Download 971 Quiz 01

102-1
Quiz 01
1. (10%) In a 10
SID#:
Name:
m long bar of donor-doped silicon, what donor
concentration is needed to realize a current density of 1mA / m in
2
response to an applied voltage of 1V. (  n  1350cm / V  s )
2
2. (50%)The following figure shows a silicon bar that is subjected to
hole injection from the left.
a. Determine the minority carrier concentration at x  0 .
b. Determine the minority carrier concentration at x  1m .
c. Determine the electron diffusion current density J ndiff
2
( Dn  32cm / s ).
d. Determine the hole diffusion current density J pdiff ( D p  12cm 2 / s ).
2
e. Determine the electric field E at x  2 m (  n  1350cm / V  s
 p  480cm 2 / V  s ).
f. Determine the electron drift current density J ndrift .
g Determine the hole drift current density J pdrift .
h. Determine the total current density
J.
i. Which type the silicon bar is?
3. (40%) True and false
(1) If we introduce some 3-valence atom into a Si-semiconductor, the
majority carriers of this impure semiconductor are electrons and it
usual denoted by n po .
(2) The depletion layer in a p-n junction contains null of free electron
but may be one of free hole.
(3) There are two types of carriers in a semiconductor. The holes drift
current direction is opposite to that of the applied electric field. But
the electrons drift current is in the same direction of the applied
electric field.
(4) Electron diffusion current is caused by an electric field.
.
(5) Majority carries determines the type of semiconductor. More
majority carries less resistivity.
(6) N-Type semiconductor formed by diffusing group 5 impurities.
(7) Pure (intrinsic) semiconductors are crystals. The outer orbit
electrons are trapped in covalent bonds, therefore have high
resistivity.
(8) An electric field pulls electrons and holes current flow in the same
direction.