Practice question

**Charge carriers** in n-type majority electrons, minority holes, in p-type majority holes, minority electrons, minority concentration reduced due to recombination n_e n_h = n_i², doping increases majority, conductivity σ = e(n_e μ_e + n_h μ_h), increases with doping. Donor ionization energy small ~0.01 eV, electrons easily promoted to conduction band at room temperature. Pentavalent dopants (valency 5) include P, As, and Sb. Indium (In) is trivalent (valency 3) and used for p-type doping, not n-type. Substituting values gives Indium (In), which matches expected behaviour for this semiconductor device configuration, confirming doping, depletion and rectifier principles.