Chat with tutor

Ask Questions, Get Answers


What is a semiconductor? Describe the two main types of semiconductors and contrast their conduction mechanism.

2 Answers

Substance whose conductance likes in between that of metals (conductors) and insulators are called semiconductors.
There are two main types of semiconductors :
(i) n-type semiconductors
(ii) p-type semiconductors
(i) n-type semiconductors
Silicon and germanium belong to group 14 of the periodic table and have four valence electrons each.In their crystals each atom forms four covalent bonds with its neighbours.When doped with a group 15 element like p or as which contains five valence electrons,they occupy some of the lattice sites in silicon or germanium crystal.Four out of five electrons are used in the formation of four covalent bonds with the four neighbouring silicon atoms.The fifth electrons in extra and becomes delocalised.
These delocalised electrons increase the conductivity of doped silicon (or germanium).Here the increase in conductivity is due to the negatively charged electron,hence silicon doped with electron with impurity is called n-type semiconductor
(ii) p-type semiconductors:
Silicon or germanium can also be doped with a group 13 elements like B,Al or Ga which contains only three valence electrons.The place where the fourth valence electron is missing is called electron hole or electron vacancy.An electron from a neighbouring atom can come and fill the electron hole,but in doing so it would leave an electron hole at its original position.If it happens it would appear as if the electron hole has moved in the direction opposite to that of the electron that filled it under the influence of electric field,electrons would move towards the positively charged plate through electronic holes,but it would appear as if electron holes are positively charged and are moving towards negatively charged plate.This type of semiconductors are calles p-type semiconductors.
N Type & P Type
Help Clay6 to be free
Clay6 needs your help to survive. We have roughly 7 lakh students visiting us monthly. We want to keep our services free and improve with prompt help and advanced solutions by adding more teachers and infrastructure.

A small donation from you will help us reach that goal faster. Talk to your parents, teachers and school and spread the word about clay6. You can pay online or send a cheque.

Thanks for your support.
Please choose your payment mode to continue
Home Ask Homework Questions
Your payment for is successful.
Clay6 tutors use Telegram* chat app to help students with their questions and doubts.
Do you have the Telegram chat app installed?
Already installed Install now
*Telegram is a chat app like WhatsApp / Facebook Messenger / Skype.