SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

492 CHAPTER 10. COHERENT TRANSPORT AND MESOSCOPIC DEVICES

E

Zone

edge (a)

Zone

edge (b)

Reflection

(c)

G =

(d)

t = 0 t = t 1

t = t 2 t = t 3

ELECTRON BAND TRANSPORT WITHOUT SCATTERING

2 π

a

Figure 10.2: A schematic showing how an electron starting att=0at the bottom of the conduc-
tion band (Γ-valley) travels up theEvskdiagram and gets reflected at the zone edge.

10.3RESONANTTUNNELING ............................

In absence of scattering the behavior of electron waves is similar to that of optical waves.
Effects like filtering, interference and diffraction can occur. One class of devices that has been
demonstrated and used for high performance applications is the one based on electron tunneling
through heterostructures. Resonant tunneling is a very interesting phenomenon in which an elec-
tron passes through two or more classically forbidden regions sandwiching a classically allowed