Fabrication and characterization of CuxSi1−x films on Si (111) and Si (100) by pulsed laser deposition

The CuxSi1−x thin films have been successfully fabricated by pulsed laser deposition (PLD). The influences of laser energy fluency (I0) and deposition temperature (Td) on the phase structure were investigated. The results show that Cu deposited on Si (001) at I0 = 0.5-2.0 J/cm2, and η”-Cu3Si formed on Si (111) at I0 = 1.0-2.0 J/cm2. The films were consisted of Cu, η’-Cu3Si, ε-Cu15Si4 and δ-Cu0.83Si0.17 at Td = 100-500 °C on Si (001). The films were the single phase of η-Cu3Si at Td = 700 °C. In the case of Si (111), the phase structures transformed from Cu to Cu + η’-Cu3Si to η’-Cu3Si to η’-Cu3Si + η-Cu3Si with the increasing of Td. Rectangular grains were formed on Si (001), whereas triangular grains on Si (111). Cu (001) film was epitaxially grown on Si (001) at I0 = 1.5 J/cm2 and Td = 20 °C. η-Cu3Si (001) epitaxial layer was formed on Si (111) at I0 = 1.5 J/cm2 and Td = 700 °C. The epitaxial relationships of Cu (001)[100]//Si (001)[110] and η-Cu3Si (001)[-110]//Si (111)[11-2] were identified

Morphological Evolution of Vertically Standing Molybdenum Disulfide Nanosheets by Chemical Vapor Deposition

In this study, we demonstrated the chemical vapor deposition (CVD) of vertically standing molybdenum disulfide (MoS2) nanosheets, with an unconventional combination of molybdenum hexacarbonyl (Mo(CO)6) and 1,2-ethanedithiol (C2H6S2) as the novel kind of Mo and S precursors respectively. The effect of the distance between the precursor’s outlet and substrates (denoted as d) on the growth characteristics of MoS2, including surface morphology and nanosheet structure, was investigated. Meanwhile, the relationship between the structure characteristics of MoS2 nanosheets and their catalytic performance for hydrogen evolution reaction (HER) was elucidated. The formation of vertically standing nanosheets was analyzed and verified by means of an extrusion growth model. The crystallinity, average length, and average depth between peak and valley (Rz) of MoS2 nanosheets differed depending on the spatial location of the substrate. Good crystalized MoS2 nanosheets grown at d = 5.5 cm with the largest average length of 440 nm, and the highest Rz of 162 nm contributed to a better HER performance, with a respective Tafel slope and exchange current density of 138.9 mV/decade, and 22.6 μA/cm2 for raw data (127.8 mV/decade and 19.3 μA/cm2 for iR-corrected data)

DFT calculations of the electronic structure of CoPt in L1₁ and A1 structures

Spintronics applications for high-density non-volatile memories require simultaneous optimization of the perpendicular magnetic anisotropy (PMA) and current-induced magnetization switching. These properties determine, respectively, the thermal stability of a ferromagnetic memory cell and a low operation power consumption, which are mutually incompatible with the spin transfer torque as the driving force for the switching. Here, we demonstrate a strategy of alloy engineering to overcome this obstacle by using electrically induced orbital currents instead of spin currents. A non-equilibrium orbital density generated in paramagnetic γ-FeMn flows into CoPt coupled to the magnetization through spin-orbit interaction, ultimately creating an orbital torque. Controlling the atomic arrangement of Pt and Co by structural phase transition, we show that the propagation length of the transferred angular momentum can be modified concurrently with the PMA strength. We find a strong correlation to the phase transition-induced changes of d orbitals with mₗ = ±1 and mₗ = ±2 character. The close link of orbital hybridization to the dynamic orbital response and magnetic properties offers new possibilities to realize optimally designed orbitronics memory and logic applications.This dataset contains the DFT calculations for the electronic structure of CoPt in L1₁ and A1 structures that are discussed the corresponding publication

Effects of Long-Term Aerobic Exercise on Perivascular Adipose Tissue Function and Akt/eNOS/NO Pathway in Obese Rats

Abstract Background Perivascular adipose tissue (PVAT) in obesity critically contributes to vascular dysfunction, which might be restored by long-term exercise. Protein kinase B/nitric oxide synthase/nitric oxide (Akt/eNOS/NO) down-regulation within PVAT might be involved in the impaired anti-contractile function of arteries. Therefore, the present study evaluated the effect of long-term aerobic exercise on PVAT function and the potential regulator during this process. Methods Male Sprague Dawley rats were divided into normal diet control group (NC), normal diet exercise group (NE), high-fat diet control group (HC), and high-fat diet exercise group (HE) (n = 12 in each group). Upon the establishment of obesity (20 weeks of high-fat diet), exercise program was performed on a treadmill for 17 weeks. After the intervention, circulating biomarkers and PVAT morphology were evaluated. Vascular contraction and relaxation were determined with or without PVAT. Production of NO and the phosphorylations of Akt (Ser473) and eNOS (Ser1177) within PVAT were quantified. Results Metabolic abnormalities, systemic inflammation, and circulating adipokines in obesity were significantly restored by long-term aerobic exercise (P < 0.05). The anti-contractile effect of PVAT was significantly enhanced by exercise in obese rats (P < 0.05), which was accompanied by a significant reduction in the PVAT mass and lipid droplet area (P < 0.05). Furthermore, the production of NO was significantly increased, and phosphorylation levels of Akt (Ser473) and eNOS (Ser1177) were also significantly promoted in PVAT by long-term aerobic exercise (P < 0.05). Conclusion Long-term aerobic exercise training restored PVAT morphology and anti-contractile function in obese rats, and enhanced the activation of the Akt/eNOS/NO signaling pathway in PVAT

Fast synthesis of high-quality large-area graphene by laser CVD

Few layer graphene (FLG) has attracted tremendous interest in recent years because of its unique properties. However, how to synthesize graphene quickly and control the layer number is an important issue. Herein, high-quality and layer-controlled graphene was obtained on polycrystalline nickel foil by laser chemical vapor deposition (LCVD) within a few minute, which is a cold-wall CVD type based on irradiation of a continuous wave laser with Super-Gaussian distribution spot. The number of graphene layers and quality was controlled by controlling the growth time, laser power and cooling rate. The growth mechanism of the FLG has also been discussed. (C) 2018 Elsevier B.V. All rights reserved

Epitaxial growth of 3C-SiC (111) on Si via laser CVD carbonization

A qualitative and quantitative study was performed on the carbonization temperature (T-C) and carbonization time (t(C)) with respect to the microstructure and growth rate (R-g) of a 3C-SiC epitaxial layer on Si (111) substrates by carbonization via laser chemical vapor deposition (LCVD). The results showed that the density and size of the voids depended strongly on T-C. The voids were sealed, and thin films were formed continuously and uniformly after a carbonization time of 6 min at T-C = 1200 degrees C. R-g was also dependent on T-C, and increased from 0.43 to 1.35 mu m center dot h(-1) with increases in T-C from 1000 to 1200 degrees C. These deposition rates are 10 to 100 times greater than those of observed for conventional CVD methods

Epitaxial growth of 3C-SiC on Si(111) and (001) by laser CVD

Epitaxial 3C-SiC films have been deposited on Si(111) and Si(001) substrates via laser CVD with deposition rate of 12.32 and 15.56 m/h, respectively. The activation energy of 3C-SiC on Si(111) and Si(001) was 80 and 160 kJ/mol, and the root mean square (RMS) roughness (w) as a function of the film thickness (h) follows power laws of w similar to h(0.31) and w similar to h(0.06), respectively. The growth mechanisms of epitaxial 3C-SiC films on Si(111) and Si(001) was investigated based on the structural analysis and roughness evolution