chapter 7 coulomb blockade and the single-electron transistorqli/ece685/ch7 _ second note.pdf ·...

Chapter 7 Coulomb Blockade and

the Single-electron Transistor

Lecture given by Qiliang Li

7.2 Single-Electron Transistor

• Adding gate control on a Coulomb-Blockade

structure – single-electron tunneling transistor

or simply single-electron transistor (SET)

Vg > 0 will depress the Fermi level, Ef

Vg < 0 will raise Ef

• Above, below and lie up with Ef of right/left side

The net charge on the island:

Solved:

An electron tunnel into the island from b, the change of stored energy is

Similarly for an electron from

island to Junction a:

Assume initially island is charge neutral (n=0), an

electron tunnels into the island through junction b

Now the island is has one electron (n=1), the electron

tunnels off from the island into junction a:

To observe a current from junction b to a, both condition need to be met:

Current > 0

Coulomb diamonds

Charge stability diagram

Shaded regions: no tunneling is allowed

SET has potential for high-speed, high-density and low-power dissipation.

7.3 Other SET and FET structures

Carbon nanotube FET

InP nanowire FET for single electron tunneling

Benzene Molecule as a

resonant tunneling

transistor

Molecular SET