Physical Electronics
Crystal Structure
Problems – Homework (2025-2)
Prof. Si-Hyun Park, Dept. of Electronic Eng., Yeungnam Uni.
1
Physical Electronics
Problem 1
Find the maximum fraction of the unit cell volume, which can be filled
by identical hard spheres in the face-centered cubic (FCC).
number
1
2
3
4
5
example
0.490
0.590
0.640
0.690
0.740
Physical Electronics
Problem 2
Find the distance between nearest neighbors in Ge. (At 300 K, the lattice constant for Ge is
𝑎Ge = 5.65 Å)
number
1
2
3
4
5
example
1.447 Å
2.447 Å
3.447 Å
4.447 Å
5.447 Å
Physical Electronics
Problem 3
At 300 K, the lattice constant for silicon 𝑎 is 5.43Å .
Find the surface density of the number of atoms, i.e. the number of atoms per square
centimeter in silicon in the (111) planes.
number
1
2
3
4
5
example
7.832 × 1012 atoms/cm2
7.832 × 1013 atoms/cm2
7.832 × 1014 atoms/cm2
7.832 × 1015 atoms/cm2
7.832 × 1016 atoms/cm2
Physical Electronics
Problem 4
Find the maximum fraction of the unit cell volume, which can be filled
by identical hard spheres in the diamond lattice structure.
number
1
2
3
4
5
example
0.14
0.24
0.34
0.44
0.54
Physical Electronics
Problem 5
Calculate the density of GaAs. (𝑎GaAs = 5.65 Å, 𝑀Ga = 69.72 g/mole, 𝑀As = 74.92 g/mole)
number
1
2
3
4
5
Example
2.329 g/cm3
3.329 g/cm3
4.329 g/cm3
5.329 g/cm3
6.329 g/cm3