1
Homework #4, Due Thursday 10/8/09
I.
(20 Points) Problem 3.13 of text.
For part (a) assume that the bar is actually 0.1 cm
long.
Also, remember that for samples of uniform cross section and conductivity,
multiply
conductivity
by crosssectional area and divide by length to get
conductance
,
and, equivalently, multiply
resistivity
by length and divide by cross sectional area to
get
resistance
.
For part (b), well, let me point out that you should take a moment to
think about it.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document2
II. (20 points) Referring to Fig. 325, consider a uniformly doped semiconductor bar
with
w
= 0.1 mm,
t
= 10
μ
m and
L
= 5 mm.
For a magnetic field
B
z
= 10 kG =
1Wb/m
2
(where Wb are SI units) and a current of 1mA, we have
V
AB
= –2mV and
V
CD
= 100mV.
Find the type, concentration (in units of cm
–3
ultimately) and mobility
(in units of cm
2
/Vs ultimately) of the majority carriers.
From notes:
AB
z
x
o
qtV
B
I
n
or
AB
z
x
o
qtV
B
I
p
Because V
AB
is negative we conclude that
the material is ntype
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '08
 Banjeree
 carrier concentration

Click to edit the document details