(a) If 5 x 10^17 phosphorus atoms per cm3 are add to silicon as a substitutional impurity, determine the percentage of silicon atoms per unit volume that are displaced in the single crystal lattice.
(b) Repeat part (a) for 2 x 10^15 boron atoms per cm3 added to silicon.

The percentage of silicon atoms per unit volume that are displaced in the single crystal lattice = 0.001 %

The percentage of silicon atoms per unit volume that are displaced in the single crystal lattice with boron atoms = 0.4 × %

Explanation:

No. of phosphorus atoms = 5 ×

The volume occupied by a single Si atom

2 ×

= 5 ×

Put the values in above equation we get

PCT = %

These are the percentage of silicon atoms per unit volume that are displaced in the single crystal lattice.

(b).

No. of boron atoms = 2 ×

The volume occupied by a single Si atom

2 ×

= 5 ×

Put the values in above equation we get

PCT = 0.4 × %

These are the percentage of silicon atoms per unit volume that are displaced in the single crystal lattice.