Self-Assembly of Spatially Separated Silicon Structures by Si Heteroepitaxy on Ni Disilicide

A nonlithographic approach to produce self-assembled spatially separated Si structures for nanoelectronic applications was developed, employing the metal-induced silicon growth. Densely packed Si whiskers, 500–800 nm thick and up to 2500 nm long, were obtained by magnetron sputtering of Si on a 25 nm thick Ni prelayer at 575 °C. The nucleation of the NiSi2 compound at the Ni–Si interface followed by the Si heteroepitaxy on the lattice-matched NiSi2 is suggested to be the driving force for the whisker formation

A 0.5 μm Thick Polysilicon Schottky Diode with Rectification Ratio of 10^6

Polycrystalline Si films, 0.5-mm thick, were obtained as a result of metal-induced growth by sputtering from a Si target on 25 nm thick Ni prelayers at 525 °C. Silicon grew heteroepitaxially on the NiSi2 layer formed due to the reaction between the sputtered Si atoms and Ni. Schottky diodes were fabricated on the Si films by deposition of a Schottky metal on the front surface of the film while Ni disilicide provided an intimate ohmic contact at the back. A Pd/n-Si diode using an n-Si film annealed for 2 h at 700 °C in forming gas demonstrated a rectification ratio of 106, while an as-deposited p-Si film provided an Al/p-Si diode with rectification of five orders of magnitude. Schottky barrier properties are briefly discussed

The Role of Nucleation and Heteroepitaxial Processes in Nanostructuring of Si

Self-assembly represents a large prospective class of nanoscale fabrication techniques for future electronics. Understanding the mechanisms underlying the processes of nanostructure formation is crucial for establishing the control over their dimensions, spatial distribution, and uniformity. In this work, nanostructuring of Si was studied by silicon heteroepitaxy on NiSi2 nucleated at the Ni/Si interface during low-temperature Si sputtering on a thin Ni prelayer. The formation of spatially separated Si wires is discussed in terms of nucleation phenomenon, strain relaxation in the lattice-matched systems, and Si deposition kinetics

Design and Analysis of a General Relay-Node Selection Mechanism on Intersection in Vehicular Networks

Employment of a relay node can extend the coverage of a message in vehicular networks (VNET). In addition, the prior information regarding the road structure, which determines the structure of VNET, can benefit relay-node selection. However, the non-line-of-sight (NLOS) communication in the intersection scenarios and diverse shapes for the intersection hamper the design of a general relay-node selection on intersection. To resolve this problem, in this paper, we build a model to describe the general intersection, and propose a general relay-node selection method on intersection. Additionally, based on our mathematical description of the general intersection, the performance models for the general relay-node selection on the intersection are first explored in terms of message dissemination speed and Packet Delivery Ratio (PDR). The simulation results validate these models and indicate the improvement of our proposal, especially in heavy traffic. The improvement includes, at the high density of 3.0025 vehicles/m, the huge gain of up to 23.35% in terms of message dissemination speed than that of other compared methods and PDR of over 90%

Self-Organized Si Nanowires with Room-Temperature Photo-Emission

Two-dimensional arrays of self-organized Si nanowires were synthesized using the metal induced growth (MIG) method. In MIG processing, the thermally evaporated 25∼100 nm thick Ni films serve as prelayers for magnetron sputtered Si. When sputtering at 550°C, the Si crystallization occurs via the formation of nickel disilicide followed by subsequent epitaxial growth of Si crystals on nickel disilicide due to an extremely small lattice mismatch. Scanning electron microscopy study showed that the nanowires originated from the Si thin film and grew upwards in bundles. The diameter of the nanowires was 20∼50 nm. The length of the nanowires was typically 1 νm. Transmission electron microscopy and electron diffraction analysis revealed the single crystal structure of nanowires. Quantum-size effects in the produced wires were investigated by measuring the photoluminescence spectra at both low and room temperature. An intense room temperature PL peak centered around 690 nm with FWHM of 180 nm showed the promise of MIG-Si nanowires for red light-emitting diode applications. In addition, self-aligned silicide film on the bottom provides an ultimate back Ohmic contact, which significantly simplifies the fabrication of optoelectronic devices

Paleoenvironment of marine-continental transitional shales in the lower Permian Shanxi formation, southeastern Ordos Basin, China

The paleoenvironment of shales can be reconstructed to some extent using the combinations or concentrations of elements that correlate strongly with environmental conditions. In this study, we analyzed rare earth elements (REEs), major elements, and trace elements in the marine-continental transitional shales (transitional shales for short) of the Shan 23 submember of the Shanxi Formation in the southeastern Ordos Basin. The purpose is to deduce the paleoenvironmental conditions of the shales, encompassing paleoredox, paleoclimate, paleoproductivity, and paleo-provenance. The Shan 23 submember comprises four sections, namely Shan 23-1, Shan 23-2, Shan 23-3, and Shan 23-4. The Ba/Al, P/Al, and Cu/Al ratios, along with biogenic barium (Babio), indicate that the paleoproductivity of the submember peaked during the Shan 23-1 deposition and exhibited a downtrend upward in other sections. Trends in the Uau and the Ni/Co, V/Cr, U/Th, and V/Sc ratios suggest that suboxic conditions prevailed during the Shan 23-1 deposition, with the oxidation level gradually increasing from Shan 23-1 to Shan 23-4. C-value and the Sr/Cu vs. Ga/Rb cross-plot indicate a warm and arid paleoclimate during the Shan 23-1 deposition, which transitioned to cooler, drier conditions during the deposition of other sections. Indicators sensitive to paleoclimate, such as the K/Rb and Th/U ratios, along with the ICV, PIA, and Chemical Index of Alteration (CIA), highlight elevated weathering from Shan 23-2 to Shan 23-4, with Shan 23-1 exhibiting the weakest weathering during its deposition. As suggested by the REE data, the Zr/Sc vs. Th/Sr cross-plot, provenance discriminant functions, and the cross-plots of Hf vs. La/Th, Th vs. Hf–Co, and ∑REE vs. La/Yb, the sedimentary provenance for the transitional shales of the Shan 23 submember is of multiple origins, with significant contributions from the Upper Continental Crust (UCC). Discriminant diagrams, including those of Th–Co–Zr/10, Th–Sc–Zr/10, La–Th–Sc, and K2O/Na2O vs. SiO2, suggest that the transitional shales of the Shan 23 submember were primarily deposited under tectonic settings such as continental island arcs (CIAs) and passive continental margins (PCMs)

Vasoactive intestinal peptide alleviates osteoarthritis effectively via inhibiting NF-κB signaling pathway

Abstract Background To investigate the treatment effect of vasoactive intestinal peptide (VIP) on osteoarthritis (OA) and the relative mechanism. Method The OA model on the SD rat knee was established using the modified Hulth method, and the recombinant pcDNA3.1+/VIP plasmid was constructed. One month after the plasmids VIP were injected intra-articularly into the right knee joint of OA and sham-operated rats, the pathological changes of the OA knee joint were observed by Hematoxylin-eosin (HE) and Safranin O/fast green staining. The levels of VIP and serum inflammatory cytokines (TNF-α, IL-2 and IL-4) were measured by ELISA kits. Meanwhile, synoviocytes isolated from OA rat and sham-operated rat were cultured in vitro, and transfected with the VIP plasmid. The proliferation of synoviocytes was determined using BrdU kits. The protein expressions of TNF-α, IL-2, CollagenII, osteoprotegerin (OPG), matrix-degrading enzymes (MMP-13, ADAMTS-5), and the related protein of NF-κB signaling pathway (phosphorylated p65, phosphorylated IκBα) were evaluated by western blot. Results The VIP plasmid could effectively improve the pathological state of the OA rats knee joint, significantly decrease the levels of serum TNF-α and IL-2, and clearly increase the levels of VIP and serum IL-4. At the same time, after the OA synoviocytes were treated with the VIP plasmid, the proliferation ability of OA synoviocytes was reduced, the protein expressions of Collagen II and OPG were remarkably up-regulated, and the protein expressions of TNF-α, IL-2, MMP-13 and ADAMTS-5 were significantly down-regulated. In addition, the p-p65 expression decreased and p-IκBα expression increased. Conclusion Osteoarthritis was effectively treated by VIP via inhibiting the NF-κB signaling pathway

Quantum Size Effect Silicon Structures via Molecularly Self-Assembled Hybrid Templates

A novel approach for the synthesis of advanced functional inorganic materials with atomic-scale control over the size of periodic features on the sub-30 nm scale is presented. The key innovative aspect of this technique is the direct,bottom-up formation of a two-dimensional periodic array of spatially separated nanostructures in a self-organized thin-film porous template. This thin-film template is fabricated via biologically inspired hierarchical self-assembly of organic surfactant molecules in the presence of inorganic charged silicate species. The removal of organic molecules from such an organic/inorganic hybrid system creates a periodic array of pore channels of ∼3-30 nm diameter inside the thin-film silica template. This porous template is employed as a shadow mask to directly grow various functional nanostructures inside the confined environment of the periodic pore arrays. In the present study, silicon nanostructures were grown inside the templates by both chemical and physical (sputtering) vapor deposition. The quantum size effect was clearly pronounced in the room temperature photoluminescence spectra of the samples prepared by sputtering from a Si target, which makes the approach highly promising for the fabrication of nanoscale optoelectronic devices