To Draw The I-V Characteristic Curve of a P-N Junction In Forward Bias and Reverse Bias

Procedure

For forward bias

1. The circuit connections should be as shown in the diagram.
2. All the connections should be neat, clean and tight.
3. For voltmeter (V) and milli-ammeter (mA), the least count and zero error should be noted.
4. To get the zero reading from the voltmeter and milli-ammeter, rheostat should be brought near the negative end by inserting the key K.
5. To apply the forward bias voltage (V_F) of 0.1V, the contact should be moved towards the positive end. The current remains zero.
6. Keeping current zero, increase the forward bias voltage up to 0.3 V for Ge diode.
7. To record a small current using milli-ammeter, increase the V_F to 0.4 V.
8. Increase the V_F by 0.2 V and record the corresponding current. When the V_F becomes 0.7 V, the current will increase rapidly.
9. When V_F = 0.72 V, the current increases suddenly and this is known as forward breakdown stage.
10. Take out the key if the forward current won’t change as V_F increased beyond forward breakdown.
11. Record the observations.

For reverse bias

1. The circuit connections should be as shown in the diagram.
2. All the connections should be neat, clean and tight.
3. Note the least count and zero error of voltmeter (V) and micro-ammeter (μA).
4. To get zero reading from the voltmeter V and micro-ammeter μA, insert the key K and bring the rheostat near the positive end.
5. To apply reverse bias voltage (V_R) of 0.5 V, move the rheostat to the negative end so as to flow the reverse current.
6. Increase V_R by 0.2 V and record the corresponding current. When V_R becomes 20 V, the current will increase rapidly.
7. When V_R = 25 V, the current increases suddenly and this is known as reverse breakdown stage. Record the current reading and take off the key.
8. Record the observations.