Effect Of Substrate Orientation Research Articles

Effect of substrate orientation on the structures and properties of BiFe0.91Zr0.09O3 thin films

Effect of substrate orientation on the structures and properties of BiFe0.91Zr0.09O3 thin films

An imine reductase that captures reactive intermediates in the biosynthesis of the indolocarbazole reductasporine

Imine reductases (IREDs) and reductive aminases (RedAms) have been used in the synthesis of chiral amine products for drug manufacturing; however, little is known about their biological contexts. Here we employ structural studies and site-directed mutagenesis to interrogate the mechanism of the IRED RedE from the biosynthetic pathway to the indolocarbazole natural product reductasporine. Co-crystal structures with the substrate-mimic arcyriaflavin A reveal an extended active site cleft capable of binding two indolocarbazole molecules. Site-directed mutagenesis of a conserved aspartate in the primary binding site reveals a new role for this residue in anchoring the substrate above the NADPH cofactor. Variants targeting the secondary binding site greatly reduce catalytic efficiency, while accumulating oxidized side-products. As indolocarbazole biosynthetic intermediates are susceptible to spontaneous oxidation, we propose the secondary site acts to protect against autooxidation, and the primary site drives catalysis through precise substrate orientation and desolvation effects. The structure of RedE with its extended active site can be the starting point as a new scaffold for engineering IREDs and RedAms to intercept large substrates relevant to industrial applications.

GeSn-on-GaAs with photoconductive carrier lifetime >400 ns: role of substrate orientation and atomistic simulation.

Group IV GeSn quantum material finds application in electronics and silicon-compatible photonics. Synthesizing these materials with low defect density and high carrier lifetime is a potential challenge due to lattice mismatch induced defects and tin segregation at higher growth temperature. Recent advancements in the growth of these GeSn materials on Si, Ge, GaAs, and with substrate orientations, demonstrated different properties using epitaxial and chemical deposition methods. This article addresses the effect of GaAs substrate orientation and misorientation on the materials' properties and carrier lifetimes in epitaxial Ge0.94Sn0.06 layers. With starting GaAs substrates of (100)/2°, (100)/6°, (110) and (111)A orientations, Ge0.94Sn0.06 epitaxial layers were grown with an intermediate Ge buffer layer by molecular beam epitaxy and analyzed by several analytical tools. X-ray analysis displayed good crystalline quality, and Raman spectroscopy measurements showed blue shifts in phonon wavenumber due to biaxial compressive strain in Ge0.94Sn0.06 epilayers. Cross-sectional transmission electron microscopy analysis confirmed the defect-free heterointerface of Ge0.94Sn0.06/Ge/GaAs heterostructure. Minority carrier lifetimes of the unintentionally doped n-type Ge0.94Sn0.06 epilayers displayed photoconductive carrier lifetimes of >400 ns on (100)/6°, 319 ns on (100)/2°, and 434 ns on (110) GaAs substrate at 1500 nm excitation wavelength. On the other hand, Ge0.94Sn0.06 layer showed poor carrier lifetime on (111)A GaAs substrate. The observed differences in carrier lifetimes were correlated with the formation energy of the Ge on (100)/6° and (100)/2° GaAs heterointerface using Stillinger-Weber interatomic potential model-based atomistic simulation with different heterointerfacial bonding by Synopsys QuantumATK tool. Total energy computation of 6280-atom Ge/GaAs supercell on (100)/6° leads to lower formation energy than (100)/2°, making it more thermodynamically stable. Hence, the growth of the GeSn/III-V material system using misoriented (100) substrates that are more thermodynamically stable will enhance the performances of optoelectronic devices.

Effect of substrate orientations on the electrochemical and localized corrosion behavior of a quad-layer Al alloy composite

Electrochemical and localized corrosion behavior of a 4045/7072/3003 M/4045 Al alloy composite in 3.5 wt.% NaCl solution was investigated from cross-sectional and plane directions by electrochemical impedance spectroscopy, polarization curves, and high-resolution microscopic examination. Plane directions showed higher corrosion resistance than the cross-sectional surface, with almost all localized corrosion initiated from Si-containing inclusions. The cross-section showed a complex galvanic effect among the four layers, the galvanic coupling between 4045/7072 accelerated the dissolution of 7072 because 7072 served as the anode, however, the galvanic coupling between 3003 M/4045 protected 4045 from corrosion, indicating that 3003 M served as the anode.

Computational Fluid Dynamics Insights into Chemical Vapor Deposition of Homogeneous MoS2 Film with Solid Precursors

AbstractIn this work, a comprehensive computational fluid dynamics (CFD) investigation to develop an in‐depth understanding on the fluid flow to obtain a homogenous deposition of MoS2 thin film is reported. First, the effect of substrate orientations (0, 20, 45, 70, and 90°) was simulated using ANSYS Fluent. The horizontal substrate (0°) showed a non‐uniform surface deposition rate (SDR) with relative standard deviation (RSD) of 44.1 %. The non‐uniformity gradually reduces with the increase of substrate angles and reaches the lowest for 90° with RSD of 13.1 %. The transient state analysis showed that no growth occurred for the first 8 s, followed by an SDR overshoot and finally reached a steady state >200 s. Next, the effect of horizontal separation distance (d = 1 to 6 cm) between MoO3 and the substrate is investigated. It is find that the Mo/S ratio reduces with the increase of separation distance. For d between 5 and 6 cm, the Mo/S drops by >1000 times and causes the growth environment to switch from Mo to S‐rich. This work offers a fast and cost‐effective approach to understand the fluid flow and to obtain a homogeneous deposition of MoS2 and other 2D TMD thin films.

Spatiotemporal walking gait kinematics of semi-arboreal red pandas (Ailurus fulgens).

Semi-arboreal mammals must routinely cope with the differing biomechanical challenges of terrestrial versus arboreal locomotion; however, it is not clear to what extent semi-arboreal mammals adjust footfall patterns when moving on different substrates. We opportunistically filmed quadrupedal locomotion (n = 132 walking strides) of semi-arboreal red pandas (Ailurus fulgens; n = 3) housed at Cleveland Metroparks Zoo and examined the effects of substrate type on spatiotemporal gait kinematic variables using linear mixed models. We further investigated the effects of substrate diameter and orientation on arboreal gait kinematics. Red pandas exclusively used lateral sequence (LS) gaits and most frequently utilized LS lateral couplet gaits across terrestrial and arboreal substrates. Red pandas moved significantly slower (p < 0.001), and controlling for speed, had significantly greater relative stride length (p < 0.001), mean stride duration (p = 0.002), mean duty factor (p < 0.001), and mean number of supporting limbs (p < 0.001) during arboreal locomotion. Arboreal strides on inclined substrates were characterized by significantly faster relative speeds and increased limb phase values compared with those horizontal and declined substrates. These kinematics adjustments help to reduce substrate oscillations thereby promoting stability on potentially precarious arboreal substrates. Red panda limb phase values are similar to those of (primarily terrestrial) Carnivora examined to date. Despite the similarity in footfall patterns during arboreal and terrestrial locomotion, flexibility in other kinematic variables is important for semi-arboreal red pandas that must navigate disparate biomechanical challenges inherent to arboreal versus terrestrial locomotion.

Substrate orientation effect in covalent organic frameworks/2D materials heterostructure by high-resolution atomic force microscopy

Substrate orientation effect in covalent organic frameworks/2D materials heterostructure by high-resolution atomic force microscopy

Ferromagnetism and Two Magnetic Phases in Rutile (TiO2) Implanted with Cobalt Ions: Effects of Substrate Temperature and Orientation

Ferromagnetism and Two Magnetic Phases in Rutile (TiO2) Implanted with Cobalt Ions: Effects of Substrate Temperature and Orientation

Ferromagnetism and two magnetic phases in rutile (TiO&lt;sub&gt;2&lt;/sub&gt;) implanted with cobalt ions: effect of substrate temperature and orientation

Room-temperature ferromagnetism and two magnetic phases: cobalt metal nanoparticles and a solid solution of divalent cobalt ions have been observed in single-crystal rutile (TiO2) implanted with cobalt ions to high dose level. Here we present the results of our structural and magnetic studies showing an influence both the temperature and the orientation of TiO2 substrate during a cobalt ion implantation, as well the effect of post-implantation thermal annealing (in air or in vacuum) on ferromagnetism value and magnetic phase composition of Co-implanted rutile.

Laser deposited superalloys with rotated substrate orientations: Microstructures and single-crystal formation

One- and multi-layer laser powder depositions were performed on single crystal (SX) Ni-based superalloy DD6 by rotating the substrate orientation around the [100], [010], and [001] crystallographic directions with the angle ξ[hkl] (hkl = 100, 010, 001) from the initial orientation (001)/[100], and the substrate orientation effect on the microstructure and SX nature were determined. It shows that for the one-layer deposition, the substrates with different rotation manners produce various dendritic domain distributions and stray grain (SG) susceptibilities in the deposited bead. Remarkably, one epitaxial dendrite domain can be only obtained for the [010]-axis rotation with ξ[010] = ±45°, which can suppress the formation of SGs effectively. However, at least two dendrite domains exist for [100]- or [001]-axis rotations, leading to slight dependence of SG susceptibility on the orientation. The multi-layer deposition experiments reveal that the SX nature can be retained with ξ[010] = 45°. The underlying mechanism of the orientation-dependent SG susceptibility is that different substrate orientations cause various columnar-to-equiaxed transition (CET) sensitivities. The difference in SG susceptibility between laser deposition and laser remelting is also discussed. Our results can provide an in-depth insight into controlling SG via substrate orientation in the laser processed SX superalloy.

Effect of substrate orientation on band structure of bulk III-V semiconductors

We present a detailed theory of the effects of crystal orientation on the properties of semiconductors. Our formalism allows us to study arbitrary crystallographic orientations of various compound semiconductors within any band model and crystal symmetry. For an illustration of its applicability, we present here results (band structure and effective masses) for only a few higher symmetry substrate orientations and concentrate on bulk cubic systems for materials such as GaInPAs/GaAs, GaInPAs/InP, GaInAsSb/GaSb, and GaInAsSb/InAs. Such cases were not discussed before.

Effect of substrate orientation and anisotropic strength on corrosion pits

The complexities of pitting corrosion and its associated pit morphologies are critical for predicting and preventing pit-related failure in materials. With the advances in computational tools, modeling of pitting corrosion has lately gained momentum. We recently developed a phase field model for 3-D pit morphology, and in the current work, the model is utilized to gain insight into the role of substrate orientation and anisotropic strength on crystallographic pits. The influence of these parameters on pit morphology and corrosion metrics such as pit volume, current, pit area, current density, and pit depth are studied. The crystallographic pit morphology changes with substrate orientation but not significantly with anisotropic strength. The anisotropic strength strongly influences the corrosion metrics whereas most corrosion metrics remain unaffected by substrate orientation.

Effects of sapphire substrate orientation on Sn-doped α-Ga2O3 grown by halide vapor phase epitaxy using α-Cr2O3 buffers

Heavily Sn-doped films of α-Ga2O3 were grown by halide vapor phase epitaxy (HVPE) on basal plane c-sapphire and on (10-12) r-sapphire substrates with and without α-Cr2O3 thin buffers prepared by magnetron sputtering and annealing in air at 500 °C for 3 h. For both substrate orientations, the use of α-Cr2O3 buffers led to three major effects. The first was a substantial decrease of the half-width of the symmetric and asymmetric x-ray reflections. The second was an order of magnitude decrease of the net donor concentration produced by flowing the same amounts of Sn into the reactor. Third, there was a reduction in the concentration of the major electron trap in the films near E c − 1 eV by more than a factor of two. These results show the major influence of sapphire substrate orientation on the electrical and structural properties of α-Ga2O3 grown by HVPE.

Structural and magnetic properties of FeRh films grown on MgO(0 0 1), MgO(0 1 1) and MgO(1 1 1) substrates

FeRh thin films are grown on MgO(0 0 1), MgO(0 1 1) and MgO(1 1 1) single-crystal substrates at 600 °C by dc magnetron sputtering and post-annealed at the same temperature for 1 h. Effect of substrate orientation on structural and magnetic properties of FeRh films is studied using X-ray diffraction (Cu-Kα and synchrotron radiation), temperature, and field dependent magnetization measurements. FeRh(0 0 1), (1 1 2), (0 1 1) orientated films with CsCl ordering are obtained on MgO(0 0 1), MgO(0 1 1) and MgO(1 1 1) substrates, respectively. Epitaxial quality of FeRh(0 0 1) is relatively better than FeRh(1 1 2) and FeRh(0 1 1) films. The FeRh(0 1 1) film grows on two orientation relationships: Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS). Temperature-dependent out-plane XRD measurements indicate an increase in c-parameter ∼0.56% to 0.62% across the AF-FM phase transition. The c/a ratio indicate that FeRh(0 0 1) film has in-plane compressive strain, while FeRh(1 1 2) and FeRh(0 1 1) films have tensile strain. The c/a ratio and temperature-dependent magnetization measurements (M–T) indicate that AF-FM phase transition can be tuned by appx. 52 K (388 K to 440 K) by variation of lattice strain at FeRh/MgO interface. Thermal hysteresis of appx. 12.8 K, 17 K and 22.9 K is observed for FeRh(0 0 1), FeRh(1 1 2) and FeRh(0 1 1) thin films. Larger thermal hysteresis is expected due to relatively poor epitaxial quality of the FeRh(1 1 2) and FeRh(0 1 1) films as compared to FeRh(0 0 1) film. The larger remnant FM component is observed in nominal AF state (room temperature) in all the samples, and is expected due to combined effect of composition inhomogeneity, substrate-induced strain and defects.

Phase Field Modeling of Crystallographic Corrosion Pits

The modeling of corrosion to understand and predict corrosion behavior is a topical issue. Here, a 3D phase field model is developed to simulate the pit morphology, primarily focusing on crystallographic pits. A crystallographic function is employed to incorporate different corrosion rates for different crystallographic planes. The model is benchmarked and validated against an analytical solution for a simple case. 3D crystallographic pits in a single crystal are simulated and the effect of substrate orientation on the pit morphology is studied. The crystallographic pit morphology changes significantly with the substrate orientation and these morphologies have a symmetry consistent with the substrate orientation. This first 3D phase field model of crystallographic pits will help in predicting the intricate shapes of pits, thereby, pushing the frontiers of pitting corrosion modeling.

Examining enzyme active site dynamics using linear and nonlinear infrared spectroscopy: substrate orientation, cofactor composition, and solvent effects

The active sites of enzymes undergo motions spanning a broad range of timescales but the role of dynamics in catalysis is still unknown. We apply linear and nonlinear infrared spectroscopic techniques, combined with site-specific vibrational labeling, to gain insights into the ultrafast dynamics of the active site as a function of orientation of the substrate, composition of the active site, and the presence of cosolvents in the solution. We are examining these phenomena in three model enzymes bound to vibrationally labeled substrate analog probes.

Effects of AlN substrate orientation on crystalline quality of wurtzite GaN films investigated via molecular dynamics

Molecular dynamics (MD) simulation was applied to investigate the deposition process of gallium nitride (GaN) films on aluminum nitride (AlN) substrates, in which the effects of different crystallographic orientations and growth temperatures of AlN substrates were investigated. Furthermore, evolution of the surface morphologies, the dislocations, the crystalline structures and the atomic stress were discussed in detail. It could be indicated that the deposited heteroepitaxial GaN films were consisted of zinc blende and wurtzite crystal structures with obvious dislocations when deposited on the polar plane of the AlN substrate. The dislocation density varied in a similar trend as the crystal structure changes. On the other hand, there is no misfit dislocations in the GaN films when deposition on the semi-polar and non-polar planes of the AlN substrate. According to the simulation results, the epitaxial GaN films deposited on the non-polar a-plane of the AlN substrates could be of higher crystalline quality under the same growth conditions.

Effect of substrate orientation on crystal growth in selective electron beam melting of nickel-based superalloy

Selective electron beam melting (SEBM) has proven to be a possible method for fabricating single-crystal structures owing to its high preheating temperature and directional temperature gradient, which can promote the directional growth of columnar grains. Researchers have conducted experiments to obtain a CMSX-4 single-crystal structure; however, when a polycrystalline substrate was adopted, a 9–15 mm competitive growth stage could not be avoided. There are still two key questions that need to be addressed: 1) Whether the use of a single-crystal substrate can avoid the competitive growth stage and a single-crystal structure grown directly from the substrate, and 2) the effect of single-crystal substrate orientation (001, 001, or 111) on grain growth behavior.Polycrystalline substrates and single-crystal substrates with different crystallographic orientations were used in this study. It was found that the (001) substrate promoted single-crystal structure growth in the SEBM process. When SEBM was carried out with (011) and (111) substrates, because of the complicated temperature field and crystallographic orientation in the first few layers, stray grains were found and epitaxial growth was difficult to maintain. These findings provide an important foundation for the direct fabrication of single-crystal blades.

Solid-source metal–organic molecular beam epitaxy of epitaxial RuO2

A seemingly simple oxide with a rutile structure, RuO2, has been shown to possess several intriguing properties ranging from strain-stabilized superconductivity to a strong catalytic activity. Much interest has arisen surrounding the controlled synthesis of RuO2 films, but unfortunately, utilizing atomically controlled deposition techniques, such as molecular beam epitaxy (MBE), has been difficult due to the ultra-low vapor pressure and low oxidation potential of Ru. Here, we demonstrate the growth of epitaxial, single crystalline RuO2 films on different substrate orientations using the novel solid-source metal–organic (MO) MBE. This approach circumvents these issues by supplying Ru using a “pre-oxidized” solid MO precursor containing Ru. High-quality epitaxial RuO2 films with a bulk-like room-temperature resistivity of 55 μΩ cm were obtained at a substrate temperature as low as 300 °C. By combining x-ray diffraction, transmission electron microscopy, and electrical measurements, we discuss the effect of substrate temperature, orientation, film thickness, and strain on the structure and electrical properties of these films. Our results illustrating the use of a novel solid-source metal–organic MBE approach pave the way to the atomic-layer controlled synthesis of complex oxides of “stubborn” metals, which are not only difficult to evaporate but also hard to oxidize.

Growth performance, carcass composition, and digestive enzyme activity of Labeo fimbriatus in tanks provided with feed and periphyton substrate in two orientations

ABSTRACT The effect of substrate orientation on the growth of Labeo fimbriatus in periphyton-based culture system was evaluated through an on-farm growth trial conducted for 90 days in 4x4x1.2 m soil-based, fertilized out-door cement tanks. The treatments consisted of triplicate tanks receiving no feed (NF), receiving feed (F), and those receiving sugarcane bagasse as periphyton substrates vertically suspended in the water column (SV) or applied directly to the tank bottom (SB). Bagasse used at 2 t/ha was hung vertically in SV tanks, while it was spread at the tank bottom in SB. Fish in F treatment tanks were fed daily with a 25% crude protein diet. No significant effect of periphyton substrate on growth performance and production of L. fimbriatus was observed when compared with the group receiving feed. Survival was not affected by the treatments. Production did not vary between the substrate orientations. Carcass of fish in F, SV, and SB had similar proximate composition. Activity of gut digestive enzymes was higher in treatments with substrate as compared to no substrate treatments.