ABSTRACT
The solution of the Schrödinger equation for a typical crystal reveals the existence of Brillouin zones. A plot between the energy
E
of an electron in a solid and its wave vector
k
represents the allowed energy bands. It may be noted that the lattice structure affects the motion of an electron when
k
is close to
n
p
/
l
(where
n
is any integer and
l
is the crystal periodicity) and the effect of this constraint is to introduce an energy band gap between the allowed energy bands. Figure 35.1a shows portions of two
E
vs.
