Introduction to NanoWires

A nanowire is a wire with a diameter of the order of a nanometer (10⁻⁹ meters).

There are many different types of nanowires.

Concerning their electrical conductance , they can be classified as:

- metallic (e.g., Ni, Pt, Au),

- semiconducting (e.g., Si, InP, GaN, etc.)

- insulating (e.g., SiO₂,TiO₂).

Because of their high aspect ratio (length / diameter rapport often in excess of 1000),

they are reffered often as 1 dimensional structures.

Production of nanowires

Nanowires can be synthesized by different methods, the most well known been presented briefly below.

- Vapor-Liquid-Solid (VLS) - common technique for creating a nanowire is the Vapor-Liquid-Solid (VLS) synthesis method. A source gas (such as silane ) saturates nanoclusters of liquid metal(such as gold). Once super saturation is reached, the source solidifies and grows outward from the nanocluster.

- Electro Deposition – wires are grown in a porous membrane. The metal of the nanowires is deposited by electrodeposition(a process resembling with electrolysis). When the process is finished, the membrane is chemically.dissolved.

Examples of Ni nanowires grown in a polycarbonate membrane.

- you can also create suspended wires by

o chemical etching a bigger wires

o bombarding bigger wires with high energy particles

o indenting the tip of an STM in a metal near the melting point and retracting it

Thanks to Stephane Xavier for the details on nanowires production and for the images.

The nanowires presented were fabricated by Stephane Xavier in collaboration with the "Université catholique de Louvain".