What happens to electrons when they move to the conduction band?

When electrons move to the conduction band, they gain enough energy to overcome the energy gap between the valence band and the conduction band. In the conduction band, these electrons are no longer bound to individual atoms and become free to move throughout the material. This freedom allows them to participate in conduction, enabling the flow of electric current in the material.

In contrast, if we consider trapping, filling holes, or remaining inactive, none of these accurately describe what occurs in the conduction band. The primary role of electrons in the conduction band is their ability to move and contribute to conductivity, which is fundamental in the operation of various opto-electronic devices.