Question

In N-type semiconductors current is due –
A. Electrons
B. Holes
C. Electrons and holes
D. None

Answer 1

Hint:Semiconductor is a material that has a conductivity between conductor and insulator. Two types of semiconductors are here, one is a pure(intrinsic) semiconductor and another is an impure(extrinsic) semiconductor. This extrinsic semiconductor is of two types, one is a p-type semiconductor, another is an n-type semiconductor. Pure semiconductors are silicon (Si), germanium (Ge), etc.

Complete step by step answer:
An n-type semiconductor is made by doping some impure substances having $5$ valence electrons like (Arsenic - As) with a pure semiconductor to raise its conductivity. Here the majority charge carrier is the electron -negative charge and the minor charge carrier is the hole -positive charge.

Now we consider the given options-
Option A – Electrons- the number density of electrons in an n-type semiconductor is high. So, the major carrier of n-type semiconductor is an electron.
Option B- holes- there are a few numbers of holes present in an n-type semiconductor that means the number density of holes is lesser.
Option C- Both A and B. Electrons and holes both are present in a N-type semiconductor. In an N type semiconductor, the current flows due to the movement of free electrons and holes. Since the free electrons being the majority carriers and holes being the minority carriers, the net current will be due to the majority carriers i.e., free electrons.

Hence, option (A) is the correct answer.

Note:A process of adding substances with the pure semiconductor material is known as doping. Adding some arsenic (As), phosphorus(P) with pure silicon, and germanium we get an n-type semiconductor. Here the majority charge carrier is an ‘electron’ and the minor charge carrier is the ‘hole’.