IV - Characteristics of P-N diode

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Purpose:-
To study the forward and reverse bias characteristics of a given P-N junction diode and calculate forward reverse resistance, and Knee voltage.

Apparatus:-
Semiconductor Diode, Voltmeter, Milli-ammeter, DC source and connecting wires, breadboard.

Principle:- 
A semiconductor diode conducts electric current in forward bias mode and no significant current in reverse bias state .hence its resistance is low in forward bias and high in reverse bias.

Circuit diagram:-



Theory:-
A semiconductor diode is a two-terminal P-N junction device. In forward bias state positive terminal of the external source is connected to P-type & negative to N-type & reverse bias vice versa.
Knee voltage:- It is that forward voltage from which currently starts increasing.
Dynamic resistance (rd):- it is the resistance of the P-N diode in forward bias mode.
Break down voltage:- It is that reverse voltage at which sudden heavy current flows & a P-N  mode must not be operated at this voltage.

Nature of graph:-



Procedure:-
1) connect the circuit as shown in the diagrams
2) Vary the applied voltage (V) in steps of 0.1-V till knee voltage & then in steps of 0.01-V 
3) Note the corresponding ammeter reading (I)
4) Plot a graph of I v/s V in the first quadrant of the graph.
5) Find the dynamic resistance rd = ∆V/∆I & knee voltage.

Tabular column:-



Result:-  
1) studied I-V characteristics of P-N junction diode for forward and reverse biased.
2) Diode dynamic resistance is   
rd= ( delta  Vf /delta  If )

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