| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 97 === In the present study, large-area Si nanotips were fabricated by selective chemical etching of self-assembled Ge quantum dots on Si. Taking advantage of the relatively low etching rate, high-density Ge dots act as virtual nanomasks for the underlying Si substrate. During selective chemical etching, Ge nanomasks shrink into the small Ge-core islands, which determine the apex sharpness of the resulting Si pyramidal tips. The Si pyramidal tips exhibited excellent antireflective and electron field emission characteristics compared to as-grown Ge islands. The high field enhancement factor of Si nanotips can be attributed to high tip density, nanoscale apex and the well controlled spacing between the nanostructures.
Besides, in our study, high-density ordered SiGe nanorods were fabricated by reactive ion etching of monolayer polystyrene arrays. The morphology of the SiGe nanorods were controlled by variation of gas composition, power and duration of the dry etching. The fabricated nanorods exhibited low reflectance at 300nm-2000nm and excellent photo- luminescence property.
By using nanosphere lithography with dry etching and wet etching of Ge masks, various morphologies of SiGe nanostructures were successfully fabricated. The morphology evolution, size and height of produced nanostructures have been investigated by AFM, SEM, TEM. We also measured field-emission, PL and reflectance properties of the nanostructures. The etching techniques in our study are really low-cost and efficient for fabricating various shapes of SiGe nanostructures.
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