Transcript PRACTICAL # 02

To draw the I-V curve of Si diode in forward biased
By: Engr.Irshad Raheem Memon
OBJECTIVE
 Objective of this practical is to learn that how a diode
can be made forward biased and what are the values of
voltage across and current through forward biased
diode.
Some Concept Regarding Diode &
its Forward Bias Operation
 What is Diode?
Diode is a two terminal semiconductor device with an
ability to conduct current only in one direction after a
certain amount of voltage called barrier potential is
applied to it in a proper way.
Diode Forward Bias Operation
 Diode is said to be forward biased; if positive terminal
of diode is connected with positive of voltage source
and negative terminal of diode is connected with
negative of voltage source.
Diode Connected in Forward Bias
Forward Bias operation
 Silicon diode will conduct current at 0.7volt and
germanium diode will conduct current at 0.3volt when
forward biased. 0.7volt is also called barrier potential
for silicon diode and 0.3volt is barrier potential for
germanium diode. Before the value of voltage across
diode reaches its barrier potential; there is very small
amount of current that is flowing through diode. After
the value of voltage across diode reached its barrier
potential; there is a rapid change in the value of
current through diode.
Detail Operation of Forward Bias
with the help of picture
 Forward Bias Diode showing flow of Majority Carriers
and the Voltage due to barrier potential across the
Depletion Region
 Its picture will be shown in next slide
Picture Showing F.B Operation
V-I Characteristics of Si & Ge Diode
Coming Towards Objective Now
 Required Apparatus:-
Few diodes
Breadboard
Multimeter
Connecting wire
Procedure
 Connect positive terminal of a diode with positive of
battery and connect negative terminal of a diode with
negative of battery and current limiting resistor may
also be added in series with diode.
 Voltmeter is Connected in parallel with diode and
Ammeter is connected in series with diode
Procedure Figure in Multism
OBSERVATION
 When value of forward voltage across diode is less
than its barrier potential; the value of forward current
is very small. As soon as value of forward voltage across
diode is reached to its barrier potential; there is rapid
increase in forward current.
ANY QUERY?