Fabrication And Optical Properties Of FeGa Core/Shell Nanostructured Arrays Based On Colloidal Template

The ordered nanostructured arrays have attracted much interest in recent years due to theirwide applications in photonic crystals, surface enhance Raman spectroscopy(SERS),photocatalysis, bio-sensor, etc. Nanoarrays is composed of many order neighboring units,compared with common materials, it not only can possess the inherent performance of material,also show new performance due to the coupling between units, which greatly extends itspotential application. Colloidal crystal template method is one of the common method to preparenanoarrays among the many approaches due to the characteristics of easy operating, inexpensive,strong controllability. The approaches of preparing nanoarrays based on colloidal crystaltemplates mainly include chemical deposition(for instance solution/sol dipping method,electrodeposition, etc.) and physical deposition(such as thermal evaporation deposition, e-beamevaporation, pulsed laser deposition (PLD), atomic layer deposition (ALD), sputtering, etc.).Compared with the former, the physical routes can resolve the problem that the impuritiesproduce by the precursor on the surface of nanoarrays during the process of deposition, and it iseasier to obtain ordered arrangement nanoarrays with larger area such as nanoparticle arrays,nanocluster arrays, nanopore arrays, nanopillars, nanoring, et al, so physical route have attractedextensive interest. Moreover, nanoarrays with more complex structure can be obtain bydesigning of synthesis routes and selective of deposition methods.For nanostructured arrays, their properties depends on the morphology and structure size,hence the controllable synthesis of morphology and structure of nanoarrays are very importantfor the study of their optical properties. In this work, FeGa shell nanoarrays with Periodichexagonal structure are prepared by magnetron sputtering technology based on colloidal crystalmonolayer templates, and their optical properties are studied. The main research contains treeparts:(1)The colloidal crystal templates are prepared by self-assembly at air/water interface, themorphology of nanoarrays are tuned by changing the size of colloidal sphere and deposition time.The results show that the nanoarrays is ordered arrangement with hollow sphere structure. The unit size of nanoarrays and thickness increase with the increasing of colloidal sphere anddeposition time. In addition, the thickness of the FeGa shell is not uniform, it decrease from topto bottom.(2) The optical properties of nanoarrays are measured, it turns out that the absorptionpeak can be red shift in large scale with the increasing of the size of nanoarrays, and the position,intensity, width of peak can be tuned by changing the unit size and thickness of FeGa nanoarrys.In addition, we also study the theory of optical absorption.(3) FeGa alloys is a new magneticmaterial with large magnetostriction and low saturation magnetization, when applying anexternal magnetic field, it can often occur magnetostrictive. In our experiment, the results showthat the intensity of light absorption decrease with the increasing of external magnetic field invertical direction. It is because the unite of nanoarrays are stretched horizontally in the process ofmagnetostriction, which cause the curvature of the units decreased, thus the light reflectionenhance and the light absorption decrease.