Thursday 11 May 2017

I will start by giving short notes about the diodes in very simple language.
first comes the most basic fundamental component of the electronics world THE P-N JUNCTION DIODE.
P-N JUNCTION DIODE:

→It is the simplest electronics device.
→ The semiconductors are divided into two parts, one is intrinsic and the other is extrinsic where the intrinsic is pure semiconductor and extrinsic is formed when the semiconductor id doped.
→ Now when the intrinsic semiconductor is doped with acceptor in one side and donor on other side that is one becomes p type and the other n type respectively the p-n junction diode is formed.
→ So basically it is a two terminal device.
→ It was found in the years around 1940s and 1950s.
→ The p-n junction diodes are graded simply meaning that they are non-uniformly doped further they      can be step graded and linearly graded.
→ We know that n type has electrons in majority and p type has holes in majority.
→ Now when p and n type are joined (not literally putting them physically together like a wooden block) a junction is formed.
→ The electrons from n type flows towards the junction and holes from p type flows towards the junction.
→ The diode has two conditions- biased and unbiased.
→ When the p-n junction diode is unbiased or we can say that when 0 voltage is applied the electrons flows to the p side and holes flows to the n side from the junction.
→ This clearly shows that the holes of p type and electrons of n side are left unutilized so they form an electric field and oppose further diffusion of these carriers.
→ The region now shows no further movement and is called depletion region or space charge.
→ When the p-n junction diode is biased, specifically forward bias that is when it is connected with positive terminal of the battery the depletion region ↓ and electrons and holes flow across the junction.When it is reverse biased that is when it is connected with negative terminal of the battery the depletion region ↑ and electrons and holes does not flow across the junction.




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