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. Each Si atom has 4 valence electrons (2s and 2p). For N atoms, the total number of outer electrons is 4N , contributing to the covalent bonding in the lattice. Substituting values gives 4N, which matches expected behaviour for this semiconductor device configuration, confirming doping, depletion and rectifier principles.