Peculiarities Of Growth Research Articles

Epitaxial Ni films for ballistic ferromagnetic nanostructures

Nickel films of 170 nm thick were grown on sapphire substrates of the A, R and C orientations. Their electric characteristics and surface morphology were studied. Peculiarities of the film growth and optimum growth conditions for films of high electron mobility were determined. Nickel films grown on the sapphire A-plane with a high residual electron mean free path were found suitable for the fabrication of ballistic planar ferromagnetic nanostructures. Ballistic electron transport was observed in cross-type epitaxial Ni (111) nanostructures.

Core-shell structure and unique faceting of Sn-catalyzed silicon nanowires

The potential of tin (Sn) as a catalyst for the vapor-liquid-solid (VLS) growth of silicon nanowires (SiNWs) has been relatively unexplored. Compared to the more commonly used catalysts (e.g., gold), Sn features a low eutectic point (at 235 °C) and a very low equilibrium Si solubility. These features make it possible to tune the supersaturation in the catalyst and the growth kinetics at the SiNW/catalyst interface. Here, we investigate the peculiarities of Sn-catalyzed VLS growth and show that the local growth kinetics, modified by the high supersaturation in the Sn catalyst, can lead to the formation of core-shell structures and sidewall faceting of the SiNWs. Challenges facing Sn-catalyzed growth of SiNWs in VLS mode are also discussed. We suggest that the unique features of Sn catalyst will help tailor SiNW structures to meet specific application needs.

Development of Novel UV Emitting Single Crystalline Film Scintillators

The work is dedicated to the development of new types of UV-emitting scintillators based on single crystalline films (SCF) of aluminum perovskites and garnets grown by the liquid phase epitaxy method. The peculiarities of growth and properties of the following three types of UV SCF scintillators are considered in this work: i) Ce-doped SCF of Y-Lu-Al-perovskites with the Ce3+ emission in the 360-370 nm range of the decay time of 16-17 ns; ii) Pr-doped SCF of Y-Lu-Al garnets with the Pr3+ emission in the 300-400 nm range of the decay time of 13-17 ns; iii) La3+ or Sc3+ doped SCF of Y-Lu-Al-garnets, emitting in the 290-400 nm range due to formation of the LaY,Lu, ScY,Lu and ScA1 centers with decay time of the order of hundreds of nanoseconds. Preliminary test of these SCFs scintillators for visualization of X-ray images at European Synchrotrons Radiation Facility are presented as well.

Body composition and phase angle in Russian children in remission from acute lymphoblastic leukemia

Elevated degree of body fatness and changes in other body composition parameters are known to be common effects of treatment for acute lymphoblastic leukemia (ALL) in children. In order to study peculiarities of somatic growth and development in ALL survivors, we describe the results of BIA body composition analysis of 112 boys and 108 girls aged 5-18 years in remission from ALL (remission time range 1-13 years) compared to data from the same number of age- and sex-matched healthy controls (n=220). Detrimental effect on height in ALL boys was observed, whereas girls experienced additional weight gain compared to healthy subjects. In ALL patients, resistance, body fat, and percent body fat were significantly increased. The reactance, phase angle, absolute and relative values of skeletal muscle and body cell mass were significantly decreased. Principal component analysis revealed an early prevalence of adiposity traits in the somatic growth and development of ALL girls compared to healthy controls.

Growth and luminescence properties of Pr3+-doped single crystalline films of garnets and perovskites

Abstract Peculiarities of growth of single crystalline films (SCF) of Pr 3+ doped Y 3 Al 5 O 12 and Lu 3 Al 5 O 12 garnets and YAlO 3 and LuAlO 3 perovskites by the liquid phase epitaxy method from melt-solutions based on PbO–B 2 O 3 flux as well as luminescent and scintillation properties of these SCFs were studied in this work. Dependence the intensity of the Pr 3+ d-f and f-f-luminescence on the activator concentration and influence of Pb 2+ flux dopant on the light yield of SCFs of the mentioned garnets and perovskites were analyzed.

Physicochemical and technological peculiarities of multicomponent oxide crystal growth from melt by modified Stepanov technique

The peculiarities of the modified Stepanov technique are considered. The advantages of the method for growth of oxide crystals from melts of complex compositions are shown. Crystallization conditions are given to obtain optically homogeneous SrxBa1 − xNb2O6, BaWO4, SrMoO4, LiNbO3, and Ca3(Nb, Ga)2Ga3O12 single crystals using dies of capillary type.

Transition and growth: What was taught and what happened

The paper demonstrates why the transition process is taking more time than predicted and why many countries are still far away from the projected goal: a developed market economy. Analyzing the causes and re-examining the endogenous character of the transition progress, the authors conclude that the majority of reforms were implemented at a pace conditional on the initial, pre-transition conditions. The results obtained show a significant impact on the economic and institutional heritage of a country, which lasts much longer than was predicted on the eve of the reform process: initial conditions strongly and significantly affect the speed of transition throughout the entire observed period (1989-2007). They also affect the performance of a country: in the first years the transition progress may affect growth in a positive way, but later it becomes insignificant. This can explain some growth peculiarities previously remarked when transition countries were analyzed by means of long-run growth models. Using Barro and Levine-Renelt models the authors show that despite somewhat better results for the second decade of transition many peculiar patterns remain, which could temporarily block poorer transition economies in their attempts to catch up and cause unnecessary losses since transition policies were not properly adjusted to the initial conditions.

Nitride-based laser diodes by plasma-assisted MBE—From violet to green emission

We present recent progress in growth of nitride-based laser diodes (LDs) and efficient light-emitting diodes (LEDs) made by plasma-assisted MBE (PAMBE). This technology is ammonia free, and nitrogen for growth is activated by RF plasma source from nitrogen molecules. The recent demonstration of CW blue InGaN LDs has opened a new perspective for PAMBE in optoelectronics. The LDs were fabricated on low threading dislocation density (TDD) bulk GaN substrates at low growth temperatures 600–700 °C. In this work, we describe the nitride growth fundamentals, the influence of the TDD on the layer morphology, the peculiarities of InGaN growth as well as properties of LEDs and LDs made by PAMBE.

Crystal growth peculiarities of new oxide conductor La2Mo2O9in the system La2O3–MoO3

Crystal growth peculiarities of new oxide conductor La₂Mo₂O₉in the system La₂O₃–MoO₃

Some growth peculiarities and membrane characteristics of probiotic strains of Escherichia coli

It is found that the probiotic strains of Escherichia coli, G35 N 59 isolated from “Okarin” and from “ASAP” drug formulas, and the commensal strain 5–1 isolated from healthy human intestine, manifest higher specific growth rates, lower acidifying capacity during glucose fermentation in the external medium, and lower rates of decrease in redox potential in comparison with the wild-type strain (MC4100). At the same time, despite similar values of their membrane potentials, these bacteria differ essentially in total and N,N′-dicyclohexylcarbodiimide-sensitive rates of energy-dependent transmembrane H+ and K+ transport and display a low level of H2 production. It is suggested that the difference between their membrane characteristics reflects changes in the activity of proton-translocating F0F1-ATPase and is crucial for bacterial growth and probiotic activity of E. coli.

Inhomogeneous ordered states and translational nature of the gauge group in the Landau continuum theory: II. Applications of the general theory

A group theory approach to description of phase transitions to an inhomogeneous ordered state, proposed in the preceding paper, is applied to two problems. First, a theory of the state of a liquid-crystalline smectic type-A phase under the action of uniaxial pressure is developed. Second, a model of strengthening in quasicrystals is constructed. According to the proposed approach, the so-called elastic dislocations always appear during the phase transitions in an inhomogeneous deformed state in addition to static dislocations, which are caused by peculiarities of the crystal growth or by other features in the prehistory of a sample. The density of static dislocations weakly depends on the external factors, whereas the density of elastic dislocations depends on the state. An analogy between the proposed theory of the inhomogeneous ordered state and the quantum-field theory of interaction between material fields is considered. On this basis, the phenomenological Ginzburg-Landau equation for the superconducting state is derived using the principle of locality of the transformation properties of the superconducting order parameter with respect to temporal translations.

Growth peculiarities of silicon nanoparticles in an oxide matrix prepared by magnetron sputtering

AbstractThe process of thermal decomposition of SiOx layers prepared by magnetron sputtering is studied by photoluminescence, AFM, Auger and SIMS methods. The dependence of the depth distribution of the chemical composition on excess silicon content is obtained. It is shown that as‐sputtered SiOx layers are characterized by homogeneous enough chemical composition and do not exhibit photoluminescence. High‐temperature annealing in nitrogen atmosphere stimulates not only Si nanoparticle formation but also the appearance of a Si depleted region near layer‐substrate interface. This last process is found to be dependent on excess Si content. The decrease of silicon content in the depth of the annealed layers is accompanied by the decrease of Si particle sizes as proved by the blue shift of the photoluminescence maximum. The mechanisms of SiOx decomposition and possible reasons for the appearance of the Si depleted region are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Probabilistic approach to protein crystal nucleation

AbstractSimple probabilistic model for step‐wise growth of polymers is used for making some parallels with the nucleation of protein crystals. Although the considerations are made within 1D case, this approximation still shows some important peculiarities of protein crystal nucleation and growth. Thus, the present approach turns out to be useful for interpretation of some important experimental results regarding these processes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Adsorption of the Additives MPA, MPSA, and SPS onto Cu(111) from Sulfuric Acid Solutions

The adsorption of three different thiol-based additives, commonly used in sulfuric acid copper plating baths, on Cu(111) has been studied by cyclic voltammetry and in situ scanning tunneling microscopy. Adsorption rates were determined and the adlayer growth was monitored for various thiol concentrations. The observed growth peculiarities were tentatively explained by the lifting of a sulfate-induced reconstruction of Cu(111) and, in the case of 3-mercaptopropionic acid, by a bilayer formation.

Electrochemical Pore Etching in n- and p-Type Ge

Little was known about porous Ge until recently; here some substantial progress in producing porous Ge will be reported, mostly for the first time. i) n-type Ge in aqueous solution: Pore geometries, morphologies and growth peculiarities were found to be quite different from other semiconductors, such as Si and III-V. Nucleation is generally difficult, the preferred growth direction is <100> (and <111>), major stop planes are of the {110} type, but others are also found. In addition, there is always a strong electropolishing component compromising pore geometry and stability. ii) n- and p-type Ge in organic solution: In DMSO solution, the growth direction is <111>, and the stopping planes are still mainly {110}; somewhat unexpected, because this has never been observed in Si, and because no pores have been found in other p-type semiconductors so far, with the exception of Si. Nucleation seems to be difficult too, and new domain-forming phenomena are observed. Smooth or rough pore walls can be obtained, dependent on the experimental conditions.

Silicon nanowire growth by electron beam evaporation: Kinetic and energetic contributions to the growth morphology

The vertical and epitaxial growth of long (up to a few microns) silicon nanowires on Si(1 1 1) substrates by electron beam evaporation (EBE) (10 −6–10 −7 mbar) is demonstrated at temperatures between 600 and 700 °C following the vapour–liquid–solid (VLS) growth mechanism from gold nanoparticles. The silicon atoms are provided by evaporating silicon at varying evaporation currents ( I E) between 35 and 80 mA, which results in growth rates between 1 and 100 nm/min. The growth peculiarities in the interaction triangle, evaporation current ( I E), growth temperature ( T S) and gold layer thickness ( d Au) will be reported. Kinetic and energetic contributions to the morphology of silicon nanowires will be discussed.

Growth peculiarities during vapor–liquid–solid growth of silicon nanowhiskers by electron-beam evaporation

One-dimensional (1D) silicon (Si) nanostructures were grown by electron-beam evaporation catalyzed by gold nanoparticles on silicon substrates following the vapor–liquid–solid growth mechanism. We report three strikingly different growth morphologies of the 1D Si nanostructures and discuss their formation. The morphology of the silicon nanostructures strongly depends on gold layer thickness, annealing temperature before deposition and growth temperature during the deposition. The formation of nanoscale silicon features such as nanobelts, nanowires and nanowhiskers was observed. The nanoscale silicon features were characterized by transmission and scanning electron microscopy using imaging, diffraction and energy-dispersive X-ray spectroscopy, atomic force microscopy and UV micro-Raman spectroscopy.

Electrochemical pore etching in germanium

Abstract Nucleation and growth of electrochemically etched pores in Germanium (Ge) was investigated for n- and p-type Ge single crystals with {1 0 0}, {1 1 0}, and {1 1 1} orientations and doping concentrations of (10 14 –10 18 ) cm −3 . Various types of electrolytes, illumination conditions (front side, back side or none), and pre-treatments for optimizing nucleation were used. Several kinds of macropores could be obtained, mostly for the first time. In particular, pores could be obtained in p-type Ge samples. Pore geometries, morphologies, and growth peculiarities were found to be quite different from other semiconductors. Nucleation is generally difficult, the preferred growth direction is 〈1 0 0〉 or 〈1 1 1〉, stop planes are of {1 1 0} type, and there is always a strong electropolishing component compromising pore geometry and stability. Porous membranes have been produced showing electrocapillarity effects.

Formation of clusters through generation of free atoms

We consider, from a general point of view, conversion of a supersaturated vapour of metal atoms located in a buffer gas into metal clusters. A simplified set of balance equations for the size distribution function of clusters allows us to describe the time evolution of its parameters for various methods of cluster generation, such as the laser method, evaporation of metal atoms from a heated metallic surface, and the magnetron method of cluster generation by cathode erosion. Parameters of the distribution function together with certain peculiarities of cluster growth can be used for the analysis of certain methods of cluster generation under given external conditions. We illustrate this on the analysis of generation of titanium clusters in magnetron discharge where metal atoms from the cathode are captured by a buffer gas flow and are transformed there into clusters. The buffer gas together with metal clusters passes through an orifice, so that clusters can attach to a substrate. The analysis of this method allows us to find optimal parameters of this process.

Possibilities of C 1s XPS and N( E) C KVV Auger spectroscopy for identification of inherent peculiarities of diamond growth

The interaction of C-atoms and CH n -radicals with uncleaned and argon cleaned silicon substrate and with diamond surface after H-treatment have been studied in situ by XPS and Auger spectroscopy. It was found the formation of a new chemical surface state of carbon atoms in the case of carbon atoms and radicals interaction with cleaned silicon. The same chemical state was revealed on the H-treated diamond surface. Graphite-like structure of carbon atoms was observed on the surface of unlearned silicon and H-treated diamond after interaction with carbon atoms and radicals. N( E) C KVV Auger spectrum for the new chemical state of carbon atoms significantly differs from typical spectra for sp 2- and sp 3-bonded carbon materials. The high energy part of this spectrum was interpreted under the hypothesis of sp 3-bonded carbon atoms but with shifted fermi level position.