The regular repeated structure of atoms or molecules in crystalline solids. For silicon and germanium the lattice takes the form of repeated tetrahedrons, while in gallium arsenide the lattice has a cubic form. Semiconducting materials suitable for manufacturing electronics devices such as diodes, transistors, and integrated circuits need to have a lattice structure with a very low level of defects, i.e. irregularities in the lattice caused by missing or misplaced atoms, or the presence of other impurity atoms.