Question

Photolithograph or e-beam lithography is known as a top-down approach to nanostructures while chemical synthesis is known as a bottom-up approach to nanostructures. Compare the advantages and disadvantages of these two different approaches in terms of cost, capital investment, control, precision, volume of production, and diversity of materials.

Answer 1

In Bottom up method atoms (produced from reduction of ions) are assembled to generate nanostructures, and in top down method material is removed from the bulk material, leaving only the desired nanostructures.

Common top down techniques are photolithography and electron beam lithography . Top down techniques suffer from the need to remove large amounts of material, while bottom up techniques suffer from poor monodispersity due to the need to arrest growth at the same point (by additing capping agents such as surfactant to avoid agglomeration of nanoparticles) for all the nanoparticles which is quite difficult .

Top down method are not cheap and quick to manufacture, Also slow and not suitable for large scale structure.

Fabrication is much less expensive in bottom top.

So according to me bottom up is better than top up.

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