A generalized theory of space charge layers is used to obtain calculation formulas for the principal electrophysical parameters of these layers in a semiconductor (charge Q_sc, capacitance C_sc, excess electron and hole densities ΔP and ΔN, and surface conductance σ_□). Allowance is made for the degeneracy of the electron–hole gas, conduction band nonparabolicity (considered in the Kane approximation), and possible charge exchange between homogeneously distributed levels throughout the bulk of a sample and self‐consistent calculations are carried out on the basis of the effective‐mass approximation. High frequency (1 MHz) capacitance‐voltage characteristics of the “indium” subgroup of III–V compounds and Cd_xHg_1−xTe, obtained by the complex field effect method in electrolyte, are reported.