Electron hole definition
A hole is also called an electron hole. In solid physics, it refers to the phenomenon of losing an electron on a covalent bond, and finally leaving a vacancy on the covalent bond. That is, some valence electrons in the covalent bond obtain some energy due to thermal motion, so that they are free of the covalent bond and become free electrons, while leaving vacancies on the covalent bond, we call these vacancies holes.