(a) If 5 × 10¹⁷ 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 × 10¹⁵ boron atoms per cm³ added to silicon.

(a) In the single crystal lattice,0.001 % of silicon atoms per unit volume that displaced.

(b)In the single crystal lattice, of silicon atoms per unit volume that displaced.

Explanation:

Unit cell:

Total number of atoms per unit cell of silica is  =8 .

Dimension of unit cell is .

The volume occupied by a single Si atom in the crystal structure is

The concentration of Si atom is

(a)

       =0.001 %

In the single crystal lattice,0.001 % of silicon atoms per unit volume that displaced.

(b)

        %

In the single crystal lattice, of silicon atoms per unit volume that displaced.

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