How to make a Rectifying Diode
The armchair nanotube acts like any other metal, whereas the zigzag nanotube acts as p-type semiconductor [6]. This means it contains positive ‘holes', which move in the opposite direction to electrons, in the direction of the current (n.b. the holes do not actually move at all, one hole is filled by one electron - the ‘gap' appears to move along).
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If the top is connected to a positive electrode, and the bottom to a negative electrode, there will be no current. This is because the electrons at the negative electrode will simply fill up the holes on the semiconductor end. Therefore, current cannot flow from top to bottom. |
On the other hand, if the top is connected to a negative electrode and the bottom is connected to a positive electrode, then electrons move down to fill the holes and the holes move up towards the negative charge moving towards them, i.e. current flows. Therefore, current can flow from bottom to top. |
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