Question

Which are true about p-type of semiconductor?

• A. There are doped with 15^th group elements (Arsenic & Phosphorous)
• B. They are doped with 13^th group elements(Boron and Aluminium)
• C. They have holes which helps in conduct electricity.
• D. They have free e^- which helps in conduct electricity.

Answer 1

Answer: (B), (C)

The correct options are
B

They are doped with 13^th group elements(Boron and Aluminium)

C

They have holes which helps in conduct electricity.

Let’s take the example to explain this. If Aluminum (${13}^{th}$ group element which has 3 valence electrons )doped into silicon which has 4 valence electron . Then $3e^{-}$ of silicon bonds with $3e^{-}$ of Aluminum forming 3 covalent bonds. Fourth bond can’t be formed as there no enough e^-s. This leaves hole in the valence band. This hole helps in conducting electricity. So, semiconductor like silicon when doped with ${13}^{th}$ group elements,have holes which help in conducting electricity and there type of semiconductors are called p-type semiconductors.