Semiconductors are materials that have conductivity between conductors (metals) and insulators (non-metals). The electrical conductivity of a semiconductor is due to the presence of charge carriers. These charge carriers can be either electrons or holes.

Intrinsic Semiconductors:
When a semiconductor has equal numbers of electrons and holes, it is called an intrinsic semiconductor. These electrons and holes are generated due to thermal excitation. Intrinsic semiconductors have a well-defined energy gap between the valence band and the conduction band. At room temperature, most of the electrons remain in the valence band, and only a few electrons are excited to the conduction band. Therefore, intrinsic semiconductors have low electrical conductivity at room temperature.

Breaking of Covalent Bonds:
In a semiconductor, each atom is bonded to its neighboring atoms through covalent bonds. When a covalent bond is broken, an electron and a hole are generated. The electron is free to move in the conduction band, while the hole is free to move in the valence band. This process is called electron-hole pair generation.

Electrical Conductivity:
When an electric field is applied to a semiconductor, the free electrons and holes move in opposite directions, resulting in a current flow. The electrical conductivity of a semiconductor depends on the number of charge carriers present in the material. Intrinsic semiconductors have low electrical conductivity because the number of charge carriers is low.

Conclusion:
When the electrical conductivity of a semiconductor is due to the breaking of its covalent bonds, then the semiconductor is said to be intrinsic. Intrinsic semiconductors have a well-defined energy gap between the valence band and the conduction band, and they have low electrical conductivity at room temperature.