Interfacil charge approximations and structures at doped semiconductor interfaces were proposed. Rectifying phenomena at the III-V compound semiconductor (p-GaP, p-InP, n-GaAs)/<TEXT>$CsNO_3$</TEXT> aqueous electrolyte interfaces were qualitatively analyzed in terms of their cyclic current-voltage characteristics. The current-voltage characteristic curves, the ion adsorption and potential barrier processes at the semiconductor interfaces were verified using continuous cyclic voltammetric methods. The pn or np junction structures and the related rectifying types at the doped semi-condudtor-electrolyte inferfaces are determined by the space charges.