8. Fracture in Semiconductors

Most semiconductors are crystalline inorganic solids, and usually they are classified according to their location in the periodic table. Generally, metallic elements are known for their ductility at room temperature while ceramics such as semiconductors are mostly insulators and almost to nonductile features. Compared to the large deformation strain before fracture in metals even in the range of 5–100% strain, in brittle inorganic semiconductors the strain is very small of about 0.1–0.2%. One could recall the reason for this difference, namely, semiconductors (like ceramic insulators) are primarily held by ionic and/or covalent bonds, and they are not flexible, thus in general they have poor (or none) ductility and low electrical conductivity. Therefore, almost all semiconductors, elemental (Si. Ge) or binary (SiC. GaAs) are brittle and insulating or very low in their conductivity. The electrical conductivity in semiconductors can vary in a wide range from 10⁻⁷ Sm⁻¹ to 10⁵ Sm⁻¹ (S stands for Siemenns and defined as [S] = [W⁻¹] = [A/V], where A stands for ampere, V for volt and W for Ohm). On the other hand, the ductility in metals is attributed to the intrinsic defects present in them with unique character of dislocations and the chemical bonding characterized by a cloud of electros surrounding the nuclei to form electrostatic interactions the so-called metallic bond.