Chapter:

P - N junction

When a p- type semiconductor is suitably joined to an n-type semiconductor the contact surface so formed is called p-n junction.

When a p- type semiconductor is suitably joined to an n-type semiconductor the contact surface so formed is called p-n junction. All the semiconductor devices contain one or more p-n junction. P-N junction is fabricated by special techniques namely growing, alloying and diffusion methods. The p-type semiconductor is having egative acceptor ions and positively charged electrons. The n-type semiconductor is having positive donor ions and negatively charged electrons. When the two pieces are joined together and suitably treated they form a p-n junction. The moment they form a p-n junction, some of the conduction electrons from n-type material diffuse over to the p- type material and undergo electron - hole recombination with the holes available in the valence band. Simultaneously holes from p-type material diffuse over to n- type material and undergo hole-electron combination with the electrons available in the conduction band. This process is called diffusion. When a p-n junction is connected across an electric supply, the junction is said to be under biasing. The potential difference across the p- n junction can be applied in two ways, namely- forward biasing and reverse biasing. When the positive terminal of a dc source is connected to p-type, and negative terminal is connected n-type semiconductor of a p-n junction, the junction is said to be in forward biasing. When the positive terminal of a dc source is connected to n-type, and negative terminal is connected p-type semiconductor of a p-n junction, the junction is said to be in reverse biasing. With forward bias, a low resistance path is set up in the p-n junction, and hence current flows through the circuit. With reverse bias, a high resistance path is set up and no current flows through the circuit. This property is best suited for rectification of ac into dc.

Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail

: P - N junction |