594 Microwave Engineering
The electric ux (D) at the junction is continuous and is given by
D = = = =ε ε ε ε ε ε
0 0r1 1 1 1 r2 2 2 2
E E E E( ) ( )
(14.12)
In Equation 14.12,
ε
0
is the permittivity of free space,
ε
r1
and
ε
r2
are the relative
permittivities of the two materials; thus, their permittivities are
ε
1
(=
ε
0
ε
r1
)
and
ε
2
(=
ε
0
ε
r2
). E
1
and E
2
are the electric elds on the two sides. Space charges
on the two sides follow the equality relation
x N x N
1 d 2 a
=
(14.13)
where x
1
and x
2
are the depletion widths for n-Ge and p-GaAs, respectively.
Also, E elds for the two sides can be written as
1 1 1 1
0
(14.14a)
(14.14b)
where V
1
and V
2
are the portions of biased voltages in n-Ge and p-GaAs,
respectively. ...