共查询到20条相似文献,搜索用时 15 毫秒
1.
《Materials Letters》2006,60(25-26):3076-3078
GaN nanowires have been synthesized on Si(111) substrate through ammoniating Ga2O3/BN films under flowing ammonia atmosphere at the temperature of 900 °C. The as-synthesized GaN nanowires were characterized by X-ray diffraction (XRD), selected-area electron diffraction (SAED), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). The results demonstrated that the nanowires are hexagonal wurtzite GaN and possess a smooth surface with diameters ranging from 40 to 100 nm and lengths up to several tens of micrometers. The growth mechanism of crystalline GaN nanowires is discussed briefly. 相似文献
2.
Lili Sun Chuanwei Sun Huizhao Zhuang Jinhua Chen Zhaozhu Yang 《Materials Letters》2007,61(30):5220-5222
GaN nanorods have been synthesized by ammoniating Ga2O3 films on a TiO2 middle layer deposited on Si(111) substrates. The products were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transformed infrared spectra (FTIR) and high-resolution transmission electron microscopy (HRTEM). The XRD analysis indicates that the crystallization of GaN film fabricated on TiO2 middle layer is rather excellent. The FTIR, SEM and HRTEM demonstrate that these nanorods are hexagonal GaN and possess a rough morphology with a diameter ranging from 200 nm to 500 nm and a length less than 10 μm, the growth mechanism of crystalline GaN nanorods is discussed briefly. 相似文献
3.
GaN nanowires were synthesized by ammoniating Ga2O3 films on Ti layers deposited on Si (111) substrates at 950 °C. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM). The XRD, FTIR and HRTEM studies showed that these nanowires were hexagonal GaN single crystals. SEM observation demonstrated that these GaN nanorods with diameters ranging from 50 nm to 100 nm and lengths up to several micrometers intervene with each other on the substrate. 相似文献
4.
The GaN nanowires were successfully synthesized on Si(111) substrates by ammoniating the Ga2O3/ZnO films at 900 °C. The structure and morphology of the as-prepared GaN nanowires were studied by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM) and field-emission transmission electron microscopy (FETEM). The results show that the single-crystal GaN nanowires have a hexagonal wurtzite structure with lengths of about several micrometers and diameters ranging from 30 nm to 120 nm, which are conducive to the application of nanodevices. Finally, the growth mechanism is also briefly discussed. 相似文献
5.
Dongdong Zhang Huizhao Zhuang Haibo Sun Yuping Cao Yinglong Huang Zouping Wang Ying Wang Yongfu Guo 《Materials Letters》2009,63(12):978-981
GaN nanowires doped with Mg have been synthesized on Si (111) substrate through ammoniating Ga2O3 films doped with Mg under flowing ammonia atmosphere. The Mg-doped GaN nanowires were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). The results demonstrate that the nanowires were single crystalline with hexagonal wurzite structure. The diameters of the nanowires ranged 20-30 nm and the lengths were about hundreds of micrometers. The intense PL peak at 359 nm showed a blueshift from the bulk band gap emission, attributed to Burstein-Moss effect. The growth mechanism of the crystalline GaN nanowires is discussed briefly. 相似文献
6.
Feng Shi Chengshan Xue 《Journal of Materials Science: Materials in Electronics》2011,22(12):1835-1840
GaN nanowires have been fabricated successfully on Si (111) substrates coated with NiCl2 thin films by chemical vapor deposition method using Ga2O3 as raw material. The growth of GaN nanowires was investigated as a function of reaction times so as to study the influence
of different durations on the components, microstructure, morphologies and optical properties of GaN samples in particular
by X-ray diffraction, FT-IR spectrophotometer, scanning electron microscope, and photoluminescence. The results show that
the samples after reaction are single crystal GaN with hexagonal wurtzite structure and high-quality crystalline after reaction
at 1,100 °C for 60 min, which have good optical properties as revealed by PL spectra. Reaction time greatly influences the
growth of GaN nanowires, that is, with the increase in reaction time, the crystalline quality of GaN nanowires is improved
accordingly. The growth of the GaN nanowires follows the vapor–liquid-solid mechanism and Ni plays an important role as catalyst,
which forms nucleation point in the growth of GaN nanowires. 相似文献
7.
H.Y. Kwon J.Y. Moon Y.J. Choi M.J. Shin H.S. Ahn M. Yang J.H. Chang S.N. Yi D.H. Ha 《Materials Science and Engineering: B》2010,166(1):28-33
We developed a novel technique for obtaining a residual-strain-free GaN layer by the hydride vapor phase epitaxy (HVPE) method using one-dimensional nanostructures. The GaN layer was grown on a Si(1 1 1) substrate with a conventional AlN film and one-dimensional GaN nanostructures. The nanostructures were grown for 2 h with a HCl:NH3 gas flow ratio of 1:50. The growth rate of nanoneedles at 600 °C and nanorods at 650 °C were 2.553 and 2.193 μm/h, respectively. The overgrown GaN layer was grown at 1050 °C for 5 and 10 min. We obtained a GaN layer of 1.833 μm thickness and c = 5.1849 Å. The morphology, crystalline structure, and optical characteristics of the GaN layer were examined by field emission scanning electron microscopy, X-ray diffraction, and photoluminescence. 相似文献
8.
《Materials Research Bulletin》2013,48(4):1545-1552
For the first time, high quality tin oxide (SnO2) nanowires have been synthesized at a low substrate temperature of 450 °C via vapor–liquid–solid mechanism using an electron beam evaporation technique. The grown nanowires have shown length of 2–4 μm and diameter of 20–60 nm. High resolution transmission electron microscope studies on the grown nanowires have shown the single crystalline nature of the SnO2 nanowires. We investigated the effect of growth temperature and oxygen partial pressure on SnO2 nanowires growth. Variation of substrate temperature at a constant oxygen partial pressure of 4 × 10−4 mbar suggested that a temperature equal to or greater than 450 °C was the best condition for phase pure SnO2 nanowires growth. The SnO2 nanowires grown on a SiO2 substrate were subjected to UV photo detection. The responsivity and quantum efficiency of SnO2 NWs photo detector (at 10V applied bias) was 12 A/W and 45, respectively, for 12 μW/cm2 UV lamp (330 nm) intensity on the photo detector.. 相似文献
9.
The growth of GaN nanowires from Ga and NH3 sources in the flow of Ar carrier gas using a chemical vapor deposition (CVD) system was systematically studied. The substrates used were Si(111) and Si(100). Fabricated nanowires were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). We investigated the influence of growth temperature, catalyst used, Ga amount, and the ratio of Ar and NH3 flow rates on the morphology and properties of GaN nanowires. We found that the best results were obtained for a growth temperature of 950 °C. Optimal catalysts were Au and metallic Ni, while the use of nickel nitrate was found to lead to formation of SiOx nanowire bunches in addition to GaN nanowires. For the optimal temperature and catalyst used, the influence of the Ga to N ratio on the nanowire growth was studied. It was found that different types of nanostructures are observed in relatively Ga-rich and in relatively N-rich conditions. Growth mechanisms of different types of nanowires, including the stacked-cone nanowires and the microscale structures formed by lateral growth under N-rich conditions, are discussed. 相似文献
10.
In this paper, we developed a direct sublimation method to synthesize large-scale rutile SnO2 nanowires on 6H–SiC substrate using SnO2 nanoparticles as starting material. The structural properties of these straight nanowires were investigated in detail. These nanowires grow along [121], and the average diameter and length of these nanowires are 80 nm and 5 μm, respectively. In addition, the dielectric measurement indicates that the dielectric response of the SnO2 nanowires is significantly enhanced in the low-frequency range. It is suggested that both the rotation direction polarization (RDP) and the space charge polarization (SCP) process should be responsible for the enhancement of εr of these SnO2 nanowires. 相似文献
11.
This work reports a simple and environmental friendly approach for the fabrication of Fe nanowires under normal pressure and low temperature in the absence of any inorganic or organic templates, substrate, surfactant, external field or magnetic field. This approach involved the production of Fe(OH)3/NaCl by mechanically milling a mixture of Fe(OH)3 and NaCl, and the reduction of Fe(OH)3/NaCl to Fe nanowires. The as-prepared product (Fe/NaCl) and the Fe nanowires obtained by dissolving the NaCl from Fe/NaCl were characterized using transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. The results showed that the Fe nanowires are about 10-100 nm in diameter and 8-16 μm in length and their saturation magnetization (Ms) and coercivity (Hc) values are 145 emu/g and 206 Oe, respectively. 相似文献
12.
The Co nanowire arrays were synthesized by electrodeposition in polycarbonate template (PC) with 4 μm thickness. Electron field emission properties of cobalt nanowires were studied for wires with different aspect ratios, R ranged between 10 and 60, while the diameter of wires was fixed about 50 nm. The field emission properties of the samples showed low turn on electric field (Eto) with values varying between 2.9 and 11.3 V/μm showing a minimum value for R = 20 (Eto < 3 V/μm). On the other hand, the enhancement factor shows a peak for nanowires length about 1 μm. Field emission data using the Fowler-Nordhiem theory showed nearly straight-line nature confirming cold field emission of electrons. The fabricated field emitter arrays of cobalt nanowires in the PC templates opens the possibility of fabricating flexible flat panel displays. 相似文献
13.
GaN nanostructures have been synthesized on silicon substrates using chemical vapor deposition. Prior to growth silicon substrates were engraved using stainless-steel micro-tips. Straight as well as twisted nanowires were observed along the engraved lines/regions. Straight nanowires were few tens of microns in length and the twisted ones were few microns in length with diameter variation between 30 nm and 100 nm. The electron microscopy analysis indicates that the nanowires were grown parallel to the c-axis and possible growth mechanism is described. Raman scattering indicates good quality of nanowires exhibiting intense E2(high) mode and A1(LO) mode and a huge red-shift in the mode position indicates nano-size effects. Such engraved substrates without any explicit catalyst can provide site controlled growth of nanowires and this methodology is extendable for growing nanowires of related materials. 相似文献
14.
High-quality GaN nanowires (NWs) and zigzag-shaped NWs were grown on catalyst-free Si(1 1 1) substrate by thermal chemical vapor deposition (TCVD). Gallium (Ga) metal and aqueous NH3 solution are used as a source of materials. Ga vapor was directly reacts with gaseous NH3 under controlled nitrogen flow at 1050 °C. Scanning electron microscopy (SEM) images showed that the morphology of GaN displayed various densities of NWs and zigzag NWs depending on the gas flow rate, and increased nitrogen flow rate caused density reduction. The GaN NWs exhibited clear X-ray diffraction analysis (XRD) peaks that corresponded to GaN with hexagonal wurtzite structures. The photoluminescence spectra showed that the ultraviolet band emission of GaN NWs had a strong near band-edge emission (NBE) at 361–367 nm. Yellow band emissions were observed at low and high flow rates due to nitrogen and Ga vacancies, respectively. Moderate N2 flow resulted in a strong NBE emission and a high optical quality of the NWs. This study shows the possibility of low-cost synthesis of GaN nanostructures on Si wafers using aqueous NH3 solution. 相似文献
15.
Smooth single-crystal α-Mn2O3 nanowires have been fabricated using a one-step solid-state reaction method. X-ray diffraction patterns show that the nanowires have pure phase of α-Mn2O3. Transmission electron microscopy was employed to investigate the size and morphology of the products. The α-Mn2O3 nanowires exhibit mean diameter of 50 nm and length of 10 μm. Selected-area electron diffraction pattern demonstrates the single-crystal structure of the α-Mn2O3 nanowires, which are in good agreement with the X-ray diffraction results. The processes of the reactions and the phase transitions were also studied by using a simultaneous thermal gravimetric/differential thermal analyzer. It is found that the concentration of the precursor MnCO3 is a crucial factor in the formation of the nanowires. This work provides the probability of the industrialization of fabricating smooth single-crystal α-Mn2O3 nanowires. 相似文献
16.
Synthesis of GaN nanorods by ammoniating Ga2O3 films on In2O3 layer deposited on Si (111) substrates
GaN nanorods were synthesized by ammoniating Ga2O3/In2O3 thin films deposited on Si (111) with magnetron sputtering. X-ray diffraction, Scanning electronic microscope and high-resolution TEM results show that they are GaN single crystals, the sizes of which vary from 2 to 7 μm in length and 200 to 300 nm in diameter. In2O3 middle layer plays an important role in the GaN nanorod growth. 相似文献
17.
Zhou Yu Zhiwei Li Huabing Song Yunsen Zhang Zhifeng Jiao Jianguo Zhu 《Materials Letters》2009,63(1):37-40
This paper focuses on a new but much simple approach in synthesizing cubic spinel-structure ZnGa2O4 nanowires through the reaction of β-Ga2O3 nanowires templates and ZnO vapor at high temperature. Characterization has been achieved by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The length of as-synthesized ZnGa2O4 nanowires is scaled over 10 μm and the diameter is 80 nm respectively. It has been noticed that the concentration of ZnO vapor plays an important role for synthesizing ZnGa2O4 nanowires. And with different concentration of ZnO vapor, the very nanowires could be compounded in the form of β-Ga2O3:ZnGa2O4, ZnGa2O4 and ZnO:ZnGa2O4. The corresponding photoluminescence emission bands centered at 460 nm, 405 nm and 381 nm have also been observed. 相似文献
18.
M.R. Mahmoudian Y. Alias W.J. Basirun A. Moradi Golsheikh Farid Jamali-Sheini 《Materials Chemistry and Physics》2013
This study focuses on the synthesis and application of polypyrrole coated manganese nanowires (Mn/PPy NWs) as an enzyme-less sensor for the detection of hydrogen peroxide (H2O2). The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirm a core–shell structure with the Mn nanowires encapsulated by the PPy. An electrochemical sensor based on the Mn/PPy NWs for amperometric determination of H2O2 is prepared. The electrochemical behaviour of H2O2 is investigated by cyclic voltammetry with the use of modified glassy carbon electrode (GCE) with Mn/PPy NWs film. The modified glassy carbon electrode (GCE) with Mn/PPy NWs shows enhanced amperometric response for the detection of H2O2. This is due to the high available surface area of Mn/PPy NWs which can provide a suitable area for the reaction of H2O2. The detection limit and limit of quantification (S/N = 3) for two linear segments (low and high concentration of H2O2) are estimated to be 2.12 μmol L−1, 7.07 μmol L−1 and 22.3 μmol L−1, 74.5 μmol L−1, respectively. In addition, the sensitivity for these two linear segments is 0.4762 μA mM−1 and 0.0452 μA mM−1 respectively. 相似文献
19.
Y. P. Cao F. Shi X. W. Xiu H. B. Sun Y. F. Guo W. J. Liu Chengshan Xue 《Inorganic Materials》2010,46(10):1096-1099
The synthesis of Tb-doped GaN nanowires on Si (111) substrates through ammoniating Ga2O3 films doped with Tb was investigated. X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope,
high-resolution transmission electron microscopy and photoluminescence were used to characterize the composition, structure,
morphology and optical properties of the products. The results show that the as-synthesized GaN nanowires doped with 3 at
% Tb are of single-crystalline hexagonal wurtzite structure. The nanowires have diameters ranging from 30 to 50 nm and the
lengths up to tens of micrometers. An f-f intra-atomic transition of rare earth at 545 nm corresponding to 5
D
4–7
F
5 of the Tb3+ and other two peaks related with doping are observed in PL spectrum, confirming the doping of Tb into GaN. The growth mechanism
of GaN nanowires was discussed briefly. 相似文献
20.
《Materials Letters》2007,61(8-9):1679-1682
ZnO nanowires (ZNWs) were synthesized on Co-coated Si wafer via a carbon thermal reduction vapor transport method. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy investigations show that these ZNWs present a high-quality single-crystalline hexagonal structure. Field emission (FE) characteristics of the ZNWs film were measured. A low turn-on voltage for driving a current density of 0.1 μA/cm2 is about 3.9 V/μm. The field enhancement factor was determined to be ∼ 1180 for ZNWs film. Exposure of H2 during FE causes a permanent increase in the FE current and a decrease in the turn-on field. Also, the field enhancement factor γ was finally increased from 1180 ± 20 to 1510 ± 20 after FE saturation. 相似文献