Question

In an extrinsic semiconductor, the number density of holes is 4 × 10²⁰ m^-3. If the number density of intrinsic carriers is 1.2 × 10¹⁵ m^-3, the number density of electrons in it is ______.

Options

• 1.8 × 10⁹ m^-3

• 2.4 × 10¹⁰ m^-3

• 3.6 × 10⁹ m^-3

• 3.2 × 10¹⁰ m^-3

Answer 1

In an extrinsic semiconductor, the number density of holes is 4 × 10²⁰ m^-3. If the number density of intrinsic carriers is 1.2 × 10¹⁵ m^-3, the number density of electrons in it is 3.6 × 10⁹ m^-3.

Explanation:

We know that,

Number of density of electrons = `(n_i^2)/(n_h)`

Where, n_i is density of intrinsic carrier, n_h is the density of holes.

Given:

`n_i = 1.2 xx 10^15` m^-3

`n_h = 4 xx 10^20` m^-3

`n_e = (n_i^2)/(n_h)`

`n_e = (1.2 xx 10^15)^2/(4 xx 10^20)`

`n_e = 3.6 xx 10^9` m^-3