability. Variation in the terrace–step bunching morphology is caused by graphene–metal interaction. The mechanism for this morphological variation was elucidated in terms of the crystal lattice matching by the observation of step bunching formation using in situ scanning electron microscopy and analysis of the crystal orientation of the same microscopic field using electron backscatter diffraction. The cross-sectional structure was also observed using transmission electron microscopy (TEM). These combined methods enable a reliable analysis of the step bunching region. The lattice matching was also evaluated according to the 0-lattice theory. From the structural analysis using TEM and the application of the 0-lattice theory, the graphene-covered surface was confirmed to consist of good and poor lattice-matching regions. The steps ejected from the terrace region piled up in the poor lattice-matching region to form a low Miller index plane. It was concluded that step flow occurs on the good lattice-matching region and steps are piled up and arranged very closely on the poor matching region based on the lattice-matching evaluation by the 0-lattice theory.

Dislocation structures at the seed/grown-crystal interface in PVT-grown 4H-SiC crystals are investigated. The dislocation density is found to show a sharp increase at the interface and its main contribution is probably ascribable to TEDs which stem from BPDs generating at the interface through the structural transformation. Intense TEM observations reveal an intriguing in-plane distribution structure of the interface BPDs; the BPDs form a two-dimensional dislocation network comprising of {-1100} partial dislocations associated with expanded areas of stacking faults at the nodes of the network.

We investigated the effect of the solution flow on crystalline morphology in the off-axis 4H-SiC solution growth. In particular, we focused on the relation between the Si solution flow and step flow directions. In step parallel flow in which the solution drifted transversely to the step flow direction of the off-axis substrate, it was possible to attain a better surface morphology than in the flow in which the solution drifted toward the other direction. Furthermore, it was found that the surface morphology was found to be improved as the solution flow velocity increased. These improvements in the morphological stability are presumed to be caused by aligning the solute concentration fluctuation along the steps.

A long-term growth of high-quality 4H-SiC single crystals by a top-seeded solution growth method using a Si–Cr-based melt was investigated. A new growth technique called “solution growth on concave surface” (SGCS) was developed to help prevent solvent inclusions. The concave shape of the growth surface was achieved by controlling the meniscus height, which enhances the step provision from the periphery to the center. In contrast, under the growth surface, the solution flows from the center to the periphery through convection by inductive heating. The opposite directions of the step flow and solution flow during solution growth create a smooth surface without solvent inclusions. SGCS was used to successfully grow a 1-in. diameter 4H-SiC crystal with a thickness of 30 mm, which is the thickest reported for a solution growth technique, and 1.7-in. diameter high-quality wafers without solvent inclusions were obtained. Schottky barrier diodes were fabricated on 4H-SiC substrates grown by SGCS, which demonstrat...

The off-axis solution growth of 4H-SiC was studied focusing on the morphological instabilities by using conventional TSSG technique. The morphology depends strongly on the crystalline polarity, and that on Si surface can be characterized by wandering while that on C surface is characterized by strong step-bunching. By raising the temperature gradient, step bunching on Si surface is considerably suppressed which can be consistent to the constitutional super cooling scheme. However, C surface exhibits strong step bunching as the temperature gradient increase. These behaviors can be explained by the difference in Ehrlich-Schwoebel barrier and diffusion behavior of adatoms.

Solution growth of SiC is currently regarded as a promising process to produce high-quality SiC crystals. To date, Si–Cr, Si–Ti, and Fe–Si solvents have been used for rapid solution growth of SiC. However, optimization of the solvent system and composition is still needed to maximize the growth rate of high-quality SiC crystals. In this paper, to clarify the features of respective solvents from the viewpoint of the solubility of carbon, the C–Cr–Si, C–Ti–Si, and C–Fe–Si systems were evaluated by thermodynamic analysis. Phase relations in the respective ternary systems were investigated by the calculation of phase diagrams method. In addition, the solubility of carbon in Si–Cr, Si–Ti, and Fe–Si alloys at saturation with SiC was measured and its consistency with the estimated results was examined. Correlation of the experimental growth rate of SiC using Si–Cr, Si–Ti, and Fe–Si solvents was analyzed in terms of the supersaturation of carbon in each solution evaluated from the estimated temperature dependence of carbon solubility. Rate determining step for solution growth was presumed to be mass transfer in the liquid phase.

The top-seeded solution growth of 4H-SiC at three inches in diameter has been investigated using Si–Ti alloy as a solvent. A perforated graphite disk called “immersion guide” (IG) was positioned in the solution in order to control solution flow. The morphological instability was improved and growth rate was significantly increased using the IG compared with conventional growth without the IG. Numerical fluid flow analysis with coupled heat and mass transportation was performed as well to understand convection and growth behavior. The origins of these improvements in the growth performance are discussed based on the numerical results. By controlling solution flow, we could successfully grow a three-inch-diameter 4H-SiC with 4-mm thickness.

The nitrogen doping behavior of 4H–SiC was investigated by the top-seeded solution growth technique using Si–Ti solvent. Growth experiments were performed under a mixed gas of helium and nitrogen at atmospheric pressure at 1940 °C, in which nitrogen content ranged between 0.17 and 0.5 vol%. The electrical property and structural quality of nitrogen-doped crystals were examined. The nitrogen doping level increased with the increase of nitrogen content in the growth furnace. The most heavily nitrogen-doped SiC with a concentration of 1.1×10 20 cm −3 was obtained; however, stacking faults (SFs) were abruptly generated above a nitrogen concentration of 3.0×10 19 cm −3 . The lowest resistivity of approximately 0.010 Ω cm was obtained with SFs-free. Based on the both undoped and nitrogen-doped growth experimental results, the nitrogen incorporation behavior by employing our solution growth technique was discussed.

We performed top-seeded solution growth of 4H-SiC for obtaining longer length crystal. Si-Cr and Si-Ti melts were used as solvents. Meniscus formation technique was applied to the present study. Special attention was paid to improve the process stability during long-term growth. One of major technological problems in the solution growth is that the precipitation of polycrystalline SiC which hiders the stable single crystal growth. Another problem is the fluctuation of supersaturation at the growth interface during the growth. Through the optimization of growth process conditions, we have successfully grown 4H-SiC single crystals up to 14 mm long with three-inch-diameter, and evaluated their crystalline quality.

The solution growth behavior of silicon carbide (SiC) by a temperature difference method using Fe–Si solvent below 1773 K was investigated to clarify the dominant factor affecting growth kinetics. Solution growth experiments were conducted both under the suppression of buoyancy convection and under forced convection controlled by rotating the seed and supply source substrates. In addition, the fluid flow in the solution was estimated by numerical analysis. When buoyancy convection was suppressed, a ridge of SiC grew on the seed substrate only around the edge of the contact area with the solution, which was affected by Marangoni flow generated by the large temperature gradient. Under forced convection in the solution by substrates rotation, lateral growth of SiC was observed over the entire region of the contacting area. Growth rates of SiC of 60–160 μm/h were obtained for various temperature conditions and were increased proportionally by increasing the supersaturation of carbon at the growth interface. It was thus clarified that the mass transfer of carbon in the solution was the rate-determining step of the solution growth process of SiC.

In this study, we have investigated the rate-limiting process of 4H-SiC solution growth using Si-Cr based melt, and have tried high-speed growth. It is revealed that the rate-limiting process of SiC growth under our experimental condition is interface kinetics, which can be controlled by such factors as temperature and supersaturation of carbon. By enhancing the interface kinetics, SiC crystal has been grown at a high rate of 2 mm/h. The FWHM values of X-ray rocking curves and threading dislocation density of the grown crystals are almost the same as those of seed crystal. Possibility of high-speed and high-quality growth of 4H-SiC has been indicated.

4H-SiC single crystal with 3-inch diameter was grown by top seeded solution growth (TSSG) technique. We used a new convection control member called “Immersion Guide (IG)” which causes the high and homogenous fluid flow in the solution. As a result, we achieved relatively high growth rate and morphological stability

The improvement of interconnection technology is becoming a top priority for the operation of high power devices such as SiC at higher temperatures. We proposed a interconnection method using Nickel Nano-particles direct bonding to form bonds between the chip electrodes and substrates. SiC devices assembled with the Ni bonding interconnection were confirmed to be operated successfully in a high temperature environment over 300 °C.

We report the results of the systematic investigation into correlations between energetics and hexagonal stacking configurations for carbon, silicon, SiC, BN, AlN, GaN, and InN polytypes with sp3-bonded networks. The atomistic geometry, energetics, and electronic structure for these compounds with up to the periodic stacking length of L = 8 have been carefully calculated based on the density functional theory within the generalized gradient approximation (GGA). Using the Axial Next-Nearest-Neighbor Ising model extracted from the GGA calculations, we have also studied the energetics for more than 6 million kinds of nonequivalent stacking polytypes with up to L = 30, whose configurations have been deduced by the efficient polytype generation algorithm [E. Estevez-Rams and J. Martinez-Mojicar, Acta Crystallogr., Sect. A: Found. Crystallogr. 64, 529 (2008)], and illustrated some trends of structural and energetic properties for these compounds.

Crystallinity of 4H-SiC bulk crystal obtained by solution growth technique was characterized mainly by KOH etching of the off-ground and serially ground specimen. Marked reduction of basal plane dislocation, threading edge and screw dislocations during the growth of on-axis crystal was confirmed. Cross-sectional TEM observation revealed the rapid reduction behavior of threading dislocations microscopically. AFM observation of as-grown morphology showed that screw dislocation dipoles is related to the reduction of threading screw dislocations and single domain formation, which is essential for establishing the high crystallinity.

We have grown high-quality long cylindrical (12 mm thick) 4H-SiC bulk crystals by the meniscus formation technique, which was first applied for the solution growth of bulk SiC. It enabled long-term growth by suppressing parasitic reactions such as polycrystal precipitation around the seed crystal. In addition, we could control the growth angle from −22° to 61° by adjusting the meniscus height. The thickness of the grown cylindrical crystals was 12 mm, which is the largest reported until now, and corresponded to a growth rate of 0.6 mm/h. Smooth morphology growth was maintained on the (000-1) C-face. In cross-sectional transmission optical microscopy images, few solvent inclusions and voids were observed. XRD measurements revealed that the FWHM values of the grown crystals were almost the same as those of the seed crystal.

We attempted the traveling solvent method (TSM) growth of SiC on 6H-SiC(0001) substrates using Si and Si-M (M=Ti, Cr and Dy) solvents at growth temperatures of 1500-1800°C. It was confirmed that 4H-SiC polytype was extremely stabilized in the highly carbon dissolved liquid phase. 4H-SiC growth on 6H-SiC, i.e. hetropolytype epitaxial growth, was observed only from Si-Dy solvent. The Dy content above 60at% was necessary to obtain 100% 4H-SiC polytype.

We performed liquid phase epitaxial growth of SiC layers on on-axis 4H-SiC substrates using Si solvent. It was found that the polytype controllability of the epilayer significantly depends on the growth process conditions. By optimizing them, polytype mixing in the epilayers can be completely suppressed. It is shown that the density of basal plane dislocations in the epilayers is much less than in the substrates due to on-axis growth. SIMS analysis showed that the concentrations of trace impurity elements (B,Al,Ti,V,Cr,Fe,Ni,P) in the epilayers are under lower detection limit. The only impurity is nitrogen resulting in an n-type layer. Carrier concentrations Nd-Na ranging from high 1016 to low 1017cm-3 are achievable.

LPE (liquid phase epitaxy) growth of low nitrogen unintentionally doped SiC epitaxial layer on on-axis 4H-SiC substrate using nitrogen getter Si based solution was investigated to realize basal plane dislocation (BPD) free epitaxial layer. A significant reduction in BPD was demonstrated.

We have successfully grown 3C-SiC(111) single crystals 10mm x 10mm in dimension on 6H-SiC(0001) substrate by the solution growth method using cold crucible technique. The growth rate of 60μm/hr was achieved. The use of Si-Ti-C ternary solution as well as the electromagnetic stirring are responsible for the relatively high growth rate in solution method. The threading dislocation density is low and the etch pit density amounts to 105-106 /cm2 at the lowest region. Polytype of the grown layer has changed from 3C to 6H with an increase in the dip depth of substrate. A mathematical model was applied to get better understanding of what happened in the crucible.

Top seeded solution growth of SiC on on-axis 6H-SiC was performed using Si solvent at growth temperature as high as 1645-1870°C. It was found that different polytypes of SiC layers were grown on 6H-SiC depending on gas species during growth. The growth under He atmosphere produced 6H-SiC homoepitaxial layers. On the other hand, the growth under N2-He atmosphere led to 3C-SiC epitaxial layers. It was obvious that the nitrogen dissolved in solvent strongly favoured the 3C-SiC polytype formation on 6H-SiC. We also conducted characterization of 3C-SiC layers grown on 6H-SiC (0001)Si by TEM, molten KOH etching and precise XRD measurement.

Solution growth on off-axis 4H-SiC sublimation substrate as a buffer layer for the subsequent CVD epitaxial growth was investigated. Dislocation conversion and propagation from the substrate to the CVD epitaxial layer through the solution grown buffer layer was inspected by molten KOH etch pit observation. Effective dislocation conversion from BPD to TED as an effect of the buffer layer insertion with no drastic change in the total EPD was confirmed.

We carried out the characterization of the crystallinity of the solution growth self-standing silicon carbide (SiC) crystals, which were grown from Si-C-Ti ternary solution with Accelerated Crucible Rotation Technique (ACRT). The self-standing crystal exhibited homogeneous green color without cracks and inclusions. The crystallinity of the self-standing crystal was characterized by various precise XRD diffraction measurements, such as の-scan rocking curve measurement, X-ray topography and reciprocal lattice mapping. The Full Width at Half Maximum (FWHM) of the の-scan rocking curves was about 20 arcsec. The X-ray topography showed a large area with a homogeneous orientation. The reciprocal lattice mapping exhibited a sharp single peak indicating the excellent crystallinity. Finally we confirmed rather high crystallinity of the self-standing crystals by etch pits measurement using molten KOH etching.

We have grown AlN single crystal on 6H-SiC substrate using Al-Cu solution of 1500-1600 °C. Nitrogen is supplied from gas phase under atmospheric pressure and the cold crucible technique is applied. Thickness of AlN reached 40 μm with the growth rate of 10 μm/h. Rather high growth rate in solution method is due to the increase in the melt surface area, dynamic convection of the melt and high temperature gradient along the seeded axis, which are easily realized in cold crucible technique. TEM observation reveals that the dislocation density beyond 10μm from the interface decreases by a factor of 10 to the power of -1 or -2. The melt included in between the substrate and AlN epi-layer eases stress in epi-layer and reduces cracks. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We performed solution growth of SiC single crystals from Si-Ti-C ternary solution using the accelerated crucible rotation technique (ACRT). It was confirmed that the growth rate exceeding 200 μm/hr was achievable by several ACRT conditions. This high growth rate might be due to the enhancement of the carbon transport from the graphite crucible to the growth interface using the ACRT. Moreover, the incorporation of inclusions of the Si-Ti solvent in the grown crystal was significantly suppressed by using the ACRT. It was thought that the intensive convection near the growth interface resulted in not only the marked increase of SiC growth rate but also the superior homogeneity in the surface morphology. It was concluded that faster stable growth can be accomplished in the SiC solution growth using the ACRT.

We carried out the growth of single crystalline silicon carbide (SiC) from Si-C-X (X= Co, Fe) ternary solutions. These ternary solutions are expected to show large carbon solubility compared with Si solvent (self-flux) by means of CALPHAD (CALculation of PHAse Diagrams) method. We investigated the growth rate and the polytype of the grown crystal from the ternary solutions. Then we found that the growth rate from the ternary solutions is much larger than that from the self-flux. The growth rate from Si-C-Co (Si-C-Fe) system was about 6mm/hr (12mm/hr) while that from the self-flux was only 2mm/hr. The grown crystal from the ternary solutions is classified into 6H that takes over the seed polytype.

Liquid-phase epitaxial (LPE) growth on silicon carbide simultaneously covers macroscale defects, e.g. micropipes, and improves the quality of the crystal. In this study, an epi-layer grown over a macrodefect was evaluated by micro-Raman scattering spectroscopy. Before the growth process, the density of the stacking fault was high and the carrier density spatially inhomogeneous in the vicinity of the macrodefects. On the other hand, after growth, the layer over the macrodefect displayed good quality; the density of the stacking fault was less than that before growth and the homogeneity of the carrier density improved.

Precipitation and growth behavior of AlN from Cu-Al-Ti-N solution under the atmospheric pressure of nitrogen has been studied. The solubility of AlN in Cu flux ranges from 5 mol% to 20 mol% at the temperatures between 1700 ∘C and 2000 ∘C. The addition of the proper amount of Ti drastically enhances the solubility of AlN. Acicular crystallites and platelets of AlN precipitants, which were all water white colored, were obtained by super-cooling the Cu-Al-Ti-N solution. The largest pencil type AlN reached more than 3 mm in its length and 0.2 mm in its diameter. The axis of the pencil was c-axis of wurtzite AlN and it contained no dislocation, no diffractive defects. A platelet of AlN of which diameter exceeded 1.5 mm was also obtained by regrowth technique. Thermodynamic calculation reveals the validity of using Cu-Al-Ti-N solution for the growth of AlN.

Crystal growth processes of low-density framework forms of crystalline silicon, named Si clathrates ( Si34 and Si46), during solid phase epitaxy (SPE) have been successfully observed in molecular-dynamics simulations using the Tersoff potential. The activation energy of SPE for Si34 has been found to correspond with the experimental value ( approximately 2.7 eV) for the cubic diamond phase, while the SPE rates of Si46 are much lower than that of Si34. The structural transition from Si46 to Si34 can be also observed during the Si46-[001] SPE. The present results suggest that new wide-gap Si semiconductors with clathrate structures can be prepared using epitaxial growth techniques.

Co-Al-O film was fabricated using the reactive r.f. magnetron sputtering technique. A maximum magnetoresistance (MR) of approximately 7% was established through optimizing the sputter deposition conditions such as sputter power and gas flow rate. TEM characterization of the film revealed a nano-granular structure that consisted of ferromagnetic grains with grain diameters on the order of several nm together with non-magnetic grain boundary layers with the thickness on the order of less than 1 nm. The large MR was attributed to electron tunneling thorough this very thin grain boundary layer between individual ferromagnetic grains.

Nano-structures on the surface of graphite based carbon particles have been investigated by means of high resolution transmission electron microscopy. The surfaces consist of “closed-edge” structures in a similar manner as carbon nano-tube. That is, they are composed of coaxial carbon tubes consisting of adequate coupling of graphite layer edges. These graphite particles are chemically stable and, therefore, applicable for lithium-ion secondary battery anodes. Molecular dynamics simulations based on the Tersoff potential reveal that the vibrations of the graphite layers at the free edges play an important role in the formation of the closed-edge structures. In lithium-ion secondary batteries, Li ions can intrude into bulk carbon anodes through these closed-edge structures. In order to clarify this intrusion mechanism, we have studied the barrier potentials of Li intrusion through these closed edges using the first-principles cluster calculations. From electrochemical measurements, the carbon anodes compos...

The effect of heavy boron doping on local lattice strain around platelet oxide precipitates in Czochralski silicon wafers was investigated quantitatively by convergent beam electron diffraction (CBED). Lightly boron doped (p−) polished wafers, including platelet precipitates with density of about 5×109/cm3 and with an edge length of about 500 nm, were prepared with an isothermal annealing at 800 °C for 700 h. Heavy boron doped (p/p+) epitaxial wafers, including an almost equal precipitate density and length to p− wafers, were also prepared with an isothermal annealing at 800 °C for 200 h. It was found by strain analysis from high-order Laue zone patterns in the CBED disk that (i) the type of lattice strain was coincident in p− and p/p+ wafers: the strain along the normal direction of the platelet precipitate was compressive, while the strain along the parallel direction of the platelet was tensile; (ii) the strain in p/p+ wafers was smaller than that in p− wafers; and (iii) the punched-out dislocations we...

Relationships between density of total incident hydrogen ions and full peak width at half maximum (FWHM) at (400) diffraction spot in reflection high-energy electron diffraction (RHEED) from vicinal Si (100) surface during plasma irradiation and postannealing are first reported. At the density of total incident hydrogen ions of 6.0×10 14 ions/cm 2 , the FWHM, which is normalized by that before plasma irradiation, is almost saturated at 1.8. No damaged layer and no defect are observed in cross-sectional transmission electron microscopic (XTEM) images. On the other hand, at the density of 3.6×10 15 ions/cm 2 , the normalized FWHM is slightly increased to 1.9. However, the drastic degradation of surface crystalline quality, a uniform 50-nm thick damaged layer and a lot of extended planar defects, is observed in XTEM images. During postannealing of Si wafer irradiated at the density of 6.0×10 14 ions/cm 2 , the FWHM drastically decreases between 700°C and 800°C. Considering the causes of FWHM broadening and thermal stabilities of defects and disordered lattice, it is considered that this drastic improvement of FWHM is caused by annihilation of Si point defects and rearrangement of disordered lattice at Si surface.

Structures of grain boundaries of SrTiO3 semiconductive capacitor have not been fully elucidated. Several studies were focused on the SrTiO3 systems which include additives, such as, Al2O3 or SiO2. In this study, we first investigated the grain boundaries of Sr0.975Ca0.025TiNb0.004O3 which did not contain any additives. Then Bi2O3/CuO, which is a grain boundary modifier, was also added in order to investigate the process that changes grain boundaries into insulators. Samples heat-treated with Bi2O3/CuO were quenched in water and TEM (transmission electron microscopy) was carried out on these microstructures. Grain boundaries of samples sintered in a reduced atmosphere showed segregation of TiO2 oxide phase, which included no traces of Sr. On the other hand, in grain boundaries of samples heat-treated with the Bi2O3/CuO agent, at least two phases existed. One phase included large amounts of Bi and Cu, while the other phase showed only traces of these elements. Near the grain boundaries Bi and Cu diffused into the matrix grains showing inhomogeneous diffusion of which diffusion lengths were different at each side of the grain boundary and seemingly lattice coincident with both grain boundary layers and matrix grains. In addition, steps of about 2nm in height were observed at grain boundaries.

The step arrangements on the surfaces of rapidly cooled Si(111) misoriented in [12 3 ] and [ 12 3] are investigated. We show that the step arrangements on the quenched surface are greatly influenced upon the annealing and cooling conditions. We also present the growth process of the (7 × 7) domains on cooling rapidly across the (1 × 1)−(7 × 7) transition temperature.

Co-Ni系においてホロー結晶が成長するが,このホロー結晶には筒型(pH2.0,1000～1500A/m2)とお椀型(pH3.4,200～1500A/m2)の2種類が存在した。 このホロー結晶は陰極で発生する水素バブルの周囲に沿ってできるCo(OH)2膜を介して成長する。したがってホロー結晶の形は水素バブルの形で決まるものと思われる。 Co-Ni系はZn-Ni系と同様に異常共析型であるが,Zn-Ni系に見られたひげ結晶は成長せずホロー結晶が成長した理由の一つは,酸化膜ができず水酸化膜のみが形成されたためと思われる。

Crystallographic aspects of diffusional α-Fe/Zn interface structures were examined by using a transmission electron microscope (TEM). The obtained results were summarized as follows. Ruggedness accompanying many dips with pitch of about 100 nm, which seems to be “growth ledge”, was observed at the Fe3Zn10(Γ)/α-Fe interface in the galvannealed coatings with the Fe content more than 11%. The formation of the growth ledge implies that the Γ phase grows laterally. The presence of the growth ledge also suggests that the Γ/α-Fe interface is partially coherent despite the fact that the rational orientation relationship was seldom. A HRTEM study that demonstrated the subsistence of structural ledge supported this notion. The interface structure also changed with the substrate α-Fe grain orientation, because the threshold of the growth ledge formation depends on the α-Fe grain orientation and/or the velocity of the growth ledge migration depends on that.

We report microstructures on the surface of graphite particles found in practicable carbon anodes by means of high-resolution transmission electron microscopy. The surfaces consist of “closed-edge” structures constructed in a similar manner as carbon nano-tube. We have also investigated the formation mechanism of these nano-structures using molecular dynamics simulations based on the Tersoff potential. From electrochemical measurements, the carbon anodes composed of these “closed-edge” structures show actually high battery performance with a large discharge capacity and a small irreversible capacity.

The crystallographic aspects of zinc and zinc-nickel alloys on steel sheets have been studied by means of transmission electron microscopy (TEM) and the O-lattice theory. TEM observation shows that the pure zinc and zinc-nickel hcp η-phase electrodeposits grow epitaxially on α-iron substrates with the Burgers alignment in keeping with the O-lattice theory, although the dimensions of the a-axis and c-axis vary with the Ni content. For the nickel-rich γ-phase, a cube/cube orientation relationship is observed. The relationship can also be interpreted in terms of the O-lattice theory.

Initial stage of lattice relaxation of GaAs islands grown on Si(100) substrate were investigated by combination of reflection high-energy electron diffraction and molecular beam epitaxy. In addition to the lattice constants in horizontal direction (a∥) to the substrate surface, we first measured directly those in vertical one (a⊥). At the beginning of the growth, the rapid increase of a∥ and the larger Poisson’s ratios than that of bulk were observed. Atomic bond flexibility and extension induced by surface effects might cause this rapid increase of a∥ and large Poisson’s ratios.