Some Sample Problems
ENEE 601 midterm spring 2005
April 5, 2005
1. Basic Silicon Materials.
a. Consider pure, undoped silicon. Whats its resistivity?
Again, we use Matthiessens Rule For summing resistive channels:
1
1
=+
tot
p
(1)
and:
1
= qni n = 1.6 101

Solutions to ENEE 601MidTerm Exam - Spring 2006
1.a First, we calculate the intrinsic resistivity using Matthiessiens rule for addition
or resistances due to dierent transport processes:
1
1
1
=
+
total
holes electrons
(1)
total = eni hole + eni electron

ENEE 601 MID-TERM EXAM 4 APRIL 2006
1. RESISTORS
1.a Consider the resistivity of a bar of silicon. First, calculate the resistivity when there
is no doping present (intrinsic material). Now calculate the resistivity when Na is 1.73ni .
Hint: use the consi

ENEE 601 FINAL EXAM SPRING 2005
1. Bipolar Transistors a. Assume the transistor collector current is 103 Amps,
estimate gm , r and Cdif f .
b. Reach-through occurs when the collector-base space charge extends fully through
the neutral base. Assume the fol

ENEE 601 Mid-Term Solutions
March 29, 2006
1a. By p-side and n-side parasitics the question referred to physical resistances due to
undepleted material. Some class responses took this to mean the diode forward resistance
(from the small signal model). I a

ENEE 601 Mid-Term
May 19, 2005
1. Bulk Silicon Materials
a. Consider the diode structure shown below. Calculate the anode (n+ -side) and
cathode (p-side) parasitic resistances near the cut-in voltage. (20pts) b. What is the
2 m
200m
A = 1mm2
Na=1016
Nd=10

SOLUTIONS: ENEE 601 FINAL EXAM SPRING 2005
1a. This was basically just warm-up:
Ic
103
=
= 0.0391
Vth
.0259
= 100/.039 = 2590
r =
gm
Ic
0.001104
=
=
= 3.86F
Vth
.0259
gm =
Cdif f
(1)
(2)
(3)
b. This is a bit of an arithmetic slog. First, remember:
xsc =

SEMICONDUCTOR PHYSICS-RELATED EQUATIONS
xsc =
2
si (Na
+ Nd )
(bi Va )
q (Na Nd )
(1)
kT
Na Nd
Ln 2
q
ni
(2)
bi =
np = n2
i
D
kT
=
q
v = E
q (f i )
n = ni exp(
)
kT
q (i f )
p = pi exp(
)
kT
Jn = qn f n
(3)
Jp = qp f p
dn
Jn = q [nn Ex + Dn ]
dx
J = env
1