Question

In n-type semiconductor, the fifth electron ______.

Options

• needs high energy to be set free

• is not present

• needs low energy to be set free

• is not capable of moving

Answer 1

In n-type semiconductor, the fifth electron needs low energy to be set free.

Explanation:

Assume a pentavalent impurity is introduced into any pure or intrinsic germanium or silicon semiconductor. Pentavalent impurities are those that have five valence electrons in their atoms. The impurity atoms will replace some of the semiconductor atoms in the crystal structure as soon as the impurity is added to the semiconductor.

Four of the five valence electrons of the impurity atom will now link with four nearby semiconductor atoms, while the fifth electron will be left without a home.

Even if just a tiny amount of energy is provided, the fifth electron of the impurity atom can be made available as a free-electron or negative charge carrier.