Human ability to manipulate atoms and molecules on quantum basis has generated a new dimension of physical structures for molecular scale transistors and devices. We will discuss about nanodimensional single electron transistor. This molecular device works as a switching element by controlling the electron tunneling for amplifying the current. The basic structure consists of two tunnel junctions isolated by a common insulator of nanodimensional length.

One broader aspect of nano power electronics is that, it has got significant role in nanodimensional device regime as tunneling diodes. They have got inherently fast tunneling rate, which makes them highly suitable for high-speed operation. A special type of tunneling diode is an interband tunneling diode (ITD), which is actually, a p-n diode. The V-I characteristics of such diodes are dependent upon the tunneling barrier and tunneling process itself. Another special feature of these diodes is their negative-differential-resistance characteristics. This special characteristic of such diodes makes them very useful in switching digital circuits.