Silicon Nanowires Obtained by Low Temperature Plasma-Based Chemical Vapor Deposition (original) (raw)
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2003
Abstract Silicon nanowires were selectively grown at temperatures below 400 C by plasma enhanced chemical vapor deposition using silane as the Si source and gold as the catalyst. A detailed growth study is presented using electron microscopy, focused ion beam preparation, and Raman spectroscopy. A radio-frequency plasma significantly increased the growth rate. The Si nanowires show an uncontaminated, crystalline silicon core surrounded by a 2-nm-thick oxide sheath.
Gallium assisted plasma enhanced chemical vapor deposition of silicon nanowires
Nanotechnology, 2009
Silicon nanowires have been grown with gallium as catalyst by plasma enhanced chemical vapor deposition. The morphology and crystalline structure has been studied by electron microscopy and Raman spectroscopy as a function of growth temperature and catalyst thickness. We observe that the crystalline quality of the wires increases with the temperature at which they have been synthesized. The crystalline growth direction has been found to vary between 111 and 112 , depending on both the growth temperature and catalyst thickness. Gallium has been found at the end of the nanowires, as expected from the vapor-liquid-solid growth mechanism. These results represent good progress towards finding alternative catalysts to gold for the synthesis of nanowires.
Applied Surface Science, 2011
Silicon nanowires (SiNWs) were synthesized from pure silane precursor gas and Au nanoparticles catalyst at below Au-Si eutectic temperature. The SiNWs were grown onto Si (1 1 1) substrates using very high frequency plasma enhanced chemical vapor deposition via a vapor-solid-solid mechanism at temperatures ranging from 363 to 230 • C. The morphology of the synthesized SiNWs was characterized by means of field emission scanning electron microscope equipped with energy dispersive X-ray, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscope. Results demonstrated that the SiNWs can be grown at the temperature as low as 250 • C. In addition, it was revealed that the grown wires were silicon-crystallized.
Growth study of indium-catalyzed silicon nanowires by plasma enhanced chemical vapor deposition
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Indium was used as a catalyst for the synthesis of silicon nanowires in a plasma enhanced chemical vapor deposition reactor. In order to foster the catalytic activity of indium, the indium droplets had to be exposed to a hydrogen plasma prior to nanowire growth in a silane plasma. The structure of the nanowires was investigated as a function of the growth conditions by electron microscopy and Raman spectroscopy. The nanowires were found to crystallize along the <111>, <112> or <001> growth direction. When growing on the <112> and <111> directions, they revealed a similar crystal quality and the presence of a high density of twins along the {111} planes. The high density and periodicity of I. Zardo · A. Fontcuberta i Morral ( ) Walter these twins lead to the formation of hexagonal domains inside the cubic structure. The corresponding Raman signature was found to be a peak at 495 cm −1 , in agreement with previous studies. Finally, electron energy loss spectroscopy indicates an occasional migration of indium during growth.
Plasma-Assisted Growth of Silicon Nanowires by Sn Catalyst: Step-by-Step Observation
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A comprehensive study of the silicon nanowire growth process has been carried out. Silicon nanowires were grown by plasma-assisted-vapor-solid method using tin as a catalyst. We have focused on the evolution of the silicon nanowire density, morphology, and crystallinity. For the first time, the initial growth stage, which determines the nanowire (NW) density and growth direction, has been observed step by step. We provide direct evidence of the merging of Sn catalyst droplets and the formation of Si nanowires during the first 10 s of growth. We found that the density of Sn droplets decreases from ~9000 Sn droplets/μm(2) to 2000 droplets/μm(2) after just 10 s of growth. Moreover, the long and straight nanowire density decreases from 170/μm(2) after 2 min of growth to less than 10/μm(2) after 90 min. This strong reduction in nanowire density is accompanied by an evolution of their morphology from cylindrical to conical, then to bend conical, and finally, to a bend inverted conical sha...
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.
Forest of ultra thin silicon nanowires: realization of temperature and catalyst size
Journal of Materials Science: Materials in Electronics, 2018
One of the most important progresses in the field of nano science and technology was partially due to the high surface to volume ratio of quasi one-dimensional silicon nanowires (SiNWs) with various applications in biological and chemical sensors, optoelectronic devices, catalysis, Li ion batteries and solar cells. In this study we have prepared a uniform forest of ultrathin SiNWs using plasma enhanced chemical vapor deposition method. Uniformly distributed SiNWs were obtained based on an Au layer containing gold nano-seeds with the average diameters ranging from 10 to 40 nm at various temperatures. The physicochemical properties of SiNWs were characterized using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), photoluminescence (PL) and high-resolution transmission electron microscopy. Microscopic assessments revealed that crystalline-amorphous core-shell SiNWs with different diameters and lengths ranging from 35 to 130 nm and ~ 0.7 to 1.9 µm are formed during the vapor-liquid-solid mechanism, respectively. The XRD spectra show that the main lattice directions are Si(111), Si(220) and Si(311) which confirm crystalline structure of synthesized NWs. The PL spectrum reveal two distinct emission peaks at wavelengths of about 480 nm (blue range) and 690 nm (red range) as sharp and a broad peak, respectively.
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
Superlattices and Microstructures, 2014
High-density silicon nanowires (SiNWs) were grown via Pulsed Plasma-Enhanced Chemical Vapor Deposition at 400°C. Zinc (Zn) metal thin films with varying thickness from 10 nm to 100 nm were used as a catalyst to synthesize the SiNWs. The surface morphology, crystalline structure, and optical properties of the grown SiNWs were investigated. Results indicated that increasing the Zn thickness from 10 nm to 100 nm led to an increase in wire diameter from 65 nm to 205 nm, resulting in a reduction of SiNW density. The wires grown with Zn thicknesses of 10 and 80 nm exhibited high crystallinity as shown by the X-ray diffraction patterns. Three emission bands (green, blue, and red) were observed in the photoluminescence spectra of the SiNWs prepared using various Zn catalyst thicknesses. The SiNWs prepared using 10 and 80 nm Zn thicknesses displayed a sharp Raman peak that corresponded to the first-order transverse optical phonon mode in contrast to the other samples that produced SiNWs with a broad Raman band.
Journal of Applied Physics, 2013
In this paper, we study the metal-catalyzed synthesis of Si nanowires (Si-NWs) in a plasma based chemical vapor deposition system. In these deposition systems due to the high efficiency of precursor molecule dissociation, both uncatalyzed and catalyzed growth mechanisms can take place. The first one gives rise to the formation of the quasi one-dimensional (1D) Si-NWs, while the second one to a continuous two-dimensional (2D) Si layer over the substrate or on the nucleated Si-NWs. The Si-NWs formation is then the result of the competition between these two processes. The control parameters ruling these two contributions are here explored. Samples with different weights of 1D and 2D growth are deposited and characterized by using a plasma based chemical vapor deposition apparatus operating at T < 400 C. It is found that the main control parameter of these processes is the plasma power through the distribution of the precursor dissociation products. By properly tuning the power, Si-NWs with 1 Â 10 10 cm À2 of density, up to 1 lm long and without uncatalyzed growth are obtained. The optical functionality of the samples, grown with different 1D/2D contributions, is investigated and it is demonstrated that the uncatalyzed layer produces a total reflectance as high as 4040%, similar to that found in a planar Si wafer, while the highly dense Si-NWs, without the uncatalyzed deposition, produce a total reflectance of 4015%. V C 2013 AIP Publishing LLC. [http://dx.