1.5 Machines and Computers on the Microscale and Nanoscale

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Figure 1.44: Diodes are “PN Junctions”, i. e., the interface between a p-type and an n-type semiconductor.

a) Diodes allow the current only in one direction; b) In light-emitting diodes (LED) the recombination of the

electron with the hole results in light emission.

used electrode is the indium tin oxide (ITO) electrode, since it is very conductive yet

transparent.

Nowadays, chemical reactions can also be performed on or in chips (lab-on-a-chip).

The technology to create small channels in silicon exists due to chip manufacturing.

Therefore, it is possible to flow one starting material in one channel, another in a sec-

ond channel, letting those two channels meet and the starting materials react, and then

flow out the product. This can also be combined with a sensor, e. g., an IR detector that

determines if the reaction was successful. There is one caveat that should be mentioned: