Dependence Of Growth Conditions Research Articles

ДЕНДРОКЛИМАТИЧЕСКИЙ АНАЛИЗ РАДИАЛЬНОГО ПРИРОСТА СОСНЫ ОБЫКНОВЕННОЙ В ЮЖНОЙ ТАЙГЕ НА ВОСТОЧНОЙ ОКРАИНЕ РУССКОЙ РАВНИНЫ

Regional dendroclimatological studies demonstrate the most accurate results when climatic responses of woody plantsto changes in climatic factors are identified in one particular region. Coniferous trees are the most frequent object of observation in suchstudies as they are more longevous and sensitive to changes in external factors. The paper presents the results of dendroclimatic investigation of growth variability of Scotch pine (Pinus sylvestris) growing in the southern taiga on the eastern edge of the Russian Plain. Chronology construction and data analysis were performed using CooRecorder, CDendro, COFECHA, ARSTAN and R programs. The obtainedtree-ring chronology of Scotch pine covers the time interval from 1822 to 2022, with a series duration of 201 years. The maximum growthwas observed in 1950 (1.21 mm), 1984 (1.25 mm), 2010 (1.37 mm). The minimum increment was in 1914 (0.75 mm), 1942 (0.77 mm),1977 (0.78 mm), and from 2015 to 2017. The analysis of correlation dependence of Scotch pine growth and climatic conditions showedthat the growth and development of the studied trees have been most influenced by changes in air temperature in June of the of the previousyear and current years, the correlation coefficient (R) is 0.068 and 0.156, respectively, as well as in October of the previous and currentyears - 0.352 and 0.221, respectively. The amount of precipitation has a smaller impact on growth. Thus, the factor of growth and development of Scotch pine on the eastern edge of the Russian Plain in the southern taiga subzone is mainly the air temperature in the fall monthsof the previous year and current year as well as the June temperature of the current year.

Androgenic response of spring barley (Hordeum vulgare L.) varieties and lines – sources of high grain protein content

Aim. Protein content is known to be one of the most important characters of grain quality. Investigation was aimed to determine the capability to haploid production in anther culture in vitro of spring barley accessions which are the sources of high protein content in grain. Methods. Infrared spectroscopy was used for evaluation of variability of barley genotypes in protein content. Anthers isolated from cold-pretreated spikes were cultivated on agar solidified nutrient medium containing N6 macro-and MS micronutrients, physiologically active substances and maltose (9.0 %). Results. Three years testing showed that mean grain protein contents in six spring barley accessions varied from 12.6 to 19.1 %. Commercial variety Yavir, accessions IR06605 and DD-21 from germplasm collection of the National Plant Gene Pool of Ukraine were selected as genotypes with a stable expression of this char-acter. Response to androgenesis in vitro varied from 6.9 to 45.9 % of morphogenic anthers and from 0.64 до 14.7 green plants per 100 cultivated anthers in dependence of genotype and donor plant growth conditions. Conclusions. Because of association between high protein content in grains and a relatively high androgenic response, varieties Velikan and Yavir were considered to be the most valuable ones for use in spring barley breeding for improvement of protein content via anther culture in vitro.

(Invited) MOCVD GaN-on-GaN Towards Vertical Power Devices & MOCVD Development of β-Ga2O3

Gallium nitride (GaN) has been considered as a promising candidate for power device applications due to the wide band gap (3.4 eV), high critical electric field (3 MV/cm) and high electron mobility (>1000 cm2/Vs). Baliga’s figure of merit (BFOM) of GaN is more than 500 times higher than silicon (Si) and more than three time higher than silicon carbide (SiC). Due to the availability of native GaN substrates, it is feasible to develop high performance GaN vertical power devices on low-defect GaN substrate. GaN-on-GaN vertical PN diode with record high VBR ~5 KV was reported [1], presenting the potential of GaN as a high-performance material for power devices. Compared with SiC, the performance of GaN vertical PN diodes is still limited by its high background doping in n-type drift layer at mid-1015 to low-1016 cm-3 range. Therefore, it is of great importance to study the sources and incorporation mechanisms of unintentionally doped background impurities in metal-organic chemical vapor deposition (MOCVD) GaN growth, to control the impurity incorporation, in order to maximize device performance for GaN based vertical power devices. This talk will discuss the dependence of MOCVD growth conditions on the impurity incorporations such as C, Si, O, H, and Fe. Quantitative SIMS and CV measurements are used for material characterization.Ultrawide bandgap (UWBG) gallium oxide (Ga2O3) with a band gap of 4.5-4.9 eV, represents an emerging semiconductor material with excellent chemical and thermal stability. The monoclinic β-phase Ga2O3 represents the thermodynamically stable crystal among the known five known phases (α, β, γ, d , ε). The breakdown field of β-Ga2O3 is estimated to be 6-8 MV/cm. These unique properties make β-Ga2O3 a promising candidate for high power electronic device and solar blind photodetector applications. Single crystal β-Ga2O3 substrates can be synthesized by scalable and low cost melting based growth techniques. MOCVD growth technique was used to develop high quality β-Ga2O3 thin films and its ternary alloy (AlxGa1-x)2O3. Control of background and n-type doping in β-Ga2O3 will be discussed. Record carrier mobilities of 194 cm2/V·s at room temperature and ~10,000 cm2/V·s at low temperature were measured for MOCVD β-Ga2O3 thin films [2]. MOCVD growth of β-AlGaO targeting for Al composition of > 40% will be discussed [3, 4]. Acknowledgement: The authors acknowledge the funding support from Advanced Research Projects Agency-Energy (ARPA-E) DE-AR0001036, U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under the Advanced Manufacturing Office, FY18/FY19 Lab Call, the Air Force Office of Scientific Research FA9550-18-1-0479 (AFOSR, Dr. Ali Sayir) and the National Science Foundation (1810041, 1755479). [1] H. Ohta, N. Asai, F. Horikiri, Y. Narita, T. Yoshida, and T. Mishima, Jpn. J. Appl. Phys. 58, SCCD03 (2019).[2] Z. Feng, A F M A. U. Bhuiyan, M. R. Karim, H. Zhao, Appl. Phys. Letts., 114, 250601, 2019.[3] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, Z. Chen, H. -L. Huang, J. Hwang, H. Zhao, Appl. Phys. Lett., 115, 120602, 2019.[4] A F M A. U. Bhuiyan, Z. Feng, J. M. Johnson, H.-L. Huang, J. Sarker, M. Zhu, M. R. Karim, B. Mazumder, J. Hwang, and H. Zhao, APL Materials, 8, 031104, 2020.

InAs heteroepitaxy on nanopillar-patterned GaAs (111)A

Heteroepitaxy on nanopatterned substrates is a means of defect reduction at semiconductor heterointerfaces by exploiting substrate compliance and enhanced elastic lattice relaxation resulting from reduced dimensions. We explore this possibility in the InAs/GaAs(1 1 1)A system using a combination of nanosphere lithography and reactive ion etching of the GaAs(1 1 1)A substrate for nano-patterning of the substrate, yielding pillars with honeycomb and hexagonal arrangements and varied nearest neighbour distances. Substrate patterning is followed by MBE growth of InAs at temperatures of 150–350 °C and growth rates of 0.011 nm/s and 0.11 nm/s. InAs growth in the form of nano-islands on the pillar tops is achieved by lowering the adatom migration length by choosing a low growth temperature of 150 °C at the growth rate 0.011 nm/s. The choice of a higher growth rate of 0.11 nm/s results in higher InAs island nucleation and the formation of hillocks concentrated at the pillar bases due to reduced adatom migration length. A common feature of the growth morphology for all explored conditions is the formation of hillocks or pyramids with sometimes well-defined facets due to the presence of a concave surface curvature at the pillar bases acting as adatom sinks. This InAs growth at the pillar bases and between pillars is investigated in detail in dependence of MBE growth conditions.

Study of the Fracture Toughness of K2NixCo(1 – x)(SO4)2 · 6H2O Crystals in Dependence of the Growth Direction and Rate

K2Ni(SO4)2 · 6H2O (KNSH), K2Co(SO4)2 · 6H2O (KCSH), and K2NixCo(1 – x)(SO4)2 · 6H2O (KCNSH) crystals have been grown by traditional and accelerated techniques. The microhardness and crack lengths were measured by indentation with a Vickers pyramid in dependence of the crystal growth conditions in order to improve the crystal structure and properties. It was shown that, with an increase in the growth rate, the stress intensity factor of the crystals (which characterizes the fracture toughness) changes in dependence of the composition: it decreases for KCSH (due to the rise in inhomogeneity) but increases for KCNSH, which is explained by lowering the level of both the mosaic and radial inhomogeneity. In the case of KNSH crystals, the fracture toughness of the {110} sector decreases, whereas the changes in the sector {001} of “slow” crystal are differently directed, which is explained by the high inhomogeneity of its composition.

Iron Transport through Ferroportin Is Induced by Intracellular Ascorbate and Involves IRP2 and HIF2α

A few tightly regulated transport proteins mediate iron absorption across the intestinal epithelium. At the basolateral border of intestinal cells there is one identified transporter, ferroportin, for the transfer of intracellular iron to the vascular system. Here, we investigate the effects of ascorbate (vitamin C) on the regulation of ferroportin in human intestinal Caco-2 cells using ELISA and Western Blot analyses. The results indicate that ferroportin protein levels peak at 100 μM of added ascorbate with an increase of 274% (p = 0.02). At 150 μM of ascorbate, the increase was only 28% (p = 0.04), and at 200 μM there was no significant change from the baseline control. In addition, the ascorbate-induced, (at 150 μM) up-regulated ferroportin levels were associated with increased 55Fe transport across the basolateral border (19%, p = 0.03). Ascorbate-induced up-regulation of cellular ferroportin levels (no added iron) was associated with increased levels of the iron regulatory protein IRP2 (230%, p = 0.0009), and the hypoxia-inducible factor HIF2α (69%, p = 0.03). Thus, iron transport across the basal border via ferroportin is influenced by the intracellular status of ascorbate and IRP2 and HIF2α are involved. We discuss possible reasons for the ascorbate-effects and the dependence of cellular growth conditions for iron transport-related protein expression.

Analysis and calculation of the formation of grown-in microdefects in dislocation-free silicon single crystals

The physical model of the formation of grown-in microdefects in dislocation-free Si single crystals has been analyzed. The mathematical models used to describe the processes of defect formation in crystals during their growth are proven to be adequate to the physical model. A technique is proposed to determine and calculate the defect structure in dependence of the crystal growth conditions (growth technique, growth rate, temperature gradients, cooling rate). It is shown that the theoretical study of the real crystal structure in the dependence of the thermal growth conditions using an original virtual technique for analyzing and calculating the formation of grown-in microdefects is a new experimental technique.

Dependence of growth conditions on copper germanate nanowires and their electrochemical characteristics

Copper germanate (CuGeO3) nanowires have been synthesized by the hydrothermal deposition process using GeO2 and copper foil as the resource as well as the deposition substrate. The factors including hydrothermal temperature, pressure and duration of the process were investigated in order to analyze the processing parameters that control the formation process, morphology and size of the nanowires. The dependence of the nanowires properties on the growth conditions shows that the CuGeO3 nanowires can be synthesized in a large range of different hydrothermal parameters from 400 °C to 250 °C. The hydrothermal pressure has an important effect on the formation and growth of the CuGeO3 nanowires. The CuGeO3 nanowires exhibit good electrochemical cyclic voltammetry characteristics owing to offering many advantages in sensing applications including their small size, high aspect ratio and conductance.

Large-scale synthesis and growth conditions dependence on the formation of CuGeO 3 nanowires

CuGeO 3 nanowires in bulk with the diameter of 20–100 nm and length of several dozens of micrometers have been synthesized via a facile hydrothermal process using GeO 2 and Cu(CH 3COO) 2·H 2O as the raw materials in the absence of any surfactants. The synthesized nanowires are single crystals with an orthorhombic phase based on the X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy characterizations. The dependence of different growth conditions, such as reaction temperature, reaction time, compactness, GeO 2 concentration, copper source materials, surfactants and solvents on the formation, morphologies and sizes of CuGeO 3 nanostructures have been investigated. Proper selection and combination of the growth conditions are the key aspect to control the formation, morphology and size of the CuGeO 3 nanostructures. The nucleation and crystalline growth mechanism are proposed to explain the formation and growth of CuGeO 3 nanowires. The photoluminescence spectrum of the CuGeO 3 nanowires exhibits three fluorescence emission peaks centered at 421 nm, 488 nm and 529 nm as the excitation wavelength is 235 nm.

Preparation and Characterization of BPO Film as Electrode for Using of FeRAM

Conductive perovskite BaPbO3 (BPO) films as a potential electrode material of PZT capacitors used in ferroelectric random access memory are prepared by rf magnetron sputtering. An x-ray diffractometer and standard four probe method are employed to investigate the dependence of growth conditions on crystal structure and conductivity of BPO films. It is found that BPO films with perovskite phase can be obtained at substrate temperatures above 425° C, and the sample with the lowest resistivity is obtained at 450° C under pure argon atmosphere. Using this BPO film as electrode, ferroelectric properties of BPO/PZT/BPO and Pt/PZT/BPO sandwiched structures are evaluated. Their remanent polarization and coercive field are 36.6μC/cm2 (81.3kV/cm) and 36.9μC/cm2 (89.1 kV/cm), respectively. The coercive field of the former structure is lower than that of the latter, but remanent polarizations are almost the same. In addition, the results imply that BPO electrode is helpful to improve the fatigue resistance of PZT. The reasons are discussed.

Influence of target–substrate angle on properties of laser deposited YBa 2Cu 3O 7− δ thin films and step-edge Josephson junctions

YBa 2Cu 3O 7− δ (YBCO) thin films have been made by pulsed laser deposition (PLD) under variable angles α between target and substrate orientation. For several angles α the laser pulse energy E and the oxygen pressure p O 2 were varied to study the dependence of optimal film growth conditions on α. Film properties which were analyzed include the film thickness, the droplet density, the critical temperature T c0, the surface morphology as seen by scanning electron microscopy (SEM) as well as crystal quality measured by Rutherford backscattering spectroscopy. With increasing angle α we find a shift of the optimal growth conditions towards higher laser pulse energy. Step-edge Josephson junctions prepared from YBCO films which were deposited under different angles α show a maximum product of critical current density and normal resistivity at α=20–45°.

Dependence of growth conditions on morphology in lateral epitaxial overgrowth of GaN by sublimation method

Lateral epitaxial overgrowth (LEO) of GaN by sublimation has been carried out to understand the dependence of growth conditions on the morphology and quality of the layers. Growth conditions have been optimised to have flat and smooth lateral overgrown surfaces with (1 1 2 ̄ 0) stripe window opening. The changing feature from triangular stripe to rectangular stripe growth with change in growth temperature have been observed using scanning electron microscopy (SEM). Atomic force microscopy (AFM) result shows the dominance of step growth mechanism leading to two-dimensional growth in the lateral overgrown GaN layers.

Growth and Morphology of Nd3+, Er3+ and Cr3+ doped YAl3(BO3)4 Single Crystals

Nd3+, Er3+ and Cr3+ doped large single crystals of YAl3(BO3)4 were grown by spontaneous crystallisation and by top-seeded solution growth (TSSG) from a K2Mo3O10 and B2O3 flux. The crystals were grown in orientation with cooling rate 2.4°C/day. The small crystals grown by spontaneous nucleation usually had simple needle shape, while the large crystals grown by TSSG method had either isometrical habit or tabular one. The results suggest that the extremely large pinacoid faces appearing in the case of YAB:Cr3+ growth are due to a high temperature gradient in the flux, and evaporation of the solution. The lattice structure of crystals checked by powder X-ray diffraction is isomorphous to YAB with space group R32. The dependence of crystal habits and growth conditions is discussed.

Growth and Morphology of Nd3+, Er3+ and Cr3+ doped YAl3(BO3)4 Single Crystals

Nd 3+ , Er 3+ and Cr 3+ doped large single crystals of YAl 3 (BO 3 ) 4 were grown by spontaneous crystallisation and by top-seeded solution growth (TSSG) from a K 2 Mo 3 O 10 and B 2 O 3 flux. The crystals were grown in orientation with cooling rate 2.4°C/day. The small crystals grown by spontaneous nucleation usually had simple needle shape, while the large crystals grown by TSSG method had either isometrical habit or tabular one. The results suggest that the extremely large pinacoid faces appearing in the case of YAB:Cr 3+ growth are due to a high temperature gradient in the flux, and evaporation of the solution. The lattice structure of crystals checked by powder X-ray diffraction is isomorphous to YAB with space group R32. The dependence of crystal habits and growth conditions is discussed.

Spectroscopic study of nanocrystalline TiO2 thin films grown by atomic layer deposition

Photoluminescence characteristics of nanocrystalline TiO 2 films grown by atomic layer deposition were studied. In dependence of growth conditions the films consisted of anatase, rutile and TiO 2-II phases. A broad band and two sharp peaks were observed in the photoluminescence spectra measured under continuous-wave Ar + laser excitation at temperatures 5–165 K. At 5 K the maximum of the broad band was at 2.24 eV in the anatase films, and at 2.37–2.40 eV in the rutile and TiO 2-II films. The intensity of sharp lines peaking at 3.31 and 3.37 eV depended on the crystal structure of the films and increased significantly after X-ray irradiation. The temperature dependence and decay times of different emission bands were also investigated. The data obtained allowed a defect-trapped-exciton interpretation of the sharp peaks although the free-exciton origin of the 3.31 eV peak could still be argued. The broad-band emission at 2.24–2.40 eV was obviously due to self-trapped exciton recombination.

Growth mechanism of GaP on Si substrate by MOVPE

Gallium phosphide (GaP) was grown directly on a silicon (Si) substrate by metalorganic vapour phase epitaxy (MOVPE) for various growth pressures of 76–380 Torr and for various phosphine/trimethygallium ratios (V/III ratios). The dependence of growth conditions (V/III ratios and growth pressures) on the initial growth of GaP on a Si substrate was studied. GaP grown on a Si substrate with a smoother surface could be obtained easily for a higher growth pressure or for a higher V/III ratio. A model for the improvement of GaP is proposed, which model is that not a high vI III source material ratio but a high phosphorus-to-gallium ratio on the Si surface prevents the island-type growth of GaP.