When the conductivity of a semiconductor is only due to breaking of covalent bonds, the semiconductor is called

In a pure semiconductor, the conductivity is solely due to the thermal excitation of electrons from the valence band to the conduction band, which occurs by the breaking of covalent bonds. Such a semiconductor, without any added impurities, is called an intrinsic semiconductor.

Extrinsic semiconductors (p-type and n-type) have their conductivity significantly enhanced by the addition of specific impurities (doping).

Answer: intrinsic.