Looking inside nanowires

Semiconductor nanowires are expected to be important components in future electronics and photonics devices, and have already been used to fabricate high-performance field-effect transistors, biochemical sensors and lasers. Because of their small size and large surface areas, their properties are strongly influenced by individual atomic-scale structural features. In the August issue of Nature Materials, Anders Mikkelsen and colleagues at Lund University in Sweden demonstrate a technique that allows them to visualize the interior of semiconductor nanowires with atomic resolution for the first time. Mikkelsen and colleagues use a scanning tunnelling microscopy, in which a very sharp metallic tip is scanned over a conducting sample, producing a current that can be related to the topography and electronic nature of the sample. Although this technique has provided atomic-scale information on all sorts of nanoscale objects, up to now it has been difficult to image the interior of nanowires because of their geometry. The Swedish group got around this problem by a procedure in which nanowires were grown such that only a one micrometre section protruded from a surface. This meant they could cleave the sample and expose an atomically flat cross-section of the nanowire along its length, or take a slice through the nanowire across its circumference. This new method will enable researchers to study the structure of impurities and defects on the atomic scale inside nanowires and other nanoscale objects, and should also permit easy access to structures grown inside nanowires.

Direct imaging of the atomic structure inside a nanowire by scanning tunnelling microscopy  pp519-523

Anders Mikkelsen, Niklas Sköld, Lassana Ouattara, Magnus Borgström, Jesper N. Andersen, Lars Samuelson, Werner Seifert and Edvin Lundgren

Published online: 4 July 2004 | doi 10.1038/nmat1164

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