Tác giả Ralf B. Wehrspohn
One significant difficulty with nanostructures is how to prepare them. One can distinguish two approaches: top-down and bottom-up. In the top-down approach, objects of ever-smaller dimensions are carved out of larger objects. This approach is taken in the semiconductor industry where advanced lithography aided by specific steps such as selective oxidation has unrelentlessly shrunk the typical dimensions to well below 1 μm. However, this approach is increasingly complicated and expensive. The bottomup approach consists of growing small objects to their desired size and shape. This is usually accomplished by chemical means. This approach is very flexible and usually inexpensive, but it too suffers from significant problems, chief among them are size and positioning control and throughput.
Link:[PHP]http://www.mediafire.com/?xkbmn5pilin[/PHP]
