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1.
Structural and optical properties of ZnO nanostructures grown on silicon substrate by thermal evaporation process 总被引:1,自引:0,他引:1
Ahmad Umar 《Materials Letters》2008,62(1):167-171
Two types of one-dimensional ZnO nanostructures have been synthesized on silicon substrate by the thermal evaporation of metallic zinc powder in the presence of oxygen without the use of any catalyst or additives. Detailed structural analysis revealed that the formed ZnO nanostructures are single crystalline with wurtzite hexagonal phase and grow along the [0001] direction in preference. Presence of a sharp and strong, optical phonon Raman-active E2 (high) mode and suppressed E1 (LO) mode in the Raman spectra, in both the cases, confirmed the good crystallinity with the wurtzite hexagonal phase for the as-grown products. A sharp and dominant near band edge emission with a suppressed green emission is observed from the as-synthesized nanostructures which affirmed the good optical properties with very less structural defects for the grown nanostructures. 相似文献
2.
Umar A Kim SH Kim JH Park YK Hahn YB 《Journal of nanoscience and nanotechnology》2007,7(12):4421-4427
Flower-shaped ZnO nanostructures, containing the triangular-shaped petals (sharpened tips and wider bases) have been achieved by simple thermal evaporation of high purity metallic zinc powder in the presence of oxygen at 440 degrees C on steel alloy substrate without the use of metal catalyst or additives. Detailed structural studies confirm that the obtained flower-shaped nanostructures are single crystalline and possesses a wurtzite hexagonal structure, grown along the c-axis in the [0001] direction. Raman and room temperature photoluminescence analysis substantiate a wurtzite hexagonal phase with a good crystal quality and a strong UV emission at 378 nm, respectively, indicating few or no structural defects. Additionally, a detailed possible growth mechanism has also been discussed. 相似文献
3.
The growth of perfectly hexagonal-shaped ZnO nanorods, with Zn-terminated (0001) facets bounded with [Formula: see text] surfaces, has been performed on nickel-coated Si(100) substrate via thermal evaporation using metallic zinc powder and oxygen. Detailed structural investigations confirmed that the synthesized nanorods are single crystalline with the wurtzite hexagonal phase and preferentially grow along the c-axis direction. Raman spectra of the as-grown ZnO nanorods showed an optical-phonon E(2) mode at 438?cm(-1), indicating that as-grown nanostructures are in good crystallinity with the wurtzite hexagonal phase. The ZnO nanorods were found to show strong band edge emission with very weak or no deep-level emission, as shown by photoluminescence measurements. The clear observation of free excitons at low temperatures (13-50?K) indicates that the as-grown ZnO nanorods are of high quality. 相似文献
4.
Ahmad Umar 《Materials Letters》2007,61(27):4954-4958
Well-crystallized with excellent optical properties, needle-shaped ZnO nanowires have been synthesized on silicon substrate in a high density via the thermal evaporation of metallic zinc powder without the use of catalysts or additives. Extensive structural analysis showed that the grown nanowires are highly crystalline with the wurtzite hexagonal phase, grown along the [0001] in the c-axis direction. The presence of an optical-phonon E2 mode in Raman spectrum at 437 cm− 1 and sharp and strong UV emission at 379 nm with no green emission in the room-temperature photoluminescence (PL) spectrum confirms good crystallinity with the excellent optical properties for the deposited nanowires. 相似文献
5.
Jun Wang Shunxiao Zhang Jia You Huijun Yan Zhanshuang Li Xiaoyan Jing Milin Zhang 《Bulletin of Materials Science》2008,31(4):597-601
Synthesis of flower-shaped ZnO nanostructures composed of ZnO nanosticks was achieved by the solution process using zinc acetate
dihydrate, sodium hydroxide and polyethylene glycol-20000 (PEG-20000) at 180°C for 4 h. The diameter of individual nanosticks
was about 100 nm. Detailed structure characterizations demonstrate that the synthesized products are wurtzite hexagonal phase,
grown along the [001] direction. The infrared (IR) spectrum shows the standard peak of zinc oxide at 571 cm−1. Raman scattering exhibits a sharp and strong E
2 mode at 441 cm−1 which further confirms the good crystal and wurtzite hexagonal phase of the grown nanostructures. 相似文献
6.
Synthesis of flower-shaped ZnO nanostructures composed of hexagonal ZnO nanorods was achieved by the solution process using zinc acetate dihydrate and sodium hydroxide at very low temperature of 90 °C in 30 min. The individual nanorods are of hexagonal shape with sharp tip, and base diameter of about 300-350 nm. Detailed structural characterizations demonstrate that the synthesized products are single crystalline with the wurtzite hexagonal phase, grown along the [0 0 0 1] direction. The IR spectrum shows the standard peak of zinc oxide at 523 cm−1. Raman scattering exhibits a sharp and strong E2 mode at 437 cm−1 which further confirms the good crystallinity and wurtzite hexagonal phase of the grown nanostructures. The photoelectron spectroscopic measurement shows the presence of Zn, O, C, zinc acetate and Na. The binding energy ca. 1021.2 eV (Zn 2p3/2) and 1044.3 eV (Zn 2p1/2), are found very close to the standard bulk ZnO binding energy values. The O 1s peak is found centered at 531.4 eV with a shoulder at 529.8 eV. Room-temperature photoluminescence (PL) demonstrate a strong and dominated peak at 381 nm with a suppressed and broad green emission at 515 nm, suggests that the flower-shaped ZnO nanostructures have good optical properties with very less structural defects. 相似文献
7.
8.
Zhiwei Peng 《Materials Letters》2010,64(8):898-900
Star-like ZnO nanostructures were synthesized in bulk quantity by thermal evaporation method. The morphologies and structure of ZnO nanostructures were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results demonstrated that the as-synthesized products consisted of star-like ZnO nanostructure with hexagonal wurtzite phase. The legs of the star-like nanostructures were preferentially grown up along the [0001] direction. A vapor-solid (VS) growth mechanism was proposed to explain the formation of the star-like structures. Photoluminescence spectrum exhibited a narrow ultraviolet emission at around 380 nm and a broad green emission around 491 nm. Raman spectrum of the ZnO nanostructures was also discussed. 相似文献
9.
Large-scale and dense ZnO thin films with novel petal-like architectures were directly electrodeposited on the Au/ITO glass substrates from aqueous solution of Zn(NO3)2 and HMTA at a low temperature of 70 °C for the first time. Scanning electron microscopic (SEM) investigation revealed that the Au/ITO glass substrates are fully covered with densely distributed ZnO petal-like architectures. X-ray powder diffraction (XRD) pattern indicated that as-prepared unique films are highly crystalline and wurtzite hexagonal phase with extremely preferred orientation along [0001] direction. The optical band gap energy was found to be 3.85 eV for ZnO film with petal-like architectures on the Au/ITO substrate. Moreover, a strong and sharp ultraviolet (UV) emission at 386 nm but very weak defect-related deep level emission (DLE) in the room temperature photoluminescence (PL) spectrum also indicated that as-grown films are of good crystal quality. The possible growth mechanism for the novel petal-like architectures suggested that both the inherent highly anisotropic structure of ZnO and large lattice mismatch between ZnO and Au played crucial roles in determining final surface microstructures of the products. 相似文献
10.
Zinc oxide nanostructures have been synthesized using an eco-friendly bottom-up synthesis technique. Effect of hydroxy-propyl methyl cellulose-capping concentration is observed for the effectiveness in limiting the particle growth. It is observed that the structural and optical characteristics have strong dependence on capping concentration. Detailed structural characterizations confirmed that the as-prepared products possess a wurtzite hexagonal phase and the preferred direction of growth is along the c-direction. UV–Visible absorption investigation reveal variation in optical band gap. Room temperature energy resolved photoluminescence spectra of the obtained nanostructures show band edge emission as well as blue-green emission. 相似文献
11.
Chen ZG Li F Liu G Tang Y Cong H Lu GQ Cheng HM 《Journal of nanoscience and nanotechnology》2006,6(3):704-707
High purity one-dimensional ZnO nanobelts were synthesized by thermally evaporating commercial ZnS powders in a hydrogen-oxygen mixture gas at 1050 degrees C. It was found that these ZnO nanobelts had a single crystal hexagonal wurtzite structure growing along the [0001] direction. They had a rectangle-shaped cross-section with typical widths of 20 to 100 nanometers and lengths of up to hundreds of micrometers with lattice constants of a = 0.325 nm and c = 0.520 nm. The self-catalytic hydrogen-oxygen assisted growth of ZnO nanobelt is discussed. The photoluminescence (PL) characterization of the ZnO nanobelts shows strong near-band UV emission (about 383 nm) and one broad peak at 501 nm, which indicates that the ZnO nanobelts have good potential application in optoelectronic devices. 相似文献
12.
ZnO nanowire arrays were synthesized on zinc foil by a simple thermal evaporation process at relatively low temperature. Morphology and size controlled synthesis of the ZnO nanostructures was achieved by variation of the synthesis temperature, reaction time and the surface roughness of the substrate. A gas-solid and self-catalytic liquid-solid mechanism is proposed for the growth of nanowires at different temperatures. High-resolution transmission electron microscopy (HRTEM) showed that the as-grown nanowires were of single crystal hexagonal wurtzite structure, growing along the [101] direction. Photoluminescence exhibited strong UV emission at ~382?nm and a broad green emission at ~513?nm with 325?nm excitation. Raman spectroscopy revealed a phonon confinement effect when compared with results from bulk ZnO. The nanowire arrays also exhibited a field emission property. 相似文献
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14.
In-doped ZnO nanostructures with four different morphologies, which are nanotetrapods, nanocombs, nanowires, and nanodisks, have been synthesized on silicon substrates by a simple thermal evaporation method. The XRD patterns show the In-doped ZnO nanostructures are all with the hexagonal wurtzite structure, and a slight difference in lattice parameters had been detected among the samples with various morphologies. The Raman spectra demonstrate that the vibrational mode of 2LA, which is very weak in undoped ZnO, was strongly enhanced with indium ion doping into ZnO structures. The photoluminescence (PL) measurements indicate that the nanodisks have a relative strong ultraviolet (UV) emission than other three kinds of samples. 相似文献
15.
Feng Shi Hong Li Chengshan Xue 《Journal of Materials Science: Materials in Electronics》2010,21(12):1249-1254
Single-crystalline GaN nanowires and nanorods have been fabricated through ammoniating Ga2O3 films catalyzed with tantalum (Ta) by RF magnetron sputtering, and microstructure, morphology and optical properties were
investigated in particular. The results indicate that the nanowires have a hexagonal wurtzite structure with size about 50 nm
in diameter and more than ten microns in length, however, the nanorods are rod-like structures with smooth surface and 100–300 nm
in diameter. The growth direction of these nanostructures are perpendicular to the (100) crystal plane. The photoluminescence
spectrum at room temperature exhibits a strong UV light emission band centered at 364 nm. 相似文献
16.
Vertically aligned S-doped ZnO nanorod arrays have been successfully synthesized by hydrothermal method at 90 °C for 2 h. The obtained nanorod is ~ 70 nm in diameter and 1.2 μm in length. The XRD pattern and the Raman spectra indicate that the S-doped nanorod arrays are orientated at [001] and are single crystals with hexagonal wurtzite structure. The photoluminescence (PL) spectra show that S-doped ZnO nanorod arrays exhibit a relative weak ultraviolet (UV) emission, a violet emission and a strong green emission. The effects of S-doping on the structure and photoluminescence of ZnO nanorod arrays are discussed in detail. 相似文献
17.
In this paper, we prepared the ZnO nanoparticles by a simple hydrothermal method and fabricated the ZnO/SiO2 core/shell nanostructures through a sol-gel chemistry process successfully. The hollow SiO2 nanostructures were obtained by selective removal of the ZnO cores. The structure, morphology and composition of the products were determined by the techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The results indicated that the ZnO nanoparticles were sphere-like shape with the average size of 60 nm and belonged to hexagonal wurtzite crystal structure. With the coating of SiO2, the vibration modes of Si-O-Si and Si-OH were found. Furthermore, the measurement results of optical properties showed that spectra of bare ZnO nanoparticles and ZnO/SiO2 core/shell nanocomposites exhibited similar emission features, including a blue emission peak and an orange emission band. 相似文献
18.
以硬脂酸锌和过氧化氢为原料,采用油相法一步合成出一种特殊的氧化锌花状纳米结构。利用透射电镜、高分辨电镜、X射线衍射等对其形貌和结构的分析表明:花状氧化锌纳米颗粒结构为六方晶相,大小约为30nm。吸收光谱和荧光光谱测量显示该纳米结构有显著的近带边紫光发射特性,对应的缺陷发光强度较弱,表明这一纳米结构有较好的光学特性,因此在生物荧光标记方面有着潜在的应用价值。 相似文献
19.
Umar A Al Hajry A Al-Ghamdi AA Al-Heniti S 《Journal of nanoscience and nanotechnology》2010,10(10):6659-6665
Ultraviolet-emitting, single-crystalline aligned zinc oxide (ZnO) nanocones with hexagonal caps were grown on silicon substrate via simple non-catalytic thermal evaporation process. High-purity metallic zinc powder and oxygen were used as source materials for zinc and oxygen, respectively. The detailed structural characterizations confirmed that the formed products are single-crystalline, possess a wurtzite hexagonal phase and grown along the c-axis direction. Raman-active optical-phonon E2(high) mode at 437 cm(-1) with sharp and strong UV emission at 385 nm in room-temperature photoluminescence (PL) spectrum demonstrated that the as-grown ZnO nanocones with hexagonal caps possess good-crystal quality with the excellent optical properties. Finally, a plausible growth mechanism for the formation of as-grown ZnO nanocones with hexagonal caps was also proposed. 相似文献
20.
Structural and magnetic properties of Zn1-xcoxO nanorods prepared by microwave irradiation technique
Ahmed F Kumar S Arshi N Anwar MS Koo BH Lee CG 《Journal of nanoscience and nanotechnology》2012,12(2):1386-1389
We have successfully synthesized large-scale aggregative flowerlike Zn1-xCo(x)O (0.0 < or = x < or = 0.07) nanostructures, consisting of many branches of nanorods at different orientations with diameter within 100-150 nm (tip diameter approximately 50 nm) and length of approximately 1 microm. The rods were prepared using Zinc nitrate, cobalt nitrate and KOH in 180 Watt microwave radiation for short time interval. The synthesized nanorods were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM) and DC magnetization measurements. XRD and TEM results indicate that the novel flowerlike nanostructures are hexagonal with wurtzite structure and Co ions were successfully incorporated into the lattice position of Zn ions in ZnO matrix. The selected area electron diffraction (SAED) pattern reveals that the nanorods are single crystal in nature and preferentially grow along [0 0 1] direction. Magnetic studies show that Zn1-xCo(x)O nanorods exhibit room temperature ferromagnetism. This novel nanostructure could be a promising candidate for a variety of future spintronic applications. 相似文献