(i) The document describes an experiment to obtain the voltage-current (V-I) characteristics of a PN junction diode. (ii) The objectives are to understand the concept and working of the PN junction diode and obtain its V-I characteristics. (iii) The experiment involves measuring the voltage across and current through the diode under both forward and reverse bias conditions and recording the readings to plot the V-I characteristics graph.

1. Department of Electrical Engineering
Faculty of Engineering & Applied Sciences
Riphah International University, Islamabad, Pakistan
Program: B.Sc. Electrical Engineering Semester: III
Subject EE-241 Basic Electronics Date: …………….
Experiment 1: To obtain the V-I characteristics of PN junction diode
OBJECTIVES:
(i) To understand the concept and working of PN junction diode.
(ii) To obtain V-I characteristics of PN junction diode.
Name : Roll no:
Performance Lab Report
Description Total
Marks
Marks
Obtained
Description Total
Marks
Marks
Obtained
Ability to
conduct
Experiment
5 Organization/Structure 5
Data Analysis &
Interpretation
5 Calculation & Data
Presentation
5
Total Marks obtained
Remarks (if any): ………………………………….
Name & Signature of faculty: …………………………………

2. Introduction:
The semiconductor diode is formed by doping P-type impurity in one side and N-
type of impurity in another side of the semiconductor crystal forming a p-n junction
as shown in the following figure.
At the junction initially free charge carriers from both side recombine forming
negatively charged ions in P side of junction (an atom in P -side accept electron and
becomes negatively charged ion) and positively charged ion on n side(an atom in n-
side accepts hole i.e. donates electron and becomes positively charged ion)region.
This region deplete of any type of free charge carrier is called as depletion region.
Further recombination of free carrier on both sides is prevented because of the
depletion voltage generated due to charge carriers kept at distance by depletion
(acts as a sort of insulation) layer as shown dotted in the above figure.
Working principle:
When voltage is not applied across the diode, depletion region forms as shown in
the above figure. When the voltage is applied between the two terminals of the diode
(anode and cathode) two possibilities arises depending on polarity of DC supply.
1. Forward-Bias Condition: When the +Ve terminal of the battery is connected to
P-type material & -Ve terminal to N-type terminal as shown in the circuit diagram,
the diode is said to be forward biased. The application of forward bias voltage will
force electrons in N-type and holes in P-type material to recombine with the ions
near boundary and to flow crossing junction. This reduces width of depletion
region. This further will result in increase in majority carriers flow across the
junction. If forward bias is further increased in magnitude the depletion region
width will continue to decrease resulting in exponential rise in current as in ideal

3. diode characteristic curve.
2. Reverse-biased: If the negative terminal of battery (DC power supply) is
connected with P-type terminal of diode and +Ve terminal of battery connected to
N type then diode is said to be reverse biased. In this condition the free charge
carriers (i.e. electrons in N-type and holes in P-type) will move away from
junction widening depletion region width. The minority carriers (i.e. -ve electrons
in p-type and +ve holes in n-type) can cross the depletion region resulting in
minority carrier current flow called as reverse saturation current (Is). As no of
minority carrier is very small so the
magnitude of few microamperes. Ideally current in reverse bias is zero.
In short current flows through diode in forward bias, and does not flow through diode
in reverse bias. Diode can pass current only in one direction.
Experiment Procedure:
 Connect the power supply, voltmeter, current meter with the diode as shown in
the figure for forward bias diode. You can use two multimeter (one to measure
current through diode and other to measure voltage across diode) 
 Increase voltage from the power supply from 0V to 20V in step as shown
in the observation table 

 Measure voltage across diode and current through diode. Note down
readings in the observation table. 

 Reverse DC power supply polarity for reverse bias 

 Repeat the above procedure for the different values of supply voltage for 
reverse bias
Draw VI characteristics for forward bias and reverse bias in one graph
Circuit diagram (forward bias)
Circuit diagram (Reverse bias)

4. Observation table: (Forward bias)
Sr. Supply Diode Diode
No Voltage Voltage Current
(Volts) Vd Id
1 0.2 0.144 0
2 0.4 0.364 0
3 0.6 0.456 0.05
4 0.8 0.516 0.21
5 1.0 0.547 0.43
6 2.0 0.599 1.3
3.0 0.626 2.3
4.0 0.642 3.4
5.0 0.654 4.3
6.0 0.664 5.4
Observation table: (Reverse bias)
Sr. Supply Diode Diode
No Voltage Voltage Current
(Volts) Vd Id
1 0.2 0.12 0
2 0.4 0.36 0
3 0.6 0.54 0
4 0.8 0.72 0
5 1.0 0.89 0
6 2.0 1.93 0
3.0 2.99 0
4.0 3.99 0
5.0 4.99 0
6.0 5.93 0
Draw V-I characteristics of PN junction diode:

5. Questions:
[1] List important specifications of the diode
Ans: Specifications of Diode
 Maximum repetitive reverse voltage = 100 V.
 Average rectified forward current = 200 mA.
 Maximum direct forward current = 300 mA.
 Maximum forward voltage drop = 1.0 V at 10 mA.
 Non-repetitive peak forward surge current = 1.0 A (pulse width = 1 s)
 Total power dissipation = 500 MW.
[2] What is breakdown voltage? What is the breakdown voltage of diode 1N4001
and 1N4007?
Ans:. Breakdown Voltage: The breakdown voltage of an insulator is the
minimum voltage thatcauses a portion of an insulator to become electrically
conductive. For diodes, the breakdownvoltage is the minimum reverse voltage that
makes the diode conduct appreciably in reverse.1N4001 Diode will break down at
50 volts or less and 1N4007 diode will breakdown at1000V.
[3] List different types of the diode
Ans: Types of Diodes
Laser diode.
Avalanche diode.
Light Emitting Diode.
Zener diode.
Schottky diode.
Photodiode.
PN junction diode.
[5] How to check diode with help of multimeter?
Ans: Connect the red probe of the multimeter to the anode and black probe to the
cathode. This means the diode is forward-biased. Observe the reading on multimeter's
display. If the displayed voltage value is in between 0.6 to 0.7 (for a Silicon Diode), then
the diode is healthy and perfect
[6] What is the reason for reverse saturation current ?
Ans: The reverse saturation current is the part of the reverse current in a semiconductor
diode which is caused by the diffusion of minority carriers from the neutral regions to the
depletion region.
[7] What is the forward voltage drop of silicon diode and germanium diode?
Ans: Forward voltage for a diode varies only slightly for changes in forward current and
temperature, and is fixed by the chemical composition of the P-N junction. Silicon
diodes have a forward voltage of approximately 0.7 volts. Germanium diodes have a
forward voltage of approximately 0.3 volts.

6. Observations & Discussion
Whena diode isconnectedina ForwardBias condition,anegative voltage isappliedtothe
N-type material andapositive voltageisappliedtothe P-type material.Inthe forwardbiased
condition, the current varies with the voltage. When a diode is connected in a Reverse
Biascondition,apositive voltage isappliedtothe N-type material andanegative voltageis
appliedtothe P-type material.Inreversedbiasedconditionthe voltagesremainsame,butthe
currentis zeroat any point.This isdue the wide depletionregionthe smallcurrentflowsbut
itsalmostzeroand neglected.
Conclusion:
In today’s lab I learned about the diode, types of Diode its specifications and its
characteristics.Ialsolearnedaboutthe workingof the Diode,itsPN Junction,holes,and
electrons depletion region. I also learned about the Forward biased and Reverse biased
Conditionsof the diode.Ilearnedaboutthe interiorof the diode.