Why does pure silicon conduct electricity poorly at room temperature?

Pure silicon conducts electricity poorly at room temperature because its electrons are primarily locked in place by covalent bonds within its crystal structure.12

In a pure (intrinsic) silicon crystal, each atom shares its four outer electrons with four neighbors, filling the valence band completely. For electrical conduction to occur, electrons must reach the conduction band, which is separated from the valence band by an energy gap of 1.12 electron volts.12

At room temperature, only a small amount of thermal energy is available to break these covalent bonds, meaning very few electrons gain enough energy to cross the bandgap and become free charge carriers. Because the number of available free electrons and holes is low, the material exhibits poor electrical conductivity compared to conductors. To significantly improve conductivity, doping—the intentional introduction of impurities—is required to provide additional charge carriers.123