# IGBT Modules - Technologies, Driver and Application (Second Edition) - page 19

7
Zones with amovable electron excess are known as n-regions and those withmovable
hole excess are p-regions. It should be borne inmind that both n-regions and p-regions
are electrically neutral, as they are both compensated by the same number of stationary
pentavalent or trivalent atoms with a positive or negative charge. Accordingly
alsoapplies for thedoped semiconductor.
Fig. 1.6
Doping of silicon
In schematic drawings of semiconductor components, doping is indicated by the indices
n, p, n
-
, p
-
and n
+
andp
+
. The following guideline generally applies:
n
-
,
p
-
Corresponds to a doping concentration in the range of approximately 10
12
cm
-3
to 10
16
cm
-3
.
n
,
p
Corresponds to a doping concentration in the range of approximately 10
15
cm
-3
to 10
18
cm
-3
.
n
+
,
p
+
Corresponds to a doping concentration in the range of approximately 10
17
cm
-3
to 10
21
cm
-3
.
The electrons in an n-region are called majority carriers since there are more of these
electrons than there are holes. The holes in an n-region are calledminority carriers. The
same applies for a p-region: Holes are the majority carriers and electrons the minority
carriers. If the doping concentrations are known, it is possible to estimate the
concentration of themajority andminority carriers using
n
Example:
For a silicon semiconductor with a doping concentration of the n
-
-region of 10
14
cm
-3
there is a concentrationofminority carriers at 25°C (approximately 300K) of
(
)
3
6
3
14
23
10
2
K300 ,i
K300
cm 101.2
cm 10
cm 10 45.1
n
n
p
=
=
=
.
If the temperature rises to 125°C (approx. 400K), the density of the minority carriers
increases to
1...,9,10,11,12,13,14,15,16,17,18 20,21,22,23,24,25,26,27,28,29,...548