Question

In the energy band diagram of the material shown below, the open circles and filled circles denote holes and electrons respectively. The material mostly likely a/an

A. p-type semiconductor
B. insulator
C. metal
D. n-type semiconductor

Answer 1

Hint: Recall the concept of metal, insulator and semiconductors. We know that what factor differentiates the metals, insulators and semiconductors. n-type and p-type are the types of semiconductors. The number density of electrons and holes in the conduction band and valence band respectively differentiates the type of semiconductor.

Complete step by step answer:
There are two types of semiconductor: p-type and n-type semiconductor.
In p-type semiconductor, the number density of holes in the valence is greater than the number density of electrons in the conduction band. Therefore, the conduction band has a smaller number of electrons than the holes in the valence band.
In the given figure, the valence band has more holes as compared to the number of electrons in the conduction band. Therefore, the material is most likely a p-type semiconductor.
So, the correct answer is option (A).
Let’s analyze other options as well.

(B) Insulator
In insulators, the band gap is infinite. But the band gap is not infinite in the above figure.
Therefore, the option (B) is incorrect.

(C) Metal
In metals, the band gap is zero. But in the above figure, the material has a certain band gap.
Therefore, the option (C) is incorrect.

(D) n-type semiconductor
In n-type semiconductor, the number density of holes in the valence is less than the number density of electrons in the conduction band. Therefore, the conduction band has a greater number of electrons than the holes in the valence band.

So, the correct answer is “Option A”.

Note:
The energy band diagram plays an important role for recognition of material as metal, insulator or semiconductor.
In the given figure, the valence band has more holes as compared to the number of electrons in the conduction band.