Download 971 Quiz 01

103-1
1.
Quiz 01
SID#:
Name:
(50%)The following figure shows a silicon bar that is subjected to
electrons injection from the right.
5  1016 carriers
1  10 carriers
16
cm3
cm3
electrons
Silicon
0 m n  1.45 1010 carriers
i
4 m
cm
3
a. Determine the minority carrier concentration at x  0 .
b. Determine the minority carrier concentration at x  1m .
2
c. Determine the electron diffusion current density J ndiff ( 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. (50%) True and false
(1) Germanium is the most widely used semiconductor material
because of its stability at high temperatures.
(2) The depletion layer in a p-n junction contains null of positive and negative
ions.
(3) There are two types of carriers in a semiconductor. The holes diffusion
current direction is opposite to that of the applied electric field. But the
electrons diffusion current is in the same direction of the applied electric
field.
(4) When a depletion region of a transistor is large the barrier voltage
is also large
.
(5) The P-N junction is a barrier to electron flow.
(6) P-Type semiconductor formed by diffusing group 5 impurities.
(7) An electric field pulls electrons and holes current flow in the opposite
direction.
(8) Electron drift current is caused by an electric field. The electron drift current
density J ndrift   n n qE .
(9) Majority carries determines the type of semiconductor. More majority
carries more conductivity.
(10) Forbidden gap is the gap between conduction band and valance band. In
conductor, Forbidden gap is very large.