W/S Flashcards
A semiconductor atom, such as silicon, contains how many valence electrons?
four
What is the name given to semiconductor materials that are doped with trivalent impurity atoms?
P-type
What is the name given to semiconductor materials that are doped with pentavalent impurity atoms?
N-type
Semiconductor materials exhibit a “negative temperature coefficient of resistance” . What does this mean?
as temp increases, resistance decreases
What is the typical voltage drop expected across a silicon diode that is conducting in the forward direction?
0.7v
What does the term “PIV” mean?
“Peak inverse voltage” The max reverse biased voltage the diode can block
In order to conduct, the polarity of the cathode must be ____________ with respect to the anode
negative
When using an ohmmeter for testing a diode, what indication would you expect if the diode is?
a) shorted?
b) open?
c) good?
a) low in both directions
b) high in both directions
c) low in forward bias and high in reverse bias
When pure silicon is doors with trivalent material, a ______-type material is produced with an excess of ________?
P- type
holes
When pure silicon is doped with a pentavalent material, a ______-type material is produced with an excess of _________?
N- type , electrons
What is meant when silicon has a negative temperature coefficient?
as temp rises, resistance goes down
forward voltage drop for a silicon diode?
0.7v
Forward voltage drop for a germanium diode?
0.3v
When reverse biased, does a silicon diode act as a conductor or as an open?
open
When using a digital multimeter diode checker, what value does the meter read if the diode is good? (approx)
600mV
When installing a freewheeling diode, how should the diode be installed?
reverse bias to load
What is the process called that mixes pure silicon and an impurity?
doping
What determines whether a material is a conductor or a semiconductor?
number of valence electrons
Why is silicon used more as a semiconductor than germanium?
withstands higher temp
What is the name of the device that sheds heat around a semiconductor?
heat sink
What is meant by the term “forward bias”?
anode is positive with respect to cathode
what is meant by the term “reverse bias”?
anode is negative with respect to the cathode
what are two leads of a diode called?
anode and cathode
what is a “free-wheeling diode”?
In parallel with the winding and used as circuit protection
How do we reverse bias a diode?
reverse polarities
Increasing the amount of light falling on a photodiode will___________ the current going through it?
increase
In order for a zener diode to act as a voltage regulator it must be in __________ with the load and ________ biased?
series
reverse
To forward bias a diode we want the _______ to be more positive than the _________?
anode
cathode
What is the purpose of a field discharge diode?
prevent arcing
barrier potential for a germanium diode?
.3v
typical range of forward current rating for rectifier diodes?
1-1000
using an ohmmeter to check a diode, with the leads hooked up in either polarity, an infinite reading was observed. What is wrong with the diode?
It’s open
Gallium is often used as an impurity for doping purposes for the ___________anode/cathode of a diode?
anode
the majority current carries in a semiconductor substrate doped with arsenic are ___________ electrons/holes?
electrons
In order for a rectifier diode to conduct, the PN junction must be ______ biased?
forward
