Vapor-induced solid–liquid–solid process for silicon-based nanowire growth (original) (raw)
Related papers
Controlled growth of silicon nanowires synthesized via solid–liquid–solid mechanism
Science and Technology of Advanced Materials, 2005
The growth of silicon nanowires using solid-liquid-solid method is described. In this method, silicon substrates coated with a thin layer of gold were heat treated in nitrogen ambient. Gold particles started to diffuse into the silicon substrate and Au-Si alloy formed at the interface. The alloy would have molten to form liquid droplets on the substrate when temperature increases above their eutectic point, and more Si atoms diffused into these alloy droplets when heating continues. Rapid cooling of the droplet surface due to nitrogen flow into the chamber would eventually lead to the phase separation of silicon atoms from the surface of the alloy, created the nucleation and thus the growth of silicon nanowires. Controlled growth of the nanowire could be achieved by annealing the sample at 1000 8C with nitrogen flow rate set to around 1.5 l/min. The synthesized nanowires with diameter varied from 30 to 70 nm, were straight and grew along the N 2 flow. Larger amount and longer nanowires were grown when longer period of heating was applied. Nanowires with lengths more than several hundreds of micrometers were achieved by annealing the sample for 4 h. q
Nanotechnology, 2009
Vertically aligned silicon oxide nanowires can be synthesized over a large area by a low-temperature, ion-enhanced, reactive vapour-liquid-solid (VLS) method. Synthesis of these randomly ordered arrays begins with a thin indium film deposited on a Si or SiO 2 surface. At the processing temperature of 190 • C, the indium film becomes a self-organized seed layer of molten droplets, receiving atomic silicon from a DC magnetron sputtering source rather than from the gaseous precursors used in conventional VLS growth. Simultaneous vigorous ion bombardment aligns the objects vertically and expedites mixing of oxygen and silicon into the indium. Silicon oxide precipitates from each droplet in the form of multiple thin strands having diameters as small as 5 nm. These strands form a single loose bundle growing normal to the surface, eventually consolidating to form one nanowire. The vertical rate of growth can reach 300 nm min −1 in an environment containing argon, hydrogen, and traces of water vapour. This paper discusses the physical and chemical factors leading to the formation of the nanostructures. It also demonstrates how the shape of the resulting nanostructures can be further controlled by sputtering, during both VLS growth and post-VLS processing. Key technological advantages of the developed process are nanowire growth at low substrate temperatures and the ability to form aligned nanostructure arrays, without the use of lithography or templates, on any substrate onto which a thin silicon film can be deposited.
Applied Physics Express, 2008
We report 350 C as a critical growth temperature for overcoming the aggregation of gold (Au) in the synthesis of high-density silicon nanowires (SiNWs) with controlled diameters in a vapor-liquid-solid (VLS) mechanism by the low-temperature decomposition of Si 2 H 6. Low-temperature growth is considered essential for preserving the initial distribution of Au droplets (8 AE 5 nm) during SiNW nucleation with small (12 nm) and uniform (AE5 nm) diameters. Au-Si eutectics increase in size with aggregation at high temperatures, resulting in SiNWs with large and random diameters. The crystal quality, defect formation, and morphology of the wires, grown in the (111) direction, are size dependent.
Chemical Vapor Deposition Growth of Composite Silicon-Silica Nanowires from Silicon Monoxide Vapor
Si/SiO2 nanowires were synthesized directly by and on silicon substrate surface without the use of a metal catalyst. Since these nanowires grow directly from the silicon substrate, they do not need to be manipulated or aligned for subsequent applications. The obtained nanowires are amorphous with diameters ranging between 50 to 200 nm and few micrometers in length. Parameters like heating temperature, deposition time, and carrier gas flow-rate were found critical in determining the size, structure, growth yield and morphology of the obtained nanowires. FTIR absorption spectra showed high intensity Si–O asymmetric stretching mode and no absorption for Si-Si backbone vibration mode at 620 cm−1 which indicates the non-crystalline nature of grown wires.
Growth mechanism and dynamics of in-plane solid-liquid-solid silicon nanowires
Physical Review B, 2010
In this paper, we investigate the growth mechanism and dynamic behavior of in-plane solid-liquid-solid ͑IPSLS͒ silicon nanowires ͑SiNWs͒, mediated by indium drops which transform hydrogenated amorphous silicon into crystalline SiNWs. Two distinctive growth modes of the SiNWs have been identified: ͑1͒ the grounded-growth ͑GG͒ mode in which the produced SiNWs are fixed to the substrate and ͑2͒ the suspendedgrowth ͑SG͒ mode where the SiNWs are carried by and move together with the catalyst drops. A comparative study of the SiNWs produced in SG and GG modes provides important insights into the IPSLS mechanism and reveals the unique growth balance condition in the moving SiNWs/catalyst drop system. For the GG-SiNWs, the interplay between the front absorption interface and the rear deposition interface of the catalyst drop leads to an interesting growth dynamics, which can be described by a kinetic equation model. For the SG-SiNWs, direct evidences of the rolling-forward behavior of the liquid catalyst drop have been witnessed.
Silicon Nanowires: Innovative Control Growth Enabling Advanced Applications
BJSTR, 2022
This article reviews the growth concept of silicon nanowires with an attention to semiconductor nanowires filling the gap in the knowledge from the very original work to the very recent innovative experimental work. The objectives of this article are as follows: 1) To describe the original work of epitaxial growth of semiconductor nanowires, 2) To discuss the recently emerged technique of nanoscale templating controlling the growth position of nanowires, and 3) To explore the possible technological applications of position-controlled silicon nanowires. Comprehensive description of the first reported successful Vapor-Liquid- Solid (VLS) 1-D growth of silicon crystals is given. The growth approach of bottom-up, and the supersaturation in a three-phase system of VLS is presented along with the nucleation at the Chemical Vapor Deposition (CVD) processes. Positional assembly of silicon nanowires using current available techniques along with the recently invented one of Nanoscale Chemical Templating (NCT).
Vanadium oxide assisted synthesis of networked silicon oxide nanowires and their growth dependence
Particuology, 2011
Networked silicon oxide nanowires have been synthesized by VO 2-assisted chemical vapor deposition at 1000 • C on silicon substrate without supplying any gaseous or liquid Si source. Systematic study on the nanowire growth has indicated that morphology and composition of the final products are sensitive to the catalyst components, reaction atmosphere and temperature. Compared to Au and VO 2 as catalysts individually, co-catalysts of Au and VO 2 play a critical role in the formation of networked SiO 2 nanowires. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations indicate that the silicon oxide nanowires have smooth surfaces with uniform diameters of 30-100 nm, and their lengths reach several hundred micrometers. X-ray photoelectron spectroscopy (XPS) results reveal the atomic ratio of silicon to oxygen is about 1:2. Growth dependence of the networked nanowires on hydrogen and temperature is also discussed. Vapor-liquid-solid (VLS) process is proposed for the growth mechanism of the networked nanowires. It is also found that the growth mechanism of SiO 2 nanowires by increasing the temperature up to 1200 • C changes to vapor-solid (VS) processes since wire-like structures can be formed without any catalyst or H 2 gas introduced into the system.
Chemical-vapour-deposition growth and electrical characterization of intrinsic silicon nanowires
2009
In this work, we present the elaboration and the electrical characterisation of undoped silicon nanowires (SiNWs) which are grown via vapour-liquid-solid mechanism using Au nucleation catalyst and SiH 4 as the silicon source. The nanowires were investigated by high-resolution transmission electron microscopy. An electrical test structure was realized by a dispersion of the nanowires on SiO 2 /Si substrate with photolithography pre-patterned Au/Ti microelectrodes. The connexion is made on a single nanowire using a cross beam plate form allowing scanning electron microscopy imaging and the deposition of tungsten wiring by focussed ion beam deposition. The current-voltage characteristics of the nanowires are linear which indicates an ohmic contact between tungsten allow and SiNWs. The total resistance of the nanowires increases from 135 M to 5 G when the diameter decreases from 190 to 130 nm. This effect is may be due to the reduction of the conductive inner volume of the nanowires and to charged defects at the Si-SiO 2 interface if we assume that the contact resistance is constant. Moreover, gate-dependent current versus bias voltage measurement show that the nanowires exhibit a field effect response characteristic of a p-type semiconductor.
Silicon Nanowires Obtained by Low Temperature Plasma-Based Chemical Vapor Deposition
MRS Proceedings, 2012
Silicon Nanowires (Si-NWs) are obtained by vapor-liquid-solid growth using an inductively coupled chemical vapor deposition system which works at temperatures lower than 400 °C. Gold nanodots are used as metal catalyst. The selective growth of Si-NWs on the gold nanodots is obtained by controlling the contribution coming from the uncatalyzed growth on the bare Si substrate. In this way the final NW length can be controlled, and it is not influenced by the thickness of the uncatalyzed layer. The important parameter ruling the NW growth is found to be the plasma power which governs the dissociation of the Si precursor gas. Final NW lengths of 1 m are obtained at temperatures of 380 °C with a thickness of uncatalyzed layer equal to zero. Also the NW density is addressed in this work and it is optimised by increasing the gold equivalent thickness. The NW density is increased from 2.9×10 8 to 1.3×10 10 cm -2 , when the gold equivalent thickness passes from 1.8 nm to 2.2 nm.