Practice question

**Semiconductor properties** distinguish from conductors and insulators by temperature dependence and doping response. At 0 K intrinsic acts as insulator, conductivity due to thermally generated electron-hole pairs, number of outer electrons 4 for Si/Ge forming covalent bonds, each atom shares electrons, crystal with N atoms has 4N valence electrons, 2N bonds. At equilibrium, the rate of generation of electron-hole pairs equals the rate of recombination, maintaining a constant number of carriers ( n_e = n_h = n_i ). Substituting values gives Generation equals recombination, which matches expected behaviour for this semiconductor device configuration, confirming doping, depletion and rectifier principles.