| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 96 === In the present study, we have demonstrated that 2D periodic arrays of nickel metal and silicide nanodots can be successfully fabricated on (111)Si substrates by using the polystyrene (PS) nanosphere lithography (NSL) technique and thermal annealing. The results of an investigation on the interfacial reactions between the Ni nanodots and (111)Si substrates after different heat treatments are reported.
From the TEM and SAED analysis, only epitaxial NiSi2 nanodots were found to form on (111)Si at a temperature as low as 300 °C. The results indicated that the growth of epitaxial NiSi2 is more favorable for the samples with smaller Ni nanodot sizes. The epitaxial NiSi2 nanodots were found to grow with an epitaxial orientation with respect to the (111)Si substrates: [111]NiSi2//[111]Si and {220}NiSi2//{220}Si. In addition, these epitaxial NiSi2 nanodots formed on (111)Si were observed to be heavily faceted and the faceted edges of the NiSi2 nanodot were identified to be parallel to <1 0>Si directions. On the other hand, during the experiments, the double-layered arrays of PS spheres were occasionally found to form on silicon substrates. The epitaxial NiSi2 nanodot arrays formed from the bilayer masks exhibit larger interparticle spacings and smaller particle sizes.
By combining the nanosphere lithography, heat treatments, wet chemical etching and electrodeposition techniques, we also successfully fabricate large-area shape- and size-tunable metal nanostructures (nanobowls and nanopillars) and nanohole arrays on Si and SiGe substrates. The morphology evolution, size uniformity and crystal structure of the produced nanostructures have been systematically investigated by SEM, AFM, TEM, and SAED analyses. The observed results present the exciting prospect that with appropriate controls, the colloidal NSL technique promises to offer an effective and economical patterning method for fabrication of a variety of well-ordered nanostructures with selected shape, size, and periodicity on different substrates without complex lithography.
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