Hydrothermal Synthesis of One Dimensional Mo Doped n-Type ZnO Nanowires on p-Type Si Substrate (original) (raw)
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Korean Journal of Chemical Engineering, 2006
Synthesis of ZnO nanowires was achieved on Si(100) substrate by the thermal evaporation of high purity metallic zinc powder without the use of any metal catalyst or additives. The diameter and length of the as-grown nanowires were in the range of 20–35 nm and few micrometers, respectively. The shapes and sizes of ZnO nanowires were dependent on the growth time. The high resolution transmission electron microscopy and selected area electron diffraction patterns indicated that the as-grown products are single crystalline with wurtzite hexagonal phase. Room temperature photoluminescence studies exhibited a strong UV emission and a suppressed green emission, confirming the good optical properties for the deposited nanowires.
A Comparison of ZnO Nanowires and Nanorods Grown Using MOCVD and Hydrothermal Processes
Journal of Electronic Materials, 2013
A comparison of ZnO nanowires (NWs) and nanorods (NRs) grown using metalorganic chemical vapor deposition (MOCVD) and hydrothermal synthesis, respectively, on p-Si (100), GaN/sapphire, and SiO 2 substrates is reported. Scanning electron microscopy (SEM) images reveal that ZnO NWs grown using MOCVD had diameters varying from 20 nm to 150 nm and approximate lengths ranging from 0.7 lm to 2 lm. The NWs exhibited clean termination/tips in the absence of any secondary nucleation. The NRs grown using the hydrothermal method had diameters varying between 200 nm and 350 nm with approximate lengths between 0.7 lm and 1 lm. However, the NRs grown on p-Si overlapped with each other and showed secondary nucleation. x-Ray diffraction (XRD) of (0002)-oriented ZnO NWs grown on GaN using MOCVD demonstrated a full-width at half-maximum (FWHM) of 0.0498 (h) compared with 0.052 (h) for ZnO NRs grown on similar substrates using hydrothermal synthesis, showing better crystal quality. Similar crystal quality was observed for NWs grown on p-Si and SiO 2 substrates. Photoluminescence (PL) of the NWs grown on p-Si and SiO 2 showed a single absorption peak attributed to exciton-exciton recombination. ZnO NWs grown on GaN/sapphire had defects associated with oxygen interstitials and oxygen vacancies.
Photoluminescence properties of ZnO nanowire arrays fabricated on silicon substrate
2013 13th IEEE International Conference on Nanotechnology (IEEE-NANO 2013), 2013
Photoluminescence studies of zinc oxide nanowires produced by a carbo--thermal method on a nickel foil substrate are reported. Two types of as--grown samples: the first -containing only buffer film, and the secondcontaining both zinc oxide nanowires and buffer film grown in the same technological process, were investigated by means of the temperature-dependent photoluminescence. X-ray diffraction measurements of buffer film show that it is polycrystalline and is composed from wurtzite-type ZnO (main phase) and includes minority phases: rock salt type (Ni,Zn)O and hexagonal C3N4. The shape of the apparently monocrystalline nanowires is characterized by hexagonal section matching with the expectations of the hexagonal ZnO structure. The presence of LO-phonon replicas in photoluminescence spectra for the second sample is used as an argument for confirmation that ZnO nanowires are single crystalline. The method of growth of ZnO nanowires on nickel oxide opens perspectives to produce Zn1−xNixO diluted magnetic semiconductor nanowires.
A low temperature combination method for the production of ZnO nanowires
Nanotechnology, 2005
The growth of large-area, patterned and oriented ZnO nanowires on silicon using a low temperature silicon-CMOS compatible process is demonstrated. Nanowire synthesis takes place using a thin nucleation layer of ZnO deposited by radiofrequency magnetron sputtering, followed by a hydrothermal growth step. No metal catalysts are used in the growth process. The ZnO nanowires have a wurtzite structure, grow along the c-axis direction and are distributed on the silicon substrate according to the pre-patterned nucleation layer. Room temperature PL measurements of the as-grown nanowires exhibit strong yellow-red emission under 325 nm excitation that is replaced by ultraviolet emission after annealing. This method can be used to integrate patterned 1D nanostructures in optoelectronic and sensing applications on standard silicon CMOS wafers.
High-quality ZnO nanowire arrays directly synthesized from Zn vapor deposition without catalyst
Journal of the Korean Crystal Growth and Crystal Technology
Vertically well-aligned ZnO nanowire (NW) arrays were synthesized directly on GaN/sapphire and Si substrate from Zn vapor deposition without catalysts. Experimental results showed that the number density, diameter, crystallinity and degree of the alignment of ZnO NWs depended strongly on both the substrate position and kind of the substrates used for the growth. The photoluminescence (PL) characteristics of the grown ZnO NW arrays exhibit a strong and sharp ultraviolet (UV) emission at 379 nm and a broad weak emission in the visible range, indicating that the obtained ZnO NWs have a high crystal quality with excellent optical properties. The as-grown ZnO NWs were characterized by using scanning electron microscopy (SEM), high resolution transmission electronic microscopy (HR-TEM), and X-ray diffraction (XRD).
Electronics, 2019
ZnO films with a thickness of ~200 nm were deposited on SiO2/Si substrates as the seed layer. Then Zn(NO3)2-6H2O and C6H12N4 containing different concentrations of Eu(NO3)2-6H2O or In(NO3)2-6H2O were used as precursors, and a hydrothermal process was used to synthesize pure ZnO as well as Eu-doped and In-doped ZnO nanowires at different synthesis temperatures. X-ray diffraction (XRD) was used to analyze the crystallization properties of the pure ZnO and the Eu-doped and In-doped ZnO nanowires, and field emission scanning electronic microscopy (FESEM) was used to analyze their surface morphologies. The important novelty in our approach is that the ZnO-based nanowires with different concentrations of Eu3+ and In3+ ions could be easily synthesized using a hydrothermal process. In addition, the effect of different concentrations of Eu3+ and In3+ ions on the physical and optical properties of ZnO-based nanowires was well investigated. FESEM observations found that the undoped ZnO nanowir...
Hierarchical-Oriented Si/ZnO Heterostructured Nanowires
Science of Advanced Materials, 2014
In this work, self-catalytic growth of zinc oxide (ZnO) nanostructures on silicon nanowires (Si NWs) was studied using a vapor transport and condensation (VTC) method. ZnO seeded Si NWs were used as a base for the growth of ZnO nanostructure branches. We investigated the changes in morphologies of the ZnO nanostructures by varying the average size of the ZnO seeds and ZnO evaporation time. Our observations showed that the larger ZnO seeds are energetically more stable in promoting growth of ZnO nanorods (NRs) along the [0001] direction (c-axis). Increase in ZnO evaporation time lengthens the ZnO NRs, however, results in non-uniform diameter along the NRs due to irregular supply and precipitation of ZnO vapors on the non-polar surfaces of the NRs. The mechanisms of the seed size-dependent growth and time-dependent growth of ZnO nanostructures on Si NWs base were addressed. The hierarchical oriented Si/ZnO heterostructure NWs revealed interesting optical properties, among which, an enhancement in near band edge emission and suppression in optical reflection of the Si NWs.
2016
As a low temperature and low cost synthesis method, the hydrothermal deposition is widely used to grow ZnO nanowire arrays. Their optical properties are closely related to concentration of the structural defects in the ZnO nanowires. In this work we report on investigation on the evolution of the structural defects of ZnO nanowire arrays for different growth time, before and after post-annealing. The photo-emission properties of the ZnO nanowire arrays have been investigated in detail by using photoluminescence (PL) spectroscopy both on the as-grown nanowires and on the annealed ones. The PL analysis results showed an increasing intensity in the visible emission band with the growth time which is closely related to the change of the concentration of the structural defects in the ZnO nanowires regarding to the UV near-edge emission. The visible PL emission band can be deconvoluted into three Gaussians components, which correspond to the green, yellow-orange and red emissions, respectively. It is further revealed that the intensity of the orange and red emission bands increase with the increase of the growth time, which are ascribed to the interstitial oxygen and/or hydroxide groups and adsorbed oxygen, respectively. The correlation between energy-dispersive X-ray spectroscopy (EDS) analysis and PL measurements revealed that the excess zinc can be formed in the nanowires during the hydrothermal process.
Materials Science and Engineering: B, 2011
Electrodeposition is a low temperature and low cost growth method of high quality nanostructured active materials for optoelectronic devices. We report the electrochemical preparation of ZnO nanorod/nanowire arrays on n-Si(1 1 1) and p-Si(1 1 1). The effects of thermal annealing and type of substrates on the optical properties of ZnO nanowires electroplated on silicon (1 1 1) substrate are reported. We fabricated ZnO nanowires/p-Si structure that exhibits a strong UV photoluminescence emission and a negligible visible emission. This UV photoluminescence emission proves to be strongly influenced by the thermal annealing at 150-800 • C. Photo-detectors have been fabricated based on the ZnO nanowires/p-Si heterojunction.
Structural analysis of ZnO nanowires synthesized by using a low-temperature hydro-thermal method
Journal of the Korean Physical Society, 2012
The structural properties of vertically aligned ZnO nanowires (NWs) prepared using hydrothermal synthesis at various temperatures and different precursor concentrations are systematically described. The ZnO NWs were synthesized on ZnO seed layers via an aqueous solution method with zinc nitrate (Zn(NO3)2•6H2O) hexahydrate and hexamethylenetetramine (HMT). The growth speed and the shape of the ZnO NWs were determined for various mole concentrations. A structural analysis of the ZnO NWs was performed using X-ray diffraction, scanning electron microscopy and tunneling electron microscopy. Finally, the correlation of structural results with growth conditions, such as the mole concentration and the growth temperature of chemical precursors, based on Gibbs free energy.