Question

Draw the circuit arrangement for studying V-I characteristics of a p-n junction diode in

(i) forward biasing

(ii) reverse biasing. Draw the typical V-I characteristics of a silicon diode.

Describe briefly the following terms:

(i) minority carrier injection in forward biasing 

(ii) breakdown voltage in reverse biasing.

Answer 1

Consider the p-n junction diode in biased condition

p-n junction under forward biasing

p-n junction under reverse bias

In forward biasing positive terminal of battery is connected to the p side and negative terminal to n side. Due which p-n junction width becomes slightly narrower.

In reverse biasing negative terminal of battery is connected to p-side and positive terminal of battery to n-side. Here junction width is slightly widen.

I-V characteristics of p-n junction diode

I-V characteristics of a junction diode is given as

With increase in forward biasing current increases very slowly up to knee voltage (cut in voltage). Beyond it current increase rapidly. (exponentially)

Minority carrier injection:

In forward biasing hole from p side is injected toward the n-side of diode this is called as minority carrier injection. After that hole diffuses in n region to reach up to terminal of p-n junction diode.

Breakdown voltage In reverse biasing

In case of reverse bias the reverse current is approximately independent of reverse biasing after increasing the reverse voltage up to a certain value, the junction gets breakdown. This voltage is called breakdown voltage.

The breakdown is of two types:

(1) Zener breakdown

(2) Avalanche breakdown