Final Exam ECE 315 Spring 2006
Open Book and two pages of notes
1.
10pts
. Below is a semiconductor which has been patterned into the shape
illustrated.
The thickness of the material is 1um with a mobility of 1000 cm
2
/V
sec.
Assume the fields transform abruptly at the interface.
The doping in region
1 and region 3
is 1x10
17
cm
3
the doping in region 2 is 1x10
16
cm
3
L
1
=10um, L
2
=50um, L
3
=20um and W
1
=100um, W
2
=10um, W
3
=50um
a.
Calculate the total resistance of each layer.
b.
What is the current in each layer if a voltage of
1V
is applied to as shown
c.
What is the electron drift velocity in each layer
d.
If the voltage is increased and the saturation velocity is 1x10
7
cm/sec.
What is the voltage V
A
where saturation velocity is achieved in the materia
1,3
17
19
2
16
19
1
.0624
(10 )(1000)(1.602x10
)
1
.624
(10 )(1000)(1.602x10
)
ρ


=
=
=
=
W
3
W
1
L
1
L
3
Contact
V
W
2
L
2
Region 3
Region 2
Region 1
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
4
1
2
4
4
4
4
4
3
4
4
(.0624)(10x10 )
(.624)(50x10 )
R
62.4, R
31200,
(100x10 )(10 )
(10x10 )(10 )
(.0624)(20x10 )
R
249.6
(50x10 )(10 )









=
=
=
=
=
=
1
I
.0317ma
62.4 31200 249.6
=
=
+
+
for all layers
5
1
2
4
4
3
4
62.4
31200
1x
1x
31512
31512
v
(1000)
1980cm/sec, v
(1000)
1.980x10 cm/sec
10x10
50x10
249.6
1x
31512
v
(1000)
3960.3cm /sec
20x10



=
=
=
=
=
=
Assume all voltage drops across region 2
7
A
A
4
V
1000x
10
V
50
50x10

=
=
2.
15pts
. For a MOS Capacitor biased as shown below V
tn
=1V.
a.
Sketch the charge vs distance for
(V
A
=1V and V
B
=0) and (V
A
=1V and
VB=.5V)
b.
Sketch the Electic Field vs distance.
for (V
A
=1V and V
B
=0) and(V
A
=1V
and VB=.5V)
c.
Sketch the Potential vs distance.
for
(V
A
=1V and V
B
=0) and (V
A
=1V and
VB=.5V)
d.
Sketch the carrier densisty (n, p) verses distance. for, (V
A
=1V and V
B
=0)
and
(V
A
=1V and VB=.5V)
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '07
 SPENCER
 Microelectronics, small signal, drain voltage, small signal diagram

Click to edit the document details