Growth Of Silica Nanowires Research Articles

Ni‐Catalyzed Growth of Silica Nanowires From Amorphous Silicon Films and Growth Mechanism

The fabrication of amorphous silica nanowires (NWs) using an amorphous silicon (a‐Si) film grown by plasma‐enhanced chemical vapor deposition is demonstrated. Fabrication is achieved by conventional high‐temperature annealing of an a‐Si layer coated with a thin Ni film. Annealing of the Ni (≈20 nm)/a‐Si (≈1 μm) structure at 1100 °C for 1 h is shown to clearly result in the formation of densely packed amorphous silica NWs with diameters in the range from 35 to 70 nm. A comparison of energy dispersive X‐ray analyses on the tip and body of an NW demonstrates that NW growth proceeded via the solid–liquid–solid mechanism.

Growth of Silica Nanowires by Using Amorphous Silicon Films

Growth of Silica Nanowires by Using Amorphous Silicon Films

Synthesis and characterization of amorphous SiO2 nanowires directly grown on Cu substrates

A novel procedure for the growth of Silica nanowires directly from Cu substrates is reported. The single-step synthesis procedure consists of a thermal treatment at 900 °C in Ar-H2 atmosphere, without the need for additional catalysts. Nanowires grow from Cu protrusions generated on the surface during annealing via Vapor–Liquid–Solid method, giving rise to a branched structure. These SiO2 nanostructures present an amorphous structure as evidenced by transmission electron microscopy. Silica nanowires grown on Cu and Si substrates have been characterized by XPS. Additionally, room-temperature photoluminescence measurements show a blue-green emission peak at ca. 509 nm (2.44 eV) attributed to oxygen deficiencies in the structure. The success of this procedure allows for future possible incorporation of these nanowires in optoelectronic devices. New procedure for the growth of silica nanowires (SiO2NWs) directly on Cu substrates, via a single-step thermal treatment process without the need for additional catalysts. The process follows a VLS mechanism where SiO acts as the gaseous precursor of both: the SiO2NWs grown on the top Si fragment and those grown on the Cu substrate, roots-like nanowires (SiO2NRs). This synthesis permits to preserve the PL properties of the SiO2NWs on conductive Cu substrates, which could be of paramount importance in the design and implementation of integrated electronics and devices.

Growth of silica nanowires in vacuum

Silica nanowires were grown on a Pt-coated Si substrate in flowing Ar, dynamic vacuum, and sealed vacuum tubes.

Annealing effect on the structural and optical properties of embedded Au nanoparticles in silicon suboxide films

Au/SiOx nanocomposite films have been fabricated by co-sputtering Au wires and SiO2 target using an RF magnetron co-sputtering system before the thermal annealing process at different temperatures. The structural and optical properties of the samples were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), optical transmission, and reflection spectroscopy. XPS analysis confirms that the as-prepared SiOx films are silicon-rich suboxide films. FESEM images reveal that with an increase in annealing temperature, the embedded Au NPs tend to diffuse toward the surface of the SiOx films. In IR spectra, the intensity of the Si–O–Si absorption band increases with the annealing temperature. Optical spectra reveal that the position and intensity of the surface plasmon resonance (SPR) peak are dominated by the effect of the inter-particle distance and size of the Au NPs embedded in the SiOx films, respectively. The SPR absorption peak shows the blue-shift from 672 to 600 nm with an increase in annealing temperature. The growth of silica nanowires (SiOx NWs) is observed in the film prepared on a c-Si substrate instead of a quartz substrate and annealed at temperatures of 1000 °C.

Metal-Catalyst-Free Growth of Silica Nanowires and Carbon Nanotubes Using Ge Nanostructures

The use of Ge nanostructures is investigated for the metal-catalyst-free growth of silica nanowires and carbon nanotubes (CNTs). Silica nanowires with diameters of 10–50 nm and lengths of ≤1 µm were grown from SiGe islands, Ge dots, and Ge nanoparticles. High-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) reveal that the nanowires grow from oxide nanoparticles on the sample surface. We propose that the growth mechanism is thermal diffusion of oxide through the GeO2 nanostructures. CNTs with diameters 0.6–2.5 nm and lengths of less than a few µm were similarly grown by chemical vapor deposition from different types of Ge nanostructures. Raman measurements show the presence of radial breathing mode peaks and the absence of the disorder induced D-band, indicating single walled CNTs with a low defect density. HRTEM images reveal that the CNTs also grow from oxide nanoparticles, comprising a mixture of GeO2 and SiO2.

Statistical Weight Kinetics Modeling and Estimation for Silica Nanowire Growth Catalyzed by Pd Thin Film

This work intends to understand and model the kinetic aspect or the change of substrate weight over time in the selective growth of silica nanowires (NWs) catalyzed through Pd thin film. Various adsorption-induced, diffusion-induced, or unified vapor-liquid-solid (VLS) growth models have been developed to describe the NW length varying with time. Since NW length has been difficult to be measured, substrate weight change is therefore used as an alternative in this study to investigate growth kinetics of NWs. We investigate six different weight kinetics models in predicting weight changes during growth. Model estimation and comparison are conducted using both maximum-likelihood estimation (MLE) and Bayesian approaches. Owing to the embedded kinetics information in the nonlinear growth models, the Bayesian hierarchical model is shown to be more desirable when process data is limited.

Large-scale synthesis, characterization and photoluminescence properties of amorphous silica nanowires by thermal evaporation of silicon monoxide

A single step non-catalytic process based on thermal evaporation of silicon monoxide has been established for large-scale synthesis of silica nanowires. Scanning electron microscopy, high-resolution transmission electron microscopy equipped with energy dispersive X-ray spectrometry (EDAX), X-ray diffractometry were used to characterize the morphology and structure of the material. The as-synthesized nanowires had amorphous structures with diameters in the range 30–100 nm and hundreds of micrometers in length. The EDAX analysis revealed that the nanowires consisted of mainly two elements Si and O in an atomic ratio of approximately 1:2 corresponding to silicon dioxide. Photoluminescence spectra of the silica nanowires showed strong blue emission around 393 nm. Nucleation and growth of silica nanowires has been discussed on the basis of tiny oxide cluster formation that acts as nucleation centers for the nanowires growth.

Electron-Beam Induced Growth of Silica Nanowires and Silica/Carbon Heterostructures

AbstractA novel synthesis of silica nanowires and silica/carbon heterostructures by electron beam irradiation on porous silicon films was investigated. The method allows us to monitor the growth process in real time at atomic scales. Depending on the electron dose we obtain nanowires with diameters in the range of 15-49nm and lengths up to 500 nm. We found that the adequate electron dose was between 0.01 Acm-2 and 2 Acm-2. Additional electron dose causes plastic and failure deformations in the silica nanowires. A growth model consistent with our findings is presented that involves the flow of mass from the substrate to the nanowire driven by the local electric fields. Heterostructures showing a nanopalm-like shape are obtained after exposing the silica nanowire to poor vacuum conditions in which carbon aggregation from the surrounding gas is promoted by the local electric fields enhanced at the tip of the silica wires.

Growth of Silica Nanowires Catalysed by Pd Ion Implantation into Si(100)

ABSTRACTSelective synthesis of silica nanowires on silicon wafers catalyzed by Pd ion implantation is reported.Nanoclusters of palladium silicide acts as seeds for nucleation of wires following a Vapor-Liquid-Solid (VLS) growth model. The consumption of silicide towards nanowire growth is confirmed through Rutherford Backscattering Spectrometry (RBS).The influence of growth time, implantation dose and heating temperature on the structure and morphology of the wires is investigated. Optimization of the these tunable parameters would be needed to facilitate controlled and directed bottom-up growth of silica nanowires.Such selective synthesis may enable a large number of applications in wide areas of future technologies such as localization of light, low dimensional waveguides for functional microphotonics, scanning near field optical microscopy (SNOM), optical interconnects, sacrificial templates, optical transmission antennae and biosensors.