Impact Of Crystal Orientation Research Articles

Effect of crystal orientation on elastic stresses and vibration characteristics of nickel-based single crystal turbine blade

The impact of crystal orientation on the elastic stress and vibration properties of nickel-based single-crystal turbine blades is complex and can affect their performance. By defining and describing single-crystal blade orientation by Euler angles rotation, this work presents the influence rule of crystal orientation on the elastic stress and dynamic frequency of blade through lotus leaf diagrams. The results shows that the rotations of three Euler angles can affect significantly the distribution of the region where the stress extremum occurs, and the difference between the maximum and minimum of stress is 210.11 MPa. In addition, the degree and mechanism of influence of Euler angles rotations on the several order frequencies are different. From the 1st to 3st order mode, the influence range of the crystal orientation on the dynamic frequency increases gradually, but the frequency ranges of the 3st, 4st and 5st order are roughly the same, and the frequency range of 6st order is the largest variation range. The blade is most likely to generate resonance when the second-order frequency reaches the minimum fmin2. The Euler angle β has a significant influence on the resonance margin, and the larger resonance margin can be obtained easily when the Euler angle β is large enough.

Impact of crystal orientation on pop-in behavior of magnesium

Impact of crystal orientation on pop-in behavior of magnesium

Impact of crystal orientation and surface scattering on DG-MOSFETs in quasi-ballistic region * * Project supported by the National High-Tech R&D Program (No. 2015AA016501).

The characteristics of nano scale n-type double gate MOSFETs with (100) and (110) surfaces are studied using 3D full band ensemble Monte Carlo simulator. The anisotropic surface scattering mechanism is investigated. The (100) case is sensitive to the gate voltage more than the (110) case. The impact of crystal orientation and surface scattering on transport features mainly reflects in the carrier velocity distribution. The electron transport features with (100) direction are greater than that with (110) direction, but are more likely to be affected by the surface scattering.

Surface morphology of tungsten exposed to helium plasma at temperatures below fuzz formation threshold 1073 K

Impact of crystal orientation on the surface morphology of the helium plasma exposed tungsten has been investigated on the linear device PSI-2. A nanoscale undulating surface structure having a periodic arrangement is formed for temperatures below 1073 K, in contrast to the fuzz nanostructure formation in a higher temperature range. The crests of undulation align with the direction. The interval of the undulation is narrowest at the crystal grain of {1 1 0} surface. The interval becomes wider as the crystal grain surface tilts away from the {1 1 0} surface, and the undulating surface structure is not formed near the {1 0 0} surface. The height of undulations is nm, independently of the interval of the undulations, and it corresponds to the depth of the layer heavily damaged due to helium plasma exposure.

Charge mobility anisotropy of functionalized pentacenes in organic field effect transistors fabricated by solution processing

To understand and optimize the performance of thin-film electronic devices incorporating crystalline organic semiconductors, it is important to consider the impact of their structural anisotropy on the charge transport. Here we report on the charge mobility anisotropy in 6,13-bis(triisopropylsilylethynyl) (TIPS) and 6,13-bis(triethylsilylethynyl) (TES) pentacene field effect transistors, in which microstructure is controlled by solution processing conditions. Thin-film structures that range from millimetre size, crystalline domains to macroscopic, high-aspect-ratio (∼1 μm wide and >1 cm long) needles are systematically produced by controlling the substrate displacement rate during zone-cast deposition. Through precise control of the microstructure we experimentally explore the differences in charge transport anisotropy between TIPS- and TES-pentacene molecules. Aligned needles of TIPS- pentacene result in a mobility anisotropy (μ∥/μ⊥) of ∼20 (mobility of ∼0.7 cm2 V−1 s−1) whereas TES-pentacene produce an order of magnitude lower mobility (∼0.06 cm2 V−1 s−1) but much higher mobility anisotropy (>45). Such significant changes in absolute mobility and mobility anisotropy are attributed to their different packing structures, which permit 2D charge transport in TIPS-pentacene and 1D transport in TES-pentacene. Bulky TIPS- side groups (diameter ∼7.5 A) force a brick-wall type packing structure, whereas TES- side groups (diameter ∼6.6 A) pack in a 1D slipped-stack. Furthermore, through precise control of the molecular alignment, the impact of crystal orientation on charge transport is investigated. TIPS-pentacene achieves the highest mobility when the angle between the needle long-axis and charge transport directions is ∼35°, whereas in TES-pentacene it is much closer to 0°. These results are supported by theoretical simulations.

Impact of Crystalline Orientation on the Switching Field in Barium Titanate Using Piezoresponse Force Spectroscopy

ABSTRACTUnderstanding crystal orientation at the ferroelectric domain level, using a non destructive technique, is crucial for the design and characterization of nano-scale devices. In this study, piezoresponse force spectroscopy (PFS) is used to identify ferroelectric domain orientation. The impact of crystal orientation on the switching field of ferroelectric BaTiO3 is also investigated at the domain level. The preferential domain orientations for BaTiO3 thin films prepared by pulsed laser deposition (PLD) in this study are [001], [101] and [111]. They have been mapped onto PFS spectra to show three corresponding switching fields of 460, 330 and 120 kV/cm respectively. In addition, the electric field at which the enhanced piezoresponse occurs was found to vary, due to a phase change. The polarization reversal occurs via a 2-step process (rotation and switching) for [101] and [111] orientations. The piezoresponse enhancement is absent for the [001] (pure switching) domains. The results demonstrate that an electric field induced phase change causes the [101] and [111] domains to reverse polarization at a lower field than the [001] domain.

Impact of crystal orientation on the adsorption kinetics of a porous coordination polymer–quartz crystal microbalance hybrid sensor

The hybridization of porous coordination polymers (PCPs) with electronic devices is a powerful strategy for developing systems that are suitable for advanced applications, such as chemical sensing. The quartz crystal microbalance (QCM) technique is one that allows minute mass changes to be resolved with a high temporal resolution, and the growth of PCP crystals that provide selective adsorption properties on a QCM substrate can facilitate the rapid detection of certain molecules from a gas or vapour mixture. Herein, we demonstrate the immobilization of the flexible PCP Zn(NO2-ip)(bpy) (Zn-CID-5; NO2-ip2− = 5-nitroisophthalate, bpy = 4,4′-bipyridine) on QCM substrates and investigate the adsorptive properties of the fabricated systems. Notably, the crystal orientation could be controlled by the anchoring of chemical functionalities on the substrate surface, or by the addition of coordination modulators (e.g. 4-phenylpyridine) at the time of growth of the PCP crystals on the substrates. Here, the crystal orientation plays a significant role in determining the detection kinetics of organic vapours (e.g. methanol), and the [010]-oriented case which displays the fastest adsorption kinetics among the samples tested is studied under mixed component (methanol–hexane) conditions to demonstrate its response profile. In all, the results demonstrate the potential utility of PCP/QCM hybrid systems in sensor applications, and also serve to highlight the importance of optimizing the physical orientation of crystal growth in such systems to maximize the overall performance of the system.

New insights in the passivation of high-k/InP through interface characterization and metal–oxide–semiconductor field effect transistor demonstration: Impact of crystal orientation

We have systematically studied the passivation of InP (100) and (111)A substrate using atomic-layer-deposited Al2O3 as gate dielectric. Modified high- and low-frequency method and full conductance method has been applied to evaluate the interface trap density (Dit) distribution at Al2O3/InP interface through MOS capacitor (MOSCAP) and MOSFET measurements. Lower Dit towards conduction band is obtained from (111)A surface, accompanied by an increase in midgap Dit. This leads to the demonstration of record-high drive current (Ids=600 μA/μm) for a InP (111)A NMOSFET with gate length (LG) of 1 μm and relatively large subthreshold swing of 230 mV/dec at off-state. Detailed DC IV and current drift measurements confirm the trap distribution from capacitance-voltage characterization. A trap neutral level (E0) model is proposed to explain all observations from MOSCAP and MOSFET characterizations. A universal behavior of the E0 shift on III-V (111)A surface is also analyzed and this observation can play a pivotal role in interface engineering for future III-V CMOS technology with 3D structures.

Influence of the crystal orientation on the electrical properties of AlN thin films on LTCC substrates

In this study, the influence of the crystal orientation on the electrical properties of sputter deposited aluminium nitride (AlN) thin films on low temperature co-fired ceramics (LTCC) substrates is investigated. The degree of c-axis orientation can be tailored by the deposition conditions such as plasma power, gas pressure and gas composition in the deposition chamber. Due to the large surface roughness of LTCC substrates ( R a = ∼0.4 μm) the quality of thin films is lower compared to silicon. Between areas of columnar grains arranged perpendicular to the LTCC surface, defects like voids are generated due to the wavy surface characteristics. The impact of crystal orientation and temperature up to 400 °C on the electrical performance is evaluated, as these layers are targeted as potential candidates for dielectric heat spreaders on multilayered ceramic substrates for high frequency applications. These AlN thin films having a good c-axis orientation exhibit lower leakage current levels over the complete temperature range compared to those with a poor alignment with respect to this crystallographic plane. The leakage current behaviour, however, is dominated according to the Pool–Frenkel electron emission independent of the degree of c-axis orientation.