Technical Report
nam2503
lecture_6_hall_effect1.pptx
Hall Effect Experiment
Microelectronics II
The Hall effect experiment allows the concentration, the polarity, and the mobility of “MAJORITY” carriers to be determined
J
J
P-Si
Flow of holes from left to right
1
Hall Effect Experiment
Microelectronics II
J
J
P-Si
When the magnetic field is turned on .. A force (F) acts on the holes
B is the magnetic field intensity
J is the current density
Holes will be deflected upward so that the upper face charges positively with respect to the lower surface
VH
+
-
A potential difference (VH) the “Hall voltage” will appear across the faces
B
2
Hall Effect Experiment
Microelectronics II
As the Hall voltage build up, there is now an electric field acting on the holes in the opposite direction to the magnetic field
The establishment of this electric field is known as the
Hall effect
Since there is no current flow upward or downward, then
Acts downward
EH is the Hall field
The Hall coefficient (RH) is defined by
For electrons in n-type SC
3
4
Hall Effect Experiment
Microelectronics II
If the conductivity measured at a given temperature (using 4-point probe) and the Hall voltage gives RH at the same temperature, then we have for p-type SC
And So
Similarly for electrons in n-type SC
Note again that the Hall effect gives us the concentration, the polarity, and the mobility of “MAJORITY” carriers
W
d
s
I
V
CF is the correction factor and depends on the ratio of d/s . If d/s > 20 then CF = 4.54
J
B
F
=
0
=
+
force
Electric
force
Magnetic
0
=
-
+
)
(
H
E
e
p
B
J
B
J
p
e
E
H
1
=
p
e
JB
E
R
H
H
1
=
=
n
e
JB
E
R
H
H
1
-
=
-
=
H
p
p
R
e
p
m
m
s
=
=
s
m
H
p
R
=
s
m
H
n
R
=
F
C
I
V
W
=
=
s
r
1
