共查询到20条相似文献,搜索用时 12 毫秒
1.
We report a study on the effects of various parameters on the synthesis of silicon nanowires (5--50 nm in diameter) by pulsed laser ablation. A novel silicon nanodendrite structure is observed by changing some of the growth parameters abruptly. This growth mechanism is explained by a qualitative model. These nanodendrites show a promise of being used as a template in fabricating nanocircuits. Thermal quantum confinement effects were also observed on the silicon nanowires and have been reported. 相似文献
2.
Qi Shao Rong-hui QueMing-wang Shao Qing ZhouDorothy Duo Duo Ma Shuit-Tong Lee 《Applied Surface Science》2011,257(13):5559-5562
Silicon oxide nanowires were synthesized with high-temperature evaporation using silicon monoxide as starting materials and tin and gallium as catalysts. The products take the shape of flowers with petals composed of silicon oxide nanowires. The pH response of the products reveals excellent linear relation due to their vast surface area. 相似文献
3.
采用纳米球光刻和金属辅助刻蚀法以p型单晶硅片制备了硅纳米线阵列, 并以此作为基底, 通过溅射不同时长的金属钒薄膜并进行热退火氧化处理, 制备出硅纳米线/氧化钒纳米棒复合材料. 采用扫描电子显微镜和X射线衍射仪表征了该复合材料的微观特性, 结果表明该结构增大了材料的比表面积, 有利于气体传感, 并且镀膜时间对后续生长的氧化钒纳米棒形貌有明显影响. 采用静态配气法在室温下测试了该复合材料对NO2的气敏性能, 气敏测试结果表明沉积钒膜的时间对复合材料的气敏性能影响较大. 当选择合适的镀膜时间时, 适量氧化钒纳米棒增加了材料表面积并形成大量pn结结构, 相比纯硅纳米线对NO2气体的灵敏度有明显提升, 且在室温下表现出优良的选择性. 同时, 对气敏机理做了定性解释, 认为硅纳米线与氧化钒纳米棒之间形成的pn结及能带结构在接触NO2 时的动态变化是其气敏响应提升的主要机制. 相似文献
4.
Quasi‐aligned molybdenum oxide nanowires are synthesized on silicon substrate by a thermal evaporation method, at a low temperature of 550 °C without using any catalyst. The diameter of these nanowires is about 100 nm, with steps in the top to form a sharp tip. The field emission measurement shows that these nanowires have strong electron field emission abilities, with high field enhancement factor and a relatively low turn‐on field of 2.16 V µm–1, suggesting that these molybdenum oxide nanowire arrays might be promising candidates as field emitters.
5.
Silicon oxide nanowires were synthesized from monosilane–argon–hydrogen mixture by the gas-jet electron-beam plasma chemical deposition method with simultaneous oxygen injection into the vacuum chamber. The synthesis was performed on monocrystalline silicon substrates covered with micron and nanometer tin catalyst particles. The nanowires are formed the via vapor–liquid–solid mechanism in the “catalyst-on-bottom” mode, in which many nanowires grow from one catalyst particle. The process of synthesizing nanowires on a substrate with catalyst consists of three stages: heating to synthesis temperature, hydrogen plasma treatment, and nanowire growth. In the substrate region corresponding to the jet axis, different structures are formed depending on the catalyst particle size. For catalyst particles under 100 nm, there are formed structures of chaotically oriented and interlaced bundles of silica nanowires. For catalyst particles of 0.3–1 micron, there are formed oriented arrays of cylindrically shaped nanowire bundles (“microropes”). Cocoon-like structures are formed for catalyst particles of more than 1 micron.We propose a model of nanowire growth by this method, which is based on nonuniform heating of a catalyst particle by a directed plasma flow. It was found that for synthesis of oriented microrope arrays the initial tin film thickness should be less than 100 nm and the synthesis process should include a hydrogen plasma treatment stage. 相似文献
6.
Aligned straight silica nanowires (NWs) have been synthesized on Si wafer by thermal evaporation of mixed powders of zinc carbonate hydroxide and graphite at 1100 °C and condensation on Si substrate without using any catalyst. The straight silica NWs have diameters ranging from 50 to 100 nm, and lengths of several micrometers, with cone-shaped tips at their ends. High deposition temperature and relatively high SiOx vapor concentration near the growth substrate would be beneficial to the formation of the aligned straight silica NWs. Different morphologies of silica nanostructures have also been obtained by varying the deposition temperature and the vapor concentration of the SiOx molecules. Room temperature photoluminescence measurements on the oriented silica NWs show that two green emission bands at 510 and 560 nm, respectively, revealing that the aligned straight silica NWs might have potential applications in the future optoelectronic devices. 相似文献
7.
Yi-Sheng Lai Jyh-Liang Wang Sz-Chian Liou Chia-Hsun Tu 《Applied Physics A: Materials Science & Processing》2009,94(2):357-363
In this work, we demonstrate a fast approach to grow SiO2 nanowires by rapid thermal annealing (RTA). The material characteristics of SiO2 nanowires are investigated by field emission scanning electron microscopy, high-resolution transmission electron microscopy
(HRTEM), high-angle annular dark-field (HAADF) imaging, electron energy loss spectroscopy (EELS), and energy-filtered TEM
(EFTEM). The HAADF images show that the wire tip is predominantly composed of Pt with brighter contrast, while the elemental
mappings in EFTEM and EELS spectra reveal that the wire consists of Si and O elements. The SiO2 nanowires are amorphous with featureless contrast in HRTEM images after RTA at 900°C. Furthermore, the nanowire length and
diameter are found to be dependent on the initial Pt film thickness. It is suggested that a high SiO2 growth rate of >1 μm/min can be achieved by RTA, showing a promising way to enable large-area fabrication of nanowires. 相似文献
8.
Z. Jiang T. Xie X.Y. Yuan B.Y. Geng G.S. Wu G.Z. Wang G.W. Meng L.D. Zhang 《Applied Physics A: Materials Science & Processing》2005,81(3):477-479
A large quantity of nanowires and nanotubes of silicon oxide are produced by using Fe–Co–Ni alloy nanoparticles as catalyst. The products have a uniform diameter of around 100 nm. The nanowires have a smooth surface and the lengths are up to 100 μm or more. A new morphology called a serrated joint nanotube was found. The alloy catalyst plays a key role in the synthesis process. Room-temperature photoluminescence measurement under excitation at 360 nm showed that the silicon oxide had a strong blue-green emission at 525 nm (about 2.36 eV), which may be related to oxygen defects. PACS 81.15.Gh; 81.07.Vb; 81.07.De; 42.70.Nq; 78.55.-m 相似文献
9.
Tungsten oxide nanowires of diameters ranging from 7 to 200~nm are
prepared on a tungsten rod substrate by using the chemical vapour
deposition (CVD) method with vapour--solid (VS) mechanism. Tin
powders are used to control oxygen concentration in the furnace,
thereby assisting the growth of the tungsten oxide nanowires. The
grown tungsten oxide nanowires are determined to be of crystalline
W18O49. I--V curves are measured by an \textit{in
situ} transmission electron microscope (TEM) to investigate the
electrical properties of the nanowires. All of the I--V curves
observed are symmetric, which reveals that the tungsten oxide
nanowires are semiconducting. Quantitative analyses of the
experimental I--V curves by using a metal--semiconductor--metal
(MSM) model give some intrinsic parameters of the tungsten oxide
nanowires, such as the carrier concentration, the carrier mobility
and the conductivity. 相似文献
10.
Philip Jennings Zhong-Tao Jiang Nicholas M. W. Wyatt David Parlevliet Christine Creagh Chun-Yang Yin Hantarto Widjaja Nick Mondinos 《Applied Physics A: Materials Science & Processing》2013,113(3):723-728
Silicon nanowires (SiNWs) have been grown on crystalline silicon (Si), indium tin oxide (ITO) and stainless steel (SS) substrates using a gold catalyst coating with a thickness of 200 nm via pulsed plasma-enhanced chemical vapor deposition (PPECVD). Their morphological, mineralogical and surface characteristics have been investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman analysis. SiNWs growth is accompanied by oxidation, thus yielding partially (SiO x ) and fully oxidized (SiO2) Si sheaths. The mean diameters of these SiNWs range from 140 to 185 nm. Si with (111) and (220) planes exists in SiNWs grown on all three substrates while Si with a (311) plane is detected only for Si and ITO substrates. Computational simulation using density functional theory (DFT) has also been conducted to supplement the experimental Raman analyses for crystalline Si and SiO2. XPS results reveal that ca. 30 % of the SiNWs have been oxidized for all substrates. The results presented in this paper can be used to aid selection of appropriate substrates for SiNW growth, depending on specific applications. 相似文献
11.
Solid–liquid–solid (SLS) combined with Vapor-liquid–solid (VLS) growth mechanism has been used for synthesizing Core-clad
silicon nanowires (SiNWs) by thermal annealing onto two different catalyst substrates (Au/Si and Ni/Ti/Si). It provides a
novel method to synthesize SiNWs which is cost-effective, large-area-compatible and may give a higher degree of control of
the end product, facilitated by the simple experimental process for further device applications. The first-order Raman peaks
of the SiNWs were found to shift and to broaden asymmetrically in comparison to the c-Si Raman peak. Using a phonon confinement
model, the average diameter of the wires can be estimated from the Raman spectra but are consistently lower than the diameters
measured using high-resolution transmission electron microscopy. We interpret this as due to the confining contribution of
the oxide clad. Due to the simplicity of the method, it could be adapted in industry for large scale synthesis of SiNWs with
oxide clad for device fabrication, e.g., surround-gate field effect transistors. 相似文献
12.
13.
A. Colli S. Hofmann A. Fasoli A.C. Ferrari C. Ducati R.E. Dunin-Borkowski J. Robertson 《Applied Physics A: Materials Science & Processing》2006,85(3):247-253
We review our recent results on the growth and characterization of silicon nanowires (SiNWs). Vapour-phase deposition techniques are considered, including chemical vapour deposition (CVD), plasma-enhanced chemical vapour deposition (PECVD), high-temperature annealing, and thermal evaporation. We present complementary approaches to SiNW production. We investigate the low-temperature (down to 300 °C) selective nucleation of SiNWs by Au-catalysed CVD and PECVD. Bulk production of SiNWs is obtained by thermal-vapour deposition from Si/SiO powders in a high-temperature furnace. In this case, SiNWs grow either by condensing on Au catalyst films, or by self-condensation of the vapour in a lower-temperature region of the furnace. Finally, we also achieve controlled growth by thermolysis of nanopatterned, multi-layered Si/Au thin-film precursors. The as-produced wires are compared in terms of yield, structural quality, and optical properties. Raman and photoluminescence spectra of SiNWs are discussed. PACS 81.15.Gh; 73.21.-b; 73.21.Hb; 71.20.Mq; 78.30.-j 相似文献
14.
《Solid State Communications》2003,125(3-4):185-188
High-density (∼108/cm2), uniformly aligned silicon nanotip arrays are synthesized by a plasma-assisted hot-filament chemical vapor deposition process using mixed gases composed of hydrogen, nitrogen and methane. The silicon nanotips grow along 〈112〉, and are coated in situ with a ∼3 nm thick amorphous carbon film by increasing the methane concentration in the source gases. In comparison to the uncoated silicon nanotips arrays, the coated tips have enhanced field emission properties with a turn-on field of 1.6 V/μm (for 10 μA/cm2) and threshold field of 3 V/μm (for 10 mA/cm2), suggesting their potential applications for flat panel displays. 相似文献
15.
S. Sharma T.I. Kamins R. Stanley Williams 《Applied Physics A: Materials Science & Processing》2005,80(6):1225-1229
Silicon nanowires were synthesized using chemical vapor deposition catalyzed by gold nanoparticles deposited on silicon substrates. Silicon nanowires grew epitaxially in 111 directions on (100)-oriented silicon substrates. For a particular set of process parameters, we observed a critical thickness of the nucleating gold film, below which nanowires could not be grown. We studied the dependence of the Au-Si alloy droplet size and size distribution on the starting gold film thickness and the annealing conditions. Increasing the Cl:Si ratio in the gas phase allowed nanowires to grow on smaller Au-Si alloy droplets. We used a modified heating sequence that deconvoluted the effect of silicon substrate consumption and gas-phase silicon supply on the Au-Si alloy formation and allowed growth of nanowires with diameters less than 20 nm. The modified heating sequence was also used to demonstrate the growth of bridging silicon nanowires with diameters less than 20 nm, which is a significant step in producing electronic devices. PACS 81.07.b; 81.15.Gh 相似文献
16.
Oxygen-plasma treatment was applied to silicon nitride and silicon oxide patterns on an InP substrate, and the effect was investigated by using scanning photoelectron microscopy. After the plasma treatment, the relative intensity of the carbon content was noticeably reduced on the surfaces of the patterns and the substrate, which indicates that the plasma treatment effectively removed the remaining carbon and made the patterns more resistant to carbon contamination. The oxygen-plasma treatment formed a thick oxidized surface on the InP substrate, which results in less occurrence of carbon contamination . PACS 68.37.Xy; 52.77.Bn; 85.40.-e 相似文献
17.
Na-doped ZnO nanowires with an average diameter of ∼40 nm have been fabricated by a thermal decomposition route at temperature around 400 °C. Their properties have been investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), UV-visible spectroscopy, Raman spectra, and photoluminescence (PL) spectroscopy. Room temperature photoluminescence (RT-PL) showed that the as-synthesized ZnO samples exhibited strong visible emission with a major peak at 420 nm. Furthermore, intensity of the visible emission increased and then decreased with increase in Na concentration. The improvement of visible emission at 420 nm in the Na-doped ZnO samples should be a result of the surface defects increased by doping of Na in zinc oxide. In addition, photocatalytic studies indicated that these nanomaterials showed good photocatalytic performance for organic pollutants in water. 相似文献
18.
19.
El-Shazly M.A. Duraia Z.A. Mansorov S. Tokmolden 《Physica B: Condensed Matter》2009,404(21):3952-3956
In this work we report the successful formation of tin oxide nanowires and tin oxide nanoribbons with high yield and by using simple cheap method. We also report the formation of curved nanoribbon, wedge-like tin oxide nanowires and star-like nanowires. The growth mechanism of these structures has been studied. Scanning electron microscope was used in the analysis and the EDX analysis showed that our samples is purely Sn and O with ratio 1:2. X-ray analysis was also used in the characterization of the tin oxide nanowire and showed the high crystallinity of our nanowires. The mechanism of the growth of our1D nanostructures is closely related to the vapor–liquid–solid (VLS) process. The photoluminescence PL measurements for the tin oxide nanowires indicated that there are three stable emission peaks centered at wavelengths 630, 565 and 395 nm. The nature of the transition may be attributed to nanocrystals inside the nanobelts or to Sn or O vacancies occurring during the growth which can induce trapped states in the band gap. 相似文献
20.
Thermal evaporation was carried out in a horizontal quartz tube under an oxygen flow of about 50 ml/min and the influence of reaction time and temperature on the microstructure of the CuO nanowires (CNWs) is examined. The magnetic susceptibilities of the as-synthesized CNWs in the 5–300 K range were studied. It is interesting to note that the CNWs with a much larger diameter than 10 nm exhibit anomalous ferromagnetic behavior which has never been reported previously, demonstrating the effect of their peculiar morphology. The saturation magnetization (MS) and coercive field (Hc) of CNWs grown at 700 °C are 2.39 × 10?4 emu and 48 Oe, respectively. We fabricated gas sensors based on p-type single CNWs and demonstrate that CuO nanowires could be a promising candidate for a gas sensor with good performance. The reaction between the reducing gas and O? leads to a decrease of the hole density in the surface charge layer and an increase of the CuO resistance. 相似文献