Page 96 - Principles and Applications of NanoMEMS Physics

84 Chapter 3

3.1.2 Quantum Resonant Tunneling

One of the fundamental devices exploiting the wave nature of electrons,
and which finds practical application at room temperature, is the resonant
tunneling diode (RTD) [116], [117], see Figure 3-4.

W
B W B
E
E
E 1 1
E E E 0 0
FL E E FR
FR
E z
c
Contact Contact
E 1 1
E
FL
E 0 0
E
c Peak Current
V p
E
FR
E FL
E c E E 0 0
e
V Valley Current
V E
FR
(a)
I
RTD
I
p

I V V RTD
V p V
V
(b)
Figure 3.4. Resonant tunneling diode. (a) Energy band diagram and operation. (b) Current-
voltage characteristic.

The RTD consists of a double barrier sandwiching a potential well, and in
turn clad by two electron reservoirs (contacts). The potential well
dimensions are of the order of tens of Angstrom, such that electrons in it are
confined and, thus, can only exist in quantized energy levels. The barrier
lengths are of the order of a few Angstroms, so that electrons can tunnel
through them.