Agilent Technologies 4339B - Page 216

High
Capacitance
DUT
Measurement 4339B
Surface
Resistivity
Surface
Resistivity
is
dened
as
resistance
per
unit
surface
area.
Similar to
volume resistivity
,
surface
resistivity
is
the
resistance
of
a square
of a
material whose
side length
is 1
m, (
one
square
meter).
Surface
resistivity
is
given
as:

s
=
P
erimeter
Gap
R
s
where
,

s
Surface
resistivity
[]
P
erimeter
Eective
perimeter
[mm]
Gap
Gap
between
main
and
guard
electrodes
[mm]
R
s
Measured
surface
resistance
[]
When
the
16008B
Resistivity
Cell
is
used,
the
equations
above
become:

s
=

(
D
1
+
D
2
)
D
2
0
D
1
R
s
D
1
Main
electrode
diameter
[mm]
D
2
Guard
electrode
diameter
[mm]
Figure 7-2. Surface Resistivity
7-4 Measurement Basics