(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.

from

explanation:

wind is defined by the direction it blows from.   for example, a wind blowing from north to south is called a northerly wind.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.