The most common crystal structure among frequently used semiconductors such as silicon and germanium is the diamond lattice, shown in Fig.3.4. Each atom in the diamond lattice has a covalent bond with four adjacent atoms, which together form a tetrahedron as given in Fig.3.4b. The tetrahedral radius of the silicon atom is 1.18 Å. The misfit factor of an impurity atom shows whether it is smaller or larger than the silicon atom. The diamond lattice can also be formed from two face-centered-cubic lattices, which are displaced along the body diagonal of the cube by one quarter of that body diagonal as shown in Fig.3.4c. The violet color atoms are from the second FCC lattice.

Fig.3.5 : Zincblende (ZnS) Structure