Heat treatment effects on the surface morphology and optical properties of ZnO nanostructures (original) (raw)
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Effects of annealing temperature on morphologies and optical properties of ZnO nanostructures
Superlattices and Microstructures, 2008
Electroplated depositions of Sm were prepared using a vertical well-type electrodeposition unit with an aqueous ammonium acetate electrolyte system, with an average deposition yield just over 87%. The depositions were analyzed for morphology and thickness by scanning electron microscopy (SEM) and chemical composition by energy dispersion X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) before and after firing. The depositions were fired at 125-700°C, while varying the heating rate from 0.5 to 10°C/min in either an oxidizing or reducing atmosphere. A heating rate of 10°C/min was slow enough to prevent disruption of the deposition morphology during firing. A gas sweep enhanced the removal of any organic substituents, with an oxidizing environment being more advantageous than a reducing environment.
In this work ZnO nanocrystal powders have been synthesized by using Zinc acetate dehydrate as a precursor and sol-gel method. Then the products have been annealed at temperature of 200-1050°C, for 2 hours. The powders were characterized using X-ray diffraction (XRD), UVvis absorption and photoluminescence (PL) spectroscopy. The morphology of refrence ZnO nanoparticles have been studied using Transmission Electron Microscope (TEM). During the annealing process, increase in nanocrystal size, defects and energy gap quantitative, and decrease in specific surface area have been observed.
Research on Chemical …
Zinc oxide thin films have been deposited on glass substrates by the chemical bath deposition method; a surfactant, cetyltrimethylammonium bromide (CTAB); was used as capping agent. The films were annealed at two different temperatures: 200 and 300°C. The structural features were investigated by X-ray diffraction analysis which exhibited hexagonal wurtzite structures along with c-axis orientations. Crystallite size was estimated and found to be around 33-41 nm. The effect of post-deposition thermal annealing on the morphological and optical properties has been investigated by scanning electron microscopy and photoluminescence spectra at room temperature. The band gap energies of uncapped and CTAB-capped ZnO films were found to be 3.28 and 3.48 eV, respectively.
2007 International Semiconductor Conference, 2007
A novel and efficient low-temperature aqueous chemical method has been used to synthesize a new generation of smart and functional zinc oxide nanomaterials. The ZnO nanostructures are obtained and the physical and structural requirements of their applications in chemical sensors and solar cells are analyzed. Post-growth rapid photothermal annealing of nanostructures at 650°C in an atmosphere of N2 leads to the decrease in structure defects as compared to the as-grown nanostructures. The sensing behaviour of the nanostructured elements when exposed to 100 ppm ammonia is investigated
2020
This study carried out on the effect of precursor concentration and annealed substrate temperature on the crystal structure, electronic and optical properties of ZnO thin film. An aqueous solution of Acid Nitrite was used as precursors and its concentration was varied from 0.1 M to 0.4 M. The ZnO thin film was deposited on the glass substrate by Spray Pyrolysis Deposition and annealed with different temperature from 300 o C to 600 o C. The crystal structure, electronic and optical properties were investigated by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and UV-Spectrometer. XRD result showed that all thin films have amorphous hexagonal wurtzite crystalline. Particle sizes ranging from 21.83 to 43.67 nm were calculated through Debye-Scherer Method. It showed that the concentration of the precursor had slightly impact on the particle size. Meanwhile, the increase in particle size with increasing annealed temperature is found to be gradual. The average transparent of ...
International Journal for Research in Applied Science and Engineering Technology, 2018
Nanostructured Zinc Oxide (ZnO) thin film has been deposited with different annealing temperature (350 C, 450 C and 550 C) on glass substrate by film coating technique followed by hydrothermal method. The structural behavior of ZnO samples have been confirmed without any impurity by XRD and the crystalline size of the samples were 15 nm, 19 nm, 26 nm which has been calculated from Scherer's formula. The effect of synthesis condition on ZnO growth was systematically studied by field emission scanning electron microscopy (FE-SEM). The FE-SEM image shows that the synthesized ZnO particles are like clusters in a large-scale area, which are highly disperse in the space without any aggregation and have approximately uniform morphologies. From this study, it has shown that the ZnO nanoparticles are distributed in uniformly dense particles, and exhibit the wurzite hexagonal structure. Optical study was carried out for the coated ZnO nanoparticles, and the obtained result has shown that the grown ZnO nanoparticles exhibit good crystal quality with the band gap of 3.15 eV. Moreover, the d.c. conductivity value is 2.7 E-7 -1 cm-1 for 550 C annealed ZnO sample.
Emission modification in ZnO nanosheets at thermal annealing
MRS Online Proceeding Library
Photoluminescence (PL) and its temperature dependences, as well as the X ray diffraction (XRD), have been studied in the freshly prepared amorphous phase ZnO nanosheets, obtained by the electrochemical (anodization) method, and in the crystalline annealed ZnO nanosheets. The freshly prepared samples have been divided in two groups. One of these groups has been annealed at 400 °C for 2 hours in ambient air. Defect related PL bands with the peaks at 2.10-2.13, 2.42-2.46 and 2.65-2.69 eV are detected in amorphous state. Appreciable changes in the size of nanosheets as a function of thermal treatments have been revealed. XRD study has shown that annealing stimulates the Zn oxidation and the creation of ZnO with a wurtzite crystal lattice. In crystalline ZnO seven PL bands appeared with the PL peaks 1.46, 1.58, 2.02, 2.43, 2.70, 2.93 and 3.16 eV at 10K. The reasons of emission transformation and the nature of optical transitions related to the studied PL bands have been discussed. It is shown that the anodization method permits by a controllable way to obtain the wide range ZnO emission that is interesting for the future applications in room temperature "white" light-emitting diodes.
Zinc oxide films have been formed from thermally evaporated zinc films on polished and textured silicon wafers after heat treatment at temperatures between 400-900°C for 10min in oxygen ambient. These ZnO films show crystalline structure and the values of their refractive index are found to increase slightly from 1.85 for films annealed at 400°C to 2.05 for the films annealed at 900°C. The films formed at a heat-treatment of 450°C have a refractive index value of 1.9. These films have a direct band gap of 3.3eV that corresponds to the absorption edge at 376nm. Consequently these films are highly transparent in the entire 400-1200 nm range and are useful for silicon solar cell application. ZnO films of 80nm thickness on textured silicon exhibit an average reflectivity of ~4 % over the 400-1100nm range; however, the lowest reflectivity is found to be 2.3%. Surface morphological studies have been carried out using SEM for the ZnO thin films deposited on polished silicon wafers. The grain size of ZnO film was found to be ~20nm corresponding to annealing at 450 0 C. XRD analysis has been done for investigating the crystallographic structure and grain size of the ZnO thin films. The grain size of the ZnO thin films increases with heating temperature from 20nm corresponding to an annealing temperature of 400 0 C to 42nm corresponding to annealing at 900 0 C.
Superlattices and Microstructures, 2010
ZnO nanoparticles (NPs) have been successfully synthesized by the simple solution method at low temperature. The effects of annealing temperature on the structure and optical properties of ZnO NPs were investigated in detail by X-ray diffraction, transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) spectroscopy and photoluminescence (PL) measurements. As the annealing temperature was increased above 180 ∘C the particles morphology evolved from
Influence of process temperature on ZnO nanostructures formation
2014
The obtained new results of ZnO nanostructures formation in a zinc nitrate/hexamethylenetetramine solution by hydrothermal method on the lithium niobate substrates with synthesized seed-layer by sol-gel technique were presented. The influence of process temperature on morphometric properties of synthesized structures was investigated using scanning electron microscopy and X-ray diffractometry. ZnO nanostructured thin film with the thickness of 3.75 µm which consisted of flake-shape particles was synthesized at 65°C. ZnO nanorods with the diameter of 35-65 nm, and the length of about 0.5 µm and singlecrystal structure were formed at 95°C. ZnO nanostructured films could be used as sensing element of electrochemical enzyme sensors for biomedical or environmental monitoring, as well as the functional material of hybrid solar cells, which are photovoltaic devices of third generation, while ZnO nanorods could be used as active element of acoustic wave sensors and promote quality and accuracy enhancement of such devices.