研究目的
Investigating the photocatalytic response of Fe, Co, Ni doped ZnO based diluted magnetic semiconductors for spintronics applications.
研究成果
The present work demonstrates semiconducting, magnetic, chemical and optical performances of 10 at% Fe, Co and Ni doped ZnO and pristine ZnO thin film samples prepared by sol-gel technique. The microstructural analysis by FESEM reveals particle size increases from 10 to 16 nm and the AFM analysis of the corresponding materials shows surface roughness increases from 10.31 nm to 28.59 nm for Fe doped ZnO sample. The semi-quantitative analysis of the elements matches with the initial value of dopant concentration. The absorbance spectra of the oxides reveal intrinsic band gap of ZnO, Fe2O3, CoO and NiO are 3.29 eV, 2.53 eV, 2.42 eV and 3.64 eV respectively. The band gap of the samples lying in visible range implies the potential application of these semiconductor oxides also in the area of spintronics application allied with optoelectronic devices. The PL spectra of the films at near band edge excitation show the photochemical activity with the presence of multiple bands between 450 nm and 500 nm and oxygen vacancy formation especially for the Fe and Co doped samples. VSM analysis reveals Fe doped ZnO material posses minimum squareness of 0.118 and coercivity of 177.74 Oe which proves it to be best magnetic material amongst all four samples. Raman spectra proves effect of phonon confinement for Fe doped ZnO sample by broadening of Eg, T2g and A1g peaks, which is not so prominent for other samples, resulting best possible spintronics application with this material compared to other materials. The photochemical activity of all of these DMSs also make them potentially feasible for future spintronics application for optoelectronic devices like spin solar cell.
研究不足
The study focuses on the photocatalytic response of Fe, Co, Ni doped ZnO based diluted magnetic semiconductors for spintronics applications, but does not explore the potential for room temperature ferromagnetic materials or the effects of higher dopant concentrations.
1：Experimental Design and Method Selection:
Sol-gel method was followed to prepare pristine ZnO as well as each of 10 at.% Fe, Co and Ni doped ZnO samples both in bulk and thin film coatings.
2：Sample Selection and Data Sources:
Zinc acetate dihydrate Zn(CH3COO)2·2H2O was mixed with ferric nitrate nanohydrate Fe(NO3)3·9H2O, cobalt acetate tetrahydrate Co(CH3COO)2·4H2O, and nickel nitrate hexahydrate Ni(NO3)2·6H2O separately.
3：List of Experimental Equipment and Materials:
X-ray diffractometer (Brucker AXS D8), FE-SEM (Carl Zeiss Ultra Plus), SPM (NT-MDT-INTEGRA), UV–Vis spectrophotometer (Shimadzu UV-2450), Fluoromax-4 spectro-fluorometer, VSM (PAR 155), Renishaw spectrometer, UV–Vis Spectrophotometer (Hitachi UV5300).
4：0). Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The sol was stirred well for 3 h at room temperature for homogenization. Methyl amine was added to the sol while stirring to stabilize the sol and to increase the wettability of the sol on glass substrate. The precursor sol was left for ～24 h for aging. Then the sol was taken for film deposition on glass substrate using spin coater at 500 rpm for 90s duration. The films and the remaining sol were then cured at 100 °C for 1hr. for gelation. The samples were further heated at 500?C in a furnace under air atmosphere at heating rate 2–3 °C/min and annealed for 2 h and then cooled to room temperature.
5：Data Analysis Methods:
The XRD patterns of the films were obtained using X-ray diffractometer. FE-SEM was used to view the morphology of the thin films. SPM was used to analyze the structural and topographical properties of thin films. The absorbance spectroscopy of the thin films was performed by UV–Vis spectrophotometer. The PL spectra of the samples were obtained by Fluoromax-4 spectro-fluorometer. In the VSM instrument, the magnetic moments of the samples were recorded with applied magnetic field in the range of +10 kOe to - 10 kOe. Raman Spectroscopy of the samples was performed by Renishaw spectrometer. The photochemical analysis of the samples was performed by UV–Vis Spectrophotometer.
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