Answer:
a) Number of atoms per unit cell for Ga = 4 atoms per unit cell
Number of atoms per unit cell for As = 4 atoms per unit cell
b) Volume density of Germanium in its unit cell = 4.35 × 10²² /cm³
Explanation:
GaAs has a number density of 4.42 x 10²² atoms/cm³ from literature.
Since GaAs is known to contain almost equal amounts of Ga and As.
Number density of Ga = Number density of As = 2.21 × 10²² atoms/cm³
Number density = Number of atoms in a unit cell/volume of the unit cell
Number of atoms in the unit cell = ?
Volume of the unit cell = (lattice parameter)³ = (5.65 × 10⁻⁸)³ = 1.804 × 10⁻²² cm³
Number of atoms per unit cell for Ga and As = number density × volume of unit cell = 2.21 × 10²² × 1.804 × 10⁻²² = 4 atoms/unit cell
b) Volume density = Number of atoms per unit cell/volume of unit cell
Germanium has 8 atoms per unit cell (from literature),
Volume of unit cell = (lattice parameter)³ = (5.65 × 10⁻⁸)³ = 1.804 × 10⁻²² cm³
Volume density = 8/(1.804 × 10⁻²²) = 4.35 × 10²² /cm³
Hope this helps!
