Practice question

**Energy bands in semiconductors** consist of valence band filled at 0 K and conduction band empty, gap E_g small ~1 eV (Si 1.1 eV, Ge 0.7 eV), insulators large gap >3 eV (C diamond 5.4 eV), conductors overlapping. Intrinsic semiconductor at 0 K behaves as insulator because no thermal excitation, at T>0 K electrons jump to conduction band leaving holes, conductivity increases with temperature. Hole movement is a result of electrons jumping between covalent bonds, creating an apparent motion of the vacancy (hole) in the opposite direction, under an electric field or diffusion. Substituting values gives Electron jumps in bonds, which matches expected behaviour for